A comparative evaluation of masticatory load distribution in different types of prosthesis with varying number of implants: A FEM analysis

Aim

To identify the optimal number and position of implants to reduce stress concentration on the implant, denture, and attachment system for sustaining an overdenture prosthesis.

Materials and methods

By incorporating one to eight indigenous implants with bar-type attachments, eight 3D finite element models of mandibular overdentures were created. All models received a 200 N vertical load, and the biomechanical characteristics of peri-implant bone were assessed.

Result

The study observed that with a vertical load of 200 N, the maximum equivalent stress around peri-implant tissue in all models was within the physiological tolerance threshold of bone. The von Mises stress values ranged from 116.18 MPa to 536.7 MPa.

Conclusion

The three-implant-supported overdenture model revealed superior peri-implant stress, stability, cost-effectiveness, and hygiene maintenance outcomes. Placing a third implant in the mid-symphysis region may offer a practical solution to reduce rotations in two-implant-supported overdentures.

Denture Base Materials: An In Vitro Evaluation of the Mechanical and Color Properties

OBJECTIVES

This study aimed to compare the physical and mechanical properties of four denture base materials: Polyan IC (PA), milled polymethylmethacrylate (PMMA), three-dimensional (3D)-printed resin (3DP), and SR Ivocap (SR).

METHODS

Ninety-six samples were prepared and divided into four groups as follows. Group A consisted of 3DP (Asiga DentaBASE, Asiga) fabricated using a manufacturer-recommended 3D printer (Asiga Pro 4k, Asiga). Group B comprised milled PMMA (MP) (Ivotion Base, Ivoclar Vivadent). Group C included PA (BredentSenden), meanwhile, group D involved SR (Ivoclar VivadentSchaan). Cuboid samples (65 mm x 10 mm x 2.5 mm) were used for biaxial flexure strength testing in a universal testing machine (UTM). Cylindrical samples of 20 mm x 40 mm were used for compressive strength testing in a UTM. Additionally, cuboid samples (65 mm x 10 mm x 2.5 mm) were used for Vickers surface hardness testing in a microhardness tester. Disc samples (10 mm x 2.5 mm) were employed for color stability testing both in a coffee solution and Coca-Cola, using a digital spectrophotometer. Statistical analyses were performed using one-way analysis of variance and Tukey's post hoc analysis (α=.05).

RESULTS

MP demonstrated superior compressive strength (p=0.002) and color stability compared to that exhibited by 3DP (p<0.001) while displaying similar flexure strength (p=0.336) and hardness (p=0.708). MP and PA displayed similar compressive strength (p=0.081), flexure strength (p=0.159), and color stability in coke (p=0.071). However, MP had reduced hardness (p<0.001) and color stability in coffee (p<0.001). Moreover, MP demonstrated a higher compressive strength (p<0.001) than that displayed by SR. However, the flexure strength, hardness, and color stability were similar (p > 0.05). Furthermore, 3DP exhibited comparable compressive strength (p=0.334) to that of PA but demonstrated significantly lower flexure strength (p=0.005), hardness (p<0.001), and color stability (p<0.001) compared to PA. In comparison to SR, PA had a higher compressive strength (p <0.001), hardness (p=0.001), and color stability in coffee (p<0.001), although they demonstrated similar (p>0.05) flexure strength and color stability in coke.

CONCLUSIONS

The MP and PA demonstrated superior compressive strength than that exhibited by the other materials tested. The tested materials had similar flexure strengths, except for PA which demonstrated superiority over the 3DP. Among all tested materials, PA exhibited the highest hardness, while the 3DP was the least color-stable.

CLINICAL SIGNIFICANCE

Considering the mechanical properties and color stability, Polyan and milled polymethylmethacrylate are preferred for complete denture fabrication. However, the limited repairability and complex handling of Polyan should be considered.

Impact of loading protocol of a mandibular single implant-supported complete denture on oral health-related quality of life over a period of 5 years: A randomized controlled trial

OBJECTIVES

The aim of the present study was to assess the long-term course of OHRQoL and the impact of the loading protocol in patients receiving a single mandibular implant supporting a complete denture over a period of five years.

METHODS

In this multicenter RCT, a total of 158 edentulous patients were initially included and were randomly allocated immediately after placement of a mandibular midline implant to either immediate loading (IL) or to conventional loading (CL) with submerged healing. The assessment of OHRQoL was performed with the 49-item Oral Health Impact Profile (OHIP) at baseline and 1, 4, 12, 24, and 60 months after loading. At 5-year follow-up, 100 patients (mean age: 69.2 years; 45.0% female) with completed OHIP were available for analyses. A mixed-effects model with patients as random effect and an unstructured covariance matrix was developed to address repeated outcome measurement.

RESULTS

The OHRQoL improved substantially after loading, indicated by a decrease of mean OHIP summary scores from 51.0 points at baseline, by 14.2 (95%-CI: 9.4 - 19.1; p<0.001) points to 37.2 points at 1-month follow-up, and by continuous improvement to 20.4 OHIP points at final follow-up. Considering constant treatment effects, the loading protocol had no significant effect on OHIP scores (-3.7, 95%-CI: -9.4 - 2.2; p = 0.204). Time effect was statistically significant with -0.21 (95%-CI: -0.28 - -0.15; p<0.001) points per month.

CONCLUSION

Both the immediate and conventional loading of a single mandibular midline implant supporting a complete denture offer long-lasting high levels of OHRQoL, with no significant or clinically relevant long-term differences.

CLINICAL SIGNIFICANCE

The study firstly presents long-term data for OHRQoL by investigating the loading protocol of single mandibular implant-supported complete dentures. Since immediate loading has been associated with a reduced implant survival rate for this concept, information on patient benefits is essential for evidence-based decision making.

Effect of soft denture liners on complete denture treatments: A systematic review

PURPOSE

This systematic review examined the effectiveness of soft denture relining (SDR) materials.

STUDY SELECTION

A comprehensive search of MEDLINE, Cochrane Library, and ICHUSHI was conducted up to July 26, 2020. Target outcomes were patient satisfaction, oral health-related quality of life (OHRQOL), masticatory ability (MA), denture functional duration, residual ridge resorption (RRR), and microbial contamination. An organization specializing in literature searches performed the reference searches, and two reviewers independently selected the literature sources, extracted the data, and assessed the risk of bias. The reviewers resolved any disagreements concerning the assortment of literature sources through discussion. SDR included acrylic- and silicone-based materials, which were evaluated separately.

RESULTS

Reviewers selected 7, 5, 11, 1, 4, and 6 studies to assess patient satisfaction, OHRQOL, MA, functional duration, RRR, and microbial contamination, respectively. The results confirmed that SDR improved patient satisfaction, OHRQOL, MA, and RRR. However, the functional duration of SDR material is shorter than that of hard denture relining (HDR) or acrylic resin material. Furthermore, SDR material is more susceptible to microbial contamination in the long term. The risk of bias for the included studies tended to be high because of specific issues (difficulty in blinding SDR versus HDR).

CONCLUSIONS

For patients who wear complete dentures, SDR often provides beneficial outcomes such as pain reduction and recovery from MA. However, caution should be exercised regarding their use owing to insufficient functional duration and the possibility of microbial contamination during long-term use.

Effect of denture adhesives on masticatory performance: Multicenter randomized controlled trial

PURPOSE

The purpose of this study is to investigate the effects of denture adhesives on masticatory performance via a 10-center, parallel, randomized, controlled trial of complete denture wearers in Japan.

METHODS

The trial was conducted between September 2013 and October 2016. The inclusion criteria were complete edentulism, willingness to undergo new complete denture treatment, and willingness to return for recall treatment. The exclusion criteria were age 90 years or older, presence of severe systemic illness, inability to understand the questionnaires, wearing metal base complete dentures, denture adhesive user, wearing prosthetics for maxillofacial defects, wearing complete dentures with tissue conditioners, and severe xerostomia. Randomization of the powder-type denture adhesive (powder), cream-type denture adhesive (cream), and control (saline) groups was performed using a sealed envelope system. Masticatory performance was measured using color-changeable chewing gum. Intervention blinding was not feasible.

RESULTS

Sixty-seven control, 69 powder, and 64 cream participants are analyzed using the intention-to-treat principle. The participants in all groups show significantly improved masticatory performance at post-intervention (paired t-test with Bonferroni correction P < 0.0001). However, no significant difference in masticatory performance is detected among the three groups (one-way analysis of variance). A significant negative correlation between pre- and post-changes in masticatory performance and intraoral condition scores is observed (Pearson's correlation coefficient, P < 0.0001).

CONCLUSIONS

Although denture adhesives improved the masticatory performance of complete denture wearers, their clinical effects are comparable to those of saline solution. The use of denture adhesives is more effective in complete denture wearers with unsatisfactory intraoral conditions.

Effects of denture adhesives on denture retention and occlusal forces in complete denture wearers: A multicenter, randomized controlled trial

PURPOSE

This study aimed to determine the effects of denture adhesives on denture retention and occlusal force in complete denture wearers in a multicenter, randomized, parallel-group controlled trial.

METHODS

Two hundred edentulous patients wearing complete dentures were allocated to three groups: powder-type denture adhesive, cream-type denture adhesive, and control (saline solution). Denture adhesives and saline solution were applied to the dentures for 4 days. The retentive force of the dentures and occlusal force were measured using a force transducer occlusal force meter at baseline and after 4 days of intervention. In addition to between-group comparisons, subgroup analyses of denture retention and occlusal force were performed based on the level of difficulty of the edentulism treatment. The levels were ranked as I (easy), II, III, and IV (difficult).

RESULTS

Cream-type denture adhesives significantly improved the retentive force of the dentures (P<0.01) and occlusal force (P<0.05), with no significant differences between baseline and post-intervention forces in the powder-type denture adhesive and control groups. In within-group comparisons, cream-type denture adhesives improved both the retentive and occlusal forces at Level II (P<0.05), and powder-type denture adhesives improved the occlusal force at Level II (P<0.01).

CONCLUSIONS

Application of cream-type denture adhesives effectively improves the denture retention and occlusal force in complete denture wearers with a moderate degree of difficulty during edentulism treatment.

Prosthetic restorative modality in complete edentulism and its association with masticatory and speech discomforts: A nationwide cross-sectional study from Korea

Purpose Completely edentulous arches can be restored using various prosthetic modalities, and the treatment outcome may include masticatory and speech discomforts. This study aimed to investigate the current status of prosthetic restoration modalities used for completely edentulous patients and investigate the association between prosthetic restoration modalities and subjective discomfort in mastication and speech by analyzing nationwide big data.Methods Of 97,622 individuals, data from 1,576 adults aged ≥40 years with no natural teeth and no requirement for 
additional prosthetic treatments were included. Oral examination data were analyzed, and the prostheses of the edentulous arches were categorized as follows: CD, removable complete denture; OD, implant-retained overdenture; and IF, implant-supported fixed dental prosthesis. Discomforts in mastication and speech according to the prosthetic restorative modality groups was statistically analyzed using analysis of covariance (α = 0.05).Results The maxillary/mandibular prosthetic restorative modality most commonly used was CD/CD, followed by CD/OD, IF/IF, OD/OD, and CD/IF, with weighted percentages of 93.23%, 2.48%, 1.83%, 1.46%, and 0.84%, respectively. Even after adjusting for various covariates, masticatory discomfort in the CD/CD group was significantly greater than that in the OD/OD (P = 0.0004) and IF/IF (P = 0.0002). The CD/CD group also had significantly greater discomfort in speech than did the IF/IF group (P = 0.0119).Conclusions Most completely edentulous patients were rehabilitated with bimaxillary removable complete dentures; however, the discomforts in mastication and speech were the lowest when both arches were restored with implant-supported fixed restorations.

Effects of build orientation and bar addition on accuracy of complete denture base fabricated with digital light projection: An in vitro study

PURPOSE

We evaluated the effects of build orientation and bar addition between lingual flanges on the accuracy of mandibular denture bases fabricated using a digital light processing (DLP) device.

METHODS

Mandibular denture bases with and without a bar at the lingual flanges were virtually designed and assigned to eight build orientations. Six dentures per condition were fabricated using a DLP device with a methacrylate-based photopolymerizable monomer (Dima Print denture base) (n=96). The fabricated denture surfaces were digitized, and intaglio surfaces were obtained. These digitized surfaces were compared via superimposition using graphical software (Artec studio12 profession) to their original designed files, and root mean square estimates were obtained. The trueness of the entire and intaglio data was statistically analyzed non-parametrically.

RESULTS

The range of trueness of the entire and intaglio denture bases was 0.15-0.31 mm and 0.11-0.38 mm, respectively. The trueness at 135° and 270° for the entire denture base and that at 270° for the intaglio data without the bar were significantly lower than those for the other build orientations. The trueness at 270° was <0.15 mm irrespective of the conditions. The trueness with the bar of all build orientations, except that of 0° for intaglio data, was significantly smaller than or equal to the trueness without the bar of the corresponding build orientations.

CONCLUSIONS

Build orientation and bar addition influenced the accuracy of the complete dentures fabricated using DLP. A build orientation of 270° is recommended for fabricating a mandibular complete denture, irrespective of the bar addition.

Influence of edentulism on the structure and function of temporomandibular joint

Background

With the acceleration of the aging process of the population, the number of edentulous patients continuously increased. Edentulism induces the loss of occlusal relationship and cause adverse effects on the stomatognathic system. Temporomandibular joint (TMJ), as a significant component of this system, may also be affected by edentulism in the process of supporting mandibular movement.

Purpose

Provide a comprehensive review of the structure and function of TMJ in the edentulous population, as well as the prevalence of temporomandibular joint disorder (TMD) in edentulous group.

Study selection

An electronic search was conducted on articles prior to December 2022 to filter all papers relevant to the structure and function of TMJ in edentulous population. The internet databases (PubMed, Cochrane Library, Embase) were searched using various combinations of keywords for "edentulism" or "edentulous" and "TMJ" or "TMD".

Results

Firstly, 522 articles were selected from the internet database, and finally, a total of 44 articles met the inclusion and exclusion criteria. The research content of these articles mainly focuses on the structure and function of TMJ in edentulous patients, as well as the clinical signs and symptoms of TMD.

Conclusions

Edentulous arch induces the loss of occlusal relationship, which may lead to degenerative changes of TMJ components consisting of changes in morphology and bone mass density of condyle, articular fossa, and articular eminence. In addition, the condyle could be shifted backward and upward, and displacement of the articular disc may occur after dentition loss. And the condyle and the articular disc may be guided back to the normal position after effective prosthodontic treatment. But the conclusions of the study on the function of TMJ and the prevalence of TMD in edentulous people are inconsistent. The condition of TMJ, especially the position of condyle-fossa and the symptoms and signs of TMD should not be ignored. If necessary, radiographic examinations should be performed.

The effects of different surface treatments applied to milled PMMA denture base material on repair bond strength

The high cost of CAD/CAM systems and materials is a severe economic burden. Therefore, repair of CAD/CAM PMMA, selecting appropriate repair materials, and surface modifications are clinically important. This study aims to evaluate the shear bond strength of PMMA repair materials after various surface treatments on CAD/CAM PMMA denture base material. For this purpose, a total of 480 CAD/CAM PMMA denture base test specimens were manufactured. Then all test specimens were divided into 6 groups, and different surface treatments were applied. Group A: sandblasting, Group B: 4% hydro fluoric acid, Group C: tungsten carbide bur, Group D: dichloromethane + methyl methacrylate mixture, Group E: dichloromethane and methyl methacrylate, Group F: no surface treatment. Each group is then divided into 4 different subcategories; repair processes were performed using; heat-cured acrylic resin (n:20), auto-polymerized acrylic resin (n:20), gingiva composite (n:20), and CAD/CAM PMMA tooth material (n:20). After repairs, thermal aging was applied to half of the test specimens in each subcategory. The shear bond strength value was measured with a universal test device. Sandblasting group showed the highest surface roughness value in all test specimens (p < 0.001). Heat-cured acrylic resin with sandblasting exhibited the highest bond strength, while the untreated gingiva composite resin exhibited the lowest value. Thermal aging decreased bond strength in all repair materials (p < 0.001). Among the surface treatment groups, sandblasting with Al2O3 particles exhibited the highest surface roughness value and repair bond strength. The application of organic solvents to the surface increased the surface roughness and repair bond strength. Applying dichloromethane and methyl methacrylate monomer separately is more effective than applying it as a mixture. The ideal bonding among repair materials was obtained with heat-cured acrylic resin.

The effect of single-implant overdentures on cognitive function in older adults: A 3-year follow-up report

OBJECTIVE

To investigate the occurrence of mild cognitive impairment in edentulous patients up to 3 years after they received single-implant overdentures (1-IODs).

METHODS

This was a follow-up study for a crossover randomized controlled trial comparing 1-IODs and conventional complete dentures, with patient satisfaction as the primary outcome. In the present study, the cognitive function of the patients, measured with the Japanese version of the Montreal cognitive assessment (MoCA-J), was evaluated as the secondary outcome at baseline and 2 months, 1 year, 2 years, and 3 years after 1-IOD placement. The total and domain (memory, executive function, visuospatial skills, language, attention, and orientation) MoCA-J scores of the patients at each timepoint were analyzed and compared.

RESULTS

Twenty-two patients with edentulous mandibles received 1-IODs. Within-group comparisons revealed that the total MoCA-J scores at 1 year and 3 years after 1-IOD placement were significantly increased compared with baseline scores. Additionally, the memory domain scores at all timepoint were significantly increased compared with the baseline scores, and the executive function domain scores at the 2-month, 2-year and 3-year timepoint were significantly increased compared with the baseline scores.

CONCLUSION

Patients with edentulous mandibles who underwent 1-IOD placement showed significantly improved total scores of MoCA-J after 1 year and 3 years of wearing 1-IODs. In addition, they showed significantly improved memory domain scores at 2 months, 1 year, 2 years, and 3 years after 1-IOD placement and executive function domain scores at 2 months, 2 years, and 3 years after 1-IOD placement.

CLINICAL SIGNIFICANCE

The results of this study suggest that 1-IOD treatment for older adults, especially those with edentulous mandibles, may prevent cognitive decline regardless of the condition of the maxilla.

Evaluation of bite force, quality of life, and patients' satisfaction in elderly edentulous patients using implant overdentures

Purpose

This study aimed to compare the bite force (BF) between complete dentures and implant overdentures (IODs) retained by two mandibular implants. Additionally, we evaluated the quality of life (QoL) and patient satisfaction among individuals using IODs. In addition, the effects of demographic parameters such as age and sex, and clinical parameters such as implant length, implant diameter, attachment height, attachment color, and interimplant distance on BF, QoL, and patient satisfaction were evaluated.

Materials and methods

A total of 51 edentulous patients rehabilitated with the maxillary complete dentures and mandibular IODs retained by two implants were included in this study. BF was measured using a force meter pre- and post-implant in the same patients. Oral health-related quality of life (OHRQoL) was assessed with the Oral Health Impact Profile (OHIP-14) and patient satisfaction was assessed with the Visual Analog Scale (VAS) questionnaires.

Results

It was found that BF values were statistically higher for IODs than complete dentures (P < .001). In terms of attachment height of the OHIP scores, there was a significant difference in the psychological disability and social disability domains (P < .05). When examining the change in patient satisfaction as a function of sex, it was found that mandibular retention satisfaction differed significantly by sex (P < .05), but there was no significant difference in the other domains.

Conclusion

Within the limitations of this study, it was observed that the BF increased after the use of IODs. Several factors, including age, interimplant distance, attachment height, and attachment color, were found to impact OHRQoL. Sex and implant diameter were identified as factors affecting patient satisfaction.

Influence of wearing complete denture on the glycemic control, serum lipid, and proteins in patients with diabetes

Aims

The aim of this study was to assess the impact of prosthodontic rehabilitation on glycemic and lipid control in functionally and completely edentulous patients with diabetes.

Setting and Design

An in vivo study conducted with the intention of studying the potential link between edentulism and impaired masticatory efficiency with the nutritional status in diabetic patients.

Materials and Methods

A total of 20 diabetic patients based on the inclusion criteria were selected. They were rehabilitated using a removable prosthesis, and observations were made across three parameters - glycosylated hemoglobin (HbA1C), serum cholesterol (S col), and serum protein (SP) at three stages - baseline, 3 months, and 6 months posttreatment. This was done to gauge the impact of the prosthetic rehabilitation on their health due to an increased masticatory efficiency potentially causing changes in dietary patterns.

Statistical Analysis Used

•Inter group comparison (>2 groups) was done using one way ANOVA followed by pair wise comparison using post hoc test. •Intra group comparison was done using repeated measures ANOVA (for>2 observations) followed by post Hoc test. For all the statistical tests, P < 0.05 was considered to be statistically significant, keeping α error at 5% and β error ati20%, thus giving a power to the study as 80%.

Results

Hba1c at the baseline had a mean value of 8.04%, which reduced to 7.87% at the 3-month stage and 7.38% at the 6-month stage. S col at the baseline had a mean of 151.6 mg/dL; at the 3-month follow-up, it was 166.5 mg/dL, and at the 6-month follow-up, it was 173.95 mg/dL. SP had a mean baseline value of 6.38 mg/dL, which progressed to 6.67 mg/dL at the 3-month stage and 6.97 at the 6-month stage.

Conclusion

Within the limitations of this study, it can be concluded that after 6 months of prosthetic rehabilitation in edentulous/functionally edentulous patients: There was a reduction in HbA1c (8.04%-7.38%); however, it was found to be statistically insignificant at that stage There was an increase in S col (151.6 mg/dL-173.95 mg/dL); it was found to be statistically significant There was an increase in SP (6.38 mg/dL-6.97 mg/dL); however, it was found to be statistically insignificant at that stage.

Accuracy of tooth positioning in 3D-printing aided manufactured complete dentures: An in vitro study

PURPOSE

In this study, we propose a 3D printing-aided method for manufacturing complete dentures and evaluate its accuracy of artificial tooth positioning.

METHODS

Complete dentures were designed and 3D printed and put on a plaster cast; and pack and press technique was used to fabricate the final denture during which artificial teeth were inserted in the teeth holes formed by the printed denture. In this study, fused deposition moulding (FDM) and stereolithography (SLA) techniques were used to fabricate complete dentures (10 pairs of maxillary and mandibular dentures each). After 3D scanning the final dentures, 3D comparison between the scanned teeth on the denture and its computer-aided design (CAD) data was made and single-tooth deflection angles were measured to evaluate the tooth position. Values were compared using independent-sample t-tests or the Mann-Whitney U test.

RESULTS

In the result of 3D comparison, the root mean square values of artificial teeth were 0.107 ± 0.018 mm (SLA group) and 0.136 ± 0.023 mm (FDM group; P < 0.05). In the result of single-tooth deflection angles, the mandibular anterior teeth demonstrated the maximum deflection angle, followed by the molars, premolars, and maxillary anterior teeth.

CONCLUSIONS

It is feasible to fabricate complete dentures using 3D-printed complete dentures as prototypes and combine conventional methods. The accuracy of the final denture fabricated using SLA printing was better than that of dentures produced using the FDM method.

CLINICAL SIGNIFICANCE

The 3D printing-aided manufacturing for complete dentures refers to using the 3D-printed dentures as a prototype along with the traditional process to fabricate final dentures and is an effective alternative when the dentures cannot be directly processed using computer-aided manufacturing (CAM).

Effect of build orientation and layer thickness on manufacturing accuracy, printing time, and material consumption of 3D printed complete denture bases

OBJECTIVES

To evaluate the influence of build orientation and layer thickness on manufacturing accuracy, material consumption, and printing time of complete denture (CD) bases fabricated using digital light processing (DLP).

METHODS

The CD base was designed on the basis of a standard maxillary edentulous model. Seventy CD bases were fabricated using a DLP 3D printer (Pro95, SprintRay, USA) and printable CD base material (DENTCA Denture Base II, Dentca, USA) at seven build orientations (0°, labial 45°, labial 90°, posterior 45°, posterior 90°, buccal 45°, and buccal 90°) and two types of layer thicknesses (50- and 100 μm) (n = 5). All test CD bases were digitalized and superimposed on the reference cast by section-based best-fit alignment. For evaluating manufacturing accuracy, deviation analysis was performed to compare the test data with the reference cast using the "3D Compare" in the 3D metrology software. The printing time and material consumption were calculated using slicing software and recorded, respectively. The two-way ANOVA test was used for accuracy evaluation, and the non-parametric test was used to evaluate printing time and material consumption (α = 0.05).

RESULTS

Statistically significant differences were found in the manufacturing accuracy (p < 0.001), printing time (p < 0.001), and material consumption (p < 0.001) among the build orientation groups. The labial 45° and labial 90° groups showed the best accuracy. The 90° build orientations required the least material consumption and longest printing time; the labial 45° group consumed the most printing materials; the 0° group required the shortest printing time to fabricate a CD base. Moreover, the layer thickness influenced the printing time (p < 0.001) rather than the accuracy (p = 0.560) and material consumption (p = 1.000).

CONCLUSIONS

When DLP was used to fabricate the CD bases, the build orientation influenced the manufacturing accuracy, material consumption, and printing time. However, the layer thickness only affected the printing time.

CLINICAL SIGNIFICANCE

This study suggests that optimizing the build orientation can improve the manufacturing accuracy and reduce the material consumption and printing time of a DLP-printed CD base. The fast-printing setting (100 μm layer thickness) can reduce the printing time without compromising the manufacturing accuracy of the CD base.

Analysis of the trueness and precision of complete denture bases manufactured using digital and analog technologies

PURPOSE

Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs).

MATERIALS AND METHODS

Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Δ-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Δ-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs.

RESULTS

There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P < .001), but no significant difference between the other two manufacturing methods (P = .1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P = .0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed.

CONCLUSION

The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Δ-error values well within the clinical tolerance limit.

Palatal brushing for the treatment of denture stomatitis: A multicentre randomized controlled trial

PURPOSE

To determine the effectiveness of palatal brushing in the treatment of denture-related erythematous stomatitis (DES) in complete denture wearers.

METHODS

This two-parallel-arm RCT was conducted in three university clinics in Brazil, Canada, and Chile. Participants (n=77) were randomly allocated to receive (i) instructions for palatal brushing and standard oral/denture hygiene ("intervention"); or (ii) standard oral/denture hygiene instructions only ("control"). Data collection was carried out at the baseline and at 3 and 6 months after intervention. Outcomes included the magnitude of oral Candida carriage and the degree of inflammation of denture-bearing tissues. Groups were compared using generalized estimating equations and chi-square test (α=0.05).

RESULTS

Palatal inflammation levels were reduced significantly in the "intervention" compared to "control" group at 6 months (intervention: 70%, control: 40%; chi-square, p=0.04). There was no between-group significant difference in the Candida count from denture and palatal biofilms; however, a subgroup analysis restricted to baseline Candida carriers showed further reduction with the intervention at 6 months. No adversity was observed by trialist or reported by participants.

CONCLUSIONS

Including palatal brushing in oral instructions for denture wearers has positive impact on DES-related mucosal inflammation. Thus, our findings endorse the inclusion of palatal brushing in standard oral hygiene instructions to treat DES.

Patient satisfaction and crestal bone changes with one-piece and two-piece single implant-retained mandibular overdenture: A randomized controlled clinical study

PURPOSE

The present study was done to assess patient satisfaction and crestal bone changes with one-piece and two-piece single implant-retained mandibular overdentures (SIMOs).

METHODS

The participants included in Group 1 (n=12) received one-piece SIMOs; the participants in Group 2 (n=12) received two-piece SIMOs.Scheduled follow-ups were done at 1 month and 1 year after implant placement. Patient satisfaction and crestal bone changes were evaluated. The data obtained were analyzed statistically with independent Student t-test.

RESULTS

Visual analogue scale (VAS) score for patient satisfaction with one-piece and two-piece SIMOs were statistically significant at 1-year of follow-up. The patient satisfaction level on the VAS score increased (38.1 to 51.1) with group one-piece SIMOs and two-piece SIMOs (36.6 to 46.8) at baseline to 1 month (P=0.13). The patient satisfaction level increased (38.1 to 56.6) with group one-piece SIMOs and two-piece SIMOs (36.6 to 52.2) at baseline to 1 year (P=0.03). At the 1 year follow-ups, group 1 had mean crestal bone loss of 0.80 ± 0.49 mm and group 2 had 1.24 ± 0.90 mm (P=0.16). Crestal bone loss was greater in the two-piece SIMOs group at 1 month and 1 year follow-ups, but statistically it was insignificant.

CONCLUSIONS

One-piece SIMOs seemed to be a viable treatment option with increased patient satisfaction on a VAS. Crestal bone loss was greater in the patients with two-piece SIMOs during follow-up. One-piece SIMOs was comparatively simple with less invasive procedures and needed fewer components,so considerable number of patients requiring implant retained dentures could be benefited.

A Comparison of the Surface and Mechanical Properties of 3D Printable Denture-Base Resin Material and Conventional Polymethylmethacrylate (PMMA)

PURPOSE

To study the surface and mechanical properties of 3D printed denture-base resin materials and compare them with conventional heat-cured polymethylmethacrylate (PMMA).

MATERIALS AND METHODS

Three brands of 3D printed denture-base resin materials and one conventional heat-cured PMMA were tested in this study: NextDent 3D printed resin, Dentona 3D printed resin, ASIGA 3D printed resin, and Meliodent conventional PMMA. Sixty specimens (25 × 25 × 3 mm) were fabricated (n=15 per group) to perform the following tests: wettability, surface roughness, and microhardness. One hundred twenty specimens (65 × 10 × 3 mm) were fabricated (n=30 per group) and stored in distilled water at (37 ±1°C) for 7 days. Specimens (N = 15) in each group were subjected to the three-point bending test and impact strength test, employing the Charpy configuration on un-notched specimens. The morphology of the fractured specimens was studied under scanning electron microscope (SEM). Statistical analysis was performed using one-way ANOVA and Tukey-pairwise multiple comparisons with 95% confidence interval. P-values of ≤0.05 were considered significant.

RESULTS

The conventional heat-cured specimens demonstrated the highest means of surface roughness (0.23 ± 0.07 μm), Vickers hardness number (18.11 ±0.65) and flexural strength (92.44 ±7.91 MPa), and the lowest mean of contact angle (66.71° ±3.38°). ASIGA group showed the highest mean of contact angle (73.44° ±2.74°) and the lowest mean of surface roughness (0.19 ±0.03 μm). The highest mean of impact strength was recorded in the Dentona group (17.98 ±1.76 kg/m² ). NextDent specimens showed the lowest means of Vickers hardness number (16.20 ±0.93), flexural strength (74.89 ±8.44 MPa), impact strength (15.20 ±0.69 kg/m² ), and recorded the highest mean of bending modulus (2,115.80 ±178.95 MPa).

CONCLUSIONS

3D printed resin exhibited noticeable differences in surface and mechanical properties between different brands and with conventional heat-polymerized PMMA.

An evaluation of the effect of wearing complete dentures on temporomandibular joint vibrations over time using the joint vibration analyzer

Aim

To evaluate the changes in temporomandibular joint (TMJ) vibrations after insertion of the complete denture in edentulous patients.

Settings and Design

An observational in vivo study conducted to evaluate the changes in maximum mouth opening, total integrals, peak amplitude, and peak frequency in TMJ vibrations on the day of complete denture insertion and 6 months of follow up.

Materials and Methods

Twenty patients (male: 12 and female: 8) were selected for the fabrication of balanced complete dentures following conventional procedure. Joint vibration analysis was recorded using the joint vibration analyzer. The patients were instructed to open as wide as possible and close to the intercuspal position with rhythmic speed following the metronome projected on the screen. The TMJ vibrations were amplified and displayed as waveforms in a graphical representation by system software.

Statistical Analysis Used

Wilcoxon test.

Results

A significant decrease in the total integral (P = 0.001) and peak amplitude (P = 0.044) for opening and closing movements of the left and right joints was observed. There was no significant change in maximum mouth opening (P = 0.624). A decrease in peak frequency was noted only at left opening movements between the day of insertion and at 6 months (P = 0.025).

Conclusion

The function of TMJ mechanics was improved till 6 months after insertion of complete denture with balanced articulation (BA).

Complete Denture - Border Molding Technique Using a Laboratory Condensation Silicone Putty: Review

During the fabrication of a complete denture, functional impression is taken. Literature studies show that polydimethylsiloxane (condensation silicone) has not been reported by United States dental schools to perform border molding. Thus, the purpose of this article is to review the functional impression technique when border molding is performed with a laboratory condensation silicone putty.

Effect of Ball and Bar Attachment Type on Patient Satisfaction Using Two-Implant-Retained Mandibular Overdenture: A Crossover Randomized Clinical Trial

Background

Considering the two-implant-retained overdenture as a first treatment of choice for edentulous mandible, patients using the overdentures need to be satisfied with the type of attachment used. The purpose of this study was to determine level of patient satisfaction with two-implant-retained mandibular overdentures opposing conventional maxillary complete denture using ball-socket and bar-clip attachments.

Materials and Methods

In this within-subject crossover randomized clinical trial, total 20 edentulous patients were given conventional complete dentures for 3 months to use. All completed a satisfaction questionnaire before implant placement. They were randomly assigned to receive an overdenture retained by either ball or bar attachment. After 3 months satisfaction questionnaires were repeated, and crossover was done by changing the attachments. After use of 3 months of alternate attachments, patients were asked to complete the final questionnaires and asked to choose their preferred type. The patient satisfaction scores were recorded after using 3 months of conventional complete denture, 3 months of first attachment and 3 months of second attachment. Data were analyzed using Wilcoxon signed rank test. The P values were adjusted using Bonferroni multiple testing correction, and P < .05 were considered as statistically significant.

Results

There was no significant difference in patient satisfaction between ball and bar attachments. However, patient satisfaction improved significantly between baseline and either-attachment-retained prosthesis. At the end of the comparative crossover experiment, 11 patients voted for the ball attachments and 9 for the bar attachments, thereby indicating them as their preferred attachments.

Conclusions

Among ball and bar attachment, there was no statistically significant difference in satisfaction scores. Neither ball nor bar attachment was chosen as a preference over the other.

Expectation of treatment outcomes in complete denture wearers

Edentulism is a condition associated with age, and the outcome of prosthodontic treatment depends on a number of dental and nondental factors. In complete denture therapy, patient satisfaction is a key objective and various other variables affect this parameter. The ability to foresee its preferences may assist dentists in making informed treatment selections. The study purpose is to assess the expectations of treatment outcomes in complete denture users. For the study, all cases referred for total denture therapy during September 2020 and February 2021 were included. Both new and old denture users completed questionnaires on factors such as retention, mastication, phonetics, esthetics, and comfort. Excel was used to compile the data, which was then imported into SPSS for statistical analysis. The study's statistical significance level was established at P < 0.05. Male patients over the age of 60 years wearing dentures were very common. Denture wearers were highly prevalent in the age group of >60 years among male patients. Retention, esthetics, and phonetics are highly satisfied in existing denture wearers and mastication is highly satisfied in new denture wearers. The comfort factor is commonly satisfied in both the denture wearers. The results were statistically significant with a P = 0.05. Clinician can plan their treatments more effectively if they are aware of the treatment's expectations.

Clinical efficacy of mandibular complete dentures with a resilient liner: study protocol for a multicenter randomized controlled trial

BACKGROUND

During restoration of poorly fitting complete dentures (CDs) in edentulous patients, liners are used to reconstruct the concave surfaces of CDs with a new base material. These relining materials are classified into resilient liners (RLs) and non-resilient liners (NRLs), but the clinical effects of these liners and their selection criteria remain unclear. The purpose of this study is to evaluate the clinical efficacy of relining mandibular CDs using RL and NRL and to conduct a follow-up study.

METHODS

The study is currently being conducted at eight centers, and a parallel-group randomized controlled trial (RCT) is underway. One hundred thirty-two edentulous patients with poorly fitting mandibular CDs will be assigned to two groups based on whether they will receive RL or NRL. Participants will have an RL or NRL applied for relining their CDs using an indirect method of dynamic impressions. Data will be recorded at 1 week and 3, 6, and 12 months after denture delivery. The primary outcome will be assessment of the patients' general satisfaction by using a 100-mm visual analog scale (VAS). Secondary outcomes will be measured as patient-reported outcomes, including food intake status and oral hygiene-related quality of life. Masticatory performance and the number of sore spots on the oral mucosa will also be recorded. Comparisons between the two groups and within-subject comparisons of pre- and post-intervention measurements will be conducted.

DISCUSSION

For dentists and prosthetic researchers in Japan, this RCT will provide information on the clinical efficacy of RL materials in comparison to RNL in CD wearers. The new evidence regarding the use of RL materials in an aging population will also be useful to dentists in other countries in their routine clinical practice.

TRIAL REGISTRATION

This clinical trial has been registered at the University Hospital Medical Information Network (UMIN) Center (UMIN000041950).

Comparison of case-based learning combined with Rain Classroom teaching and traditional method in complete denture course for undergraduate interns

BACKGROUND

Complete denture, as an important restoration method for edentulism, is difficult to study for beginners, especially in linking the theory with clinical practice.

OBJECTIVE

This study was aimed to compare the teaching effects between case-based learning combined with Rain Classroom teaching and traditional lecture method in the clinical course of complete denture prosthesis for undergraduate interns.

METHODS

In a course called "Problems and treatment strategies of complete denture after wearing", interns were divided into two groups: one for traditional lecture-based teaching with PowerPoint slideshow (the control group, n = 28); and the other for case-based learning combined with Rain Classroom teaching, which published information before class, discussed specific clinic cases in class and got real-time interns' feedback via WeChat (the test group, n = 22). Both groups received the same exam and questionnaire survey after class. The Q&A participation of interns in class, theoretical test scores and questionnaire survey responses were used to evaluate the teaching effects. An independent sample t-test and the chi-square test or Fisher's exact test were used for statistical analysis in this study.

RESULTS

The Q&A participation of interns in the test group was much better than that of the control group. The average score on the theoretical test after class in the test group (72.14 ± 12.24) was significantly higher than that in the control group (61.29 ± 20.12) (P < 0.05). In the test group, 94.54% (21/22) of the interns preferred the new teaching mode.

CONCLUSION

Case-based learning combined with Rain Classroom teaching is helpful to enliven the classroom atmosphere, inspire studying enthusiasm, and achieve a good learning effect in both theory and clinical practice related to complete denture prosthesis.

Polymethylmethacrylate denture base layering as a new approach for the addition of antifungal agents

PURPOSE

To introduce a new technique, denture base layering, for the addition of titanium dioxide nanoparticles (TiO₂ NPs) to polymethylmethacrylate (PMMA) and to investigate the effects of the layering technique on Candida albicans (C. albicans) adhesion and on surface roughness, hardness, translucency, and flexural strength.

MATERIALS & METHODS

In total, 210 heat-polymerized acrylic resin specimens were prepared as discs (15 × 2 mm) for testing C. albicans adhesion (n = 70) and surface roughness, hardness, and translucency (n = 70); and as acrylic plates (65 × 10 × 2.5 mm) for testing flexural strength (n = 70). Specimens were divided into 4 groups: control (n = 30), one-layer (n = 60), double-layer (n = 60), and dotted-layer (n = 60) according to the packing and layering technique. Each group was divided according to the concentration of TiO₂ NPs 1% and 2.5% (n = 10). The control group comprised one layer of unmodified resin. The one-layer group comprised one layer of a mixture of PMMA/TiO₂ NPs packed conventionally. The double-layer group consisted of two different layers packed in two steps, as follows: unmodified resin first, followed by a continuous thin layer of the PMMA/TiO₂ NPs mixture. Similarly, the dotted-layer group consisted of two different layers packed in two steps, as follows: unmodified resin first, followed by a thin layer of the PMMA/TiO₂ NPs. However, the second mixture was added in a dotted manner. The direct culture method for C. albicans adhesion before and after ultraviolet light activation, and surface roughness, hardness, translucency, and flexural strength were measured. An analysis of variance and Tukey's post hoc test were used for data analysis (α = 0.05).

RESULTS

The addition of TiO₂ NPs reduced C. albicans adhesion (P ˂.001). However, no significant difference was found between both concentrations within the same group before and after ultraviolet light activation (P >0.05), except in the 1% dotted-layer (P = .022). Surface roughness and hardness were not affected by the additions of different concentrations of TiO₂ NPs (P = .905) and (P = .059), respectively. Translucency was significantly reduced in all the groups (P ˂.001) except in the 1% dotted-layer (P = .332). Flexural strength decreased as the TiO₂ NPs concentration increased, with the greatest reduction in strength observed in the one-layer group (P ˂.001).

CONCLUSIONS

The double and dotted layering techniques were effective in reducing C. albicans adhesion, without affecting surface roughness, hardness, or flexural strength. However, translucency was reduced in all the groups, except the 1% dotted-layer group. This article is protected by copyright. All rights reserved.

Evaluation of functional suitable digital complete denture system based on 3D printing technology

PURPOSE

To improve the clinical effects of complete denture use and simplify its clinical application, a digital complete denture restoration workflow (Functional Suitable Digital Complete Denture System, FSD) was proposed and preliminary clinical evaluation was done.

MATERIALS AND METHODS

Forty edentulous patients were enrolled, of which half were treated by a prosthodontic chief physician, and the others were treated by a postgraduate student. Based on the primary impression and jaw relation obtained at the first visit, diagnostic denture was designed and printed to create a definitive impression, jaw relation, and esthetic confirmation at the second visit. A redesigned complete denture was printed as a mold to fabricate final denture that was delivered at the third visit. To evaluate accuracy of impression made by diagnostic denture, the final denture was used as a tray to make impression, and 3D comparison was used to analyze their difference. To evaluate the clinical effect of FSD, visual analogue scores (VAS) were determined by both dentists and patients.

RESULTS

Two visits were reduced before denture delivery. The RMS values of 3D comparison between the impression made via diagnostic dentures and the final dentures were 0.165 ± 0.033 mm in the upper jaw and 0.139 ± 0.031 mm in the lower jaw. VAS ratings were between 8.5 and 9.6 in the chief physician group, while 7.7 and 9.5 in the student group; there was no statistical difference between the two groups.

CONCLUSION

FSD can simplify the complete denture restoration process and reduce the number of visits. The accuracy of impressions made by diagnostic dentures was acceptable in clinic. The VASs of both dentists and patients were satisfied.

Comparison of general satisfaction, oral health-related quality of life, and patient's self-assessment between mandibular single-implant overdentures and experimental removable complete dentures: A randomized crossover clinical trial

Objective Patient satisfaction with single-implant overdentures (1-IODs) is unclear. This randomized crossover trial aimed to compare the general satisfaction, oral health-related quality of life, and patients' self-assessment between mandibular 1-IODs and experimental removable complete dentures (eRCDs). Methods New mandibular RCDs were fabricated for 22 patients with edentulous mandibles. After adapting to the RCDs, one implant was inserted in the mandibular midline. The participants were then randomly classified into groups 1 and 2. Group 1 received IODs for the first 2 months, while group 2 used eRCDs with a non-loaded implant in the midline. After 2 months, the treatment was switched. Four validated, patient-reported dental outcome measures were assessed: general satisfaction, Japanese version of the Oral Health Impact Profile for edentulous subjects (OHIP EDENT-J), General Oral Health Assessment Index (GOHAI), and Patient's Denture Assessment (PDA). The assessments were performed at the end of the IOD- and eRCD- use periods. Results General satisfaction was significantly higher during the IOD period (p = 0.002). Significant differences were observed in all domains of the OHIP, except orofacial pain (p = 0.084). Further, the total score (p<0.001) and the scores of the physical (p<0.001) and psychosocial functioning (p = 0.001) domains of the GOHAI differed significantly. The total PDA score (p = 0.001) and the scores of the function (p = 0.004), lower denture (p = 0.002), esthetics and speech (p = 0.026), and importance (p = 0.009) domains were significantly higher during the IOD period than during the eRCD period. Conclusion General satisfaction, oral health-related quality of life, and patient self-assessment scores were significantly higher for 1-IODs than for eRCDs. Clinical significance Within the limitations of this study, we found that mandibular single-implant overdentures may be an efficient alternative to mandibular experimental removable complete dentures due to higher general satisfaction, oral health-related quality of life, and patient self-assessment scores of dentures.

Comparison of the flexural and surface properties of milled, 3D-printed, and heat polymerized PMMA resins for denture bases: an in vitro study

PURPOSE

To compare the flexural properties and the adhesion of Lactobacillus salivarius (LS), Streptococcus mutans (SM), and Candida albicans (CA) on heat-polymerized (CV), CAD-CAM milled (CAD), or 3D-printed (3D) Poly (methylmethacrylate) (PMMA).

METHODS

Ultimate Flexural Strength (UFS), Flexural Strain (FS) (%) at Flexural Strength, and Flexural Modulus (FM) of specimens (65.0×10.0×3.3 mm) from each PMMA group (n=6) were calculated by using the 3-point bending test. The surface roughness profiles (R) were measured before and after polishing with a contact profilometer. LS, SM, and CA adhesion on PMMA specimens (n=18) (10 mm in diameter, 3 mm in height) was assessed after 90 minutes and 16 hours by using scanning electron microscopy. The Kruskal-Wallis test with post hoc analysis was performed to compare the groups (alpha=0.05).

RESULTS

Mean UFS values were 80.79±7.64 MPa for CV, 110.23±5.03 MPa for CAD, and 87.34±6.39 MPa for 3D. Mean FS values were 4.37±1.04% for CV, 4.71±0.62% for CAD, and 6.19±0.13 % for 3D. Mean FM values were 2542±301 MPa for CV, 3435±346 MPa for CAD, and 2371±197 MPa for 3D. CAD had the lowest average R value (0.29±0.16 µm) before polishing, and bacterial adhesion after 90 minutes of incubation. R value and microbial adhesion were not different amongst groups after polishing and 16 hours of incubation, respectively.

CONCLUSION

The CAD group displayed the best flexural properties, except for FS, the lowest roughness before polishing and bacterial adhesion after 90 minutes of incubation. All tested PMMAs had similar surface roughness after polishing, and microbial adhesion after 16 hours of incubation.

Traumatic Ulcerations Frequencies and Postinsertion Adjustment Appointments in Complete Denture Patients

BACKGROUND AND AIM

The patient who is wearing a denture after missing teeth faces traumatic ulceration very frequently. This ulceration creates difficulties in denture wearing. Hence, this study aimed to evaluate the most common locations of traumatic injuries in form of ulcerations, their frequency, and also the duration and number of adjustment visits required to achieve patient comfort following placement of complete removable dentures.

MATERIALS AND METHODS

Eighty edentulous patients were selected from a private clinic. Complete removable dentures were fabricated for all patients. All patients were evaluated for their complaints after denture insertion. Patients were followed up till the problem persisted. Descriptive analysis was done. Chi-squared test was used to differentiate the associations between lesions, postinsertion visits, and gender.

RESULTS

About 85.62% of patients need denture adjustment because of mucosal injuries during their first visit following. Approximately four appointments are needed for maxillary and six appointments needed for mandibular denture. Male and female have no difference in the number of mucosal injuries in the anatomical area evaluated in the maxilla and mandible using Fisher's exact test (P > 0.05). Mandibular dentures need more appointments than maxillary dentures after post insertion (P < 0.001).

CONCLUSION

The vestibule was the most common site for mucosal injuries which can be corrected by proper extension of denture flanges during border molding. Pressure indicator ink (arti spot) and paste is used to correct the overextended denture flanges.

Average rate of ridge resorption in denture treatment: A Systematic Review

Purpose To clarify the rate of posterior residual ridge resorption (PRRR) in different denture treatments and the factors that can affect PRRR.Study selection A bibliographical electronic search was conducted on MeSH, Web of Science, and Ovid databases. Hand searching was also conducted. Longitudinal studies recording the average rate of PRRR in the mandible were included. The effect size was calculated based on the mean rate of PRRR with standard deviation and group size. The random-effects analysis was used to perform meta-analyses across qualified studies.Results A total of 2245 eligible studies were collected from the MeSH, Web of Science, and Ovid databases and hand searching. In the end, 19 studies met the inclusion criteria and were extracted. The average rate of PRRR in different mandibular denture treatments was assessed in this systematic review. The mean combined effect size was -1.05 ± 0.5 (95% confidence interval [CI]: -3.18-1.08) between four-implant overdentures and two-implant overdentures. The combined effect size was -0.01 ± 0.22 (95% CI: -0.93-0.82) between complete dentures and two-implant overdentures. Body mass index, number of dentures used, denture wearing habit, impression technique, artificial tooth material, and peri-implant bone resorption showed no significant effect on the rate of PRRR. Gender, denture material, and relining frequency showed a significant effect on the rate of PRRR.Conclusions This review summarized different average rates of PRRR in mandibular denture treatments. Meta-analyses have reported that four-implant overdenture treatments can lower the rate of PRRR compared to two-implant overdenture treatments. However, there was no significant difference in the treatment effect between the complete denture and two-implant overdenture treatments.

Immediately loaded single-implant mandibular overdentures compared to conventional complete dentures: A cost-effectiveness analysis

BACKGROUND

In recent years, the single-implant mandibular overdenture (SIMO) has been proposed as an alternative to more complex overdenture designs as a simplified implant intervention for edentulous patients.

OBJECTIVE

The aim of this study was to run a cost-effectiveness analysis alongside a randomized clinical trial comparing the SIMO and the conventional complete denture (CCD) treatment. Imediately loaded external hexagon implant and ball attachment were used for the overdenture goup. Direct costs related to therapies were identified and valuated throughout a 1-year period after delivery, in Brazilian currency (R$) and converted into international dollars (I$) using purchase power parity exchange rates. Treatment effectiveness was measured using the OHIP-Edent and satisfaction scores for calculation of incremental cost-effectiveness ratios (ICER).

RESULTS

Outcomes were assessed at the 1-year follow-up for 65 patients (CCD=34; SIMO=31). Overall OHIP-Edent and satisfaction scores improved significantly in the SIMO group, while remained unchanged in the CCD group. The mean overall costs were R$1,179.04 (I$590.99) for the CCD group and R$2,127.91 (I$1,068.20) for the SIMO group - 80.7% incremental cost for SIMO. The ICER calculation for SIMO treatment showed a mean cost of I$48.20 for 1-point reduction in OHIP-Edent scores, and I$12.56 for 1-point increase in satisfaction score.

CONCLUSIONS

Findings support the effectiveness of this simplified and low-cost implant intervention for edentulous patients. SIMO also seems a cost-effective alternative to the CCD and the relatively low incremental cost may potentially increase the utilization of dental implants among older subjects, especially those with limited financial resources.

CLINICAL SIGNIFICANCE

The immediately loaded single-implant mandibular overdenture was superior to the conventional complete denture in terms of patient-reported outcome measures at a low incremental cost.

Factors associated with edentulous patients' willingness about implant-supported complete denture: a multivariate analysis

OBJECTIVE

The aim of this study was to evaluate the factors influencing edentulous patients' willingness about mandibular implant-supported complete denture.

MATERIALS AND METHODS

A cross-sectional study was carried out with 117 bimaxillary edentulous patients wearing removable complete dentures (CDs). Patients were assessed concerning denture-related items (number of previous mandibular CDs, previous denture wearing period, dentures maker professional, and regular wearing of previous mandibular dentures) and individual-related aspects, such as mandibular edentulousness period, mandibular bone height, and willingness to the use of mandibular implant-supported complete denture. Masticatory performance was evaluated by the median particle diameter. Mandibular bone height and satisfaction were assessed using a validated method. The Chi-square test was used for data analysis and prevalence ratios were adjusted by using multivariate Poisson regression, both with 95% confidence interval.

RESULTS

A total of 78 participants (66.7%) were interested in mandibular implant-supported overdenture (mean age 65.33 ± 9.49). Masticatory performance was not influenced by choosing mandibular implant-supported complete denture. The preference about mandibular implant-supported complete denture was correlated with longer mandibular complete denture experience (p = 0.021) and it was significantly associated with dissatisfaction about retention (p = 0.005).

CONCLUSION

Previous experience with mandibular complete dentures and dissatisfaction about retention influence the willingness about mandibular implant-supported overdenture.

CLINICAL RELEVANCE

Many factors are associated with rehabilitation preferences for edentulous patients and mandibular implant-supported complete denture is one of the available alternatives. Therefore, this study has demonstrated the factors influencing the decision to replace a mandibular conventional complete denture by dental implant treatment based on patient's outcomes. Such finding may be considered as a relevant aspect towards shared decision-making for prosthodontic rehabilitation of edentulous patients.

Assessment of the Effect of Complete Dentures on Respiratory Performance: A Spirometric Analysis

Background

Among the vital functions, respiration can be claimed to be one of the most important. A thorough understanding of the patient should be an important aspect a prosthodontist should dwell into so as to predispose patients to acknowledge the kind of prosthesis they require. Hence, the present study was conducted for assessing the effect of complete dentures on respiratory performance.

Materials and Methods

Fifty patients with the presence of complete edentulous arch and who had a history of complete denture usage for at least 5 years were enrolled. All the spirometric procedures were performed by trained technicians. A diagnostic spirometer was employed for performing the spirometric test. Testing was carried out in the following steps: Stage 1: testing in the absence of denture, Stage 2: testing in the presence of both dentures, Stage 3: testing in the presence of maxillary denture only, and Stage 4: testing in the presence of mandibular dentures only. Forced vital capacity (FVC) value, peak expiratory flow (PEF) value, forced expiratory volume in 1 s (FEV1) value, and forced expiratory flow 25%-75% (FEF_25-75) value were recorded with the spirometric test. Analysis of all the results was done by SPSS software.

Results

The spirometric value of FVC, PEF, FEV1, and FEF_25-75 in the absence of both maxillary and mandibular dentures (Stage 1) was found to be 3.18, 5.83, 2.44, and 2.80, respectively. The spirometric value of FVC, PEF, FEV1, and FEF_25-75 in the presence of both maxillary and mandibular dentures (Stage 2) was found to be 3.09, 5.67, 2.41, and 2.67, respectively. While analyzing statistically, it was seen that there was a significant decrease in the value of spirometric variables in the presence of dentures.

Conclusion

Chronic denture wearer edentulous patients are subjected to the risk of development of spirometric alterations. Hence, these patients should be given timely instructions about the various respiratory exercise protocols.

Multivariate analysis reveals oral health-related quality of life of complete denture wearers with denture adhesives: a multicenter randomized controlled trial

Purpose To investigate the difference in improvement of oral health-related quality of life (OHR-QoL) depending on the oral and denture conditions of a complete denture wearer when using a cream or powder type denture adhesive in a 10-center parallel randomized clinical trial.Methods Two hundred edentulous subjects who wore complete dentures were allocated to each of the three groups according to denture adhesive type: cream, powder, and control (saline solution). The materials were applied to the mucosal surface of the dentures for 4 days, and baseline data and data after the intervention were collected. OHR-QoL was assessed using the Japanese version of the modified Oral Health Impact Profile for Edentulous Patients (OHIP-EDENT-J) scale for outcome. Multivariate analysis was used to investigate improvements in OHR-QoL according to participant characteristics among complete denture wearers using these materials.Results OHIP-EDENT-J scores were significantly decreased in all groups after the intervention (p < 0.05); however, there were no statistically significant differences among the groups. Multiple logistic regression analysis revealed a significant association between the vertical height of the maxillary and mandibular alveolar ridge and OHIP-EDENT-J scores in the cream-type denture adhesive group. In contrast, there were no significant association between participant characteristics and OHIP-EDENT-J scores in the powder-type adhesive and control groups.Conclusions The use of denture adhesives could improve OHR-QoL for complete denture wearers. The cream-type denture adhesives may be expected to improve OHR-QoL in patients with poor residual ridge conditions compared with patients with good residual ridge conditions.

The effect of complete dentures on edentulous patients' oral health-related quality of life in long-term: A systematic review and meta-analysis

BACKGROUND

To evaluate whether the long-term use of complete dentures (CD) into promotes significant changes in the oral health-related quality of life (OHRQoL) in edentulous patients.

METHODS

A systematic review and meta-analysis was conducted. A broad search in Pubmed, Web of Science, Scopus, Cochrane Library, Grey Literature, clinical trials registers and manual search was done. The eligibility criteria were based on population, intervention, comparisons and outcome: (P) edentulous patients, (I) CDs rehabilitation, (C) OHRQoL after CD, (O) change in scores of OHRQoL. Two independent reviewers applied the eligibility criteria, collected qualitative data, performed methodological quality and evaluated the certainty of the evidence (grading of recommendations assessment, development and evaluation). The meta-analysis was analyzed in RevMan 5.4 with 95% confidence intervals (CIs) and P < 0.05.

RESULTS

A total of 2452 records were identified. Twenty-four articles were included in qualitative synthesis. Nineteen studies were qualified as good, 3 as fair and 2 as poor quality. Twelve studies were included in quantitative analysis (meta-analysis). The use of CD did not improved OHRQoL in a period of 3 months through the assessment of the Geriatric Oral Health Assessment Index (GOHAI) instrument (P = 0.55; CI; 6.86 [-15.60, 29.31]), and Oral Health Impact Profile-14 (OHIP-14) (P = 0.05; CI; -14.91 [-29.87, 0.04]), with very low certainty of evidence. In a long term, 6 months, GOHAI instrument (P < 0.00001; CI; 16.22 [10.70, 21.74]), OHIP 20 (P = 0.02; CI; -11.09 [-20.54, -1.64]) and OHIP-EDENT (P = 0.0004; CI; -8.59 [-13.32, -3.86]) showed improvement on OHRQoL, with very low and low evidence of certainty, respectively.

CONCLUSION

CD has the strong potential to contribute to oral health-related quality of life in long-term.

Reliability and validity of the Turkish version of oral health impact profile for edentulous subjects

Purpose

The validated translations of the OHIP-EDENT exist in different languages; however, there is no reliable and validated Turkish translation. The present study was conducted to evaluate the reliability and to validate the Oral Health Impact Profile in edentulous subjects translated to Turkish (OHIP-EDENT-T).

Materials and methods

The study sample included 104 conventional complete denture wearers (58 women and 46 men, mean age: 61.13 ± 9.43 years). The original English version of OHIPEDENT was translated into Turkish using a forward-backward method and applied to the subjects. The reliability of the OHIP-EDENT-T was evaluated using internal consistency and the test-retest method. Validity was determined as construct and convergent validity. The construct validity of OHIP-EDENT-T was assessed using exploratory and confirmatory factor analysis.

Results

The Cronbach's alpha value for OHIP-EDENT-T was 0.890. The intraclass correlation coefficient (ICC) was 0.749 for the OHIP-EDENT-T total score, and ICCs for the subscales ranged from 0.630 (95% CI = 0.501-0.823) to 0.859 (95% CI = 0.531-0.897), indicating good to excellent agreement. The Kaiser-Meyer-Olkin value for sampling adequacy was 0.820 and results of Bartlett's sphericity test indicated statistical significance (χ2=1139.767; df=171, p=0.001). This showed that factorial analysis could be applied to the data set. The three-factor structure of the scale explained 81.1% of the observed variance. The agreement of the three-factor solution was further tested with confirmatory factor analysis, and the fit index was found to be acceptable (chi-square fit test=1.449, RMSEA=0.040, GFI=0.94, CFI=0.93).

Conclusion

Within the limitations of this study, it can be concluded that OHIP-EDENT-T is a valid and reliable instrument for evaluating the quality of life of edentulous patients.

Properties of Acrylic Resin For CAD/CAM: A Systematic Review and Meta-Analysis of In Vitro Studies

PURPOSE

This systematic review and meta-analysis of in vitro studies compared the prepolymerized acrylic resin used for CAD/CAM complete denture manufacturing versus the heat-polymerized acrylic resin for conventional complete dentures in terms of surface roughness, wettability, hardness and flexural strength.

MATERIALS AND METHODS

An electronic search was performed in the PubMed, Embase, LILACS and Web of Science databases, without language or date restrictions. Gray literature and manual search tools were also used. The systematic review was carried out by two researchers independently, following the inclusion criteria: in vitro studies testing the CAD/CAM acrylic resin with a control group of heat-polymerized acrylic resin which compared at least one of the four material properties above. The meta-analysis was performed separately for each property, using a random effect model.

RESULTS

Of the 914 studies found by means of search strategies, 698 were selected for the systematic review. After applying the eligibility criteria, only 17 articles were selected for the qualitative analysis in the systematic review; among these, 14 were included in the quantitative meta-analysis. The CAD/CAM prepolymerized acrylic resin in blocks had similar properties when compared to heat-polymerized acrylic resin in almost all outcome measures, with the exception of a statistically significant reduction in surface roughness.

CONCLUSIONS

Based on the findings of this systematic review and meta-analysis, equally satisfactory results can be expected from dental prosthesis manufactured by the CAD/CAM system when compared to conventional ones, with the additional potential of reducing the pigmentation and attached microorganisms due to the reduced surface roughness of the prepolymerized resin.

Patient preferences for different tooth replacement strategies for the edentulous mandible: A willingness-to-pay analysis

PURPOSE

The aim of this study was to evaluate patients' economic preferences for two different tooth replacement strategies for the edentulous mandible namely conventional complete dentures (CCDs) and implant overdentures supported by two implants (IODs), using a willingness-to-pay (WTP) analysis.

METHODS

Twenty-six elderly patients who had been rehabilitated with either a mandibular CCD or IOD were invited to participate in this study. All participants were provided with the details of the two treatment protocols, including advantages, disadvantages, and treatment costs. The patients were then asked to indicate their maximum WTP values for each protocol using a payment card method for contingency evaluation.

RESULTS

Fifteen patients with mandibular CCD (CCD-Group) and 12 patients with IOD (IOD-Group) participated in the study. Overall, the median and maximum WTP values recorded for IOD therapy were significantly higher than those for CCD therapy (p<0.05). Both treatment groups recorded maximum WTP values for CCD therapy, which exceeded the market cost (¥30,000 [US$280]), CCD-Group: ¥50,000 (interquartile range [IQR]: 40,000 - 65,000), and IOD-Group: ¥45,000 (IQR: 30,000-85,000)]. However, both groups registered a median and maximum WTP values for IOD therapy lower than the market cost (¥780,000 [US$7,300]), (CCD-Group: ¥500,000 [IQR: 300,000 - 750,000], IOD-Group: ¥700,000 [IQR: 500,000-800,000]).

CONCLUSION

The maximum WTP values recorded for IOD therapy were significantly higher than CCD therapy in both treatment groups. While patients were willing to pay more than the current market costs for CCDs, they were not willing to meet the market value for IODs.

Effect of complete dentures on oral stereognostic ability in edentulous patients: A systematic review

Aim:

Oral stereognosis is an important sensation for a human being to percept any type of materials that are introduced in the oral cavity. It is defined as the ability of an individual to recognize objects using only tactile sensation without using vision, audition, balance, somatic function, taste, or smell. The primary purpose of this review was to evaluate the effect of complete dentures on oral stereognostic ability in edentulous subjects.

Settings and Design:

Systematic review based on PRISMA guidelines.

Materials and Methods:

A systematic search of the electronic databases like PubMed and Web of Science was done using keywords – “stereognosis,” “oral stereognosis,” “complete denture,” and “complete edentulism.” In addition to this, a manual search of references mentioned in the articles and gray literature was done. Data extraction and assessment were done by two independent reviewers.

Statistical Analysis Used:

Qualitative analysis.

Results:

The literature search yielded a total of 61 articles. Thirteen duplicate articles were removed and 36 articles were rejected after initial screening of titles and abstracts. A total of 12 articles were selected for full text reading and 5 of them were included for qualitative analysis.

Conclusion:

All the included studies showed complete denture treatment therapy improved stereognostic ability in terms of correct identification of test pieces and time taken to identify the objects. There is also a direct relationship between the adaptability of dentures and stereognostic ability.

Real-time in vitro measurement of denture-mucosa pressure distribution in a typical edentulous patient with and without implants: Development of a methodology

PURPOSE

To measure the pressure distribution on the oral mucosa in vitro by comparing the pressure distributions under a complete denture and that of an implant overdenture.

MATERIALS AND METHOD

Anatomically accurate models and conventional Class I complete denture (CD) were produced and subjected to cyclic loading using a 100 N vertical centric and unilateral masticatory load with the universal testing machine (Instron 3369). Four miniature pressure sensors were positioned at four different locations in the intaglio surface of the denture and recorded pressure at 100 Hz frequency measured during a 10-cycle load at 1 Hz. Testing was repeated in different clinical combinations; CD vs. single implant overdentures (1-IOD), CD vs. two, three and four implant overdentures (2-IOD, 3-IOD vs. 4-IOD). The pressure profile (kPa) of complete dentures were measured and compared to the implant overdenture combinations. Collected data was statically analysed using SPSS and one-way analysis of variance.

RESULTS

The highest mean pressure was observed in CD group, with the mean mandible buccal ridge pressure value of 212.82 kPa ± 136.9 due to its surface area. There were no statistically significant differences between the group combinations (p = 0.146) but between various locations in the mean pressure recorded across the five denture/overdenture combinations.

CONCLUSION

CD experienced large pressure values on mandibular denture. 1-IOD demonstrated the most pressure in comparison to CD where with an increase in the number of implants used, it transformed the denture from being pure-borne mucosa to an implant overdenture, providing support and distributing the pressure amongst the implants.

Increase in masseter muscle activity by newly fabricated complete dentures improved brain function

PURPOSE

To reveal effects of improvement of masseter muscle activity on brain function in elderly people wearing complete dentures.

METHODS

Subjects were 14 edentulous patients with a chief complaint of the inconvenience of their complete dentures. The surface electromyographic (EMG) activity of the masseter muscles was measured. Brain activities were analyzed with functional magnetic resonance imaging (fMRI), employing chewing gum as the task program. Cognitive functions were evaluated with Trail Making Test Part A (TMT-A), Rey Auditory Verbal Learning Test (RAVLT) and Rey-Osterrieth Complex Figure Test (R-OCFT). Those evaluations were performed in which subjects wore their old dentures (OD) or newly fabricated dentures (ND).

RESULTS

We compared ND condition with OD condition. The masseter muscle activity significantly increased in ND condition (p < 0.05, Wilcoxon signed rank test). The brain activity increased significantly in the superior frontal gyrus, precentral gyrus, putamen, inferior parietal lobule, cerebellum, inferior frontal lobe, and middle frontal gyrus under the ND condition than under the OD condition (p < 0.01, uncorrected, cluster size > 10 voxels). Results of TMT-A, RAVLT, and R-OCFT were also significantly improved (p < 0.05, Wilcoxon signed rank test).

CONCLUSIONS

In the edentulous elderly, the brain activity was increased following the improvement of the masseter muscle activity. Consequently, it is possible that the improvement of the masseter muscle activity might influ ence on the attention, verbal skills, and visual memory.

A systematic review and meta-analysis to evaluate the efficacy of denture adhesives

OBJECTIVES

This systematic review aims to investigate the efficacy of denture adhesives (DAs) for complete dentures (CDs), and to provide clinical recommendations for prosthodontists and general practitioners.

DATA/SOURCES

Electronic databases (Medline, Embase, CENTRAL) and gray literatures were searched (up to March 2020) for relevant randomized and non-randomized controlled clinical trials (RCTs and CCTs) evaluating the efficacy of DAs when applied to CDs. Primary outcomes were objectively assessed variables directly related to mastication (denture retention, maximum bite force and masticatory efficiency). Secondary outcomes included other objectively assessed variables and patient-reported outcomes.

STUDY SELECTION

Of the 1729 records identified, 39 studies (43 articles) were included in the analysis. Among them, 23 were RCTs and 16 were CCTs, with two multicenter clinical trials (1 RCT and 1 CCT). Meta-analysis results indicated that DAs provided significantly higher retention (SMD 1.34, 95 % CI: 0.89-1.79, P < 0.001) for CDs. Bite force (SMD 0.98, 95 % CI: 0.50-1.47, P < 0.001) and masticatory performance (SMD 0.72, 95 % CI: 0.23-1.22, P = 0.004) of the CD wearers were also improved after using DAs, but the effect size was relatively smaller.

CONCLUSION

Based on the results of this systematic review, it is concluded that DAs can improve denture retention, bite force and masticatory performance of CD wearers.

CLINICAL SIGNIFICANCE

This study investigated the effects of all types of DAs for CDs in terms of their effects on denture retention, masticatory performance, oral health-related quality of life and oral microorganisms for CD wearers.

The Patient's Denture Assessment (Thai version) is a valid and reliable tool for evaluating the outcome of treatment with complete denture

BACKGROUND

Complete tooth losses are still being major problems which resulted in lesser quality of life especially for elderly patients. However, there are still lack of questionnaire to evaluate the treatment outcome from the patient's aspect. The objective of this study is to evaluate the reliability and validity of the Patient's Denture Assessment-Thai version (PDA-T), then use this questionnaire to assess patient satisfaction with complete denture treatment outcome also investigates the factors involving their satisfaction.

METHODS

The subjects comprised 120 edentulous adult patients (49 men/71 women; average age 70 years-old) from the Prosthodontic and the Geriatric Dentistry and Special Patients Care Clinic at the Faculty of Dentistry, Chulalongkorn University during 2019 March‒2020 March. The patients were divided into two groups: the group experienced (Exper) (n = 54) with wearing complete dentures, and the non-experienced (NonExper) group (n = 66). The patients used the validated PDA-T to self-assess their treatment at different times. The Exper group completed the questionnaire at t₀ (during treatment), t_0.5 (2‒8-weeks after t₀), and t₁ (final follow-up). The NonExper group completed the questionnaire only at t₁.

RESULTS

In the Exper group, Cronbach's α and average inter-item correlation was 0.95 (range 0.76‒0.95) and 0.47 (range 0.57‒0.83), respectively. The intraclass correlation coefficients (n = 18, 95% confidence interval) were 0.98 overall. The paired t-test (p < 0.05) between t₀ and t₁ indicated a significant difference between t₀ and t₁ in every PDA-T topic, and the effect size was 1.71. In the NonExper group, the Pearson correlation analysis indicated no significant correlation between the patients' demographics and masticatory function.

CONCLUSION

The reliability and validity of the PDA-T indicate it is a valuable tool for evaluating complete denture treatment. Treatment success affected the patients' satisfaction but was not associated with the type of doctors, genders, ages, or educational level.

Comparison of shear bond strengths of different types of denture teeth to different denture base resins

PURPOSE

To determine the shear bond strengths of different denture base resins to different types of prefabricated teeth (acrylic, nanohybrid composite, and cross-linked) and denture teeth produced by computer-aided design/computer-aided manufacturing (CAD/CAM) technology.

MATERIALS AND METHODS

Prefabricated teeth and CAD/CAM (milled) denture teeth were divided into 10 groups and bonded to different denture base materials. Groups 1-3 comprised of different types of prefabricated teeth and cold-polymerized denture base resin; groups 4-6 comprised of different types of prefabricated teeth and heat-polymerized denture base resin; groups 7-9 comprised of different types of prefabricated teeth and CAD/CAM (milled) denture base resin; and group 10 comprised of milled denture teeth produced by CAD/CAM technology and CAD/CAM (milled) denture base resin. A universal testing machine was used to evaluate the shear bond strength for all specimens. One-way ANOVA and Tukey post-hoc test were used for analyzing the data (α=.05).

RESULTS

The shear bond strengths of different groups ranged from 3.37 ± 2.14 MPa to 18.10 ± 2.68 MPa. Statistical analysis showed significant differences among the tested groups (P<.0001). Among different polymerization methods, the lowest values were determined in cold-polymerized resin.There was no significant difference between the shear bond strength values of heat-polymerized and CAD/CAM (milled) denture base resins.

CONCLUSION

Different combinations of materials for removable denture base and denture teeth can affect their bond strength. Cold-polymerized resin should be avoided for attaching prefabricated teeth to a denture base. CAD/CAM (milled) and heat-polymerized denture base resins bonded to different types of prefabricated teeth show similar shear bond strength values.

Does nocturnal use of a complete denture interfere with the degree of obstructive sleep apnea? A systematic review and meta-analysis

BACKGROUND

The impact of a complete denture on obstructive sleep apnea is not well understood. Therefore, this study aimed to evaluate the relationship between nighttime use of complete dentures and obstructive sleep apnea and determine if wearing a complete denture during sleep changes the degree of obstructive sleep apnea.

METHODS

This systematic review followed the notification items for Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was recorded in the International Prospective Registry of Systematic Reviews (PROSPERO) under number CRD42020183167. An electronic search in the PubMed/MEDLINE, Scopus, and Cochrane Library databases for articles published until September 2020 was conducted. The search strategy used the terms (complete denture OR denture OR edentulous OR edentulism) AND (quality of sleep OR sleep OR apnea OR obstructive sleep apnea). Only prospective, retrospective, controlled, and randomized clinical studies of patients wearing complete dentures, studies comparing sleep with and without the prosthesis, and studies in which patients were diagnosed with obstructive sleep apnea by polysomnography were included in the review.

RESULTS

In total, four articles were selected for the qualitative and quantitative analyses. A total of 144 patients, with an average age of 60 years, were studied. The meta-analysis showed that there was no statistical difference in the apnea-hypopnea index between using and not using the prosthesis during sleep.

CONCLUSIONS

The use of complete dentures during sleep does not influence the degree of obstructive sleep apnea.

Maxillofacial Prosthetic Rehabilitation of Patients with Resection of Squamous Cell Carcinoma: A Report of Two Cases

Maxillofacial prosthetic rehabilitation is almost always indicated after surgical treatment of affected individuals with oral cavity and pharynx cancers. Few articles have described in detail the technical sequence of maxillofacial prosthesis fabrication. The first case is a 56-year-old woman who was rehabilitated with pharyngeal obturator prosthesis after a partial maxillectomy, including soft palate, tonsil, oropharynx, and retromolar space regions. The second case is an 83-year-old man who was rehabilitated with hard palatal obturator prosthesis after a maxillectomy, including hard palate and nasal floor. In both cases, the patients complained of oronasal regurgitation and difficulty in chewing, swallowing, and speaking. A multi-professional approach including oral rehabilitation should be part of the treatment plan for individuals with oral and pharyngeal cancer after tumor resection.

Ability to adjust occlusal force in implant-supported overdenture wearers

PURPOSE

The purpose of this study was to evaluate the occlusal force adjusting ability of implant-supported overdenture (IOD) wearers, as compared with natural teeth and complete dentures.

METHODS

Subjects were those with natural dentition (ND group; 19 subjects), those with implant-supported overdentures (IOD group; 7 subjects), and those with complete dentures (CD group; 14 subjects). Subjects were asked to hold test foods (peanuts and biscuits mounted on a custom-made apparatus with a force transducer) between their anterior incisors (hold phase) and split test foods (split phase). The mean value of the occlusal force during the hold phase (hold force), the peak force rate during the split phase (peak force rate), the time required to split test foods (duration), and the maximum occlusal force in the split phase (split force) were selected as outcomes. Data were analyzed with Wilcoxon's signed rank test, the Kruskal-Wallis test, and multiple regression analysis (Statistical significance levels: 5%).

RESULTS

For peanuts, the peak force rate for the ND group was significantly higher than the IOD and CD groups. The duration of the CD group was significantly longer than the ND and IOD groups. Multiple regression analysis indicated that even with adjustment for age and sex, there were significant differences in the peak force rate between the ND and the IOD, CD groups, and in the duration between the ND and CD group.

CONCLUSIONS

Subjects with IODs showed superior ability to adjust occlusal force, as compared with complete dentures, although it didn't match the natural dentition.

一种数字化全口义齿的临床疗效评价

OBJECTIVE

To compare the clinical efficacy of a kind of complete dentures fabricated using computer aided design/computer aided manufacturing (CAD/CAM) workflow with that of the complete denture fabricated using conventional workflow.

METHODS

Twenty edentulous patients were included in this prospective, single-blind, self-controlled clinical trial. Two pairs of complete dentures were fabricated for each participant: one using the functional suitable denture (FSD) system with CAD/CAM, and the other using conventional fabrication workflow. In the final delivery appointment, the conventional dentures worn by the participant for 3 months at first. Then the participant swapped to wear digital denture for another 3 months. The patients' satisfaction and oral health related quality of life (OHRQoL) were measured using the visual analogue scale (VAS) and oral health impact profile (OHIP-20E) at baseline, 2 weeks, 1 month, 2 months, and 3 months following denture delivery. In addition, the masticatory efficiency of each pair of dentures was measured after three months adaptation period for each type of dentures.

RESULTS

The VAS scores of the twenty patients in FSD denture group on general satisfaction, ease of cleaning, ability to speak, esthetics, stability and oral health status on these six domains were higher than that of conventional denture group 3 months after delivery. While the VAS cores in FSD denture group on comfort, ability to chew and ability to chew up were the same as those of conventional denture group. But there was no significant difference (P>0.05). The VAS score on each domain in FSD denture group was higher than that of conventional denture group 3 months after delivery, three domains of which reached statistical significance (P < 0.05), involving functional limitation, psychological discomfort and total. The masticatory performance of the FSD denture (1.20±0.54) was slightly higher than that for the conventional denture (1.16±0.53), but the difference did not reach statistical significance (P=0.691).

CONCLUSIONS

The clinical efficacy of the FSD complete denture is comparable to that of the conventional complete denture. As for patient satisfaction and oral health related quality of life, FSD dentures received comparable scores as conventional complete dentures did.

Do hydrothermal aging and microwave sterilization affect the trueness of milled, additive manufactured and injection molded denture bases?

Concepts for digital denture manufacturing are market-available but studies comparing the trueness of such dentures, either milled (MIL) or additive manufactured, compared to injection molded (IM) ones are still limited. Regarding the impact of artificial aging and microwave sterilization on this parameter, no data are available. Therefore, the purpose of this investigation was to assess the trueness of IM, MIL, and stereolithography (SLA) printed denture bases after manufacturing, hydrothermal cycling, and microwave sterilization. Sixteen edentulous maxillary plaster models were poured using a silicone mold and digitized by means of a desktop scanner. For group IM, 16 denture bases were injection molded using these models. For group MIL and SLA, the denture bases were virtually designed and manufactured referring to the digitized data. A total of 48 samples were scanned 1) after manufacturing, 2) after hydrothermal cycling (5-55 °C, N = 5,000), and after 3) three as well as 4) six cycles of microwave sterilization for 6 min each at 640 W. The 3D surface deviation of the total intaglio surface, the palate, the alveolar ridge, and the border seal region was evaluated on the basis of the root mean square estimation (RMSE) and positive and negative mean deviations with an inspection software. For statistical analysis, ANOVA and post hoc Tukey tests were performed (α = 0.05). MIL showed the lowest deviations of the total RMSE (P ≤ .006) compared with the scans of the plaster models. In comparison, IM showed increased, mainly positive, deviations (P = .006) at the border seal. SLA presented the highest total RMSE (P = .001) with increased negative deviations, likewise at the border seal. In contrast to SLA (P = .001), no differences between IM and MIL (P = .816) were measured after hydrothermal cycling. Following microwave sterilization, the trueness of SLA was higher compared to IM and MIL (P = .001), with no differences between MIL and IM (P = .153). Distortion of IM and MIL was measured after the 3rd cycle with no further changes observed thereafter (P ≥ .385). It can be concluded, that subtractive manufacturing of denture bases results in the highest trueness, followed by IM and SLA. In contrast to IM and SLA, hydrothermal cycling did not affect MIL. Solely SLA printed denture bases remained dimensionally stable after microwave sterilization.