Intraoral wear of PICN CAD-CAM composite restorations used in severe tooth wear treatment: 5-year results of a prospective clinical study using 3D profilometry

OBJECTIVES

To evaluate, in a prospective clinical study over 5 years with ex vivo 3D profilometry analyses, the intraoral wear of Polymer-Infiltrated Ceramic Network (PICN) CAD-CAM composite restorations used in severe tooth wear treatment with the One-Step No-Prep technique.

METHODS

192 PICN (Vita Enamic) restorations on molars and premolars were included in a prospective clinical study involving patients treated according to the One-step No-prep protocol (n = 7). All patients showed clinical signs of bruxism. Replicas of restorations on molars and premolars were realized at each evaluation time (baseline and then every year up to 5 years) and scanned to perform 3D profilometry. Baseline and recall scans were superimposed with Geomagic Control software. The mean material wear was calculated for the full occlusal area (FOA) and for the occlusal contact area (OCA), respectively. Clinical evaluation of restorations was performed at recall.

RESULTS

At 5 years, the estimated mean material wear for FOA was inferior to the accuracy threshold of the profilometry measurement chain. For OCA, the estimated mean wear of the material was - 27.97 µm. This material wear was shown to be significantly influenced by time (p < 0.0001) and patient (p = 0.026), while the type of tooth (molar or premolar) had no influence. At 5 years, the survival and the success rates of restorations were 99.48% and 90.62%, respectively.

SIGNIFICANCE

The PICN material exhibits a low wear process in the treatment of severe tooth wear despite the presence of clinical signs of bruxism, and it constitutes a suitable material for the One-step No-prep technique.

Outcomes of resin-bonded attachments for removable dental prostheses

PURPOSE

This clinical study aimed to evaluate the outcomes of resin-bonded attachments (RBAs) for precision-retained removable dental prostheses (RDPs) after at least two years of clinical maintenance.

METHODS

Since December 1998, 205 RBAs (44 bonded to posterior teeth, 161 to anterior teeth) have been inserted in 123 patients (62 females and 61 males; mean age, 63.6 ± 9.6 years) who were recalled annually. The abutment teeth underwent a minimally invasive preparation limited to the enamel. RBAs were cast in a cobalt-chromium alloy with a minimum thickness of 0.5 mm and adhesively luted with a luting composite resin (Panavia 21 Ex or Panavia V5, Kuraray, Japan). We evaluated caries activity, plaque index, periodontal condition, and tooth vitality. The Kaplan-Meier survival curves were used to account for the reasons for failure.

RESULTS

The mean observation time of RBAs until the last recall visit was 84.5 ± 51.3 months (range, 3.6-270.6). During the observation period, 33 RBAs debonded in 27 patients (16.1%). The 10-year success rate according to the Kaplan-Meier analysis was 58.4%, which dropped to 46.2% after 15 years of observation if debonding was considered a failure. If rebonded RBAs were regarded as surviving, the 10- and 15-year survival rates would be 68.3% and 61%, respectively.

CONCLUSIONS

The use of RBAs for precision-retained RDPs appears to be a promising alternative to conventionally retained RDPs. As reported in the literature, the survival rate and frequency of complications were comparable with those of conventional crown-retained attachments for RDPs.

The effect of prosthetic rehabilitation with or without dietary advice on nutritional status in elderly patients: a systematic review

BACKGROUND

Elderly people frequently report tooth loss, affecting their nutritional status. There is a gap in the scientific evidence about the influence of prosthodontic rehabilitation on nutritional status.

OBJECTIVE

To investigate the influence of prosthodontic rehabilitation combinates or not with dietary advice on nutritional status in elderly patients.

METHODS

A systematic literature search was conducted in three electronic databases to identify randomized clinical trials that evaluated the effect of prosthetic rehabilitation on nutritional status in subjects aged 60 years or older, with a follow-up of at least 1 month after prosthesis rehabilitation.

RESULTS

Of the 1517 articles identified in the initial search, 12 were selected for the final review. No significant difference between the types of prosthesis were found regarding the chewing by the elderly population. Although patients who received prosthetic treatment had significant improvement in chewing ability, a consistent pattern of improvement in nutritional status was not observed when they did not receive dietary advice. In addition, the association between the condition of the dentition, the masticatory performance and nutritional change of elderly patients has been found. Studies that evaluated simultaneous complete denture treatment and simple dietary advice showed an improvement of nutrient intake in elderly patients.

CONCLUSIONS

Isolated prosthetic rehabilitation may not have the effect of exerting a change in nutritional status of edentulous elderly patients. In general, simultaneous dietary consulting and prosthetic treatment in combination may improve dietary habits, since masticatory capacity and efficiency are not the only factors that influence the nutritional status of a patient.

Influence of Different Implant Designs on Replacement of Four Teeth of The Posterior Free-end Edentulism: Three-dimensional Finite Element Analysis and Clinic Case Validation

BACKGROUND

With periodontal disease having an increasing incidence, mandibular free-end edentulism caused by periodontitis is clinically more common. Finite element analysis and clinical case reports were used to evaluate the influence of different designs on the load distribution of implant prosthesis in mandibular posterior free-end edentulism.

METHOD

A finite element model of a mandible with posterior free-end edentulism was established. Considering the implant position and selection of single crown repair or splint repair, four designs were conducted including model A: 3435×37(four-unit fixed bridge supported by three implants, implant positions were 34, 35, 37); model B: 34,35×37, (34: a single implant crown) (35×37: three-unit fixed bridge supported by two implants, implant positions were 35, 37); model C: 34×3637(four-unit fixed bridge supported by three implants, implant positions were 34, 36, 37); and model D: 34×36, 37(37: a single implant crown)(34×36: three-unit fixed bridge supported by two implants, implant positions were 34, 36). Stress distribution and the Von Mises stress value of the implants, the crown and the bone around the implants were analyzed at vertical and 45° inclined load.

RESULTS

Stress in the cortical bone was mainly concentrated around the implant neck, and maximum Von Mises stress (MVMS) of the four models was 11.6-16.1MPa at vertical load and 61.74-96.49MPa at 45° inclined load. Stress in the cancellous bone was concentrated around the implant base, and MVMS of four models was 3.075-3.899MPa at vertical load and 5.021-6.165MPa at 45° inclined load. Stress of the restoration crowns was mainly concentrated in the connector of the bridge, and MVMS of four models was 23.38-26.28MPa at vertical load and 53.14-56.35MPa at 45° inclined load. Stress of the implant interface was mainly concentrated on the surface of the smaller implants near the bridge, and MVMS of four models was 21.12-33.25MPa at vertical load and 83.73-138.7MPa at 45° inclined load.

CONCLUSION

There was favorable stress distribution of the four models at vertical load and 45° inclined load. Design of a three-unit fixed bridge combined with a partial crown may be an available option for devising patient treatment plans with mandibular free-end edentulism.

CAD-CAM complete denture resins: Effect of relining on the shear bond strength

OBJECTIVES

The aim of this study was to compare the shear bond strength of relined CAD-CAM complete removable dental prosthesis (CRDP) resins with conventional heat-polymerized polymethylmethacrylate (PMMA) resin.

METHODS

A total of 96 resin specimens in identical dimensions of 10 mm × 10 mm × 11 mm were fabricated for four study groups [#1- Conventional heat-polymerized group: n=24 (ProBase); #2- Milled#1: n=24 (Ivobase); #3- Milled#2: n=24 (Ivotion); #4- 3D-printed: n=24, (NextDent Denture 3D+)]. Twelve specimens in each group were sectioned in the middle to produce a 3 mm defect and then were relined using a conventional denture relining material. All specimens underwent thermocycling (5-55°C) for 10,000 cycles. The shear bond tests were carried out in a universal testing machine. One-way ANOVA and Tukey's test were used for statistical analysis (p<0.05). The two-parameter Weibull distribution values were calculated.

RESULTS

Relined 3D-printed specimens had a significantly lower shear bond strength when compared with conventional (p=0.0003) and milled groups (Milled#1: p=0.0004; Milled#2: p<0.0001). There were no differences in the shear bond strengths between the milled and conventional groups. Weibull distribution presented the highest shape value for the non-relined Milled#1 (22.83) group and the lowest values for the 3D-printed relined group (4.001).

CONCLUSION

The findings of this study conclude that the shear bond strength of the conventionally-relined 3D-printed resins used for fabricating CRDPs was inferior to the shear bond strength of conventionally-relined resins employed for manufacturing CRDPs using CAD-CAM milling and conventional heat-polymerization techniques.

CLINICAL SIGNIFICANCE

When considering 3D-printing for the fabrication of CRDPs, it is recommended to employ it in clinical situations where a frequent need for denture relining is not expected.

Load-bearing capacity of pressable lithium disilicates applied as ultra-thin occlusal veneers on molars

PURPOSE

The aim was to investigate the load bearing capacity of different pressable lithium disilicates cemented as occlusal veneers on molars.

MATERIALS AND METHODS

One control group and six test groups were formed consisting of 20 specimens each (n = 20). The six test groups differed in the utilizing pressable lithium disilicate to fabricate occlusal veneers. As a control group, "group Lis", the lithium disilicate with the highest reported flexural strength was used (initial LiSi Press, GC Europe; Leuven, Belgium / flexural strength: 508 MPa). The test groups consisted of other pressable lithium disilicates with lower flexural strength values: "Ema" (IPS e.max press), "Vit" (VITA Ambria), "Liv" (Livento Press), "Amb" (Amber Press), "Mas" (Amber Press Master) and "Ros" (Rosetta SP)". After the preparation of 140 extracted human molars, which included the removal of the central enamel, the specimens were scanned using a desktop scanner. With the aid of a design software, the occlusal veneers were designed in a standardized thickness of 0.5 mm. To fabricate the restorations, all tested materials were processed using heat-pressing technique. All restorations were adhesively cemented. Afterwards, the specimens underwent cyclic fatigue during an aging procedure in a chewing simulator (1'200'000 chewing-cycles, 49 N force, 5-55°C temperature changes). Subsequently, the specimens were statically loaded and the load which was necessary to fracture the specimen (F_max) were measured. Differences between the groups were compared applying the Kruskal-Wallis (KW) test and the Wilcoxon-Mann-Whitney-Test (WMW: p < 0.05). The two-parameter Weibull distribution values were calculated.

RESULTS

The fatigue resistance was 100% for the groups Lis, Vit, Liv, Amb, Mas and Ros, whereas the group Ema showed a fatigue resistance of 95%. The control group Lis showed median F_max values of 2'328 N. The median F_max values for the test groups ranged between 1'753 N (Vit) and 2'490 N (Ros). Statistically significant difference was observed among the groups Lis (control) and Vit (KW: p < 0.001). Weibull distribution presented the highest shape values for the group Ros (12.83) and the lowest values for the group Ema (4.71).

CONCLUSION

Regarding their load-bearing capacity different pressable lithium disilicates can be recommended to fabricate ultra-thin occlusal veneers on molars when restoring occlusal tooth wear.

Impact of cement type and abutment height on pull-off force of zirconia reinforced lithium silicate crowns on titanium implant stock abutments: an in vitro study

Background

Pull-off forces of cement-retained zirconia reinforced lithium silicate (ZLS) in implant-supported single crowns on stock titanium abutments with respect to abutment height and implant cement were evaluated and compared.

Methods

Pull-off force of ZLS crowns on stock titanium abutments was evaluated concerning dental cement and abutment height. A total sample size of 64 stock abutments with heights of 3 mm (n = 32) and 5 mm (n = 32) was used. The ZLS crowns were cemented with four different types of cement (one temporary, two semi-permanent, and one permanent). After cementation, water storage, and thermocycling each sample was subjected to a pull-off test using a universal testing machine.

Results

The temporary cement showed the least pull-off force regardless of abutment height (3/5 mm: means 6 N/23 N), followed by the semi-permanent methacrylate-infiltrated zinc oxide cement (28 N/55 N), the semi-permanent methacrylate-based cement (103 N/163 N), and the permanent resin composite cement (238 N/820 N). Results of all types of cement differed statistically significantly from each other (p ≤ .012). The type of implant cement has an impact on the pull-off force of ZLS crowns and titanium abutments.

Conclusions

Permanent cements present higher retention than semi-permanent ones, and temporary cements present the lowest values. The abutment height had a subordinate impact.

Determination of radioactivity levels in feldspathic dental ceramics

Activity concentrations of 42 different feldspathic dental ceramic powders were determined using a gamma spectrometer with an HPGe detector. The average ²³⁸U, ²³²Th and ²²⁶Ra activity concentrations of the specimens were 126 ± 8 Bq kg^-1, 5.6 ± 0.5 Bq kg^-1 and 12.7 ± 1.2 Bq kg^-1, respectively. The average ⁴⁰K activity was found as 2855 ± 89 Bq kg^-1 ranging from 2252 ± 70 Bq kg^-1 to 3522 ± 110 Bq kg^-1 due to high potassium content in dental ceramics. None of the activity concentration measurements exceeded the limits by EC and ISO.

Nanosecond pulsed fiber laser irradiation for enhanced zirconia crown adhesion: Morphological, chemical, thermal and mechanical analysis

The increasing demand for aesthetics, together with advancements in technology, have contributed to the rise in popularity of all-ceramic restorations. In the last two decades, the continuous progression in ceramic materials science for dental applications has permitted the fabrication of high-strength materials. Amongst these, zirconia-based ceramics have improved in terms of fracture resistance and long-term viability in comparison with other silica-based materials. Unfortunately, while bonding of resin cement-silica ceramics can be strengthened through creation of a porous surface by applying hydrofluoric acid (5%-9.5%) and a subsequent silane coupling agent, the glass-free polycrystalline microstructure of zirconia ceramics does not allow such a reaction. The aim of the present in vitro study was to observe the effect of 1070 nm fiber nanosecond pulse laser irradiation on zirconia samples through morphological analysis (profilometry, SEM), thermal recording with Fiber Bragg Gratings (FBGs), elemental composition analysis (EDX) and bond strength testing (mechanical tests) in order to evaluate the possible advantages of this kind of treatment on zirconia surfaces, as well as to show the potential side effects and changes in chemical composition. Despite laser irradiation with a 1070 nm wavelength fiber laser and correct process parameters demonstrating suitable outcomes in terms of improved surface roughness and minimal thermal damage, comparison between irradiated and unirradiated samples did not exhibit statistically significant differences in terms of bonding strength.

An efficacious horizontal angulation separated radiographically superimposed canals in upper premolars with different root morphologies

Objectives

To determine the effect of various horizontal beam angulations on radiographically separating superimposed canals in upper premolars with different external root morphologies.

Materials and methods

The independent variables were 1) three different external root morphologies of upper premolars (n = 30); one-root (A), fused-root (B) and two-root (C), 2) thirteen angulations (0° and mesial (Ms) and distal (Ds) shifts of 15, 20, 25, 30, 35, and 40°), and 3) the superimposed canal at the apex (apx) and 5-mm from the apex (5apx). The dependent variables were the percentage of radiographs demonstrating canal separation. The separated canal distances were analysed using analysis of variance (ANOVA) and Tukey HSD.

Results

Separation distances at apx and 5apx on one-root, fused-root and two-root premolar radiographs increased as the angulation increased. Ms angulations generated a higher separation distance (SepDist) in mm compared with the Ds angulations. Significantly different separation distances were observed from various horizontal shift angulations (p < 0.05). Percentage of canal separation from 0^o was achieved differently in different morphology of upper premolars (14-80%) at apx and 10-40% at 5apx. The 20-40Ms/Ds and 25Ds/30‒40Ms/Ds resulted in 100% of radiographs with canal separation for two-root and fused-root premolars, respectively, at apx and 5apx. Only the 35/40Ms resulted in 100% of radiographs with separation at apx in one-root teeth.

Conclusion

The ideal horizontal angulation which revealed the superimposed canal at the apx/5apx for one-root, fused-root, and two-root teeth are 35M/35M, 20D/20M, and 15M/20M, respectively.

Significance

The 25Ms was the optimal angulation which strongly recommended with the highest probability of separation and acceptable image quality in endodontic and prosthodontic treatment for unknown morphologies evaluated.

A questionnaire study on the impact on oral health-related quality of life by conventional rehabilitation of edentulous patient

Purpose

This study aimed to determine whether complete dentures improve the oral health-related quality of life (OHRQoL) of edentulous patients, and to assess any associations related to age, gender, and OHRQoL.

Material and methods

Hundred edentulous patients who required conventional complete denture treatment were selected for this study. The following inclusion criteria were established: edentulous in both jaws with no previous history of denture treatment and no significant medical history. The patients were selected who satisfied the criteria associated with the class I prosthodoctic diagnostic index. OHRQoL of the patients were assessed twice, once pre treatment (at the first visit) and once post treatment (8 weeks post insertion of dentures) using an instrument called OHIP-EDENT-N. Significant differences in the OHIP-EDENT-N scores between pre treatment and post treatment were calculated using the Wilcoxon Signed-Rank test. Gender differences were assessed using the Mann–Whitney test.

Results

After provision of new complete dentures, all domains of the OHIP-EDENT-N showed significant improvements except physical pain and social disability.

Conclusions

The results of this study indicated that conventional complete denture improved the OHRQoL of edentulous patients.

Suppressive effects of 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer on the adherence of Candida species and MRSA to acrylic denture resin

Objectives

The effects of 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer on the adherence of microorganisms such as non-Candida albicans Candida (NCAC) and methicillin-resistant Staphylococcus aureus (MRSA), frequently detected in oral infections in immunocompromised and/or elderly people, to denture resin material, are still unclear. Here, we report the effects of MPC-polymer on the adherence of C. albicans, NCAC, and MRSA to acrylic denture resin.

Methods

Sixteen strains of C. albicans, seven strains of C. glabrata, two strains of C. tropicalis, one strain of C. parapsilosis, and six strains of MRSA were used. We cultured the fungal/bacterial strains and examined the cell growth and adherence of fungi/bacteria to mucin-coated acrylic denture resin plates (ADRP) with or without MPC-polymer coating, by scanning electron microscopy. The cell surface hydrophobicity of the fungal/bacterial strains was measured by the adsorption to hydrocarbons.

Results

MPC-polymer did not affect the growth of all strains of Candida species and MRSA, but significantly suppressed adherence to ADRP in most strains of C. albicans and all strains of NCAC and MRSA. A significant positive correlation was found between cell hydrophobicity and the reduction rates of microbial adherence to ADRP treated with 5% of MPC-polymer.

Conclusions

MPC-polymer treatment for acrylic resin material suppresses the adherence of C. albicans, NCAC and MRSA via their hydrophilicity interaction.

Clinical significance

The application of MPC-polymer for denture hygiene is potent to prevent oral candidiasis, denture stomatitis and opportunistic infection, caused by Candida species and MRSA, via suppressing the adherence of those fungus/bacteria.

Dental follow-up and maintenance index: the development of a novel multidisciplinary protocol

Objectives

To develop a comprehensive yet simple dental follow up and maintenance protocol based on existing guidelines and recommendations.

Methods

A multidisciplinary team reviewed available maintenance and follow up guidelines and recommendations then developed a single protocol for adult dental patients.

Results

The protocol includes ten questions that categorize dental patients into one of three risk categories. Based on the risk category, each patient is assigned a recall interval and recommendations for in office and at home dental care.

Conclusions

Development of a single multidisciplinary follow up and maintenance protocol.

Corticotomy in orthodontic treatment: systematic review

OBJECTIVE

The aim of this study is to evaluate corticotomies effects to accelerate or facilitate dental movements in different kind of orthodontic treatments.

DATA

This report followed the PRISMA Statement. A total of 9 articles were included in review.

SOURCES

Two reviewers performed a literature search up to December 2018 in four databases: PubMed, Web of Science, Scopus and SciELO.

STUDY SELECTION

Controlled clinical trials and randomized controlled clinical trials conducted in human patients and published during the last 10 years in English were eligible to be selected. The articles should give detailed information about the results and treatment parameters. There were no limitations established in terms of the type of malocclusion to be corrected or the type of orthodontic treatment performed.

RESULTS

The methodological quality and evidence of the selected studies was low. Most of the studies observed a statistically significant increase in the rate of dental movement, when performing alveolar corticotomies as coadjuvants of orthodontic treatment; either with the conventional technique or with piezocision. The effect of combining corticotomy with bone grafts was assessed.

CONCLUSIONS

High heterogeneity among studies made it difficult to draw clear conclusions. However, within the limitations of this review, the corticotomy procedures were able to statistically and clinically produce significant temporary decrease in orthodontic tooth movement rate. This technique does not seem to involve major complications compared to conventional orthodontic treatments.

CLINICAL RELEVANCE

The use of this technique can reduce treatment time and therefore the undesirable effects associated with prolonged treatments.

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.

Novel Confocal-Laser-Scanning-Microscopy and conventional measures investigating eroded dentine following dentifrice dab-on and brushing abrasion

Objectives

To validate novel non-contacting Confocal-Laser-Scanning-Microscopy (CLSM) methodology with conventional Contacting Profilometry (CP) measures investigating brushing or dab-on of stannous-fluoride dentifrice on early aggressive dentine erosion.

Methods

75 polished human dentine samples were prepared and eroded in agitated 6% citric acid then randomly allocated into 5 intervention groups; artificial saliva control (1); controlled use of a pressure sensitive counter-rotating oscillatory powered toothbrush with sodium-fluoride NaF (2) or stannous-fluoride SnF₂ (3), and dab-on application of NaF (4) or SnF₂ (5). Samples underwent three cycles of intervention and 2-min agitated 6 % citric acid challenges. CLSM images were taken and 3D reconstructions produced of step height using a developed software algorithm. In addition, 20 % samples were randomised and profiled using CP to measure step height and surface roughness. Vickers's diamond micro-hardness testing was carried out on all samples.

Results

Comparing CLSM and CP; Pearson correlation was 0.77 and Intra-class correlation 0.81 (p = 0.01). There were no significant statistical differences in step height between groups using both CLSM and CP. From baseline, SnF₂ brushing (3) increased micro-hardness more than control (1) (p = 0.03), NaF (4) and SnF₂ dab-on (5) (p ≤ 0.001), and increased surface roughness more than control (p = 0.02), NaF brushing (2) and NaF dab-on (4) (p ≤ 0.017). Dab-on of SnF₂ (5) produced rougher surfaces than control (1) (p = 0.014) and reduced hardness compared with NaF brushing (p = 0.04).

Conclusions

Good agreement and correlation exists between CLSM and CP measures in dentine. There were no significant differences in surface loss after interventions between groups. Compared with control, SnF₂ application increased dentine surface roughness and SnF₂ controlled powered brushing application increased dentine hardness, likely caused by exposure of uneroded dentine.

Clinical significance

Isosurfaces produced using CLSM can be used to represent dentine step height loss. They show good correlation and agreement with conventional CP measures, following early aggressive erosion-abrasion cycles of dentine. The CLSM and computer algorithm therefore provides an accurate, standalone and non-contacting three-dimensional measurement of early dentine wear. Stannous-fluoride brushing, and dab-on application offer no benefits following early aggressive erosion in dentine. To reduce dentine wear, limiting erosive challenges and avoiding brushing post-erosion is advised.

Dental invasive procedures in von Willebrand disease outpatients treated with high purity FVIII/VWF complex concentrate (Fanhdi®): experience of a single center

PURPOSE

To retrospectively assess the effectiveness and safety of customized hemostatic protocols using a plasma-derived, von Willebrand Factor (VWF)-containing Factor VIII concentrate (pdVWF/FVIII) in von Willebrand disease (VWD) patients undergoing dental invasive procedures.

METHODS

Protocol for each patient was drawn up by the Blood Unit based on the VWD type, disease severity, and type of treatment. pdFVIII/VWF infusions and doses were registered at 30-60 min before intervention (t0) and at 12-24-36-48-72 h after intervention (t12-t72) and up to day 7. Any peri- or postoperative bleeding, complication or adverse event was registered.

RESULTS

Forty-five dental procedures were performed on 20 VWD patients (six type-1, two type-2a, six type-2b, six type-3). Most pdFVIII/VWF infusions at t0 were 60 IU/kg (n = 7) and 50 IU/kg (n = 9). Subsequent infusions were mostly 30-50 IU/kg. No bleeding complications or adverse events were reported.

CONCLUSION

This study supports the safety and efficacy of pdFVIII/VWF to prevent peri- and postoperative bleeding after invasive oral procedures.

The influence of undercut depths on the accuracy of casts poured from irreversible hydrocolloid impression materials

Objectives

To evaluate the elastic recovery of a typical irreversible hydrocolloid impression material in terms of the amount of undercut identified and additional thickness of spacer provided before custom tray fabrication.

Methods

This study surveyed the undercut depths of the teeth surfaces and lingual sulci of one hundred partially dentate mandibular dental casts which were subsequently scanned and the data exported as STL files. A typical cast from each undercut category (0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm) was 3D printed. Three custom trays were constructed with spacer thicknesses representing 20%, 30% and 50% compression against the wall of the custom trays on removal, impressions recorded, and casts fabricated in dental stone. Measurements for elastic recovery of irreversible hydrocolloid were done using an internal caliper and a digital caliper. All measurements were done by the principal investigator. Non-parametric analyses were used for comparisons of the undercut values between the 3D printed and poured casts to determine the amount of elastic recovery of the irreversible hydrocolloid impression material.

Results

There was no statistically significant difference in measurements between the original 3D printed casts and the poured casts, irrespective of percentage compression (p > 0.05).

Conclusions

In removable partial denture construction, casts should be blocked out parallel to the path of insertion and then an additional 3mm of spacer applied as a standard technique before custom tray fabrication to ensure elastic recovery of the irreversible hydrocolloid impression.

Clinical implications

In severe undercut situations, accurate impressions can be taken using irreversible hydrocolloid by blocking out all undercut surfaces on the teeth and lingual sulci before adapting additional three-millimetre wax spacer on casts when constructing custom trays thereby ensuring accurate and reliable impressions for removable prosthesis construction.

Effect of different materials and undercut on the removal force and stress distribution in circumferential clasps during direct retainer action in removable partial dentures

OBJECTIVES

This study aimed to evaluate the effect of different materials and undercut on the removal force and stress distribution in the supporting tooth and in the circumferential clasp used in removable partial prosthesis.

METHODS

Upper molars prepared for Akers circumferential clasp with retention and opposing arm were modeled, scanned, elaborated with CAD software and the geometries imported in FEA and analyzed. Six different materials were selected for the clasp (Polyamide, Polyoxymethylene, Polyetheretherketone - PEEK, Gold alloy, Titanium and CoCr) and 3 different undercuts (0.25, 0.50 and 0.75mm), totaling 18 groups.

RESULTS

The clasps presented greater stress in their structure and potentially greater damage to the dental enamel when made with rigid materials and with more undercut; however, they presented greater ability to remain in position.

SIGNIFICANCE

Polyamide with a higher undercut is an esthetic alternative to rigid metallic clasps. It showed promising behavior because it strongly reduces the damage to the enamel, and even with an undercut of 0.75, the retention is lower than for CoCr with a 0.25 undercut, and this retention might still be sufficient. Polyoxymethylene and Polyetheretherketone (PEEK) are not suitable materials for the clasps, because the maximum stress occurring during removal with higher undercuts is higher than the material strength.

An auxiliary factor for increasing the retention of short abutments

Background

Retention is an essential factor in the sustainability of the prosthesis, especially for short abutment. Despite, the availability of several auxiliary applications, achieving a clinically good retention for cast crowns in prepared short teeth remains a major challenge for the practicing dentist.

Objectives

This study tests a new method for applying frustum-shaped grooves on short prepared abutments and compares them with traditional setting grooves.

Methods

Forty-eight copper machine-milled short dies with 3.5 mm length and 12^o conversion with a chamfer finish line of 0.7 mm were prepared to mimic short prepared molars and distributed into 4 groups. A control group with two opposing setting grooves and two groups with dual opposing frustums, one of which was prepared to receive two integrated metal protrusions inside the casting that fit the frustums. Frustums were prepared with Komet bur No. 807 with dimensions 0.9 mm at the base and 0.7 mm at the occlusal surface. A direct wax-up was carried out on all dies and all castings were cemented with zinc phosphate cement. A pull-off test was applied until separation. Data were analysed to compare the correlation of the four groups using one-way ANOVA and Bonferroni test (p ≤ 0.05).

Results

The mean retentive values in Newton were as follows: the control group, 457.80; the setting grooves group, 461.07; the frustum group, 597.59; and the frustum group with the two metal protrusions, 919.80. The retention was increased by 65% in frustum group and doubled in frustum group with the metal protrusions.

Conclusions

The results showed a statistical significance in retention in the frustum groups with and without metal protrusion over the retention of the control and the setting grooves groups.

Dental Patient-Reported Outcome Measures Are Essential for Evidence-Based Prosthetic Dentistry

For evidence-based dental treatment decision-making in prosthetic dentistry, evidence from scientific studies performed in the appropriate population with state-of-the-art interventions, reasonable controls, and relevant outcomes is required. This article will briefly review patient populations involved and interventions applied in prosthetic dentistry and more extensively review outcomes used for evidence-based dental treatment decision-making in prosthetic dentistry. Dental patient populations in prosthetic dentistry usually suffer from extensive loss of tooth substance and/or tooth loss. Typical interventions in prosthetic dentistry are replacement of a substantial amount of tooth structure and lost teeth with conventional or implant-supported fixed or removable dental protheses. Sufficient controls or comparisons should also involve no treatment for tooth loss as a legitimate option. For many years, prosthodontic treatment almost solely focused on disease-oriented outcomes such as numerical replacement of missing teeth to restore current oral health and prevent further deterioration, and now, dental patient-reported outcomes (dPROs), the outcomes that are directly reported by the patient, are gaining increasing attention. dPROs are what matters most for the patient, and dPRO measures have several advantages when applied in clinical practice and research settings compared with traditional disease-oriented measures such as ease of applicability and less burdensome for the clinicians. In evidence-based prosthetic dentistry, there should be a shift to fewer applied dPRO measures, with only one instrument becoming standard. Furthermore, dPROs will probably also become tools to assess patients' oral health status in clinical practice in a standardized manner. Finally, information on dPROs will become an integral part of evidence-based treatment decision-making in prosthetic dentistry.

TiC-composite materials in applications for kinematic denture connections

PURPOSE

This paper presents an own proposal for the construction of a ball latch intended for use in prosthetic dentistry. Attention was paid to the existing commercial constructions of elements of the same type, indicating their advantages and disadvantages. Based on the analysis of the present solutions, own ones were proposed.

MATERIALS AND METHODS

The following materials were chosen for the tests: pure titanium, 316 L V steel, Ti15Mo2.8Nb obtained using powder metallurgy and through mechanical alloying, 10 and 20% of titanium carbide - obtained using powder metallurgy, as well as 10 and 20% of graphite - obtained using powder metallurgy. For the prepared materials, tribological tests were performed using a friction simulator in a ring/shield system.

RESULTS

Fairly extensive tests were performed to verify the suitability of the selected material for use in the specific conditions of the oral cavity. The performed tests showed that the proposed material is not only beneficial in relation to the existing commercial dental alloys but also meets the general criteria set for this type of elements.

CONCLUSIONS

A more beneficial use of two-part ball latches (two key parts - patrix, matrix) was noticed in comparison to latches consisting of three parts (patrix, insert, matrix). On the basis of the obtained test results, it can be concluded that the proposed own design of a ball latch is a good alternative for traditional constructional and material solutions of commercial ball latches.

Electroplated telescopic retainers with zirconia primary crowns: 3-year results from a randomized clinical trial

OBJECTIVE

The objective of the study was to investigate the clinical outcome for electroplated telescopic removable dental prostheses (E-RDPs) with zirconia primary crowns.

MATERIALS AND METHODS

Sixty E-RDPs, with primary crowns manufactured from either cobalt-chromium alloy or zirconia, were fabricated for 56 participants. Electroplating was used to produce gold copings directly on the telescopic primary crowns. These copings were bonded intra-orally to the prosthesis framework. After 36 months, prosthesis survival and number of complications were assessed. Statistical analysis was performed by the use of Kaplan-Meier modeling and the log-rank test.

RESULTS

Survival of the E-RDPs, 96.4% after 3 years, was identical in both groups. The need for aftercare was high but not significantly different: technical complications were observed for 37% and 42.9% of the prostheses for the zirconia and cobalt-chromium alloy primary crowns, respectively. Fracture of composite veneer was the most frequent complication (59.1%). The incidence of fractured abutment teeth, decementation, and endodontic problems was 7.9% in the zirconia group and 14% in the control group. The majority of abutment-level complications were treated restoratively. A significant difference was found for maximum probing depth at the abutment teeth: In the zirconia group, it decreased by 0.2 mm, whereas it increased by 0.8 mm in the control group (p = 0.04).

CONCLUSIONS

After 3 years of observation, survival of zirconia E-RDPs was favorable and comparable with that of established double-crown-retained prostheses. Further studies must clarify whether there are benefits of zirconia primary crowns for periodontal health.

CLINICAL RELEVANCE

Although these results encourage the use of zirconia primary crowns, more research is necessary to reduce the number of complications observed for secondary telescopic crowns, for example, failure of the veneer.

Flexural behavior of PEEK materials for dental application

OBJECTIVES

The high-performance thermoplastic polymer PEEK (poly-ether-ether-ketone) is used as alternative implant material to metals since 1998 in many medical fields due to its bone-like mechanical properties. These iso-elastic characteristics of PEEK lead to the assumption, that it could represent a viable alternative to conventional materials also in the field of dentistry. Therefore the mechanical properties of different PEEK-compounds should be eavuated vie the three-point bending test.

METHODS

150 specimens of 11 different PEEK-compounds were tested via a three-point bending test using a universal testing machine (Z010, Zwick GmbH & Co, Ulm, Germany) after dry storage on the one hand and after incubation at 37°C in Ringer solution (Fa. Braun Melsungen AG, Melsungen, Deutschland) for one day, 7 days, 28 days und 84 days on the other hand and the material parameters bending modulus and bending strength were evaluated.

RESULTS

The results regarding the bending moduli ranged from 2.73±0.26GPa for an unfilled brand to 47.27±10.3GPa for a carbon fiber reinforced PEEK with unidirectional continuous carbon fibers. Accordingly the bending strengths of these two material types ranged from 170.37±19.31MPa to 1009.63±107.33MPa.

SIGNIFICANCE

All tested specimens showed higher values than the prevailing minimum strength for plastic materials and their application in dentistry of 65MPa (DIN EN ISO 10477). This underlines the applicability of PEEK in dentistry and points out the possibility to offer patients metal free restorations, especially in the presence of allergies and/or bruxism.

Multiple texture mapping of alveolar bone area for implant treatment in prosthetic dentistry

Treatment using implants is frequently employed in prosthetic dentistry. In this method, determining the bone density of the upper and lower jaws is important. Generally, a dentist can recognize the condition of the alveolar bone to be manipulated using a cone-beam computed tomography (CBCT) image. However, communicating the data to the patient is a challenge because it is difficult for the nonprofessional person to interpret the image, which contains a distribution of pixels with similar density. We present an intuitive texture mapping method of the alveolar bone area for application in implant treatment. Our method aims to help patients better understand the treatment process by using a textured image that includes several different texture patterns that reflect the density of the alveolar bone area. We segment the area in accordance with the density of corresponding parts in the alveolar bone and the gingiva. By simplifying the boundary of each segmented region, the distribution of pixels with similar density on the alveolar bone area can be easily recognized. Next, the texture patterns for several segmented regions are mapped onto the alveolar bone area using the graph-cut algorithm, which is used for smooth texture mapping at the boundary of the segmented region. The result is an applied texture on the alveolar bone area that corresponds to the bone structure. Our method is helpful for facilitating communication and understanding of treatment using dental implants.