Failures in the rehabilitation treatment with removable partial dentures

Oral health-related quality of life of conventional removable partial dentures, unilateral nonmetal clasp dentures, and shortened dental arch with 2- or 3-tooth unilateral distal extension tooth loss in the mandible: A randomized, crossover, clinical trial

STATEMENT OF PROBLEM

Conventional removable partial dentures with metal clasps are still a common option for patients with distal-extension tooth loss. However, unilateral nonmetal clasp dentures fabricated by using a thermoplastic denture base resin are increasingly being used. Furthermore, the shortened dental arch concept remains controversial, in spite of being advocated for many years. Nevertheless, these treatment options remain controversial, particularly in patients with the loss of a few distal teeth unilaterally.

PURPOSE

The purpose of this randomized, crossover, clinical trial was to investigate the oral health-related quality of life of participants who requested a new dental prosthesis (unilateral nonmetal clasp dentures or conventional removable partial dentures) at a private practice.

MATERIAL AND METHODS

A 3-period, randomized, crossover design was used in a within-subject, controlled, clinical trial. Twenty-four participants (mean age 59.0 years [7 men: 62.6 {45-85} years; 17 women: 57.5 {24-75} years]) were enrolled. All experimental procedures were approved by the Ethics Committee of Nagasaki University Hospital (#15022313) and registered in the International Standard Randomized Controlled Trial Number registry (ISRCTN49105064). All participants were fully dentate in the maxilla and had unilateral distal-extension loss of 2 or 3 teeth in the mandible. Participants were allocated to 1 of 6 groups and treated with prescribed options in accordance with their allocated sequences and used a dental prosthesis or nothing for 2-week periods. At the end of each intervention, the participants were asked to answer the Oral Health Impact Profile questionnaire. Differences in Oral Health Impact Profile scores among groups were estimated with a mixed-effects model (α=.05).

RESULTS

Total Oral Health Impact Profile scores were higher for unilateral nonmetal clasp dentures (P=.002) and shortened dental arch (P=.049) than for conventional removable partial dentures, with medium and small effects. The unilateral nonmetal clasp dentures had a similar effect compared with shortened dental arch (P>.05). unilateral nonmetal clasp dentures (P=.011) and shortened dental arch (P=.005) demonstrated medium effects in the oral function dimension compared with conventional removable partial dentures. Unilateral nonmetal clasp dentures exhibited large and medium effects in the orofacial appearance dimension compared with conventional removable partial dentures (P=.001) and shortened dental arch (P=.006). In the orofacial pain dimension, shortened dental arch showed effects similar to those of conventional removable partial dentures and unilateral nonmetal clasp dentures (P>.05), and no significant differences were observed in the psychosocial impact dimension (P>.05), but the unilateral nonmetal clasp denture score was lower than the conventional removable partial denture score, with a small effect. Men had significantly lower total Oral Health Impact Profile scores for shortened dental arch than women (P=.033).

CONCLUSIONS

Unilateral nonmetal clasp dentures and shortened dental arch were better than conventional removable partial dentures for the oral health-related quality of life of individuals with unilateral distal-extension tooth loss in the mandible, and sex had a significant effect on removable prosthetic planning.

Effectiveness of a 3D simulation tool to teach the designing of metal removable partial dentures: A mixed-method study

INTRODUCTION

Acquiring insights into the framework design of metal-based removable partial dentures (mRPD) is a current challenge in dental education. The aim of the present study was to explore the effectiveness of a novel 3D simulation tool to teach designing mRPD by investigating the learning gain and the acceptance and motivation towards the tool of dental students.

MATERIALS AND METHODS

A 3D tool based on 74 clinical scenarios was developed for teaching the design of mRPD. Fifty-three third year dental students were randomly divided into two groups, with the experimental group (n = 26) having access to the tool during 1 week while the control group (n = 27) had no access. Quantitative analysis was based on a pre- and post-test in order to evaluate the learning gain, technology acceptance and motivation towards using the tool. Moreover, qualitative data was collected by means of an interview and focus group to get additional insights into the quantitative results.

RESULTS

Although the results showed a higher learning gain for students in the experimental condition, the study did not find a significant difference between both conditions based on quantitative results. However, during the focus groups, all students of the experimental group revealed that the 3D tool improved their understanding of mRPD biomechanics. Moreover, survey results revealed that students positively evaluated the perceived usefulness and ease of use of the tool and indicated to have the intention to use the tool in the future. Suggestions were made for a redesign (e.g. creating scenarios themselves) and further implementation of the tool (e.g. analysing the scenarios in pairs or small groups).

CONCLUSION

First results of the evaluation of the new 3D tool for teaching the design framework of mRPD are promising. Further research based on the design-based research methodology is needed to investigate the effects of the redesign on motivation and learning gain.

Fully digital workflow for duplicating clasp-retained removable partial dentures using three-dimensional printing: A clinical report

This clinical report describes a fully digital workflow for replicating removable partial dentures (RPDs). The artificial teeth and denture base of existing dentures were duplicated and applied to new dentures with a redesigned framework. After the components of RPDs had been separated from the scan data of the existing dentures, they were fabricated using 3-dimensional printing and assembled to create a new denture.

Evaluation on a teaching software for removable partial denture framework design

BACKGROUND

Removable partial dentures (RPDs) are widely used as a dental prosthesis and have a wide application scope.

OBJECTIVE

To explore the effect of using design software in the preclinical teaching of removable partial dentures (RPDs).

METHODS

Unreal Engine software was used to build the RPD framework design teaching and training software. All 131 undergraduate students majoring in stomatology in the class of 2018, Kunming Medical University, were randomly divided into three groups and received either traditional experiment teaching, flipped classroom teaching, or software teaching for RPD design. The application effect of the software in the preclinical teaching of RPD design was evaluated by analyzing the examination results and through the use of a questionnaire survey.

RESULTS

The differences in the theoretical examination scores among the traditional teaching group, the flipped classroom group, and the software teaching group were not statistically significant (P> 0.05), while the average design scores of upper Kennedy Class I and lower Kennedy Class II subclass II in the software teaching group were significantly higher than those in the traditional teaching group (P< 0.05). Overall, 75% of the students in the software teaching group reported that this teaching method could improve their learning initiative, a higher percentage than in the traditional teaching group (55.8%, P< 0.05). Meanwhile, 90.9% of the students in the software teaching group reported that the software could make RPD-related theoretical knowledge more visual and intuitive, and 93.2% of these students felt it was helpful for understanding the RPD three-dimensional (3D) spatial structure. These percentages were higher than those in the traditional teaching and flipped classroom groups (P< 0.05).

CONCLUSION

In the preclinical teaching of RPD design, software training helped the students better understand the 3D structure of RPDs and establish clear design ideas, and it may also be valuable for in-depth research and promotion purposes.

Awareness of Fixed Partial Dentures and Implant Rehabilitation of Missing Teeth Among a Subset of Saudi Population

Background  Maintaining one's sense of self requires having healthy teeth. A person's physical well-being is greatly impacted by their dental health. They are intimately related, and the socioeconomic situation of the individual largely determines how teeth are maintained. As a result, tooth loss causes injury to the stomatognathic system as well as the masticatory function. Morale is negatively impacted by psychological discomfort as well as the reduction in general quality of life brought on by tooth loss. Objectives  The purpose of this study was to assess the awareness of patients about various dental prosthetic rehabilitative procedures in Saudi Arabia, their preference(s) regarding the choice of treatment, and the motivating factors that drive them to avail of dental prosthetic rehabilitative treatment. Methods  After randomly selecting 600 individuals for the purpose of our investigation, a nine-variable questionnaire was framed by investigators to record the responses of those who consented to participate in our study. Results  Only 68.3% of the respondents were found to be aware of the several prosthodontic replacement choices. As mentioned by the majority of the respondents, the cost element was the biggest drawback for replacement. The benefits of choosing fixed partial dentures (FPD) or dental implants were judged to be aesthetics (41.1%) and the feel of one's own teeth (40.1%). Conclusion Only 68.3% of respondents reported knowing about the several prosthodontic replacement choices. The cost aspect was cited by 348 respondents as the biggest drawback to replacement. The perceived benefits of choosing FPD or dental implants were deemed to be aesthetics (41.1%) and the feel of one's own teeth (40.1%). We believe that patients' health and quality of life can be improved by raising awareness about and changing patients' attitudes toward the most cutting-edge treatment options that are readily available. This can be done by educating people about the drawbacks of delaying the replacement of missing teeth and other treatment options.

The Trueness of Scans using One Intraoral Scanner in Different Partially Edentulous Conditions

PURPOSE

To investigate the trueness of intraoral scanning in 8 commonly seen partially edentulous conditions.

MATERIALS AND METHODS

A maxillary dentoform was modified into the 8 commonly seen partially edentulous conditions. Each modification was scanned with a laboratory desktop scanner. Each modification was then scanned 10 times (n = 10) with an intraoral scanner. All scans were exported as STL files and then imported into a surface matching software using the best-fit alignment method. The dimensional differences between the study STL files from the intraoral scanner were compared to the corresponding reference STL files. The measurements were calculated as the root mean square (RMS) and defined as the trueness of the intraoral scans. In addition to the RMS values, qualitative assessments were completed on the color maps. The color maps produced by the surface matching software were used to visualize the areas of deviation between scans from the intraoral scanner and their corresponding reference files. One-way analysis of variance (ANOVA), followed by pair-wise comparisons using Fisher's Protected Least Significant Difference were utilized to compare the differences between the groups in RMS values (α = 0.05).

RESULTS

Partially edentulous condition significantly affected the trueness of the intraoral scans. Group 8 (Class IV) had significantly lower RMS (0.1878 ±0.0455 mm) than all other groups (P < 0.001). Group 2 (Class II) and Group 7 (Class III modification I) are not significantly different from each other (Group 2: 0.5758 ±0.0300 mm; Group 7: 0.5602 ±0.0231 mm, P = 0.571), while they both had significantly higher RMS than all other groups (P < .001). The remaining groups showed the RMS values were within the range of 0.3001 ±0.0891 mm (Group 6 - Class III with Long Edentulous Span) and 0.4541 ±0.1039 mm (Group 1 - Class I).

CONCLUSION

Different partially edentulous conditions affected the trueness of the scans generated from the selected intraoral scanner. Class IV edentulous condition had the highest intraoral scan trueness. It is unknown if RMS values are clinically significant, and the validity of using intraoral scans directly for PRDP fabrication will need further studies. This article is protected by copyright. All rights reserved.

Evaluation of the mechanical properties and fit of 3D-printed polyetheretherketone removable partial dentures

Compared with CAD/CAM, fused deposition modeling (FDM) 3D printing technology is simple and safe to operate and has a low cost and high material utilization rate; thus, it is widely used. The present investigation aimed to evaluate the mechanical properties and fit of polyetheretherketone (PEEK) removable partial dentures (RPDs) constructed by FDM. We analyzed mechanical properties of PEEK samples prepared by FDM, milling, or injection molding. RPDs were designed and finite element analysis models was constructed to evaluate maximum stress and strain in the RPDs, cortical bone and mucosa. Geomagic Qualify software was used to analyze gaps between the model and the tissue surface of the framework. The results showed that the compressive strength of the 3D-printed PRDs was greater than that of the injection-molded samples. Finite element analysis demonstrated that the maximum stress on the PRDs was less than the yield strength of the material. Overall, the mechanical properties and fit of the PEEK RPD fabricated by FDM technology essentially fulfilled clinical requirements.

Current and future trends in the teaching of removable partial dentures in dental schools in Malaysia: A cross sectional study

AIMS

To investigate, using a validated questionnaire, the teaching of removable partial dentures (RPDs) in dental schools of Malaysia.

MATERIALS AND METHODS

A validated questionnaire to investigating trends in the teaching of RPDs in dental schools in Oceania was emailed (in English version form) to Heads of Restorative/Prosthodontics/course coordinators in the 13 dental schools in Malaysia. Follow-up reminders were sent and participants were given six weeks to complete and return the questionnaire. Data was entered into an Excel spreadsheet and results compiled and analyzed.

RESULTS

Completed questionnaires were received from 13 dental school - a 100% response rate. All schools (n = 13) provided a preclinical technical course in RPD design. In most schools (n = 9, 69.2%), course work was supervised by senior lecturers while rest of the institutions made use of associate professor/professors. There were significant differences (p<0.05) between dental schools in terms of the contact hours dedicated to preclinical teaching. Students received an average of 62 h of instruction. Didactic instruction was the primary focus with practical (78 h) and didactic teaching (32 h). All dental schools (n = 13) provided practical surveyor design teaching (8 h). The staff student ratio for formal lectures (1:61), tutorials (1:29) and lab demonstrations (1:12) were recorded. Majority of the schools (n = 11, 84.6%) employed paired teaching in clinical sessions. All schools (n = 13, 100%) emphasized on increased teaching of RPD design and prescription writing in future clinical RPD courses.

CONCLUSION

Teaching of RPDs in Malaysia may be considered sufficient and comparable to the teaching in other parts of the world.

CLINICAL SIGNIFICANCE

Whilst the teaching of partial dentures at Dental Schools in Malaysia provides the core competencies involved in partial denture design and construction based on sound fundamental, scientific principles they should address the challenges of teaching partial dentures and other areas of dental education including improving working conditions for dental professionals.

Subtractive versus additive indirect manufacturing techniques of digitally designed partial dentures

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy of digitally designed removable partial denture (RPD) frameworks, constructed by additive and subtractive methods castable resin patterns, using comparative 3D analysis.

MATERIALS AND METHODS

A Kennedy class III mod. 1 educational maxillary model was used in this study. The cast was scanned after modification, and a removable partial denture framework was digitally designed. Twelve frameworks were constructed. Two groups were defined: Group A: six frameworks were milled with castable resin, then casted by the lost wax technique into Co-Cr frameworks; Group B: six frameworks were printed with castable resin, then casted by the lost wax technique into Co-Cr frameworks. Comparative 3D analysis was used to measure the accuracy of the fabricated frameworks using Geomagic Control X software. Student's t-test was used for comparing data. P value ≤ .05 was considered statistically significant.

RESULTS

Regarding the accuracy of the occlusal rests, group A (milled) (0.1417 ± 0.0224) showed significantly higher accuracy than group B (printed) (0.02347 ± 0.0221). The same results were found regarding the 3D comparison of the overall accuracy, in which group A (0.1501 ± 0.0205) was significantly more accurate than group B (0.179 ± 0.0137).

CONCLUSION

In indirect fabrication techniques, subtractive manufacturing yields more accurate RPDs than additive manufacturing.

Biomechanics in Removable Partial Dentures: A Literature Review of FEA-Based Studies

The present study was aimed at reviewing the studies that used finite element analysis (FEA) to estimate the biomechanical stress arising in removable partial dentures (RPDs) and how to optimize it. A literature survey was conducted for the English full-text articles, which used only FEA to estimate the stress developed in RPDs from Jan 2000 to May 2021. In RPDs, the retaining and supporting structures are subjected to dynamic loads during insertion and removal of the prosthesis as well as during function. The majority of stresses in free-end saddle (FES) RPDs are concentrated in the shoulder of the clasp, the horizontal curvature of the gingival approaching clasp, and the part of the major connector next to terminal abutments. Clasps fabricated from flexible materials were beneficial to eliminate the stress in the abutment, while rigid materials were preferred for major connectors to eliminate the displacement of the prosthesis. In implant-assisted RPD, the implant receive the majority of the load, thereby reducing the stress on the abutment and reducing the displacement of the prosthesis. The amount of stress in the implant decreases with zero or minimal angulation, using long and wide implants, and when the implants are placed in the first molar area.

Retentive Forces of Removable Partial Denture Clasp Assemblies Made from Polyaryletherketone and Cobalt-Chromium: A Comparative Study

PURPOSE

To compare retentive forces of removable partial denture clasps traditionally fabricated with cobalt-chromium (CoCr) material and two computer-aided design and computer-aided manufactured (CAD/CAM) thermoplastic polymers.

MATERIALS AND METHODS

Forty-eight clasp assemblies (16 CoCr, 16 polyetheretherketone (PEEK) and 16 polyetherketoneketone (PEKK) thermoplastic polymer) were fabricated for 48 mandibular tooth analogs. Individual clasps were inserted and removed on the tooth analogs utilizing a chewing simulator for 15,000 cycles to simulate 10 years of use. Retentive forces were measured utilizing a mechanical load tester at baseline and intervals of 1500 cycles. Data were analyzed with one-way Analysis of Variance, Tukey post-hoc, and paired T tests.

RESULTS

Mean retentive forces between all groups were significantly different (p < 0.001). Retentive forces of CoCr clasps were significantly higher than both polymers (p < 0.001). The mean retentive forces for PEEK were not significantly different from PEKK (p = 0.23). A significant increase in retentive forces was observed for all three clasps after the first period of cycling, followed by continual decrease for the remaining cycles. At the endpoint of 15,000 cycles, no clasp assemblies showed lower retentive forces than at initial baseline.

CONCLUSION

Thermoplastic polymer clasps demonstrated lower retentive forces compared to CoCr clasps. All three groups displayed a similar pattern of initial increase, followed by a gradual decrease, of retentive force. Despite this observation, the clasps maintained similar or higher retentive forces than measured at baseline. This resistance to fatigue and ability to fabricate with CAD/CAM technologies provides support for clinical use of these high-performance polymer (HPP) materials.

Influence of reinforcement bar on accuracy of removable partial denture framework fabricated by casting with a 3D-printed pattern and selective laser sintering

PURPOSE

The purpose of this study was to investigate the accuracy of removable partial denture frameworks fabricated by 3D-printed pattern casting (AM-Cast) and selective laser sintering (SLS) under different co nditions with a reinforcement bar.

METHODS

A partially edentulous model was scanned with a dental laboratory scanner, and CAD software was used to design the framework. Reinforcement bars (n=0-2) were set on the lingual side of the framework. 3D scanning of the fabricated frameworks by AM-Cast and SLS was performed, and the obtained data were overlapped with the design data. The differences in shape among setting conditions of the bar were statistically compared using the Bonferroni method after the Kruskal-Wallis test.

RESULTS

The ranges in differences of the AM-Cast-0, AM-Cast-1, and AM-Cast-2 were -0.167 to 0.128 mm, -0.101 to 0.105 mm, and -0.185 to 0.015 mm, respectively. The ranges of SLS-0, SLS-1, and SLS-2 were -0.166 to 0.035 mm, -0.182 to 0.049 mm, and -0.138 to 0.038 mm, respectively. Large discrepancies were observed at the joining area of the lingual bar on the right side of the AM-Cast. A significant difference was found between the AM-Cast-0 and AM-Cast-1, and between the AM-Cast-0 and AM-Cast-2.

CONCLUSIONS

The setting conditions of the reinforcement bar affected the accuracy of the lingual bar in the AM-Cast; however, no effect was observed on the displacement of the central area of the lingual bar in SLS. Setting a single reinforcing bar on the retentive latticework contributed to improving the accuracy of the lingual bar in the AM-Cast but not the displacement of the central area of the lingual bar in SLS.

Nonmetal clasp dentures: What is the evidence about their use?

The aim was to discuss the indications, contraindications, advantages, and disadvantages of Nonmetal clasp dentures (NMCDs), as well as the most relevant properties of its constituent materials. A search was conducted using the keywords: “nonmetal clasp dentures,” “thermoplastic resin,” “flexible resin removable partial denture,” “polyamide,” and “nylon” in databases PubMed/Medline, Lilacs, SciELO, and textbooks between 1955 and 2020. Theses and texts without reliable sources of publication were excluded. Once the analysis instruments were determined, the data were analyzed and discussed. NMCDs present high flexibility, easy adaptation to the abutments, color compatibility and biocompatibility with the oral mucosa, and absence of visible metal clasps. However, they need laboratory relining, grinding, and polishing, do not have criteria for its planning, become rougher and stained over time, and are able to traumatize supporting tissues. The association with metal components seems to be an alternative to increase the success of NMCDs by combining esthetics and biomechanical principles of conventional removable partial dentures. The lack of long-term clinical studies makes the professionals to rely solely on previous experiences or on the manufacturers' recommendations. It suggested that NMCDs must be indicated with caution when not used temporarily.

A digital cast-free clinical workflow for oral rehabilitation with removable partial dentures: A dental technique

The present report describes a technique for a digital cast-free clinical workflow for the fabrication of a combined tooth-implant-supported removable partial denture. This technique comprises digital intraoral scanning, computer-aided design, and subtractive computer-aided manufacturing for the denture base, denture teeth, and crowns and additive computer-aided manufacturing for the denture framework (CAD-CAM).

A three-dimensional finite element analysis of mechanical function for 4 removable partial denture designs with 3 framework materials: CoCr, Ti-6Al-4V alloy and PEEK

Polyetheretherketone (PEEK) is a new material used for the frameworks of removable partial dentures (RPD). The questions whether the PEEK framework has similar stress distribution on oral tissue and displacement under masticatory forces as titanium alloy (Ti-6Al-4V) or cobalt-chromium alloy (CoCr) remain unclear and worth exploring. A patient's intraoral data were obtained via CBCT and master model scan. Four RPDs were designed by 3Shape dental system, and the models were processed by three-dimensional finite element analysis. Among three materials tested, PEEK has the lowest maximum von Mises stress (VMS) on periodontal ligament (PDL), the greatest maximum VMS on mucosa, the maximum displacement on free-end of framework, and the lowest maximum VMS on framework. Results suggested that PEEK framework has a good protective effect on PDL, suggesting applications for patients with poor periodontal conditions. However, the maximum displacement of the free-end under masticatory force is not conducive for denture stability, along with large stress on the mucosa indicate that PEEK is unsuitable for patients with more loss of posterior teeth with free-end edentulism.

Obturator fabrication incorporating computer-aided design and 3-dimensional printing technology: A clinical report

This article reports an approach to fabricating a maxillary obturator using the computer-aided design and computer-aided manufacturing (CAD-CAM) process. The maxillary definitive cast and the trial tooth arrangement were separately scanned and superimposed. The virtual cast created from the scan data was surveyed, and the framework was designed using specific software. The definitive cobalt-chromium framework was fabricated by using 3-dimensional (3D) selective laser sintering (SLS) technology. After framework trial placement, the definitive obturator prosthesis was processed using conventional heat-polymerizing resin with the lost-wax processing technique. Using CAD technology and 3D metal printing resulted in improved fit, function, and esthetics for the definitive obturator prosthesis.

An In Vitro Investigation of Accuracy and Fit of Conventional and CAD/CAM Removable Partial Denture Frameworks

PURPOSE

To evaluate the overall accuracy and fit of conventional versus computer-aided design/computer-aided manufactured (CAD/CAM) removable partial denture (RPD) frameworks based on standard tessellation language (STL) data analysis, and to evaluate the accuracy and fit of each component of the RPD framework.

MATERIALS AND METHODS

A maxillary metal framework was designed for a Kennedy class III Modification I arch. The master model was scanned and used to compare the fit and accuracy of RPD frameworks. Forty impressions (conventional and digital) of the master cast were made and divided into 4 groups based on fabrication method: group I, lost-wax technique (conventional technique), group II, CAD-printing, group III, CAD-printing from stone cast, and group IV, lost-wax technique from resin-printed model. RPD frameworks were fabricated in cobalt-chromium alloy. All frameworks were scanned, and the gap distance between the framework and scanned master model was measured at 8 locations. Color mapping was conducted using comprehensive metrology software. Data were statistically analyzed using the Kruskall-Wallis test, followed by the Bonferroni method for pairwise comparisons (α = 0.05).

RESULTS

Color mapping revealed distinct discrepancies in major connectors among the groups. When compared to 3D-printed frameworks, conventional cast frameworks fabricated using dental stone or printed resin models revealed significantly better fit (p < 0.05) particularly in the major connectors and guide plates. The biggest gap (0.33 mm ± 0.20 mm) was observed with the anterior strap of the major connector with the printed frameworks (groups II and III). The method of fabrication did not affect the adaptation of the rests or reciprocation plates.

CONCLUSIONS

Although both conventional and 3D-printing methods of framework fabrication revealed clinically acceptable adaptation, the conventional cast RPD groups revealed better overall fit and accuracy.

Overdentures borne on less than four abutments with telescopic crowns: 5-year results of a retrospective clinical study

OBJECTIVE

Retrospective evaluation of the clinical performance of tooth-supported overdentures retained by resilient telescopic crowns with occlusal clearance fit (ODRTC) in severely reduced dentition (1-3 remaining teeth).

MATERIALS AND METHODS

A total of 313 ODRTCs were inserted in an undergraduate prosthodontic program (University Medical Center, Goettingen, Germany) between 2000 und 2012. Data regarding 263 ODRTCs in 221 patients were reevaluated (observational period: 64.5 ± 34.8 months), and time-dependent survival and success rates (Kaplan-Meier-Estimator) were calculated. The number of the abutment teeth was analyzed as an influencing factor (Cox regression model (p < 0.05)).

RESULTS

The 5- and 8-year overdenture survival rates were 62% [CI: 0.55; 0.69] and 38% [CI: 0.30; 0.45]. The 5- and 8-year success-rates (biologically and technically event-free restorations) were 13% [CI: 0.09; 0.17] and 3% [CI: 0.01; 0.05]. On the abutment level, the 5- and 8-year survival rates were 55% [CI: 0.48; 0.62], and 34% [CI: 0.27; 0.42]. The number of abutment teeth significantly influenced the overdenture and abutment survival rates. Restorations with 1 or 2 abutments were significantly associated with an increased number of technical and biological complications (decementation of the primary crown, abutment fracture) compared to ODRTCs with 3 abutments.

CONCLUSIONS

The survival and success rates of ODRTCs are significantly influenced by the number of abutments.

CLINICAL RELEVANCE

For ODRTCs, reduced survival and success rates are expected, especially when only 1 or 2 abutment teeth are included.

CAD/CAM Constructed Poly(etheretherketone) (PEEK) Framework of Kennedy Class I Removable Partial Denture: A Clinical Report

The prevalence of partially edentulous adults that could be treated by removable partial dentures (RPDs) is estimated to be greater than 20% in some regions of the United States. Problems related to traditional materials for RPD construction have been documented. Advances in polymer-based materials and digital fabrication strategies would allow increased biocompatibility, durability, and elasticity, as well as more esthetically pleasing and cost-effective benefits. This article reports on poly(etheretherketone) RPD framework produced by digital and milling technology.