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Dental Materials : Official Publication... Feb 2020This 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...
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.
Topics: Dental Clasps; Denture Design; Denture Retention; Denture, Partial, Removable; Materials Testing
PubMed: 31791736
DOI: 10.1016/j.dental.2019.11.022 -
The Journal of Advanced Prosthodontics Jun 2022The purpose of the study was to assess the influence of build orientations and density of support structures on the trueness of the 3D printed removable partial denture...
PURPOSE
The purpose of the study was to assess the influence of build orientations and density of support structures on the trueness of the 3D printed removable partial denture (RPD) frameworks.
MATERIALS AND METHODS
A maxillary Kennedy class III and mandibular class I casts were 3D scanned and used to design and produce two 3D virtual models of RPD frameworks. Using digital light processing (DLP) 3D printing, 47 RPD frameworks were fabricated at 3 different build orientations (100, 135 and 150-degree angles) and 2 support structure densities. All frameworks were scanned and 3D compared to the original virtual RPD models by metrology software to check 3D deviations quantitatively and qualitatively. The accuracy data were statistically analyzed using one-way ANOVA for build orientation comparison and independent sample t-test for structure density comparison at (α = .05). Points study analysis targeting RPD components and representative color maps were also studied.
RESULTS
The build orientation of 135-degree angle of the maxillary frameworks showed the lowest deviation at the clasp arms of tooth 26 of the 135-degree angle group. The mandibular frameworks with 150-degree angle build orientation showed the least deviation at the rest on tooth 44 and the arm of the I-bar clasp of tooth 45. No significant difference was seen between different support structure densities.
CONCLUSION
Build orientation had an influence on the accuracy of the frameworks, especially at a 135-degree angle of maxillary design and 150-degree of mandibular design. The difference in the support's density structure revealed no considerable effect on the accuracy.
PubMed: 35855318
DOI: 10.4047/jap.2022.14.3.150 -
The Journal of Prosthetic Dentistry Feb 2024The retentive force and deformation of milled polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) removable partial denture (RPD) frameworks are not well...
STATEMENT OF PROBLEM
The retentive force and deformation of milled polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) removable partial denture (RPD) frameworks are not well understood.
PURPOSE
The purpose of this in vitro study was to assess the retentive force and deformation of PEEK and PEKK Akers clasps with different designs and undercut depths.
MATERIAL AND METHODS
A master model containing the first and second molar abutments was used to design Akers clasps of different cross-sectional dimensions, undercut depths (0.5 and 0.75 mm), and materials. The components of the removable partial denture framework also included an occlusal rest and were manufactured using a milling machine (n=5). The fatigue resistance of the Akers clasps was measured before and after deformation regarding the retentive forces.
RESULTS
The PEEK2-U50 clasp had the largest retentive force with no significant difference among all groups before and after the insertion and removal cycle. In addition, the increased cross-sectional dimensions of the design resulted in significant differences in retentive forces between the PEEK1 and PEEK2 groups and between the PEEK and PEKK materials.
CONCLUSIONS
Increasing the clasp's cross-sectional dimensions significantly impacted retentive forces, especially between different PEEK groups and between PEEK and PEKK materials.
Topics: Chromium Alloys; Denture, Partial, Removable; Cross-Sectional Studies; Denture Retention; Polyethylene Glycols; Ketones; Dental Clasps; Benzophenones; Polymers
PubMed: 38057199
DOI: 10.1016/j.prosdent.2023.09.042 -
Clinical Oral Investigations Apr 2021To analyze the oral health-related impact profile in patients treated with three different types of dental prosthesis in student courses.
OBJECTIVES
To analyze the oral health-related impact profile in patients treated with three different types of dental prosthesis in student courses.
MATERIALS AND METHODS
This prospective bicenter clinical trial was conducted with 151 patients being treated with fixed (n = 70), removable (n = 61), or telescopic dental prostheses (n = 20) in clinical student courses of two German universities from October 2018 to October 2019. All patients completed three standardized German versions of the Oral Health Impact Profile (OHIP-G49/53) before prosthetic treatment (T0), at control after 1 week (T1), and after 3 months (T2), divided into five dimensions: (a) appearance, (b) oral function, (c) psychosocial impact, (d) linguistic limitations, and (e) orofacial pain. Data were analyzed with Kolmogorov-Smirnov, Wilcoxon signed-rank, Kruskal-Wallis, Mann-Whitney, and Cronbach's alpha tests.
RESULTS
Within T0-T1 and T0-T2, greater improvements were determined for removable compared with fixed dental prostheses for the dimensions' oral function (p ≤ 0.014), linguistic limitations (p ≤ 0.016), and appearance (p ≤ 0.003). No significant differences were found between fixed and telescopic dental prostheses (p ≥ 0.104) or between removable (partial dental prosthesis with clasps and complete dental prosthesis) and telescopic dental prostheses (p ≥ 0.100). Within T1-T2, a significant improvement in orofacial pain could be determined (p = 0.007).
CONCLUSIONS
Restorations presented an improvement in oral health-related quality of life. Removable dental prostheses showed better improvement than fixed ones in various dimensions.
CLINICAL RELEVANCE
Knowledge about the influence of oral health-related quality of life on the three different types of prosthesis used in student courses can be of decisive help in dental consultations.
Topics: Dental Prosthesis; Dental Prosthesis, Implant-Supported; Denture, Partial, Removable; Humans; Oral Health; Prospective Studies; Quality of Life; Students
PubMed: 32852596
DOI: 10.1007/s00784-020-03532-w -
Indian Journal of Dental Research :... 2020The majority of maxillary defects can be rehabilitated with pedicled flaps. However, when there are very large resections of the maxilla and flap success is...
The majority of maxillary defects can be rehabilitated with pedicled flaps. However, when there are very large resections of the maxilla and flap success is questionable, then the defect may be obturated with a conventional hollow bulb clasp retained obturator or implant retained obturator prosthesis. However, inadequate retention, stability and support may be associated with the use of a conventional obturator and in case of recurrence the success of implant is questionable. A precision attachment becomes the silver lining. They have been used to retain obturator for some time. The use of precision attachments in a dentate maxillectomy patient can yield significant functional improvement while maintaining the obturator's aesthetic advantages. This clinical report describes the successful prosthetic rehabilitation of maxillary defects with an obturator retained using two different extracoronal resilient precision attachments. Attachment retained prosthesis provides a successful closure for the defect but also better esthetics, retention, better tolerability and better mastication and speech.
Topics: Esthetics, Dental; Humans; Maxilla; Palatal Obturators; Speech; Surgical Flaps
PubMed: 33433523
DOI: 10.4103/ijdr.IJDR_123_18 -
The Journal of Prosthetic Dentistry Sep 2020Removable partial dentures (RPDs) are a cost-effective treatment designed to replace missing teeth for partially edentulous patients. However, RPDs often have...
STATEMENT OF PROBLEM
Removable partial dentures (RPDs) are a cost-effective treatment designed to replace missing teeth for partially edentulous patients. However, RPDs often have insufficient retention, which results in treatment failure and patient dissatisfaction.
PURPOSE
The purpose of this clinical study was to investigate the factors related to RPD retention that affect patient satisfaction, to clinically validate a newly published model for predicting RPD retention based on the number and position of missing teeth and clasps, and to identify the predictions of patient satisfaction to improve the guidelines for RPD design.
MATERIAL AND METHODS
Seventy-five patients treated with 107 RPDs delivered at the McGill University Dental Clinic (Montreal, Canada) and Estaing University Hospital (Clermont-Ferrand, France) participated in this study. Data on the RPD design were collected from the clinical records, and the retention of each RPD was tested with the mathematical model designed for predicting RPD retention. Data on patient satisfaction with their RPDs were collected by using a standardized questionnaire (McGill Denture Satisfaction Instrument). Statistical analysis of factors related to RPD retention and patient satisfaction was performed by using the chi-square test and Mann-Whitney test, while the developed model for predicting RPD retention was evaluated by using sensitivity and specificity analysis.
RESULTS
The average satisfaction score for all RPDs was 8.2 ±1.7 out of 10. Patients were more satisfied with RPDs in the maxillary arch, tooth-supported, or retained by ≥3 clasps than with RPDs in the mandibular arch, with distal extension bases, or retained by <3 clasps. The materials used for RPD fabrication (metal-based or acrylic resin-based), the number of missing teeth, and the presence of indirect retention were not associated with patient satisfaction. Participants were significantly more satisfied with RPD designs predicted by the developed mathematical model to have enough retention than with RPD designs predicted to have insufficient retention. The mathematical model for predicting the RPD retention showed a clinical specificity of 83% in predicting patient satisfaction.
CONCLUSIONS
RPD retention predicted from the number and position of clasps and missing teeth might help to determine patient satisfaction. In addition, patient satisfaction with RPDs was influenced by the arch type, the presence of a distal extension base, and the number of clasps.
Topics: Canada; Dental Clasps; Denture Design; Denture Retention; Denture, Partial, Removable; Humans; Maxilla; Tooth
PubMed: 31810612
DOI: 10.1016/j.prosdent.2019.10.005 -
BMC Medical Education Jun 2021Wire-bending skills is commonly taught through live demonstrations (LD) though flipped classroom (FC) method has gained popularity. Continuous formative assessment...
BACKGROUND
Wire-bending skills is commonly taught through live demonstrations (LD) though flipped classroom (FC) method has gained popularity. Continuous formative assessment promotes personalised learning via closely monitored progress, with the identification of students' strengths and weaknesses. This study aims to evaluate the effects of LD and FC teaching methods, supplemented with continuous formative assessment, on dental students' learning of wire-bending skills for six types of removable orthodontic appliance components. A deeper understanding of the relative effectiveness between LD and FC teaching methods can help identify the most appropriate method to achieve student learning objectives, which is especially important given the current Covid-19 pandemic.
METHODS
Forty third-year undergraduate dental students were randomly assigned into FC (n = 20) or LD (n = 20) cohort. Each student attended six teaching sessions, each to teach students' competency in fabricating one type of wire component, for a total competency in fabricating six wire components over the course of six teaching sessions. Either LD or FC teaching methods were used. After each session, wire assignments had to be submitted. Wire assignments were then evaluated using a blinded wire-bending assessment protocol. As part of their formative assessment, the assessment results were distributed to students, lecturers, and technicians before the next session. After the first session (T0) and at the end of all six sessions (T1), students completed a self-reported questionnaire.
RESULTS
The mean wire-bending scores for FC were significantly higher than LD for two of the six assignments, namely the Adams clasp (p < 0.01) and Z-spring (p = 0.03). Scores for both LD and FC increased significantly over time, which may be attributed to formative assessment. There was no statistically significant correlation between wire-bending scores and video usage. Students were satisfied with both teaching methods, according to T0 and T1 questionnaires.
CONCLUSIONS
Both LD and FC are equally effective in transferring practical orthodontic wire-bending skills and well-received by students. Continuous formative assessment may have enhanced students' learning of orthodontic wire-bending skills. Further studies with control group are recommended to investigate the effect of formative assessment on teaching practical dental skills.
Topics: COVID-19; Educational Measurement; Humans; Orthodontic Wires; Pandemics; Problem-Based Learning; SARS-CoV-2; Students, Dental; Teaching
PubMed: 34098931
DOI: 10.1186/s12909-021-02717-5 -
Clinical Oral Investigations May 2021To investigate the retention force of polyetheretherketone (PEEK) removable dental prosthesis clasps in comparison with a cobalt-chrome-molybdenum control group after...
OBJECTIVES
To investigate the retention force of polyetheretherketone (PEEK) removable dental prosthesis clasps in comparison with a cobalt-chrome-molybdenum control group after storage in artificial saliva.
MATERIALS AND METHODS
Clasps were milled (Dentokeep (PEEKmilled1), NT digital implant technology; breCAM BioHPP Blank (PEEKmilled2), bredent), pressed (BioHPP Granulat for 2 press (PEEKpressed), bredent), or cast (remanium GM 800+ (cobalt-chrome-molybdenum), Dentaurum); N = 60, n = 15/subgroup. Retention force was examined 50 times/specimen in a pull-off test using the universal testing machine (Zwick 1445), where pull-off force was applied with a crosshead speed of 5 mm/minute until the maximum force dropped by 10%, at different aging levels: (1) initial, after storage in artificial saliva for (2) 90 and (3) 180 days. Statistical analysis was performed using one-way ANOVA followed by post hoc Scheffé-test and mixed models (p < 0.05).
RESULTS
Cobalt-chrome-molybdenum presented the highest retention force. No differences were observed between polyetheretherketone materials. Cobalt-chrome-molybdenum showed a significant decrease of its values after artificial aging, while polyetheretherketone materials presented similar results over the course of aging. Regarding a repetitive insertion and removal, even though PEEKmilled2 and cobalt-chrome-molybdenum showed an initial increase, ultimately, a decrease in retention force was observed for all tested groups.
CONCLUSIONS
Although the control group showed significantly higher results, the retention force of polyetheretherketone materials indicate a potential clinical application. Neither the manufacturing process nor artificial aging showed an impact on the retention force of polyetheretherketone clasps.
CLINICAL RELEVANCE
Mechanical properties of novel removable dental prosthesis clasp materials devised to meet the growing esthetic demands of patients need to be investigated to ensure a successful long-term clinical application.
Topics: Benzophenones; Chromium Alloys; Dental Clasps; Dental Stress Analysis; Denture Retention; Denture, Partial, Removable; Esthetics, Dental; Humans; Ketones; Materials Testing; Polyethylene Glycols; Polymers
PubMed: 33026523
DOI: 10.1007/s00784-020-03603-y -
The European Journal of Prosthodontics... Nov 2023To assess the clinical periodontal status of abutment teeth in regards of different design components of distal-extension removable partial dentures. Subjects (N=100)...
To assess the clinical periodontal status of abutment teeth in regards of different design components of distal-extension removable partial dentures. Subjects (N=100) with acrylic or cobalt-chromium distal-extension removable partial dentures were enrolled and their periodontal parameters plaque and gingival indices [PI, GI], probing depths [PD], clinical attachment loss [CAL] and a mobility index [MI] evaluated. Denture base type, major connector, occlusal rests position, design of direct retainers, retention, stability and denture wearing habits were further evaluated. Acrylic RPDs were associated with higher mean±SE PI [1.70±0.74], GI [1.76±0.55], PD scores [2.47±1.02 mm] and CAL values [4.46±2.11 mm] compared to CO-CR RPDs [p⟨0.05]. For abutments, the PI [1.6±0.83], GI [1.72±0.57], PD [2.32±1.03] and CAL [4.26±2.08] were higher than their non-abutments counterparts [p⟨0.05]. CAL scores were found to be significantly higher for mandibular abutments compared to maxillary ones [P=0.002]. The highest PI [1.83±1.10] and GI [2.00±0.00] scores were associated with lingual bars and horse-shoe connectors, respectively. Full palatal coverage and lingual plates were associated with the highest PD [2.80±0.48] and CAL [4.70±0.37] scores. Acrylic RPDs, type of major connector, wrought wire clasps and distal occlusal rests may be considered as risk factors for periodontal disease progression in distal-extension removable partial denture wearers.
Topics: Humans; Denture, Partial, Removable; Cross-Sectional Studies; Dental Abutments; Tooth; Periodontal Diseases; Denture Retention
PubMed: 37318323
DOI: 10.1922/EJPRD_2500AlDwairi09 -
Quintessence International (Berlin,... 2021Objective: To analyze the loss of abutment teeth for double crown-retained removable partial dentures (DC-RPDs) compared to clasp-retained removable partial dentures... (Meta-Analysis)
Meta-Analysis
Objective: To analyze the loss of abutment teeth for double crown-retained removable partial dentures (DC-RPDs) compared to clasp-retained removable partial dentures (C-RPDs). Method and materials: A search was conducted in the Ovid MEDLINE, Embase, Web of Science databases, and a manual search. The search was conducted based on the PICO framework with inclusion and exclusion criteria. After extracting the data of selected studies, a meta-analysis was performed to estimate abutment loss with 95% confidence interval (CI). The statistical significance was defined as P < .05, and the heterogeneity of the data was assessed based on the chi-squared test and I2 statistics. Risk of bias assessment was conducted using Cochrane Risk of Bias tool and Newcastle-Ottawa Scale. Results: A total of 4,692 records were identified from electronic databases and 38 studies were included for quantitative synthesis of 3,393 subjects with 13,552 abutment teeth. A total of 1,226 abutment teeth were lost with > 4,016 RPDs. Seven studies were compounded for > 668 C-RPDs (mean follow-up time ≤ 5 years) and six studies for 893 C-RPDs (mean follow-up time < 5 years), where the estimates of abutment loss were 5% (95% CI 2% to 8%) and 8% (95% CI 5% to 13%), respectively. The data were not significantly different (P = .1), and were heterogenous between the studies (τ2 ≥ 0.34, I2 ≥ 87.38%). Thirteen studies were compounded for 1,223 DC-RPDs (mean follow-up time ≤ 5 years) and eight studies for 1,033 DC-RPDs (mean follow-up time > 5 years), where the estimates of abutment loss were 6% (95% CI 5% to 8%) and 12% (95% CI 8% to 18%), respectively. The data were heterogenous (τ2 ≥ 0.17, I2 ≥ 75.86%), and were significantly different between the studies (P = .005). Overall, C-RPDs were not significantly different from DC-RPDs in abutment loss (P ≥ .3). A significant predictor for abutment loss was follow-up time with DC-RPDs (P = .005), where the risk of abutment loss per year was 18% (P = .0001). In contrast, follow-up time was not a significant factor for C-RPDs (P = .1). None of the included studies were at high risk of bias. Conclusion: Within the limitations of the current systematic review and meta-analysis, abutment loss was not significantly different between C-RPDs and DC-RPDs. A significant predictor was follow-up time for DC-RPDs, whereas this factor was not significant for C-RPDs. Further research is needed to investigate critical factors for abutment loss with RPDs.
Topics: Crowns; Dental Abutments; Denture Retention; Denture, Partial, Removable; Follow-Up Studies; Humans
PubMed: 33491387
DOI: 10.3290/j.qi.b912671