Evaluation of hypermobile teeth deviation during impression taking in a partially edentulous dental arch: An in vitro study comparing digital and conventional impression techniques.

PURPOSE: This study aimed to compare the deviation of hypermobile teeth in partially edentulous dental arches during impression taking using digital and conventional techniques. METHODS: A partially edentulous mandibular model with three target hypermobile teeth (including the left first premolar, #34; left second molar, #37; and right first premolar, #44), was used as the simulation model. After reference data were acquired using a desktop scanner, impressions of the simulation model were obtained using a digital intraoral scanner (IOS) and two conventional techniques (hydrocolloid material with a stock tray and silicone material with a custom tray as impression data (n=12/group). The three-dimensional accuracy (root mean square value) and two-dimensional accuracy (mesiodistal and buccolingual displacements) of the target teeth in each impression dataset were calculated based on the reference data. The comparison among three impression techniques was statistically performed using the Kruskal-Wallis test (α=0.05). RESULTS: For #34 and #44, the three- and two-dimensional accuracies of the impressions fabricated through data acquired through digital scanning (digital impression) were significantly superior to those of the hydrocolloid impression (P < 0.05), whereas no significant difference was found between the digital and silicone impressions. For #37, no significant difference in the accuracy of the impression data for the target teeth was observed among the three impression techniques. CONCLUSIONS: Digital impression acquiring using an IOS is recommended over using a conventional hydrocolloid impression to prevent the deviation of hypermobile teeth in partially edentulous dental arches. Hypermobile tooth deviation in digital impression data depends on the tooth location.

Fracture Resistance of Zirconia Surveyed Crowns With Digitally Designed and Hand-Modified Occlusal Rest Seats.

Background In light of the trend of using zirconia crowns, clinicians will likely face abutment included in removable partial dentures (RPD) designs with existing zirconia. However, the decision to replace the existing crown with a surveyed crown or modify the existing crown to accept the RPD is unclear. To the best of our knowledge, there is a lack of literature on the effect of preparing a rest seat on the existing monolithic zirconia crown in the patient's mouth on the fracture resistance of the crown. Therefore, in this study, we aimed to evaluate the fracture resistance of computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia surveyed crowns with digitally designed rest seats and hand-modified rest seats. Methods Thirty CAD/CAM zirconia surveyed crowns were digitally designed and fabricated and divided into groups (n=10 per group) as follows: Group 1 comprised surveyed crowns with no occlusal rest seat; Group 2 comprised surveyed crowns with a digitally designed mesial rest seat; and Group 3 comprised surveyed crowns with a hand-modified mesial rest seat. Then, with all the crowns cemented to metal dies, the specimens were subjected to a fracture resistance test using a universal testing machine (Model 8501 Instron, Norwood, MA, USA). Results Surveyed crowns without any rest seat and those with digitally created and hand-modified rest seats displayed different fracture resistances: crowns with no rest seat offered the highest fracture resistance (5831 ± 895.15 N), followed by those with a digitally designed and milled rest seat (5280 ± 1673.33 N). Crowns with a hand-modified rest seat provided the lowest fracture resistance (4976 ± 322.5 N). Based on our results, surveyed crowns without a rest seat displayed higher fracture resistance than those with a rest seat. Conclusion The fracture resistance of crowns with a digitally designed and milled rest seat was statistically similar to that of control crowns with no rest seat, whereas hand-modified rest seats significantly reduced the fracture resistance of surveyed zirconia crowns.

Accurate analysis of titanium and PolyEtherEtherKetone materials as an alternative to cobalt-chrome framework in removable partial denture: A systematic review.

STATEMENT OF PROBLEM: New materials have emerged in the dental field to replace the cobalt-chrome (CoCr) alloy used for the metal frameworks in removable partial denture (RPD) such as Titanium (Ti) and PolyEtherEtherKetone (PEEK). However, few studies have demonstrated their mechanical and biological performance. PURPOSE: The purpose of this systematic review was to compare the performance of Ti and PEEK in RPD using CoCr metal framework as a reference. MATERIAL AND METHODS: This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three data bases were analyzed, including PubMed/MEDLINE, Embase and Web of Science before March 2024. Only studies assessing the mechanical and/or biological properties of RPD in Ti, PEEK and CoCr were included. The quality of the studies was assessed by using the software Rayyan. The risks of bias were assessed with the methodological index for nonrandomized studies (MINORS). The mechanical (retention force, fatigue life, deformation strength, machinability, rigidity, porosity and surface roughness) and biological (plaque indices, ion release and biocompatibility) aspects were assessed. RESULTS: Among 138 articles identified, only 18 studies were included in this review. Majority had a low to moderate risk of bias. Retention forces and fatigue were significantly lower for Ti and PEEK than for CoCr, and the same was true for Ti rigidity. PEEK showed less deformation. Both materials were suitable for machining. In terms of biological properties, both materials showed adequate biocompatibility for clinical use. CONCLUSION: Ti and PEEK seems to be promising as alternative materials to CoCr frameworks for RPD, in terms of both their mechanical and biological performance. However, additional studies are needed to better understand their clinical and long-term limitations to enable the best-informed clinical choice for the patients and the professionals.

In vitro comparison of guide planes for removable partial dentures prepared with CAD-CAM-assisted templates, guiding rod templates, and freehand.

OBJECTIVES: This study aimed to evaluate the accuracy of computer-aided design and computer-aided manufacturing (CAD-CAM)-assisted templates (CCAT), guiding rod templates (GRT), and freehand (FH) preparation of guide planes. METHODS: Forty-five identical maxillary resin casts were divided into three groups, in which the guide planes of the two abutment teeth were prepared using a CCAT (n=15), GRT (n=15), and FH (n=15). The CCAT and GRT were digitally designed on a digital cast of virtually prepared guide planes and fabricated using three-dimensional printing (3DP) technology. To assess the 3D trueness, the prepared guide planes were digitally scanned and compared to the virtually designed guide planes. The angle deviation was measured to assess the trueness of the direction of the guide plane preparation. Shapiro-Wilk and Levene's tests were used to check the normality and equivalence of the variance of the data. The data were compared by using the Kruskal‒Wallis H test (α=0.05). RESULTS: The CCAT group exhibited significantly better 3D trueness (78.5±19.8 µm) than the GRT group (211.3±42.4 µm, p<0.05) and the FH group (198.9±44.3 µm, p<0.05). Additionally, the CCAT group (1.31±0.50°) showed significantly smaller direction trueness compared to the GRT (4.65±0.72°, p<0.05) and FH (5.64±0.70°, p<0.05) groups. CONCLUSIONS: The novel CAD-CAM-assisted template significantly improved the quality of the guide planes compared with the GRT and FH procedures. This enhancement suggests that removable partial dentures can be predictably inserted immediately after guide plane preparation. CLINICAL SIGNIFICANCE: CAD-CAM-assisted templates improve the quality of guide plane preparation.

Clinical evaluation of a one-piece polyetheretherketone removable partial denture fabricated using a novel digital workflow: A self-controlled clinical trial.

PURPOSE: To explore the clinical application of one-piece polyetheretherketone (PEEK) removable partial dentures (RPDs) fabricated using a novel digital workflow and to evaluate their weights and fits in vivo and patient satisfaction. MATERIALS AND METHODS: Fifteen cases with posterior partially edentulous situations were selected, and each patient received two types of RPDs, including a novel digital workflow (test group) and a conventional workflow (control group). For the test group, one-piece RPDs were designed through three-dimensional (3D) methods by scanning stone casts and fabricated by milling PEEK discs. Each RPD was weighed. The gaps between the oral tissue and RPDs in each group were duplicated using a polyvinylsiloxane (PVS) replica and measured by 3D analysis. A visual analog scale (VAS) was used to evaluate the patient's satisfaction. Paired t-tests were used to compare the differences in the weight, the gaps of each RPD, and VAS values between the two groups. One-way analysis of variance tests was used to compare the differences in the gap among different components in each group. RESULTS: The RPD in the test group weighed less than that in the control group (p < 0.01). No statistically significant differences in the gaps of denture bases and rests (p > 0.05) were found between the two groups, but the gaps of major connectors in the test group were significantly smaller than in the control group (p < 0.05). The VAS scores for comfortableness and masticatory efficiency were not significantly different between the two groups (p > 0.05) but the scores for the aesthetic appearance of the clasps in the test group were significantly higher than that in the control group (p < 0.05). CONCLUSIONS: One-piece PEEK RPDs manufactured using a novel digital workflow weighed less than conventional RPDs and exhibited a clinically acceptable internal fit. Although the aesthetic appearance of the PEEK clasps was superior to the control, there is still room for improvement.

Accuracy of Mandibular Removable Partial Denture Frameworks Fabricated by 3D Printing and Conventional Techniques.

Herein, we used digital superimposition to evaluate the accuracy of metal frameworks for mandibular removable partial dentures fabricated using three techniques. Thirty master casts of a mandibular dentiform were categorized into three groups (n = 10) based on the framework manufacturing method: selective laser melting-based metal three-dimensional (3D) printing (SLM), digital light projection-based resin 3D printing and subsequent casting (RPC), and conventional casting (CON). The master casts were scanned twice, initially after preparation and subsequently after attaching silicone using the frameworks. These scan files were digitally superimposed to measure the silicone thickness. Statistical analysis was conducted using SPSS Statistics (Version 23.0, IBM Corp., Somers, NY, USA). One-way ANOVA and a post hoc Tukey's multiple comparison tests were performed to determine differences among the three groups (α = 0.05). The RPC group exhibited significantly higher overall and mean internal discrepancies at rest and tissue stops than the SLM and CON groups, which exhibited statistically insignificant differences. Thus, SLM fabrication resulted in comparable accuracy to that achieved by CON, whereas sequentially performing resin 3D printing and casting induced inferior accuracy. However, all frameworks across the three groups were clinically acceptable.

Effect of wall thickness on shape accuracy of hollow zirconia artificial teeth fabricated by a 3D printer.

PURPOSE: This study aimed to analyze how the wall thickness of 3D-printed hollow zirconia teeth affects shape accuracy. METHODS: Datasets with measurement points were created for different artificial teeth resembling the mandibular right first molar (Geomagic Design X, 3D Systems). Reference distances were 9.8 mm for mesio-distal direction (M-D), 10.9 mm for bucco-lingual direction (B-L), 7.0 mm for MB-BB and DB-BB, and 4.5 mm for ML-LB and DL-LB. The outer geometry was identical for all artificial teeth with wall thicknesses of 0.30, 0.50, 0.75, and 1.00 mm. Twenty zirconia teeth were fabricated using a 3D printer (CeraFab 7500 Dental, Lithoz) for each group and sintered before support removal. After performing analog distance measurements using a micrometer screw, the digital distance measurements and angular deviations between measurement points on 3D scans were analyzed. Possible effects were investigated using nonparametric ANOVA, followed by Tukey's honest significant difference (HSD) test for multiple comparisons. RESULTS: The shape accuracy was acceptable for artificial teeth with wall thicknesses of ≥0.5 mm. The largest distance deviation was observed for a wall thickness of 0.3 mm. In particular, DB-BB showed a median deviation of >56.2 µm, which is significantly larger than that for other test groups, ranging from 7.4-9.5 µm (P < 0.05). In most cases, angular deviations were the largest for teeth with 0.3-mm wall thickness (11.6°) and remained below 5.0° for the other test groups. CONCLUSIONS: Acceptable accuracy was obtained for artificial teeth with wall thicknesses of at least 0.5 mm.

Effect of Reinforcement Bar on Trueness of Printed Titanium Kennedy I Removable Partial Denture Frameworks by Selective Laser Melting.

OBJECTIVE: The addition of reinforcement bars is a commonly used method to improve the fabrication trueness of selective laser melting removable partial denture alloy frameworks. However, the effects of different reinforcement bar designs on the trueness of the entire framework remain unclear. This study investigated the trueness of removable partial denture frameworks of pure titanium fabricated by selective laser melting under different reinforcement bar settings. METHOD: A virtual framework was designed based on the Kennedy Class I partially edentulous model using computer-aided design software. Frameworks with different reinforcement bar settings (Ti-A without reinforcement bar, Ti-B with a single horizontal bar joining the lingual bar, Ti-C with two more bars at the anterior region, Ti-D with another horizontal bar at the anterior region, and Ti-E with one more bar at the posterior region, n = 5) were printed using pure titanium powder using a direct metal laser melting machine. The fabricated frameworks were scanned, and their fabrication trueness was compared with the designed virtual framework using one-way ANOVA. RESULTS: The overall mean discrepancies for Ti-A, Ti-B, Ti-C, Ti-D, and Ti-E were 0.111, 0.047, 0.073, 0.068, and 0.047 mm, respectively. For the group of Ti-A set with no reinforcement bars, larger discrepancies were observed compared with the other four groups (P < .05). Groups Ti-B and Ti-E showed better trueness of the RPI clasps, rests, and distal ends (P < .05). CONCLUSIONS: Adding reinforcement bars improved the printing trueness of the pure titanium frameworks, and different settings resulted in various degrees of improvement. Setting a single reinforcement bar to join the lingual bar or an additional reinforcement bar at the distal end significantly enhanced the printing trueness of the RPI clasps, rests, and distal ends.

Deformation and retentive forces variations of the additively manufactured cobalt-chromium and titanium alloys dental clasps.

This in vitro study aimed to evaluate the additive manufacturing (AM) of cobalt chromium Co-Cr and titanium Ti alloy clasps for clinical use. After scanning the Ni-Cr die of the first molar, Akers' clasps were designed using computer-aided design/ computer-aided manufacturing (CAD/CAM). The clasps were manufactured from Co-Cr-W dental alloy and Ti-6Al-4V alloy powder using AM machines. Then, they were divided into two groups. The initial retentive force of the clasps was measured using a universal testing machine. Cyclic loading of the clasps was carried out by a specially designed insertion-removal testing apparatus in wet condition up to 5000 cycles. Retentive force was measured at 1000, 2000, 3000, 4000, and 5000 cycles. Moreover, the intaglio surface of each clasp was scanned using the scanner; and superimposition between the pre- and post-cycling clasp files was performed to evaluate deformation after cyclic loading. The fitting surfaces of retentive clasp tips were examined with a scanning electron microscope (SEM). Finally, it has been found that the initial retentive force for the Co-Cr group was 10.81 ± 0.37 N, and for the Ti group was 5.41 ± 0.18 N. Additionally, during the testing periods, both Co-Cr and Ti clasps continued to lose retentive force within the cycles of placement and removal. This effect was more prominent in the Co-Cr than in the Ti clasps. The distances between pre- and post-cycling in the retentive arm were -0.290 ± 0.11 mm and -0.004 ± 0.01 mm in Co-Cr and Ti alloys, respectively, and in the reciprocal arm were -0.072 ± 0.04 mm and -0.032 ± 0.04 mm in Co-Cr and Ti alloys, respectively. The retentive force required to remove the Ti clasps was found to be significantly lower than those required to dislodge the Co-Cr clasps. Co-Cr and Ti clasps lost significant amounts of retentive force from the initial use to the 3.5-year periods of simulated clinical use.

Effects of denture use on occlusal force on abutment teeth in molar distal-extension edentulism.

PURPOSE: The present clinical study aimed to investigate the load exerted on abutment teeth in patients with distal extension edentulism, with and without a removable partial denture (RPD). METHODS: A total of 55 volunteers with distal extension edentulism who were fitted with an RPD participated in the present study. Occlusal force was measured by having the patients bite down on an occlusal force measuring sheet, and the occlusal forces on both the abutment teeth and the entire dentition with and without the RPD were compared using the Wilcoxon signed-rank test (P < 0.05). The occlusal forces on the abutment and non-abutment teeth were also compared. RESULTS: The median total occlusal force with the RPD in place was significantly greater than that without the RPD, while the median occlusal force on the abutment teeth without the RPD in place was significantly greater than that on the abutment teeth with the RPD. The occlusal forces on the abutment teeth were significantly greater than those on the non-abutment teeth. CONCLUSIONS: Within the limitations of the present study, we found that the occlusal forces were greater on the abutment than the non-abutment teeth, and that RPDs may reduce the occlusal forces on abutment teeth.

An in vitro evaluation of bond strength and failure behavior between 3D-printed cobalt-chromium alloy and different types of denture base resins.

OBJECTIVES: This study aimed to evaluate the shear bond strength and failure behavior between cobalt-chromium (Co-Cr) alloy and different types of denture base resins (DBRs) over time. METHODS: Seventy-two disk-shaped specimens (8 mm in diameter and 2 mm in thickness) were manufactured using a selective laser melting technology-based metal 3D printer. Three types of DBRs were used: heat-cure (HEA group), cold-cure (COL group), and 3D-printable (TDP group) DBRs (n = 12 per group). Each DBR specimen was fabricated as a 5 mm × 5 mm × 5 mm cube model. The specimens of the TDP group were manufactured using a digital light processing technology-based 3D printer. Half of the DBRs were stored in distilled water at 37 °C for 24 h, whereas the remaining half underwent thermocycling for 10,000 cycles. Shear bond strength was measured using a universal testing machine; failure modes were observed, and metal surfaces were evaluated using energy dispersive spectrometry. RESULTS: The shear bond strength did not differ between the DBR types within the non-thermocycled groups. Contrarily, the TDP group exhibited inferior strength compared to the HEA group (P = 0.008) after thermocycling. All three types of DBRs exhibited a significant decrease in the shear bond strength and an increased tendency toward adhesive failure after thermocycling. CONCLUSIONS: The bond strength between 3D-printable DBRs and Co-Cr alloy was comparable to that of heat-and cold-cure DBRs before thermocycling. However, it exhibited a considerable weakening in comparison to heat-cure DBRs after simulated short-term use. CLINICAL SIGNIFICANCE: The application of 3D-printable DBR in metal framework-incorporated removable partial dentures may be feasible during the early phase of the treatment. However, its application is currently limited because the bond strength between the 3D-printable DBR and metal may weaken after short-term use. Further studies on methods to increase the bond strength between these heterogeneous materials are required.

Effects of various prosthetic methods for patients with Kennedy Class I partial edentulism on oral hypofunction, subjective symptoms, and oral health-related quality of life.

PURPOSE: This propensity score matching, multicenter, cross-sectional study was performed to examine the effects of various prosthetic methods for dental clinic outpatients with Kennedy Class I partial edentulism (KCIPE) on oral hypofunction, subjective frailty symptoms, and oral health-related quality of life (QOL). METHODS: Patients (n = 348) were classified into the following three groups for analysis: NT, patients with natural dentition providing intermaxillary contact in four occlusal supporting zones; RPD, patients with KCIPE who received removable partial dentures; and ISFP, patients with KCIPE who received implant-supported fixed prostheses. Participants' basic characteristics were recorded, and oral function tests were conducted. Subjective symptoms of physical and oral frailty were investigated via questionnaire. Oral health-related QOL was assessed using the Japanese short version of the Oral Health Impact Profile (OHIP-JP16). Propensity score matching was performed to adjust for patient background factors that could influence oral hypofunction in each group. RESULTS: Compared with the ISFP group, the RPD group had significantly higher rates of poor oral hygiene, reduced occlusal force, decreased masticatory function, and declines in swallowing function and oral hypofunction; the odds ratio for oral hypofunction was 4.67. Compared with the ISFP group, the RPD group had significantly greater subjective symptoms of physical frailty and oral frailty, as well as higher OHIP scores. CONCLUSIONS: Prosthetic treatment of KCIPE affected oral hypofunction, subjective frailty symptoms, and oral health-related QOL in dental clinic outpatients.

Suitability and Trueness of the Removable Partial Denture Framework Fabricating by Polyether Ether Ketone with CAD-CAM Technology.

The object of the study was to evaluate the suitability and trueness of the removable partial denture (RPD) framework fabricated by polyether ether ketone (PEEK) with the CAD-CAM technology in vitro. Four different types of dentition defects were selected. In each type, five PEEK RPD frameworks were fabricated by the CAD-CAM technology, while five Co-Cr RPD frameworks were made by traditional casting. The suitability of the framework was evaluated by silicone rubber film slice measurement and the three-dimensional image overlay method. The trueness of the PEEK framework was detected by the three-dimensional image overlay method. Data were statistically analyzed with the use of an independent samples t-test (α = 0.05). The suitability values by silicone rubber film slice measurement of the PEEK group were lower than those of the Co-Cr group in four types, with the differences indicating statistical significance (p < 0.05) in type one, type two, and type four. The suitability values using the three-dimensional image overlay method showed no statistical differences (p > 0.05) between the two groups in four types. The trueness values of the PEEK group were within the allowable range of clinical error. The suitability and trueness of the PEEK RPD framework fabricated by CAD-CAM technology met the requirements of the clinical prosthesis.

Efficacy of a Virtual 3D Simulation-Based Digital Training Module for Building Dental Technology Students' Long-Term Competency in Removable Partial Denture Design: Prospective Cohort Study.

Background: Removable partial denture (RPD) design is crucial to long-term success in dental treatment, but shortcomings in RPD design training and competency acquisition among dental students have persisted for decades. Digital production is increasing in prevalence in stomatology, and a digital RPD (D-RPD) module, under the framework of the certified Objective Manipulative Skill Examination of Dental Technicians (OMEDT) system reported in our previous work, may improve on existing RPD training models for students. Objective: We aimed to determine the efficacy of a virtual 3D simulation-based progressive digital training module for RPD design compared to traditional training. Methods: We developed a prospective cohort study including dental technology students at the Stomatology College of Chongqing Medical University. Cohort 1 received traditional RPD design training (7 wk). Cohort 2 received D-RPD module training based on text and 2D sketches (7 wk). Cohort 3 received D-RPD module pilot training based on text and 2D sketches (4 wk) and continued to receive training based on 3D virtual casts of real patients (3 wk). RPD design tests based on virtual casts were conducted at 1 month and 1 year after training. We collected RPD design scores and the time spent to perform each assessment. Results: We collected the RPD design scores and the time spent to perform each assessment at 1 month and 1 year after training. The study recruited 109 students, including 58 (53.2%) female and 51 male (56.8%) students. Cohort 1 scored the lowest and cohort 3 scored the highest in both tests (cohorts 1-3 at 1 mo: mean score 65.8, SD 21.5; mean score 81.9, SD 6.88; and mean score 85.3, SD 8.55, respectively; P<.001; cohorts 1-3 at 1 y: mean score 60.3, SD 16.7; mean score 75.5, SD 3.90; and mean score 90.9, SD 4.3, respectively; P<.001). The difference between cohorts in the time spent was not statistically significant at 1 month (cohorts 1-3: mean 2407.8, SD 1370.3 s; mean 1835.0, SD 1329.2 s; and mean 1790.3, SD 1195.5 s, respectively; P=.06) but was statistically significant at 1 year (cohorts 1-3: mean 2049.16, SD 1099.0 s; mean 1857.33, SD 587.39 s; and mean 2524.3, SD 566.37 s, respectively; P<.001). Intracohort comparisons indicated that the differences in scores at 1 month and 1 year were not statistically significant for cohort 1 (95% CI -2.1 to 13.0; P=.16), while cohort 3 obtained significantly higher scores 1 year later (95% CI 2.5-8.7; P=.001), and cohort 2 obtained significantly lower scores 1 year later (95% CI -8.8 to -3.9; P<.001). Conclusions: Cohort 3 obtained the highest score at both time points with retention of competency at 1 year, indicating that progressive D-RPD training including virtual 3D simulation facilitated improved competency in RPD design. The adoption of D-RPD training may benefit learning outcomes.

Influence of Different Undercut Depths of Clasp Fabricated by Selective Laser Melting on Retentive Force.

INTRODUCTION: The purpose of this study was to investigate the influence of undercut depths on abutment teeth regarding the retentive force of clasps fabricated through selective laser melting (SLM), and to compare them with conventional cast clasps. METHODS: Akers clasps made of cobalt chromium alloy were fabricated using the SLM method (SLM), and the retentive forces were compared with clasps made with the conventional cast method (Cast). Three undercut amounts (0.25 mm, 0.15 mm, and 0 mm) were applied on the abutment tooth. The specimens were subjected to 10,000 repetitive insertion/removal cycles. RESULTS: SLM-0.15 showed slightly lower initial retentive force than the Cast specimens, it remained within an acceptable range. During insertion/removal test, the SLM-0.15 specimen showed a significant difference between the initial retentive force and the retentive force after 5,000 cycles, indicating that SLM-0.15 was the least likely to change in retentive force within the parameters established in this study. The inner clasp surface on the SLM groups had higher surface roughness before testing compared to the Cast specimen. CONCLUSIONS: Akers clasps fabricated by SLM demonstrated optimal initial retentive forces with smaller undercuts than conventional Cast clasps, and the retentive forces changed less with repetitive insertion/removal.

Efficacy of a Novel Computerized Aid in Designing Removable Partial Dentures.

BACKGROUND:  The development of computerized aids for dental education offers potential benefits in teaching complex procedures, such as the design of removable partial dentures (RPDs). This study aimed to assess the efficacy of a novel computerized tool in enhancing the ability of both dental students and practicing dentists to design RPDs, as well as to evaluate its utility as an interactive educational instrument. METHODS:  A cohort comprising a total of 75 individuals (25 practicing dentists and 50 undergraduate dental students) was enlisted. Participants were introduced to an online interactive application tailored for the design of RPDs. They were tasked with resolving clinical scenarios that necessitated the formulation of an RPD. Throughout the exercise, users were provided with hints addressing errors made during the process, fostering self-directed learning for improved RPD design. Post-interaction, the perceptions of both dentists and students regarding the tool were gauged through a comprehensive questionnaire. RESULTS:  The deployment of the online interactive application demonstrated significant promise in the effective design of RPDs, facilitated by self-directed learning. It also appeared to enhance the proficiency of practicing dentists in formulating partial dentures. CONCLUSION:  The computerized aid evaluated in this study provided an effective platform for both dental education and practice. It not only supported self-directed learning in the design of RPDs but also improved the efficiency of professional dentists in their clinical design work.

Accuracy of Digital Impression Taking in Partial Dentures: an in Vitro Study on the Degree of Adaptation of Rests / Precisão da Tomada de Impressão Digital em Próteses Parciais: um Estudo in Vitro sobre o Grau de Adaptação de Apoios

The objective of the study is to assess the precision of digital impressions in removable partial dentures through an in vitro study on the degree of abutment adaptation. A Kennedy Class III model with a prosthetic space between elements 43 and 47, featuring niches in the mesio-occlusal and cingulum regions, respectively. Conventional impressions were performed in subgroups CONC and CONM, while digital scanning was conducted in subgroups DIGC and DIGM. Simplified cobalt-chromium alloy frameworks were manufactured using the lost-wax technique on plaster and resin models. The degree of adaptation of the structures was evaluated by impressing the niches with condensation silicone, qualitatively assessing perforations, and quantitatively measuring the mold thickness under a stereomicroscope after cross-sectioning. Regular adaptation was more prevalent among the experimental groups. CONC showed a higher mean degree of abutment adaptation, while CONM had a lower mean. The study factors, impression technique, and type of abutment seat, were not statistically significant, with no interaction among the variables. Occlusal and cingulum abutment measurement points, in both impression techniques, showed no statistically significant difference. Digital scanning yielded better results in terms of abutment adaptation, with smaller average gaps between the abutment seat and the metal structure, making it clinically acceptable. The type of abutment seat and the impression technique did not have a statistically significant impact on abutment adaptation. The impression technique does not represent a factor influencing the adaptation of occlusal and cingulum abutments at different measurement points. (AU)

O Objetivo do estudo é valiar precisão da impressão digital em próteses parciais removíveis, por meio de um estudo in vitro sobre o grau de adaptação dos apoios. Um modelo Classe III de Kennedy com espaço protético entre o elemento 43 e 47, nichos na região mésio-oclusal e na do cíngulo. Foram realizadas impressões convencionais nos subgrupos CONC e CONM, e digitalização nos subgrupos DIGC e DIGM, onde estruturas simplificadas de liga de Co-Cr foram fabricadas usando a técnica de fundição perdida nos modelos de gesso e resina. O grau de adaptação das estruturas foi avaliado pela impressão dos nichos com silicone de condensação, qualitativamente as perfurações e quantitativamente a espessura do molde em um estereomicroscópio após seção transversal. A adaptação regular foi mais prevalente entre os grupos experimentais. CONC maior média do grau de adaptação do apoio, enquanto CONM menor média. Os fatores do estudo, técnica de impressão e tipo de assento de apoio, não foram estatisticamente significativos, sem interação entre as variáveis. Pontos de medição de apoio oclusal e de cíngulo, em ambas as técnicas de impressão, sem diferença estatisticamente significativa. A digitalização mostrou melhores resultados em relação ao grau de adaptação dos apoios, com menores lacunas médias entre o assento de apoio e a estrutura metálica, sendo clinicamente aceitável. O tipo de assento de apoio e a técnica de impressão não interferem estatisticamente na adaptação dos apoios. A técnica de impressão não representa um fator que influencie a adaptação de apoios oclusais e de cíngulo em diferentes pontos de medição. (AU)

Digital planning and surveying for a rotational path removable partial denture: a case report.

Digital technology has been applied to the planning and manufacture of removable partial dentures (RPDs), reducing the complexity of RPD treatment as well as the number and duration of clinical and laboratory steps. However, there is a lack of information regarding digital planning and surveying for rotational path RPDs. This article presents a case report of a digital diagnostic wax-up and survey for a rotational path RPD performed with prosthetic design software. The virtual diagnostic closure tool made it possible during the case study stage to visualize the edentulous spaces and simulate the preparations necessary for the restoration of occlusal and esthetic harmony. The virtual survey determined the dual-axis path of insertion and removal for the rotational path RPD based on the 4 major influencing factors: guiding planes, retentive undercuts, interferences, and esthetics. In this case, digital planning and surveying for a rotational path RPD were an effective means of esthetic and biomechanical analysis and allowed for minimal preparation of the abutment teeth.

A Systematic Review of Patient Satisfaction With Removable Partial Dentures (RPDs).

Removable partial dentures (RPDs) offer a broad range of aesthetics and restorative functions for partially edentulous patients. This systematic review examines patients' satisfaction rates and the factors that influence RPD satisfaction. This systematic review was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and the Cochrane Handbook for Systematic Reviews. A systematic literature search was done on PubMed, Scopus, and Google Scholar using preset inclusion criteria. A total of 923 non-duplicate articles were screened, and 35 were included in this review. Among the included studies, RPDs generally exhibited high satisfaction rates, with reported rates ranging between 50% and 81%. Several factors influenced satisfaction. Age played a major role, with older adults expressing higher satisfaction. Gender differences were also noted, especially in appearance satisfaction where women were more satisfied with RPDs than men. Prior experience with RPDs correlated positively with overall satisfaction. The number and location of missing teeth, as well as the type of RPD (metal vs. flexible), significantly influenced satisfaction levels. Flexible dentures were more satisfactory than metal RPDs. Attachments, such as magnetic attachments and implants, increased satisfaction. Patient complaints, encompassing pain, aesthetics, and cleanliness, were identified as common sources of dissatisfaction. The results underscore the significance of customizing RPD treatment to individual needs, considering factors that influence RPD satisfaction. Recognizing the importance of influential factors such as age, gender RPD experience, etc., for clinicians seeking to optimize patient outcomes in RPD therapy is crucial.

Implant-assisted removable partial dentures: Part II. a systematic review of the effects of implant position on the biomechanical behavior.

PURPOSE: This systematic review aimed to evaluate the effects of implant placement sites on the biomechanical behavior of implant-assisted removable partial dentures (IARPDs) using finite element analysis (FEA). STUDY SELECTION: Two reviewers independently conducted manual searches of the PubMed, Scopus, and ProQuest databases for articles investigating implant location in IARPDs using FEA, according to the 2020 Systematic Reviews and Meta-analyses statement. Studies published in English up to August 1, 2022, were included in the analysis based on the critical question. RESULTS: Seven articles meeting the inclusion criteria were systematically reviewed. Six studies investigated mandibular Kennedy Class I and one study investigated mandibular Kennedy Class II. Implant placement reduced the displacement and stress distribution of the IARPD components, including dental implants and abutment teeth, regardless of the Kennedy Class type and dental implant placement site. Most of the included studies showed that, based on the biomechanical behavior, the molar region, rather than the premolar region, is the preferred implant placement site. None of the selected studies investigated the maxillary Kennedy Class I and II. CONCLUSIONS: Based on the FEA regarding mandibular IARPDs, we concluded that implant placement in both the premolar and molar regions improves the biomechanical behaviors of IARPD components, regardless of the Kennedy Class. Implant placement in the molar region results in more suitable biomechanical behaviors compared with implant placement in the premolar region in Kennedy Class I. No conclusion was reached for Kennedy Class II due to the lack of relevant studies.