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Clinical Oral Investigations May 2021To examine the retention force of removable dental prosthesis (RDP) clasps made from polyetheretherketone (PEEK) and cobalt-chrome-molybdenum (CoCrMo, control group)...
OBJECTIVES
To examine the retention force of removable dental prosthesis (RDP) clasps made from polyetheretherketone (PEEK) and cobalt-chrome-molybdenum (CoCrMo, control group) after storage in water and artificial aging.
MATERIALS AND METHODS
For each material, 15 Bonwill clasps with retentive buccal and reciprocal lingual arms situated between the second pre- and first molar were manufactured by milling (Dentokeep [PEEKmilled1], NT digital implant technology; breCAM BioHPP Blank [PEEKmilled2], bredent), pressing (BioHPP Granulat for 2 press [PEEKpressed], bredent), or casting (remanium GM 800+ [CoCrMo], Dentaurum); N = 60, n = 15/subgroup. A total of 50 retention force measurements were performed for each specimen per aging level (initial; after storage [30 days, 37 °C] and 10,000 thermal cycles; after storage [60 days, 37 °C] and 20,000 thermal cycles) in a pull-off test. Data were statistically analyzed using one-way ANOVA, post hoc Scheffé and mixed models (p < 0.05).
RESULTS
Initial, PEEKpressed (80.2 ± 35.2) and PEEKmilled1 (98.9 ± 40.3) presented the lowest results, while PEEKmilled2 (170.2 ± 51.8) showed the highest values. After artificial aging, the highest retention force was observed for the control group (131.4 ± 56.8). The influence of artificial aging was significantly higher for PEEK-based materials. While PEEKmilled2 and PEEKpressed showed an initial decline in retention force, all other groups presented no impact or an increase in retention force over a repetitive insertion and removal of the clasps.
CONCLUSIONS
Within the tested PEEK materials, PEEKmilled2 presented superior results than PEEKpressed. Although CoCrMo showed higher values after artificial aging, all materials exhibited sufficient retention to recommend usage under clinical conditions.
CLINICAL RELEVANCE
As RDPs are still employed for a wide range of indications, esthetic alternatives to conventional CoCrMo clasps are sought.
Topics: Benzophenones; Chromium Alloys; Cobalt; Dental Clasps; Dental Implants; Dental Prosthesis Retention; Dental Stress Analysis; Denture Retention; Denture, Partial, Removable; Esthetics, Dental; Ketones; Materials Testing; Molybdenum; Polyethylene Glycols; Polymers
PubMed: 33064206
DOI: 10.1007/s00784-020-03642-5 -
Materials (Basel, Switzerland) Dec 2019We examined the chemical, physical, and mechanical properties and microstructures of laser-sintered Co-25Cr-5Mo-5W (SP2) and W-free Co-28Cr-6Mo alloys. The tensile and...
We examined the chemical, physical, and mechanical properties and microstructures of laser-sintered Co-25Cr-5Mo-5W (SP2) and W-free Co-28Cr-6Mo alloys. The tensile and fatigue properties of the laser-sintered Co-Cr-Mo alloys were extremely superior to those of dental-cast alloys. The ultimate tensile strength (σ) and total elongation (T.E.) were close to those of hot-forged Co-28Cr-6Mo alloys. The fatigue strengths (σ) at 10 cycles of the 90°-, 45°-, and 0°-direction-built Co-28Cr-6Mo alloys were ~500, ~560, and ~600 MPa, respectively. The ratio σ /σ was ~0.4. These superior mechanical properties were attributed to the fine π-phase particles in the grains and grain boundaries of the fine face-centered cubic (fcc) matrix formed owing to the rapid solidification. The chemical composition of 20-times-laser-sintered Co-Cr-Mo alloy without the virgin powder added was approximately the same as that of the alloy laser-sintered with the virgin powder. σ of the 90°-direction-built alloys after laser sintering 20 times was also ~500 MPa. σ of hot-forged Co-28Cr-6Mo alloys decreased with increasing annealing temperature, whereas T.E. increased. For the Co-Cr-Mo alloys annealed at 1000 to 1150 °C for 30 min after laser sintering, the rates of decrease in σ were small. σ/σ increased to near those of annealed Co-28Cr-6Mo alloys after hot forging. The durability of clasps fabricated by laser sintering was superior to that of dental-cast clasps.
PubMed: 31817292
DOI: 10.3390/ma12244039 -
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 -
Medicina Oral, Patologia Oral Y Cirugia... Mar 2021To study the association between sleep quality and oral health related variables, which still have conflicts in the literature.
BACKGROUND
To study the association between sleep quality and oral health related variables, which still have conflicts in the literature.
MATERIAL AND METHODS
This was a population-based case-control study between subjects with versus without sleep disorders from the Brazilian Public Health System (SUS), city of Maringá (N=1,643). Subjects answered self-reported questionnaires: a) Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), b) Sleep Assessment Questionnaire (SAQ) and c) North York Dental Health Survey (NYDHS).
RESULTS
No significant difference was found for gender, marital status, or income; however, non-Caucasians, people with lower levels of education, and those between 20 to 50 years old had worse scores of sleep disorders in the SAQ. Self-perceived oral health, masticatory capacity to eat foods, and gingival bleeding was significantly worse among subjects with self-reported sleep disorders. Self-reported tooth loss, edentulism and use of removable partial dentures (with clasps) or complete dentures showed no significant difference between groups. Self-reported sleep disorder subjects presented significantly higher prevalence of both self-reported tooth and TMJ pain.
CONCLUSIONS
It can be concluded that individuals with self-reported sleep disorders presented worse self-perceived oral health for most studied variables.
Topics: Adult; Brazil; Case-Control Studies; Facial Pain; Humans; Middle Aged; Oral Health; Sleep Wake Disorders; Surveys and Questionnaires; Young Adult
PubMed: 32851986
DOI: 10.4317/medoral.24096 -
The Bulletin of Tokyo Dental College Dec 2019The need for flexible thermoplastic denture base materials has increased due to patient demand for better esthetic outcomes. Designs aimed at improving esthetic outcomes...
The need for flexible thermoplastic denture base materials has increased due to patient demand for better esthetic outcomes. Designs aimed at improving esthetic outcomes can cause difficulties for prosthodontists, however, from the viewpoint of function and maintenance. Therefore, the purpose of this study was to investigate vertical displacement in unilateral extension base denture models, comparing that obtained by flexible removable dentures with that by conventional metal clasp dentures. Models of unilateral extension base flexible removable dentures for mandibular defects were prepared. Periodontal ligament and jaw mucosa were simulated using a silicone impression material. Four types of flexible removable denture, with or without a metal rest, and two metal clasp dentures made of acrylic resin as a conventional design were used as dental prostheses. The amount of vertical displacement in the defect areas was measured under a load of 50 N at the first and second molars. Among the 6 types of dentures investigated, the amount of vertical displacement was greater with flexible removable dentures than with metal clasp dentures. This vertical displacement tended to decrease significantly, however, with the use of a metal rest with the flexible removable dentures. Esteshot with a metal rest, in particular, showed the smallest amount of displacement in the flexible removable dentures (first molar, 0.265±0.007 mm; second molar, 0.423±0.008 mm). These results indicate the importance of the application of rests in unilateral extension base flexible removable dentures. It may be useful to employ a metal rest in conjunction with a flexible removable denture to reduce load on the underlying mucosa, as is done with conventional partial dentures.
Topics: Denture Bases; Denture Design; Denture, Partial; Denture, Partial, Removable; Esthetics, Dental; Humans
PubMed: 31761891
DOI: 10.2209/tdcpublication.2018-0068 -
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 -
Dental Materials Journal Apr 2022The present study was aimed to develop a probabilistic finite element method (FEM) that predicts the variability in the fatigue life of additively manufactured clasp so...
The present study was aimed to develop a probabilistic finite element method (FEM) that predicts the variability in the fatigue life of additively manufactured clasp so that it can be used as a virtual test in the design phase before manufacturing. Titanium alloy (Ti-6Al-4V) clasp with integrated chucking part, which was designed for experimental fatigue test to validate the computational method, was investigated. To predict the lower bound, an initial spherical defect was assumed in the region where stress concentration was predicted. The Smith-Watson-Topper (SWT) method, Bäumel & Seeger rule, elasto-plastic FEM, and zooming FEM were used. The influence of assumed initial defect on the fatigue life was significant, and the large variability in the fatigue life was predicted. This study demonstrated that the proposed practical computational method can simulate the large variability in the fatigue life of titanium alloy clasp, which is useful in its design before manufacturing.
Topics: Alloys; Denture Design; Finite Element Analysis; Prosthesis Failure; Titanium
PubMed: 35249900
DOI: 10.4012/dmj.2021-174 -
Dental Materials Journal Dec 2021To evaluate the flexural and fatigue properties of a polyester disk material used in milled resin clasps of removable partial dentures, experimental polyester disk...
To evaluate the flexural and fatigue properties of a polyester disk material used in milled resin clasps of removable partial dentures, experimental polyester disk (mPE), injection-molded polyester (iPE), and polymethyl methacrylate disk (mPMMA) were examined by three-point bending tests and cyclic fatigue tests at 0.75 or 1.50 mm deflection. The mPE exhibited significantly higher flexural strength than the iPE (p<0.05). Meanwhile, the mPMMA displayed higher flexural modulus and strength than the polyesters. The mPE exhibited a significantly lower residual strain than the iPE at the cyclic 0.75 mm deflection (p<0.05); however, microcracks were observed in the mPE at the 1.50 mm deflection. The mPMMA showed a high residual strain at the 0.75 mm deflection and fractured within 1,000 cycles at the 1.5 mm deflection. The higher flexural strength and lower residual strain of the mPE compared with the iPE suggest the advantages of milled resin clasps within a limited deflection.
Topics: Acrylic Resins; Denture Bases; Flexural Strength; Materials Testing; Pliability; Polyesters; Polymethyl Methacrylate
PubMed: 34234049
DOI: 10.4012/dmj.2021-037 -
Journal of Prosthodontic Research Jan 2024This study aimed to investigate the retentive force and deformation of double Akers' polyetherketoneketone (PEKK) clasps on removable partial dentures (RPDs) with...
PURPOSE
This study aimed to investigate the retentive force and deformation of double Akers' polyetherketoneketone (PEKK) clasps on removable partial dentures (RPDs) with varying designs and undercut depths.
METHODS
Thirty double Akers' PEKK clasps with two different widths and heights (Groups I and II) were fabricated using computer-aided design and computer-aided manufacturing (CAD/CAM). Each design was further subdivided (n = 5) into three undercut depths (0.25, 0.50, and 0.75 mm). The retentive force of the clasps was measured after 10 years of clinical use (15,000 insertion/removal cycles), and the deformation of the clasp tips was analyzed before and after cycling.
RESULTS
Clasps with 0.50-mm and 0.75-mm undercut depths exhibited greater initial retentive forces (3.15-3.51 N) compared to those in the 0.25-mm undercut group (2.40-2.80 N). Group I maintained consistent retentive forces over the cycles (P = 0.345), whereas Group II showed declining forces after the initial use (P < 0.003). In both groups, the 0.50-mm undercut exhibited a greater retentive force than the 0.25-mm (P < 0.001 and P < 0.004, respectively), with no significant differences between the 0.50-mm and 0.75-mm undercut depths. Despite a lower initial retentive force, the 0.25-mm undercut showed less deformation and clasp tip wear.
CONCLUSIONS
The PEKK clasps did not exhibit significantly reduced retentive forces or permanent deformations after 15,000 fatigue cycles. These results suggest that the PEKK polymer displays superior mechanical properties as an esthetic clasp material, and clasps with 0.50-mm and 0.75-mm undercut depths are recommended for long-term clinical use.
PubMed: 38220161
DOI: 10.2186/jpr.JPR_D_23_00080