Accuracy of flapless surgery using an autonomous robotic system in full-arch immediate implant restoration: A case series

OBJECTIVES

This observational study aimed to evaluate the accuracy of robotic computer-assisted implant surgery (r-CAIS) for full-arch immediate restoration and to analyse possible factors contributing to deviations.

METHODS

Three edentulous patients (five arches) underwent r-CAIS. Osteotomies were performed using an autonomous robot under the surgeon's supervision, and implant placement was performed in a freehand or robotic manner. Prefabricated provisional prostheses were delivered immediately after surgery. Postoperative cone beam computed tomography scans were performed to assess the deviations between the planned and placed implants. Statistics were compared with deviations of s-CAIS outlined in a meta-analysis.

RESULTS

A sum of 28 implants were used. The mean global coronal and apical deviations measured 0.91 ± 0.43 mm and 1.01 ± 0.45 mm, respectively, and the mean angular deviation measured 1.21 ± 1.24 º. The r-CAIS showed significantly better precision than the s-CAIS in full-arch cases (P < 0.001). The implants inserted using the robotic arm exhibited fewer deviations than those placed in the freehand manner. Eighty percent of prefabricated provisional prostheses were successfully delivered.

CONCLUSIONS

Within the limitations of the present study, our data suggest that autonomous r-CAIS is a feasible approach for simultaneous immediate restoration in edentulous patients, showing better accuracy than s-CAIS. Further large-scale studies are necessary to verify the advantages and disadvantages of this novel technique and to explore possible factors that influence its accuracy.

CLINICAL SIGNIFICANCE

Autonomous r-CAIS can provide clinically acceptable implant placement accuracy in edentulous patients, significantly surpassing s-CAIS. This level of accuracy may represent a viable therapeutic approach for simultaneous immediate full-arch restoration.

Influence of the scanning path on the accuracy of intraoral scanners in the implanted edentulous patient: an in vitro study

AIM

The aim of this in vitro study was to investigate the influence of scan paths on the accuracy (trueness and precision) of intra-oral scanning of an implant impression on an edentulous patient.

MATERIAL AND METHODS

An epoxy resin maxillary model was made with 6 bone level implants (NobelParallel Conical Connection RP, NobelBiocare®). The implants were placed at the spot of the first incisor, the canine and the first molar. The trans gingival component (Multi-unit, NobelBiocare®) was screwed onto the implants. The scanbodies (IO 2C-A, Elos Accurate®) were then screwed onto the multi-units. The model was run through a coordinate measurement machine to obtain a control cast. Then, five different scanning paths, respectively the zigzag technique (ZZT), the zigzag technique with palatal (ZZTP), the wrap technique (WT), the wrap technique with palatal (WTP), and the big zigzag technique (BZZT), were applied by a single operator. Finally, each scan was compared to the control model. Results were assessed by one-way ANOVA and linear mixed effects models at P<0.05.

RESULTS

The study showed that scan paths ZZT and ZZTP had significantly lower absolute positioning errors and residual mean square errors than the others (P<0.0001). For distances between consecutive implant axes and for absolute vertical errors, their superiority was borderline (P<0.10). Overall, techniques ZZT and ZZTP were equally performant and proved to be the most accurate.

CONCLUSIONS

This in vitro experimental study demonstrates that the scan path can have an influence on the accuracy of the optical impression for full arch rehabilitation on implants.

Patterns and predictors of tooth loss among partially dentate individuals in Jordan: A cross-sectional study

Aim

This study aimed to examine the patterns of partial edentulism and the associated risk factors in Jordan.

Methods

A cross-sectional, epidemiological study was carried out across Jordan, and data was collected from adult partially dentate patients in various healthcare facilities. The data collected included sociodemographic data, dental and social history, and clinical examination findings for the jaw and teeth. Multivariate regression models were used to determine the predictors for the number of missing teeth.

Results

The sample consisted of 467 partially dentate participants. The leading cause of tooth loss was dental caries (85.4 %), followed by periodontal disease (13.7 %), and trauma (7.5 %). The mean number of missing teeth was significantly higher in the upper jaw (2.5 ± 3.1) compared to the lower jaw (2.2 ± 2.6, p = 0.02). In both jaws, the most prevalent Kennedy classification was Class 3, followed by Class 3/Modification 1 and Class 2/Modification 1. Increased age, smoking, lack of daily tooth brushing, and low education level were significantly associated with high tooth loss.

Conclusions

This study contributes to the understanding of partial edentulism in Jordan, reflecting broader oral health concerns and the factors influencing tooth loss. The findings, vital for future research and interventions, offer insights applicable to global oral health challenges, particularly for at-risk groups.

Effect of a Novel 'Scan Body' on the In Vitro Scanning Accuracy of Full-Arch Implant Impressions

OBJECTIVE

This in vitro study aimed to determine whether a newly designed arcuate scan body can improve intraoral scanning accuracy for implant rehabilitation of edentulous jaws.

MATERIAL AND METHODS

A master model containing 4 implant abutment replicas was fabricated and digitized with different scan bodies using an intraoral scanner. Four types of scan bodies were evaluated: original scan bodies (group OS), computer-aided design and computer-aided manufacturing (CAD/CAM) scan bodies without extension (group CS), CAD/CAM scan bodies with straight extension (group CSS), and CAD/CAM scan bodies with arcuate extension (group CSA). Conventional splinted open-tray impressions (group CI) were used as controls. The master model and the poured casts were digitized using a laboratory scanner. Impressions were repeated 10 times each in 5 groups. Scans in standard tessellation language format were exported to reverse engineering software and root mean square (RMS) values were used for trueness and precision assessments. In each group, 45 RMS values were acquired for precision evaluation and 10 RMS values were obtained for trueness assessment. Statistical evaluation was performed with the Kruskal-Wallis test and Dunn-Bonferroni test (α = 0.05).

RESULTS

The median trueness values were 41.40, 55.95, 39.80, 39.75, and 22.30 μm for group OS, CS, CSS, CSA, and CI, respectively. CI showed better trueness than OS (P = .020), CS (P < .001), and CSS (P = .035). The median precisions for group OS, CS, CSS, CSA, and CI were 47.40, 51.50, 43.90, 25.20, and 24.60 μm. respectively. The precision of CSA and CI were higher than OS (P < .001), CS (P < .001), and CSS (P < .001). Between CI and CSA, there was no significant difference (P = 1.000).

CONCLUSIONS

For full-arch implant rehabilitation, the scan body with arcuate extension could improve the intraoral scanning precision and showed similar 3-dimensional discrepancy compared to conventional splinted open-tray impressions.

Outcomes that may affect implant and prosthesis survival and complications in maxillary fixed prosthesis supported by four or six implants: A systematic review and meta-analysis

Objective

To investigate whether the clinical and radiographical outcomes are affected when four or six implants support the maxillary fixed complete denture (FCD).

Materials and methods

This study was registered on PROSPERO (CRD42021226432) and followed the PRISMA guidelines. The focused PICO question was, "For an edentulous maxillary patient rehabilitated with an implant-supported fixed prosthesis, do the clinical and radiographical outcomes differ when four or six implants support the prosthesis ". A thorough search of the relevant studies was designed and performed electronically. The survival rate of implant and prosthesis, marginal bone loss, and complications (mechanical and biological) were the primary outcomes, whereas implant distribution and using the surgical guide, follow-up, and framework material were evaluated as secondary outcomes.

Results

Out of 1099 articles initially retrieved, 53 clearly stated the outcomes of interest and were included in this study. There were no significant differences in implant and prosthesis survival, technical/mechanical complications, and biological complications between the 4-implant group (4-IG) and the 6-implant group (6-IG). However, marginal bone loss (MBL) was significantly higher in the 4-IG (p < 0.01). The surgical guide and follow-up period did not significantly affect implant/prosthesis survival. Additionally, using the CAD/CAM milled framework and anteroposterior implant distribution were associated with significantly higher implant survival in the 6-IG (p < 0.01).

Conclusion

The findings of this study indicated that having a greater number of implants, as seen in the 6-implant group, can lead to a decrease in technical and biological complications and reduce marginal bone loss. It is worth noting that factors such as using CAD/CAM frameworks and the anteroposterior distribution of implants were recognized as important in improving implant survival rates when more implants are present.

Effect of artificial landmarks of the prefabricated auxiliary devices located at different arch positions on the accuracy of complete-arch edentulous digital implant scanning: An in-vitro study

OBJECTIVES

To examine the effect of artificial landmarks of prefabricated auxiliary devices (PAD) located at different arch positions on the accuracy of complete-arch edentulous digital implant scanning.

METHODS

A reference model containing four analogs and PAD were fabricated by a 3D printer (AccuFab-C1s, 3DShining). 10 digital scans were performed using an intraoral scanner (Aoralscan 3, 3DShining), sv 1.0.0.3115, with artificial landmarks located at different arch positions: group I, without any artificial landmarks; group II, with artificial landmarks at the anterior region; group III, with artificial landmarks at the posterior region. group IV: with artificial landmarks at both anterior and posterior regions. For group V: Conventional open-tray splinted impressions. The reference file and conventional stone casts were digitalized by using a dental laboratory scanner. The related files were imported into inspection software for trueness and precision assessment. Statistical analysis was performed with One-way ANOVA and Kruskal-Wallis test. The level of significance was set at α=0.05.

RESULTS

For the global accuracy assessment, significantly higher global trueness was seen in group II (p < 0.01), III (p < 0.001), IV (p < 0.001) and V (p < 0.001) than group I. Significantly higher global precision was seen in group III (p < 0.001), IV (p < 0.001) and V (p < 0.001) than group I. For the local accuracy assessment, the PAD primarily improved accuracy on the linear deviations.

CONCLUSIONS

Artificial landmarks of PAD at different arch positions significantly influenced the scanning accuracy. Applying the PAD in group IV could achieve comparable outcomes to conventional open-tray splinted impressions. Artificial landmarks on the posterior region may be more pivotal than those on the anterior region.

CLINICAL SIGNIFICANCE

Group IV could achieve comparable accuracy to conventional open-tray splinted impressions.

A novel post-processing strategy to improve the accuracy of complete-arch intraoral scanning for implants: an in vitro study

OBJECTIVES

To develop a new post-processing strategy that utilizes an auxiliary device to adjust intraoral scans and improve the accuracy of 3D models of complete-arch dental implants.

MATERIALS AND METHODS

An edentulous resin model with 6 dental implants was prepared. An auxiliary device, consisting of an opaque base and artificial landmarks, was fabricated and mounted onto the resin model. Twenty intraoral scans (raw scans) were taken using this setup. A new post-processing strategy was proposed to adjust the raw scans using reverse engineering software (verified group). Additionally, ten conventional gypsum casts were duplicated and digitized using a laboratory scanner. The linear and angular trueness and precision of the models were evaluated and compared. The effect of the proposed strategy on the accuracy of complete-arch intraoral scans was analyzed using one-way ANOVA.

RESULTS

The linear trueness (29.7 µm) and precision (24.8 µm) of the verified group were significantly better than the raw scans (46.6 µm, 44.7 µm) and conventional casts (51.3 µm, 36.5 µm), particularly in cross-arch sites. However, the angular trueness (0.114°) and precision (0.085°) of the conventional casts were significantly better than both the verified models (0.298°, 0.168°) and the raw scans (0.288°, 0.202°).

CONCLUSIONS

The novel post-processing strategy is effective in enhancing the linear accuracy of complete-arch implant IO scans, especially in cross-arch sites. However, further improvement is needed to eliminate the angular deviations.

CLINICAL SIGNIFICANCE

Errors generated from intraoral scanning in complete edentulous arches exceed the clinical threshold. The elimination of stitching errors in the raw scans particularly in the cross-arch sites, through the proposed post-processing strategy would enhance the accuracy of complete-arch implant prostheses.

The All-on-four concept for fixed full-arch rehabilitation of the edentulous maxilla and mandible: a longitudinal study in Japanese patients with 3-17-year follow-up and analysis of risk factors for survival rate

PURPOSE

Implant-supported immediately loaded fixed full-arch rehabilitation via All-on-four treatment yields good long-term results for both the maxilla and the mandible. However, the risk factors affecting long-term implant survival are unknown, and the long-term prognosis of All-on-four concept procedures in Japanese individuals has not been elucidated. We aimed to determine the cumulative implant survival rate after 3-17-year follow-up and identify the associated risk factors.

METHODS

We analysed 561 cases (307 maxillae, 254 mandibles) with 2364 implants (1324 maxillae, 1040 mandibles) that received All-on-four treatment. We investigated the cumulative implant- and patient-level survival rates and various risk factors for implant failure. Statistical analysis was performed using the log-rank test for differences in Kaplan-Meier curves, univariate analysis using the Chi-square test, and multivariate analysis for risk factors affecting the survival rate.

RESULTS

The cumulative survival rate was 94.4% by patient level and 97.4% by implant level for the maxilla, and 96.7% by patient level and 98.9% by implant for the mandible, with up to 17 years of follow-up. The maxillary survival rate at the implant level was significantly lower (p < 0.05). Furthermore, the maxillary survival rate within 24 months was significantly lower at the implant level (p < 0.01). Multivariate analysis revealed that the maxilla was the most significant risk factor (p < 0.01).

CONCLUSIONS

All-on-four treatment yielded high long-term survival rates in Japanese patients. However, the maxilla showed a significantly lower cumulative survival rate than the mandible, while early failure was significantly higher. Furthermore, the maxilla was a significant risk factor influencing the survival rate.

Effect of novel prefabricated auxiliary devices attaching to scan bodies on the accuracy of intraoral scanning of complete-arch with multiple implants: An in-vitro study

OBJECTIVES

To examine the effect of novel prefabricated auxiliary devices with different geometric features called Scan Body Clasp (SBC) at different levels on the accuracy of intraoral scanning of complete-arch with multiple implants.

METHODS

An edentulous maxilla 4-implant model and SBCs with different geometric features (flat or curved) were fabricated by a 3D printer (AccuFab-C1s, 3DShining, Hangzhou, China). Test scans were performed using an intraoral scanner (Aoralscan 3, 3DShining, Hangzhou, China) software version 1.0.0.3104 under different scenarios: group A (CO), without any SBCs; group B&C (LC&HC), with curved SBCs adjacent to and away from the mucosa; group D&E (LF&HF), with flat SBCs adjacent to and away from the mucosa. 20 scans were done for each group (CO, LC, HC, LF and HF). Reference Scans were obtained by digitizing the model in group A using a dental laboratory scanner (D2000, 3Shape, Copenhagen, Denmark). The related files were imported into inspection software for trueness and precision assessment. Statistical analysis was performed with One-way ANOVA, Independent-Sample T test for trueness values. Kruskal-Wallis test and Mann-Whitney test were used to assess the precision values. The level of significance was set at α=0.05.

RESULTS

Groups with SBCs demonstrated trueness enhancement, among which LF revealed the best trueness. Significant differences were also found between LF and HC (p < .01), LF and HF (p < .001), LC and HF (p < .01). LF and HF showed precision enhancement. The best precision was LF, which was found to be more precise than LC (p < .001) and HC (p < .001). HF was more precise than LC (p < .001) and HC (p < .001).

CONCLUSIONS

Attaching the scan bodies with SBCs at different levels significantly influenced the scanning accuracy. The SBCs near the mucosa result in superior trueness, while the flat morphology benefits the precision.

CLINICAL SIGNIFICANCE

The results demonstrated the feasibility of the SBCs in enhancing intraoral complete-arch implant scanning accuracy. Among the configurations tested in the present study, low-level and flat surfaces of the artificial landmarks may be the potential pivotal elements to optimizing long-span scanning accuracy.

Evaluation of the accuracy of intraoral scanners for complete-arch scanning: A systematic review and network meta-analysis

OBJECTIVES

This network meta-analysis (NMA) aimed to compare the complete-arch scanning accuracy of different intraoral scanners (IOSs) to that of reference standard tessellation language (STL) files.

DATA

Studies comparing the trueness and precision of IOS STL files with those of reference STL scans for different arch types (dentate, edentulous, completely edentulous with implants, and partially edentulous with implants) were included in this study.

SOURCES

An electronic search of five databases restricted to the English Language was conducted in October 2021.

STUDY SELECTION

A total of 3,815 studies were identified, of which 114 were eligible for inclusion. After study selection and data extraction, pair-wise comparison and NMA were performed to define the accuracy of scanning for four arch subgroups using four outcomes (trueness and precision expressed as mean absolute deviation and root mean square values). Cochrane guidelines and the QUADAS-2 tool were used to assess the risk of bias. GRADE was used for certainty assessment.

RESULTS

Fifty-three articles were included in this NMA. Altogether, 26 IOSs were compared directly and indirectly in 10 network systems. The accuracy of IOSs scans were not significantly different from the reference scans for dentate arches (three IOSs), edentulous arches (three IOSs), and completely edentulous arches with implants (one IOS). The accuracy of the IOSs was significantly different from the reference scans for partially edentulous arches with implants. Significant accuracy differences were found between the IOSs, regardless of clinical scenarios.

CONCLUSIONS

The accuracy of complete-arch scanning by IOSs differs based on clinical scenarios.

CLINICAL SIGNIFICANCE

Different IOSs should be used according to the complete arch type.

ITI consensus report on zygomatic implants: indications, evaluation of surgical techniques and long-term treatment outcomes

OBJECTIVES

The aim of the ITI Consensus Workshop on zygomatic implants was to provide Consensus Statements and Clinical Recommendations for the use of zygomatic implants.

MATERIALS AND METHODS

Three systematic reviews and one narrative review were written to address focused questions on (1) the indications for the use of zygomatic implants; (2) the survival rates and complications associated with surgery in zygomatic implant placement; (3) long-term survival rates of zygomatic implants and (4) the biomechanical principles involved when zygoma implants are placed under functional loads. Based on the reviews, three working groups then developed Consensus Statements and Clinical Recommendations. These were discussed in a plenary and finalized in Delphi rounds.

RESULTS

A total of 21 Consensus Statements were developed from the systematic reviews. Additionally, the group developed 17 Clinical Recommendations based on the Consensus Statements and the combined expertise of the participants.

CONCLUSIONS

Zygomatic implants are mainly indicated in cases with maxillary bone atrophy or deficiency. Long-term mean zygomatic implant survival was 96.2% [95% CI 93.8; 97.7] over a mean follow-up of 75.4 months (6.3 years) with a follow-up range of 36-141.6 months (3-11.8 years). Immediate loading showed a statistically significant increase in survival over delayed loading. Sinusitis presented with a total prevalence of 14.2% [95% CI 8.8; 22.0] over a mean 65.4 months follow-up, representing the most common complication which may lead to zygomatic implant loss. The international experts suggested clinical recommendations regarding planning, surgery, restoration, outcomes, and the patient's perspective.

EPA Consensus Project Paper: Accuracy of Photogrammetry Devices, Intraoral Scanners, and Conventional Techniques for the Full-Arch Implant Impressions: A Systematic Review

PURPOSE

The objective of this systematic review was to evaluate and compare the accuracy of digital impression techniques and conventional methods for full-arch implant impressions.

METHODS

An electronic literature search in the databases Medline (Pubmed), Web of Science, and Embase was performed to identify in vitro and in vivo publications (between 2016 and 2022) directly comparing digital and conventional abutment-level impression techniques. All selected articles passed through the data extraction procedure according to defined parameters in inclusion and exclusion criteria. Measurements on linear, angular and/or surface deviations were performed in all selected articles.

RESULTS

Nine studies met the inclusion criteria and were selected for this systematic review. 3 articles were clinical studies and 6 studies were in vitro. Accuracy difference mean values of the trueness up to 162+/-77μm between digital and conventional techniques were reported in the clinical studies and up to 43μm in laboratory studies. Methodological heterogeneity was observed in both, in vivo and in vitro studies.

CONCLUSIONS

Intraoral scanning and photogrammetric method showed comparable accuracy for registering implant positions in the full-arch edentulous cases. A tolerable implant prosthesis misfit threshold and objective misfit assessment criteria (for linear and angular deviations) should be verified in clinical studies.

In vivo trueness and precision of full-arch implant scans using intraoral scanners with three different acquisition protocols

OBJECTIVES

To evaluate an in situ reference acquisition method for implant positions in complete edentulous maxillae using an industrial scanner and allowing for in vivo trueness analysis of the restorative workflow. To assess in vivo trueness and precision of intraoral scanners (IOS) using different acquisition protocols. Furthermore, to compare IOS trueness with impression-based models and implant-supported fixed dentures (IFD) in a parallel study on the same cohort using the same in situ reference scan.

METHODS

Six scan-bodies mounted to maxillary implants in five subjects were reference scanned (REF) using an industrial scanner. Subjects were scanned with IOS three times using three different protocols: control (CT), dental floss assisted (DF), and acrylic splint (SP). CAD-files of scan-bodies with inter-aligned analogues were geometry-aligned to REF, and SP. Scan-bodies were aligned to CT and DF in proprietary dental laboratory software and exported with analogue positions. Resulting six CAD-analogues per scan were Globally Aligned using a consistent geometry-based alignment. Deviations were computed after a Reference Point System Alignment at the implant/prosthetic platform for Cartesian axes with a linear Resultant.

RESULTS

Resultant trueness was CT: 41±11 µm, DF: 49±22 µm, SP: 55±8 µm. Resultant precision was CT: 48±7 µm, DF: 50±7 µm, SP: 45±6 µm.

CONCLUSIONS

This method is applicable for assessing trueness of maxillary full-arch implant scans in vivo. The CT protocol was most accurate. CT trueness showed no difference to digitised impression-based models in parallel study. CT was more accurate than IFD in a parallel study. CT displayed similar numerical trueness as existing in vitro studies.

CLINICAL SIGNIFICANCE

Using IOS to acquire full-arch implant scans is controversial. The modified protocol in this pilot shows promising results in the maxilla where great care was taken to manage non-attached tissues when a modified scanning pattern was used. However, other IOS may show varying results in vivo. A completed scan does not necessarily equate to an accurate scan.

The performance of two-implant overdentures in the atrophic maxilla: a case series with 1-year follow-up

PURPOSE

To assess the implant and prosthesis survival rates, the clinical, radiographical and patient-related outcome measures, and the masticatory performance of maxillary overdentures supported by two implants in patients with an atrophic maxilla.

METHODS

In this case series, 15 consecutive patients who were eligible for maxillary implant overdenture therapy, but who had insufficient bone volume to place at least four implants and were unwilling to be treated with reconstructive surgery were asked to participate. After giving consent, participants received two implants in the maxilla under local anaesthesia. After 3 months of osseointegration, a maxillary overdenture with palatal coverage and solitary attachments was fabricated. Implant and overdenture survival, marginal bone level change, clinical outcome measures, masticatory performance and patient-related outcomes were evaluated at baseline and 1 year after overdenture placement.

RESULTS

Fourteen out of 15 participants completed the follow-up period of 12 months. Implant and overdenture survival rate were 89.3% and 85.7%, respectively. Change in marginal bone level (- 0.5 ± 0.7 mm), change in probing depth (0.0 ± 1.0 mm), and clinical outcomes were favourable. Masticatory performance and patient-related outcomes improved significantly compared to baseline. Complications were minimal.

CONCLUSIONS

Within the limitations of this study, it can be concluded that patients with extreme resorption of the maxilla that are unwilling to be treated with reconstructive surgery, benefit from two-implant maxillary overdentures retained by solitary attachments in terms of improved masticatory functioning and denture satisfaction. However, they have relatively high risk of implant loss.

TRIAL REGISTRATION

UMCG Trial Register (RR201900060), registered 22 January 2019.

Three-dimensional position changes of unopposed molars before implant rehabilitation: a short-term retrospective cohort analysis

OBJECTIVE

To investigate the spatial changes of unopposed molars within the period between the antagonist extraction and the final implant restoration using data from cone beam computed tomography.

METHODS

A total of 59 patients with 68 unopposed molars were included in this study. Three-dimensional models reconstructed from cone beam computed tomography data before and after loss of the antagonist were superimposed to measure the spatial changes. The overeruption and tipping of target teeth were calculated by coordinate values.

RESULTS

The result of overeruption over the study period (9.2 ± 4.3 months) was expressed by two values: the mean overeruption of molar cups (0.432 mm) and the maximum overeruption of cusps (0.753 mm), which were statistically significant compared to the baseline level (p < 0.001). The average tipping was 1.717 degrees in the buccal direction.

CONCLUSIONS

Unopposed molars displayed overeruption throughout the study period (9.2 ± 4.3 months), which indicates that the clinicians should pay attention to the possibilities of overeruption and make appropriate interventions in their clinical practice. The establishment of three-dimensional measuring methods using cone beam computed tomography data helps analyze spatial changes.

Workflow for the full-mouth rehabilitation of a patient with different prosthetic materials in opposing arches: A bold move in desperate scenario

Fixed rehabilitation is an exhaustive approach for most dental practitioners to treat partial or complete edentulism. In recent years, we are witnessing a digital transformation in prosthodontics and smile makeovers. This requires an in-depth understanding of concepts and the skills to achieve desired clinical results. Many situations of the oral cavity often need fixed rehabilitation treatment. This extensive treatment primarily solves two goals: maintains crown integrity and also achieves optimal esthetics. To restore lost parts of the stomatognathic system, a multidisciplinary approach is of utmost importance. The treatment options may range from removable implant-supported dentures to fixed implant-supported prostheses. The choice of treatment relies on the limitations of anatomic structures and existing. Partial or complete edentulousness can inadvertently reduce the quality of life of the patient and may hinder physiology. This report narrates a combination of two types of dental prosthetic material to obtain a desirable outcome in fixed rehabilitation of a patient. Furthermore, it highlights the management of complete treatment in a limited period and patient appointments.

Analysis of the Volumetric Asymmetry of the Mandibular Condyles Using CBCT

Objectives

The aim of this study was to analyse volumetric asymmetries between the right and left condyles in relation to age, gender, and dental status.

Materials and methods

A retrospective analysis of 150 cone beam computed tomography (CBCT) scans was conducted. A single investigator performed the volumetric analysis of the CBCT scans using Vesalius 3D software. The volumetric data were analysed in relation to the gender, age, and dental status.

Results

The mean right condylar volume was significantly higher (P < .01) than the left condylar volume. Right and left condylar volumes were significantly higher (P < .01) in male study participants when compared to female study participants. There was no significant difference (P = .47) in the volumetric asymmetry between the male and female study participants. The volumetric asymmetry was significantly higher (P < .01) in the older age groups when compared to the younger age groups. The volumetric asymmetry was significantly higher (P < .01) in the partially and completely edentulous patients when compared to the dentate study participants. The condylar volume on the side having a partially edentulous area was significantly lower than the condylar volume of the contralateral dentate side (P < .001).

Conclusions

The volumetric asymmetry between the right and left condyle significantly increases with age and edentulousness. The result of the study encourages the clinicians to perform volumetric evaluation of the condyles in cases of radiographically evident condylar asymmetries to obtain a more accurate diagnosis.

Association of Oral Health and Mini Nutritional Assessment in Older Adults: A Systematic Review with Meta-analyses

PURPOSE

To evaluate whether poor oral health is associated with a higher risk of malnutrition based on the Mini Nutritional Assessment (MNA) or MNA-SF (short form) in older adults.

STUDY SELECTION

For this meta-analysis, cohort and cross-sectional studies with adults 65 years and older, reporting oral health outcomes (i.e. edentulism, number of teeth) and either the MNA or MNA-SF were selected. Four electronic databases were searched (Medline via PubMed, Web of Science, Cochrane Library and EMBASE) through June 2020. Risk of bias was assessed with the checklist by the Agency for Healthcare Research and Quality scale.

RESULTS

A total of 928 abstracts were reviewed with 33 studies, comprising 27,559 participants, aged ≥65 being ultimately included. Meta-analyses showed that the lack of daily oral hygiene (teeth or denture cleaning), chewing problems and being partially/fully edentulous, put older adults at higher risk of malnutrition (p<0.05). After adjustment for socio-demographic variables, the included studies reported lack of autonomy for oral care, poor/moderate oral health, no access to the dentist and being edentulous with either no dentures or only one denture were risk factors significantly associated with a higher risk of malnutrition (p<0.05).

CONCLUSION

These findings may imply that once elders become dependent on others for assistance with oral care, have decreased access to oral healthcare, and lack efficient chewing capacity, there is increased risk of malnourishment. Limitations of the study include heterogeneity of oral health variables and the observational nature of the studies. Further studies are needed to validate our findings.

The validity of self-reported number of teeth and edentulousness among Norwegian older adults, the HUNT Study

Background

Number of teeth is an established indicator of oral health and is commonly self-reported in epidemiological studies due to the costly and labor-intensive nature of clinical examinations. Although previous studies have found self-reported number of teeth to be a reasonably accurate measure, its accuracy among older adults ≥ 70 years is less explored. The aim of this study was to assess the validity of self-reported number of teeth and edentulousness in older adults and to investigate factors that may affect the accuracy of self-reports.

Methods

This study included two different samples of older adults ≥ 70 years drawn from the fourth wave of the Trøndelag Health Study (the HUNT Study), Norway. Sample 1 (n = 586) was used to evaluate the validity of self-reported number of teeth and sample 2 (n = 518) was used to evaluate self-reported edentulousness. Information on number of teeth and background variables (education, smoking, cognitive function, and self-perceived general and oral health) were self-reported in questionnaires, while clinical oral health examinations assessed number of teeth, number of teeth restored or replaced by fixed prosthodontics and edentulousness. Spearman and Pearson correlation coefficients, Bland–Altman plot, chi-square test and kappa statistics were used to assess the agreement between self-reported and clinically recorded number of teeth.

Results

The mean difference between self-reported and clinically recorded number of teeth was low (− 0.22 teeth), and more than 70% of the participants reported their number of teeth within an error of two teeth. Correlations between self-reports and clinical examinations were high for the total sample (0.86 (Spearman) and 0.91 (Pearson)). However, a lower correlation was found among participants with dementia (0.74 (Spearman) and 0.85 (Pearson)), participants having ≥ 20 teeth (0.76 (Spearman) and 0.67 (Pearson)), and participants with ≥ 5 teeth restored or replaced by fixed prosthodontics (0.75 (Spearman) and 0.77 (Pearson)). Self-reports of having teeth or being edentulous were correct in 96.3% of the cases (kappa value 0.93, p value < 0.001).

Conclusions

Among older Norwegian adults, self-reported number of teeth agreed closely with clinical tooth counts and nearly all the edentulous participants correctly reported having no teeth.

Management of Bilateral Condylar Fractures in an Edentulous Patient with Atrophic Mandible Using CADCAM Technology

Purpose

The objective of this article is to report the case of an edentulous patient with a diagnosis of bilateral condylar fracture, who was treated using virtual planning.

Methods

CAD/CAM technology was used for the design and manufacture of a Gunning splint, which was employed for open reduction of the right fracture and closed management of the left side.

Results

The reduction of the right condylar fracture projected in the planning was achieved, as well as the return of the vertical dimension and the restoration of function, after 28 months of observation.

Conclusion

In the case of total edentulism, the lack of occlusal guidance and bone atrophy are important variables to consider; however, tools such as CAD/CAM technology can be used to take more predictable treatment decisions and facilitate the execution of the procedures.

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.

Vascular and neurosensory evaluation in relation to lingual canal anatomy after mandibular midline implant installation in edentulous patients

Objectives

The aim of this study is to investigate vascular and neurosensory complications in edentulous patients following the installation of mandibular midline single implants in relation to lingual canals.

Materials and methods

After performing a cone beam computed tomography scan for the 50 recruited patients, the relationship between the potential implant site and the lingual canals was assessed, and all vascular and neurosensory complications were recorded.

Results

Six patients (12%) reported profuse bleeding during implant placement, and 13 (26%) reported transient neurosensory changes, which were resolved after 3 months. According to the virtual implant planning, 44 patients (88%) would have their implants touching the lingual canals, six of them reported vascular changes (14%), and 12 out of 44 patients reported neurosensory changes (27%). For the six patients who would have their implants not touching the lingual canals, one patient reported transient neurosensory changes.

Conclusions

The mandibular lingual canals are constant anatomic landmarks. Injury to the supra-spinosum lingual canals may occur during midline implant placement, depending on the implant length and the bone height.

Clinical relevance

Despite that injury to the supra-spinosum lingual canals during implant insertion does not result in permanent vascular or neurosensory complications, caution is required to avoid the perforation of the lingual cortices.

Accuracy of photogrammetry, intraoral scanning, and conventional impression techniques for complete-arch implant rehabilitation: an in vitro comparative study

Background

To compare the accuracy of photogrammetry, intraoral scanning and conventional impression techniques for complete-arch implant rehabilitation.

Methods

A master cast containing 6 implant abutment replicas was fabricated. Group PG: digital impressions were taken 10 times using a photogrammetry system; Group IOS: intraoral scanning was performed to fabricate 10 digital impressions; Group CNV: splinted open-tray impression technique was used to fabricate 10 definitive casts. The master cast and conventional definitive casts were digitized with a laboratory reference scanner. For all STL files obtained, scan bodies were converted to implant abutment replicas using a digital library. The accuracy of a digitizer was defined by 2 main parameters, trueness and precision. "Trueness" was used to describe the deviation between test files and reference file, and "precision" was used to describe the closeness between test files. Then, the trueness and precision of three impression techniques were evaluated and statistically compared (α = 0.05).

Results

The median trueness was 24.45, 43.45 and 28.70 μm for group PG, IOS and CNV; Group PG gave more accurate trueness than group IOS (P < 0.001) and group CNV (P = 0.033), group CNV showed more accurate trueness than group IOS (P = 0.033). The median precision was 2.00, 36.00 and 29.40 μm for group PG, IOS and CNV; Group PG gave more accurate precision than group IOS (P < 0.001) and group CNV (P < 0.001), group CNV showed more accurate precision than IOS (P = 0.002).

Conclusions

For complete-arch implant rehabilitation, the photogrammetry system showed the best accuracy of all the impression techniques evaluated, followed by the conventional impression technique, and the intraoral scanner provided the least accuracy.

Improved accuracy of digital implant impressions with newly designed scan bodies: an in vivo evaluation in beagle dogs

Background

The accuracy of digital impressions for fully edentulous cases is currently insufficient for routinely clinical application. To overcome the challenge, a modified scan body was introduced, which demonstrated satisfactory accuracy in vitro. The aim of this study was to evaluate the accuracy of digital impressions using the modified scan bodies with extensional structure versus scan bodies without extensional structure in mandible with two implants in beagle dogs.

Methods

The unilateral mandibular second premolar to second molar were extracted in four beagle dogs. Twelve weeks later, two implants were placed. Five repeated digital impressions were performed with an intraoral scanner on each dog using each of the two different scan bodies: Group I—scan body without extensional structure (SB); Group II—scan body with extensional structure (SBE). The scans were exported to Standard Tessellation Language (STL) files to serve as test data. The dogs were sacrificed and the dissected mandibles were digitalized with a lab scanner to provide reference data. Linear and angular deviations were calculated in an inspection software for accuracy assessment. Statistical analysis was performed with two-way ANOVA. The level of significance was set at α = 0.05.

Results

For trueness assessment, the mean of absolute linear/angular deviations were 119.53 μm/0.75 degrees in Group I and 68.89 μm/0.36 degrees in Group II. SBE was more accurate than SB regarding both linear (p = 0.008) and angular (p = 0.049) deviations. For precision assessment, the mean of absolute linear/angular deviations were 63.01 μm/0.47 degrees in Group I and 38.38 μm/0.24 degrees in Group II. No significant difference was found.

Conclusions

The application of SBE significantly improved the trueness of digital impressions in mandible with two implants compared to SB. No significant difference was found in terms of precision.

Oral health of the 65+ age group in Israel-2020

Background

In 2019, a reform of dental services for older adults was implemented in Israel to improve access and reduce barriers that stood in their way. The reform stipulated that preventive and restorative dentistry would be included in the basket of services of the National Health Insurance Law. The current study was conducted by the Myers-JDC-Brookdale Institute (MJB) and the Division of Dental Health of Israel’s Ministry of Health to examine the dental status and patterns of utilizations of dental services among the 65+ age group. This paper reports on the dental status of the 65+ age group in comparison with the same population two decades earlier.

Goals

To describe the dental status of Israel’s 65+ age group, and to identify the population at risk of dental morbidity.

Methodology

Telephone interviews were conducted with a representative sample of 512 older adults aged 65+, from February to April 2020.

Main findings

Some two-thirds of the 65+ age group assessed their oral health as good or very good. Twenty-four percent did not have natural teeth, while the rest had 19 teeth on average. Ten percent had not lost any teeth. In the 65–74 age group, 19% had no natural teeth and the rest had 20 teeth on average. In contrast, in the 85+ age group, 38% were edentulous and the rest had 13 teeth on average. Of the older adults who found it difficult to cover their monthly expenses, 39% were edentulous—twice the percentage of those who did manage to cover their monthly expenses (19%). Of the 65+ age group 44% had dentures—37% in the 65–74 age group, and 66% in the 85+ age group. Approximately 40% of the 65+ age group saw a dentist for preventive check-ups. The rest did not, mainly due to lack of awareness of the importance of doing so.

Conclusions and recommendations

The perceived status of oral health among the 65+ age group is currently better than it was 22 years ago. However, despite the improvement in oral health and health behavior, there are still barriers to the utilization of dental services. The main barriers are a lack of awareness of the importance of proper health behavior, and the cost of care for people with financial difficulty. This study provides decision-makers with data on the status of oral health, the utilization of dental services and the geographical disparities. The findings will help policy makers evaluate the effectiveness of the reform and fine tuning it in the future. Policies should be instated to increase awareness of constituencies and their access to the services, in addition to the entitlements the reform granted.

Effects of attachment type and number of dental implants supporting mandibular overdenture on peri-implant health: A systematic review and network meta-analysis

PURPOSE

To evaluate the effect of overdenture (OD) attachment type and the number of implants supporting mandibular ODs on peri-implant health.

STUDY SELECTION

From inception to October 2020, electronic databases (Medline/PubMed, Embase, Cochrane Library, and Scopus) were systematically searched. The outcomes of interest were marginal bone loss (MBL), pocket probing depth (PPD), plaque index, bleeding index, and implant survival rate. Bayesian network meta-analysis was performed using the GeMTC package supported by R. The weighted mean difference and 95% credible interval were estimated.

RESULTS

Twenty-eight studies with a total of 1166 participants who received 2666 dental implants were included. Except for 4 bar and 4 telescopic, which showed a statistically lower MBL than the 2 locator, all other interventions showed insignificant differences in MBL (P > 0.05). The difference in periodontal probing depth was not statistically significant when comparing the different groups. The pooled implant survival rates of the different interventions ranged from 88.9% to 100%. The rank probability test showed that 4 bar and 4 telescopic had the lowest MBL, 2 magnet and 2 bar had the highest PI, whereas 4 locator showed the least PPD.

CONCLUSIONS

Except for 4 implants+bar, or telescopic, and 4 locator that, respectively, showed less MBL and PPD compared to some interventions, it seemed that different attachment types and number of implants supporting mandibular ODs have no clear superiority over the other in terms of peri-implant health outcomes.

Flapless Localised Management of Sinus Floor (LMSF) for trans-crestal sinus floor augmentation and simultaneous implant placement. A retrospective non-randomized study: 5-year of follow-up

Background

Trans-crestal sinus lift procedures are well established.

Purpose

to retrospectively analyse the efficacy of a flapless trans-crestal maxillary sinus floor elevation and simultaneous dental implant placement based on the Localised Management of Sinus Floor (LMSF) technique suitable for cases with sufficient width of keratinized tissue and of crestal bone but insufficient vertical dimensions of the bone below the sinus.

Materials and methods

71 sinus elevations with simultaneous implant placement were performed on 52 consecutive patients. Following an initial pilot bur transmucosal perforation, the Magnetic Mallet was used with progressively larger osteotomes. The mallet osteotomes are initially directed palatally, towards the cortex of the medial wall of the sinus, below the palato-nasal recess (PNR) and then redirected in a more vertical direction to create the final osteotomy for implant placement.

Results

No significant complications were reported in the post-operative phase. The cumulative success rate during the observation period was 95%. All successful implants were successfully loaded with metal-ceramic or monolithic zirconia crowns and bridges and remained in function during the observation period.

Conclusions

Flapless Localised Management of Sinus Floor (LMSF) is a safe and effective surgical technique with minimal risks and with the advantage of low morbidity. Also, only native bone is used for augmentation and there is no need for additional grafting.

General health, healthcare costs and dental care use of elderly with a natural dentition, implant-retained overdenture or conventional denture: an 8-year cohort of Dutch elderly (aged 75 and over)

Background

Cross-sectional studies have shown that elderly with a natural dentition have better general health than edentulous elderly, but this has not been confirmed in studies with longitudinal design.

Methods

This prospective longitudinal study with a follow-up of 8 years aimed to assess differences in general health, healthcare costs and dental care use between elderly with a natural dentition and edentulous elderly wearing implant-retained or conventional dentures. Based on data of all national insurance claims for dental and medical care from Dutch elderly (aged ≥75 years) general health outcomes (chronic conditions, medication use), healthcare costs and dental care use could be assessed of three groups of elderly, viz. elderly with a natural dentition, elderly with conventional dentures and elderly with implant-retained overdentures.

Results

At baseline (2009), a total of 168,122 elderly could be included (143,199 natural dentition, 18,420 conventional dentures, 6503 implant-retained overdentures). Here we showed that after 8 years follow-up elderly with a natural dentition had more favorable general health outcomes (fewer chronic conditions, less medication use), lower healthcare costs and lower dental costs – but higher dental care use – than edentulous elderly. At baseline the general health of elderly with an implant-retained overdentures resembled the profile of elderly with a natural dentition, but over time their general health problems became comparable to elderly with conventional dentures.

Conclusions

It was concluded that elderly with a natural dentition had significant better health and lower healthcare costs compared to edentulous elderly (with or without dental implants).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02427-z.

Stability of masticatory movements after placement of implant-supported denture

The purpose of this study was to clarify the stability of masticatory movement after placement of implant-supported denture. Fourteen patients (patient group) with mandibular implants denture and maxillary complete denture and 30 dentate adults (control group) were asked to chew a boiled fishpaste, and the masticatory movement was recorded using MKG. For the 10 cycles beginning with the 5th cycle of mastication, the parameters representing the stability of masticatory movement were calculated. Data collected at 1, 3, 6, 9 months and 1, 2, 3 years after insertion of implants denture were compared between sessions and also between the patient and control groups. The mean and standard deviation of the values in the patient group at 1 month after insertion of implants denture were large, but gradually decreased 6 to 9 months after insertion of implants denture. Each parameter maintained almost the same value from 1 to 3 years. The parameter values of the patient group were significantly larger than those of control group from 1 to 9 months after insertion of implants denture, but 1 year after insertion of implants denture, there was no significant difference between the two groups in 5 out of 7 parameters. From these results, it was suggested that a certain duration, about 9 months to 1 year, was necessary for patients with implants denture to adapt to the new masticatory function and that the timing of functional evaluation should be set to 1 year after insertion of implants denture.

Tooth loss as a potential risk factor for deficient sleep: an analysis of a nationally representative sample of adults in the USA

PURPOSE

Sleep deficiency is implicated as a risk factor for several systemic conditions. Loss of teeth has a profound effect on the individual's physiologic and psychologic health and quality of life. This study aimed to assess the association between tooth loss and sleep duration and determine if anterior and/or posterior tooth loss is a significant predictor.

METHODS

A total of 22,483 individuals ≥ 18 years who participated in the United States National Health and Nutrition Examination Survey (NHANES) 2005-2016 cycles were included. Multinomial logistic regression adjusted for age, gender, race/ethnicity, smoking, diabetes, body mass index, socioeconomic level, education, alcohol, and depression was performed to examine the association between sleep duration and tooth loss.

RESULTS

Compared to individuals with > 20 remaining teeth, those who were completely edentulous, had 1-10 or 11-20 teeth remaining were more likely to be in the deficient sleep category (OR [95% CI] = 1.59 [1.35-1.87], 1.29 [1.07-1.54], and 1.26 [1.11-1.43], respectively). When the numbers of both missing anterior and posterior teeth were entered in the model, only posterior teeth were significant. There was a 4% increase in the odds of being in the deficient sleep category for each missing posterior tooth (OR [95% CI] = 1.04 [1.02-1.05]).

CONCLUSIONS

Tooth loss was significantly associated with deficient sleep and posterior tooth loss appeared to be the main contributor. Although further research is needed to clarify the nature of this association, our results suggest that improving oral health might have an impact on overall health and quality of life.

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.

Association Between Tobacco Smoking, Dental Status and Self-perceived Oral Health in Elderly Adults in Colombia

Tobacco smoking is responsible for several health problems, including mouth diseases. The aim of the present study was to establish the association between smoking and dental status and self-perceived oral health in a large group of elderly Colombian adults. Analysis of 18,937 survey records of participants aged ≥ 60 years old was conducted. Information regarding age, sex, skin color, socioeconomic level, education, marital status, denture use, partial tooth loss or edentulism, Geriatric Oral Health Assessment Index (GOHAI) and tobacco smoking was retrieved from the database. A descriptive analysis and multivariate logistic regression analysis were performed. Half of the participants were edentulous in the maxilla while mandibular teeth were more frequently retained in more than 60% of the participants. After adjusting for sex and age, smoking consistently increased the odds of partial or complete edentulism in the maxilla (OR 1.05; 95% CI 1.02-1.09) and mandible (OR 1.04; 95% CI 1.00-1.08). Nonetheless, the increase in the odds in the mandible was not statistically significant. The habit of smoking was associated with increased tooth loss that in the long-term may result in poor oral health affecting the quality of life of elderly people.

ceramic superstructures according to the All-on-4 treatment concept for the rehabilitation of the edentulous maxilla

The aim of the current study was to document the long-term clinical results of the use of two prosthetic techniques for the rehabilitation of completely edentulous maxillae according to the “All-on-Four” concept: Fixed, screw-retained prosthesis mounted on a chrome-molybdenum framework with (1) metal-ceramic veneers and (2) Acrylic prosthesis with acrylic resin prosthetic teeth. A total of 34 patients were assigned to subgroups according to their own preference of the superstructure type (ceramics [n: 17] or acrylic resin [n: 17]). Prosthetic complications, marginal bone loss, plaque accumulation, bleeding on probing, bite force and oral-health-related quality of life were assessed over a period of 6 years. Marginal bone loss around implants of the ceramic group remained well within the limits for ‘success’, as defined by the 2007 Pisa consensus over the time (1.43 ± 0.35 mm). However, marginal bone loss was significantly more pronounced around the implants in the acrylic group (2.15 ± 0.30) and the difference between two groups was statistically significant (p: 0.00). Bleeding on probing and plaque accumulation showed also positive correlation with marginal bone loss. Both acrylic and ceramic suprastructures appeared to be equivalent after 6 years; however, ceramic suprastructures revealed superior clinical results in terms of bone loss and plaque accumulation. Current study determines the long-term clinical outcomes of different prosthetic management alternatives in All-on-Four and aids to increase dental professionals’ ability to meet the patients’ expectations.

Long transmaxillary implants improve oral health-related quality of life of patients with atrophic jaws-a case series

Background

The advancement of contemporary dentistry is related to the improvement of existing techniques, materials, and technology, consistently for improving people’s oral health, which can ultimately reflect better quality of life. This study aimed to evaluate the oral-health-related quality of life (OHRQoL) of patients with atrophic jaws, who reported for the placement of long transmaxillary implants and posterior prosthetic rehabilitation. Twelve patients (n = 12), of both sexes, with a mean age of 55.83 ± 2.78 years, who were unable to receive conventional implants immediately because of lack of bone, received two long transmaxillary implants in a horizontal position, anteroposteriorly, one on each side, from the canine pillar to the maxillary tuberosity. After 6 months, the conventional clinical sequence for fabricating a fixed prosthesis type protocol or removable prosthesis type overdenture (MK1® system) was performed, when required to recover the lip volume. The Oral Health Impact Profile questionnaire (OHIP-14) was applied preoperatively and 6 months after rehabilitation using a prosthesis on the implants. The results were statistically analyzed using a significance level of 0.05.

Results

An improvement in the perception of OHRQoL was observed between the pre- and postoperative periods in the OHIP-14 total score and the domains related to functional limitation, physical pain, psychological discomfort, psychological disability, social disability, and handicap (p < 0.05).

Conclusion

It may be concluded that transmaxillary implant rehabilitation improves the OHRQoL.

non-guided insertion of Ambu AuraGain™ in edentulous patients

BACKGROUND

Supraglottic airway devices perform more poorly and have lower oropharyngeal leak pressure in edentulous patients than in patients with teeth. The Ambu Aura Gain is a newer second generation supraglottic airway device.

OBJECTIVE

This randomized clinical trial assessed the oropharyngeal leak pressure in edentulous patients using the Ambu Aura Gain with a gastric tube for insertion guidance and without insertion guidance.

MATERIAL AND METHODS

Patients with ASA (American Society of Anesthesiology) physical status I-III were recruited. Primary outcome was oropharyngeal leak pressure after insertion. Secondary outcome parameters were oropharyngeal leak pressure 15 min and 30 min after insertion, insertion time, insertion attempts and glottis view through flexible fiberscope.

RESULTS

In this study 72 patients aged between 51 and 90 years (mean 73 years) were randomly allocated to the "with guidance" (n = 36) or the "without guidance" group (n = 36). Mean (SD) oropharyngeal leak pressure in "with guidance" and "without guidance" group was 24 cm H₂O and 24 cm H₂O (ns), respectively. A difference was found in mean insertion time with guidance versus without guidance group 52 s (45 s) vs. 26 s (15 s) (p < 0.001). No difference was found in any of the other secondary outcome parameters.

CONCLUSION

A guided insertion technique does not improve oropharyngeal leak pressure of the Ambu AuraGain™ in edentulous patients. As the only difference is an increase in insertion time this technique is of no benefit for this population.

Comparison of peri-implant submucosal microbiota in arches with zirconia or titanium implant-supported fixed complete dental prostheses: a study protocol for a randomized controlled trial

Background

The success rate of implant-supported prostheses for edentulous patients is relatively high. However, the incidence of biological complications, especially peri-implant mucositis and peri-implantitis, increases yearly after the placement of prostheses. The accumulation of pathogenic bacteria adjacent to a prosthesis is the main cause of biological complications. Titanium, one of the classical materials for implant-supported prostheses, performs well in terms of biocompatibility and ease of maintenance, but is still susceptible to biofilm formation. Zirconia, which has emerged as an appealing substitute, not only has comparable properties, but presents different surface properties that influence the adherence of oral bacteria. However, evidence of a direct effect on oral flora is limited. Therefore, the aim of the present study was to assess the effects of material properties on biofilm formation and composition.

Methods

The proposed study is designed as a 5-year randomized controlled trial. We plan to enroll 44 edentulous (mandible) patients seeking full-arch, fixed, implant-supported prostheses. The participants will be randomly allocated to one of two groups: group 1, in which the participants will receive zirconia frameworks with ceramic veneering, or group 2, in which the participants will receive titanium frameworks with acrylic resin veneering. Ten follow-up examinations will be completed by the end of this 5-year trial. Mucosal conditions around the implants will be recorded every 6 months after restoration. Peri-implant submucosal plaque will be collected at each reexamination, and bacteria flora analysis will be performed with 16S rRNA gene sequencing technology in order to compare differences in microbial diversity between groups. One week before each visit, periodontal maintenance will be arranged. Each participant will receive an X-ray examination every 12 months as a key index to evaluate the marginal bone level around the implants.

Discussion

The current study aims to explore the oral microbiology of patients following dental restoration with zirconia ceramic frameworks or titanium frameworks. The features of the microbiota and the mucosal condition around the two different materials will be evaluated and compared to determine whether zirconia is an appropriate material for fixed implant-supported prostheses for edentulous patients.

Trial registration

International Clinical Trials Registry Platform (ICTRP) ChiCTR2000029470. Registered on 2 February 2020. http://www.chictr.org.cn/searchproj.aspx?

[Long-term clinical effect of full-mouth implant fixation in middle-aged and elderly patients with static computer-assisted implant surgery]

Objective: To evaluate long-term clinical outcome of implant-supported fixed prosthesis with the guidance of computer-aided design/computer-aided manufacturing (CAD/CAM) surgical template in old patients. Methods: Fifteen 50-67(58.6±5.3) year-old patients (11 males and 4 females) who received the digital implant surgery with the guidance of CAD/CAM surgical template and implant-supported fixed prosthesis in Department of Oral Implantology, Yantai Stomatological Hospital Affiliated to Binzhou Medical College from August, 2013 to Janurary, 2016 were included. There are 15 edentulous maxillas, 8 edentulous mandibles on which 145 implants were placed in total. After the placement of implant, the accuracy of CAD/CAM surgical template was assessed by comparing the post-operative 3-dimensional location of implant with the pre-operative design. The 5-year survival rate of implant and prosthesis was recorded, and marginal bone loss around implants and the development of complication were evaluated by radiological and clinical examination respectively. Results: The result on accuracy of CAD/CAM surgical template showed that deviations in neck and apex of implants were (0.78±0.59) and (1.38±0.63) mm respectively, depth deviation was (0.65±0.35) mm and angle deviation was 4.12°±2.77°. The 5-year cumulative survival rate of implants was 98.6%(143/145). In all 145 implants, the prevalence of implant-related biological complication was 4.1%(6/145). The prosthesis-related mechanical complication rate was 57%(13/23). After 5-year function, mean peri-implant bone loss was (0.69±0.35) mm. Conclusions: This 5-year follow-up retrospective study showed that implant-supported fixed prosthesis with the guidance of CAD/CAM surgical template in middle aged and elderly patients could achieve good long-term clinical outcome and patient satisfaction.

Accuracy of implant surgical guides fabricated using computer numerical control milling for edentulous jaws: a pilot clinical trial

Background

To evaluate the accuracy of a computer numerical control (CNC) milled surgical guide for implant placement in edentulous jaws.

Methods

Edentulous patients seeking implants treatment were recruited in this prospective cohort study. Radiographic guides with diagnostic templates were fabricated from wax-up dentures. Patients took cone-beam computed tomography (CBCT) wearing the radiopaque radiographic guides. Implant positions were virtually designed in the planning software based on the CBCT data, and the radiographic templates were converted into surgical guides using CNC milling technique. Forty-four implants were placed into 12 edentulous jaws following guided implant surgery protocol. Post-surgery CBCT scans were made for each jaw, and the deviations between the planned and actual implant positions were measured. Deviation of implant position was compared between maxilla and mandible, and between cases with and without anchor pins using independent t-test.

Results

Nine patients (3 males and 6 females) with 12 edentulous jaws were recruited. The mean age of patients was 59.2 ± 13.9 years old. All 44 implants was placed without complication and survived, the mean three dimensional linear deviation of implant position between virtual planning and actual placement was 1.53 ± 0.48 mm at the implant neck and 1.58 ± 0.49 mm at the apex. The angular deviation was 3.96 ± 3.05 degrees. No significant difference was found in the deviation of implant position between maxilla and mandible (P = 0.28 at neck, 0.08 at apex), nor between cases with and without anchor pins (P = 0.87 at neck, 0.06 at apex).

Conclusions

The guides fabricated using the CNC milling technique provided comparable accuracy as those fabricated by Stereolithography. The displacement of the guides on edentulous arch might be the main contributing factor of deviation.

Trial registration: Chinese Clinical Trial Registry, ChiCTR-ONC-17014159 (July 26, 2017).

Preprosthetic Dentoalveolar Surgery

Preprosthetic surgery remains a work horse of dentoalveolar surgery. Advances in rehabilitation of the edentulous mouth with the use of endosseous osseointegrating dental implants and dermal matrix substitutes have changed the narrative of traditional preprosthetic surgery while maintaining some fundamental principles. An outline of the basic techniques in preprosthetic dentoalveolar surgery is discussed in the setting of these technological and tissue engineering advances.

Alveolar antral artery in edentulous patients and their visualization through cone beam computed tomography

OBJECTIVE OF THE STUDY

The aim of this study was to assess the anatomical features of the alveolar antral artery (AAA) in edentulous patients using cone beam computed tomography (CBCT).

PATIENTS

The sample consisted of 191 CBCT scans of maxillary sinuses (n=382) of male (n=59) and female (n=132) edentulous patients (age: 38-89 years).

MATERIAL AND METHODS

The images were analyzed in Dolphin™ 11.9 software. Visualization, location, and diameter of the AAA was registered.

RESULTS

AAA was present in 88.5% of the assessed maxillary sinuses. Bilateral visualization was predominant 77% (P<0.0001). The mean vertical distance from the most anterior part of the AAA to the sinus floor was 7.9±6mm in female patients (both sides) and 12±7.22mm on the right side and 10.9±6.86mm on the left side in males. The mean diameter of the AAA was 1.2±0.7mm on both sides in females. In males, the diameter was significantly (P<0.05) larger: 1.5±0.62mm on the right side and 1.4±0.69 on the left side in females.

CONCLUSION

The AAA had a higher visualization rate, better visualization, and larger diameter when it was present bilaterally in male and female patients.

Trismus and oral health conditions during diagnosis of malignant oral neoplasms

Introduction

Trismus has been considered a late complication of cancer treatment. It can occur prior to treatment, mainly caused by tumor invasion or muscle spasms induced by the presence of the tumor.

Objective

In this study, we evaluated the incidence of trismus and its effect on oral health in patients with malignant neoplasms of the oral cavity before performing the cancer treatment.

Methods

This review was carried out via interviews, visual clinical inspection and objective measurement of maximal mouth opening in 35 consecutive patients. Trismus was defined as a maximal mouth opening <35 mm.

Results

Trismus was observed in 15 patients, with a total incidence of 42%. A high rate of tooth loss was recorded, and trismus association with tooth loss was statistically verified using the Chi-square and Fisher's exact tests, the t-student test and Mann–Whitney non-parametric test. All tests were performed at p < 0.05.

Conclusion

Edentulous patients are eight times more likely to have trismus compared to patients that are partially and fully dentate. Trismus was demonstrated to be correlated with tooth loss; however other oral health conditions were not shown to be a modifying factor.

Anatomy of the mandibular canal and surrounding structures: Part I: Morphology of the superior wall of the mandibular canal

INTRODUCTION

Previous studies of the mandibular canal (MC) have raised questions about the structure of its superior wall that have not been answered. The goal of this anatomical and radiological study was to investigate how CBCT imaging could predict the structure of the superior wall of the MC.

METHODS

Twenty sides from ten dry mandibles derived from six females and four males were used for this study. The mandibles were examined with CBCT. The specimens were then prepared by the methods of our previous study and observed inferiorly. The inferior views were classified into four groups by gross observation of the surface of the superior wall of the MC: class I (trabecular pattern), class II (osteoporotic pattern), class III (dense/irregular pattern), and class IV (smooth pattern). Coronal section CBCT images were classed according to whether the superior wall of the MC was visible.

RESULTS

Class I was most common in dentulous sections in both genders, and class IV was most common class in edentulous sections in both genders. The superior wall was visible in 59.1% in dentulous and 84.9% in edentulous sections, and non-visible in the remainder.

CONCLUSION

Tooth presence and sex are important factors influencing the superior wall of the MC. When the superior wall cannot be seen on CBCT, it is more likely to belong to class II (osteoporotic) than other classes.

Utilization of denture adhesives and the factors associated with its use: a cross-sectional survey

Background

An increase in the number of elderly edentulous patients likely leads to a greater demand for dentures and denture adhesives. As denture adhesives have both positive and negative features, dentists need to know the types of denture adhesive users to be able to provide instruction to denture wearers on how to use denture adhesives effectively. This study aims to examine the utilization of denture adhesives and associated factors.

Methods

Seven closed-ended questionnaires were developed for a web-based survey. After that, Fisher’s exact tests were performed to determine the difference in the denture adhesive usage rate by gender, type of denture, last dental visit, and smoking status. A multivariate-adjusted logistic regression analysis was performed with denture adhesive use or non-use as the dependent variable and the other items as independent variables. Next, Fisher’s exact tests and a multivariate-adjusted logistic regression analysis were performed with the type of denture adhesives as the dependent variable in the same way. Statistical analyses were performed for all denture wearers, complete denture wearers, and partial denture wearers. The level of statistical significance was set at p = 0.05.

Results

A total of 1470 denture wearers in Japan participated in this study. Of these, 318 used denture adhesives, while 212 (66.7%) used cream; 74 (23.3%) used home liner; 25 (7.9%) used powder; four (1.3%) used sheets; and three (0.9%) used several types. The Fisher’s exact tests revealed that the ratios of using denture adhesives were significantly higher for complete denture wearers (p < 0.001), last dental visit over 1 year (p = 0.005), and smokers (p = 0.005). For partial denture wearers, the ratio was significantly higher in smokers (p = 0.262). The multivariate adjusted logistic regression revealed that denture adhesive use or non-use were significantly associated with the type of denture and smoking status in all denture wearers, and just smoking status in partial denture wearers. There were no significant results about the type of denture adhesive selection.

Conclusions

From all denture wearers, complete denture wearers and smokers are more likely to use denture adhesives. In addition, smokers significantly use denture adhesives if they are partial denture wearers.

Utilising the nasal aperture for template stabilisation for guided surgery in the atrophic maxilla

Background

Templates aim to facilitate implant placement in the prosthetically preferred position. Mucosa-supported and bone-supported templates are commonly used in the edentulous maxilla. In the atrophic maxilla (Cawood V and VI), however, these templates can be easily displaced due to a lack of supportive tissues, even in cases where anterior sites offer sufficient bone for implant placement. To assist in positioning and stabilisation, we designed a template that utilises the nasal aperture as a fulcrum to create a forced and exclusive fit. The aim of this study was to assess the clinical usability of the developed template and the corresponding implant placement accuracy in patients with edentulous atrophic maxillae. Deviations between planned and placed implant positions were measured by aligning pre- and post-operative cone beam computed tomography scans.

Results

Twenty-four implants were placed in 11 patients. One template did not fit properly due to a slight undercut. All implants could be placed with good primary stability. The implants had high accuracy at the implant shoulder (global deviation 1.1 ± 0.5 mm, lateral deviation 0.8 ± 0.5 mm) and a mean angular deviation of 7.2 ± 3.4°.

Conclusions

The developed surgical template offers stabilised and secure template placement in the edentulous atrophic maxilla, resulting in satisfying implant placement accuracy when using a semi-guided approach.

Trial registration

Netherlands Trial Register, NL6561, registered 26 September 2017.

Denture wearing and mortality risk in edentulous American adults: A propensity score analysis

OBJECTIVE

To evaluate the association between complete denture use and subsequent mortality among edentulous adults.

METHODS

Data from 1649 edentulous adults who participated in the Third National Health and Nutritional Examination Survey were linked to public-use mortality files for the period up to December 2015. Denture wearing, defined as use of complete dentures in both arches (clinically inspected) all the time or only when awake, was compared to non-wearing, defined as use of dentures occasionally or not at all. The primary outcome was all-cause mortality. Data on 27 covariates, classified as sociodemographic characteristics, behavioral factors, health insurance, laboratory tests and general health status, were used to create propensity scores for weighted and matched analyses.

RESULTS

In weighted data, the difference in mortality rate between denture and non-denture wearers was 11.1 (95 %CI: 3.6-18.6) deaths per 1000 person-years and the number needed to treat (NNT) at 10 years was 12. Denture wearers had 15 % lower risk of death (HR: 0.85; 95 % CI: 0.73-0.98) than non-denture wearers. In the matched sample, the mortality rate difference between denture and non-denture wearers was 8.8 (95 %CI: 0.2-17.4) deaths per 1000 person-years and the NNT at 10 years was 11. Risk of death was 21 % lower among denture wearers (HR: 0.79; 95 % CI: 0.68, 0.92) than non-denture wearers.

CONCLUSION

This longitudinal analysis showed that the use of complete dentures was associated with longer survival and lower all-cause mortality risk among American edentulous adults. NNT is interpreted as one death prevented after 10 years for every twelve rehabilitated dentitions with removable complete dentures.

CLINICAL SIGNIFICANCE

Edentulous adults wearing complete dentures had longer survival and lower overall mortality risk than non-denture wearers, suggesting that prosthodontic rehabilitation with removable complete dentures might have benefits beyond restoring oral functioning.

A case control study to investigate the effects of denture wear on residual alveolar ridge resorption in edentulous patients

OBJECTIVES

To investigate the effect of complete denture wearing on residual ridge resorption in edentulous patient compared with edentulous patient who never wore dentures.

METHODS

Patients who had been edentulous for at least five year who had never worn dentures successfully were matched to edentulous denture wearing control patients. To control for factors possibly associated with alveolar ridge resorption patients who had been rendered edentulous in one arch before the other, smokers, those taking steroids, bisphosphonates, with histories of autoimmune diseases, diabetes mellitus or osteoporosis at any time during their period of edentulousness were excluded. Case and control groups were matched for age, sex and time since being rendered edentulous. Statistical analyses were undertaken using Person's Chi squared (X²) test and Fisher's exact test.

RESULTS

30 edentulous patients who had not worn dentures for at least five years were identified and matched with 30 controls. All control patients were the same age ± 2 years and had been edentulous for the same number of years ± 2 years of their respective controls. There was no significant difference between age and time since being rendered edentulous between case and control. Denture wearers had significantly more maxillary and mandibular residual alveolar ridge resorption than did non denture wearers. Severe ridge resorption was mostly confined to the denture wearing group.

CONCLUSION

Patients wearing complete dentures for more than 5 years had significantly more residual alveolar ridge resorption than was found in non-denture wearing edentulous patients.

Maxillomandibular advancement in edentulous patients as a treatment option for obstructive sleep apnea: report of two cases and a proposed treatment protocol

Obstructive sleep apnea (OSA) is a common disease that often causes debilitating symptoms. In its most severe form, OSA increases the risk of cardiovascular disease and mortality. OSA is characterized by repeated episodes of pharyngeal collapse leading to airway obstruction. The treatment options available in severe cases are limited to continuous positive airway pressure ventilation and maxillomandibular advancement (MMA). OSA is particularly difficult to treat successfully in edentulous patients. Two cases are presented here to illustrate use of MMA in edentulous patients with OSA. Our learning points based on these cases are shared, and a treatment and follow-up protocol is proposed for this specific patient group.

Geometric assessment of imaging methods for complete denture form: Comparisons among cone-beam computed tomography, desktop dental scanning, and handheld optical scanning

PURPOSE

The present study aimed to examine three methods for imaging a complete denture form and to discuss the geometric assessment and availability of these methods.

METHODS

Three methods were used: cone-beam computed tomography (CBCT), desktop dental scanning (DDS), and handheld optical scanning (HOS). Three sides of a cuboid resin block of a known size were measured on the captured images. Ten upper and lower complete dentures were digitized using each of the three methods. The denture forms in the standard triangulated language format were reconstructed using the computer aided design software with three resolutions: 0.1, 0.5 and 1.0. The two images were superimposed through a least-square algorithm, and the mean differences were examined among the three types of imaging methods and resolutions.

RESULTS

The smallest mean differences and variations were obtained for CBCT and DDS, followed by HOS in the experiment using resin block. The lengths of longitudinal and horizontal sides were shortened in CBCT and DDS, whereas the height was shortened in HOS. The variations in each direction were very small by repetitive imaging within every imaging method. The difference between the CBCT and DDS was significantly smaller than that in the other two groups in experiment using actual dentures. The influence of resolution was comparatively low.

CONCLUSIONS

The results suggested that CBCT and DDS had a similar geometric assessment, but that of the HOS was lower.

How to avoid iatrogenic lingual nerve injury in the retromolar area: an anatomical study of retromolar pad and lingual nerve

PURPOSE

This study aimed to investigate the relationship between the retromolar gland and pad, and the relationship between the LN and retromolar gland/pad to establish a new landmark for avoiding LN injury.

METHODS

Sixty-two lingual nerves from fresh-frozen cadavers were used for this study. The age of the specimens at the time of death ranged from 57 to 98 with a mean of 76.5 years. The mucous incision was made into the medial border of the retromolar pad and the submucosal tissue depth of the initial incision was bluntly dissected to expose the lingual nerve. When the LN was identified, the mucosa overlying the retromolar pad was removed to expose the retromolar gland to confirm if the retromolar pad corresponds to the retromolar gland.

RESULTS

On all sides, the lingual nerve was found to course medial to the retromolar pad and inferior to the inferior border of the superior pharyngeal constrictor muscle to enter the sublingual space via the pterygomandibular space. The retromolar pad corresponded to the retromolar gland on all sides. This demonstrated that the retromolar pad is an overlying mucosa of the retromolar gland. No LN was found to travel through the retromolar gland.

CONCLUSION

We suggest that the retromolar pad can be used as a new landmark for avoiding iatrogenic LN injury.