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Statement of Problem: Although pure titanium is known to have good biocompatibility, a titanium alloy with better strength is needed for fabricating clinically acceptable, partial removable dental prosthesis (RDP) frameworks., Purpose: The mechanical properties of an experimental Ti-5Al-5Cu alloy cast with a 2-step investment technique were examined for RDP framework applications., Material and Methods: Patterns for tests for various properties and denture frameworks for a preliminary trial casting were invested with a 2-step coating method using 2 types of mold materials: a less reactive spinel compound (Al(2)O(3)·MgO) and a less expensive SiO(2)-based material. The yield and tensile strength (n=5), modulus of elasticity (n=5), elongation (n=5), and hardness (n=8) of the cast Ti-5Al-5Cu alloy were determined. The external appearance and internal porosities of the preliminary trial castings of denture frameworks (n=2) were examined with a conventional dental radiographic unit. Cast Ti-6Al-4V alloy and commercially pure titanium (CP Ti) were used as controls. The data for the mechanical properties were statistically analyzed with 1-way ANOVA (α=.05)., Results: The yield strength of the cast Ti-5Al-5Cu alloy was 851 MPa and the hardness was 356 HV. These properties were comparable to those of the cast Ti-6Al-4V and were higher than those of CP Ti (P<.05). One of the acrylic resin-retention areas of the Ti-5Al-5Cu frameworks was found to have been incompletely cast., Conclusions: The cast biocompatible experimental Ti-5Al-5Cu alloy exhibited high strength when cast with a 2-step coating method. With a dedicated study to determine the effect of sprue design on the quality of castings, biocompatible Ti-5Al-5Cu RDP frameworks for a clinical trial can be produced., (Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Statement of Problems: Research-based assessments of the quality of removable partial dentures (RPDs), especially within a large patient population, are lacking., Purpose: This study evaluated the prevalence and quality of RPDs by use of the National Health and Nutrition Survey (NHANES III) data set., Material and Methods: Estimates of the health and nutritional status of the American population were obtained from the NHANES III data set (1988-1994). Calibrated dentists performed dental examinations on 17,884 adults. If the subject wore an RPD, its quality was assessed with 5 criteria: integrity, tooth wear, the presence of temporary reline material or adhesive, stability, and retention. In this study, the data on RPD defects were used to assess the prevalence of problems. The original population was divided into 4 subgroups: paired RPD data = subjects wearing both maxillary and mandibular RPDs (n = 600 prostheses, 300 maxillary and 300 mandibular); single RPD data = subjects with only one RPD (n = 1003 prostheses, 511 maxillary and 492 mandibular); maxillary versus mandibular RPD data = all subjects with all RPDs (n = 1603 prostheses, 811 maxillary and 792 mandibular); and pooled RPD data = all subjects with a single RPD plus subjects with 2 RPDs, counting only the RPD with the most defects (n = 1303 prostheses, 674 maxillary and 629 mandibular). The subjects were analyzed with descriptive statistics. The distribution of defects in the RPDs was examined for possible associations with chi(2) tests. The paired data for patients with both maxillary and mandibular RPDs were analyzed with Wilcoxon signed rank tests. The prevalence of RPDs as a function of patient age and the association between RPD defects and patient age were analyzed with chi(2) tests. The results were considered highly significant at P<.0001 and significant at P<.05., Results: Of the 17,884 adults who underwent a dental examination, 1306 had RPDs. Three patients were excluded because their records were incomplete, leaving 1303 patients available for analysis. Most of the prostheses examined (65%) had at least 1 defect. Lack of stability was the most prevalent single defect. Distinctions in the type and prevalence of defects were observed between mandibular and maxillary RPDs. Mandibular RPDs had significantly more problems related to retention, whereas maxillary RPDs had significantly more problems related to the presence of reline material and to integrity defects. Tooth wear defects were significantly associated with patient age (P<.0001). Only one third of the RPDs were considered satisfactory according to NHANES III criteria., Conclusion: A review of the database used in this study indicated that, in spite of a decline in tooth loss, RPDs are still used in all age cohorts, including young adults. A large number of RPDs were found to have defects.

Statement of Problem: The use of titanium alloys for removable partial dentures is an increasingly popular application. While the flexibility of titanium would allow for cast clasps to be placed in deeper undercuts than advisable with cobalt-chromium, it is possible that the retentive forces of the titanium clasp might not maintain sufficient retention after repeated flexing of the clasp arm during insertion and removal of the partial denture., Purpose: This study assessed the characteristics of cast clasps made of titanium and titanium alloys to determine whether these materials are suitable alternatives for removable partial denture applications., Material and Methods: Removable partial denture clasps at two undercut depths were fabricated from commercially pure titanium, titanium alloy (Ti-6A1-4V), and cobalt-chromium. Loss of retention force was measured as the clasps underwent 3 years of simulated clinical use. The data were subjected to ANOVA and Scheffé's tests to determine differences. Evidence of casting defects and porosity was evaluated by radiographic examination and nonparametric statistics. SEM microscopy was used to observe surface characteristics that were described qualitatively., Results: For the 0.75 mm undercut specimens, there was less loss of retention for clasps made from pure titanium and titanium alloy than for cobalt-chromium clasps. Porosity was more apparent in the pure titanium and titanium alloy clasps than in those made from cobalt-chromium, but the amount of porosity did not correspond to evidence of fractures or permanent deformation., Conclusions: The long-term retentive resiliency of the pure titanium and titanium alloy clasps suggests that these materials are suitable for removable partial dentures.

Statement of Problem: Controversy surrounds the use of hydrofluoric acid to prepare precementation surfaces of indirect composites., Purpose: This study was conducted to compare effects of combining hydrofluoric or orthophosphoric acid with microetching as precementation treatments., Material and Methods: Nine specimens of three composite materials were prepared to simulate heat-cured indirect restorations. The specimen surfaces were prepared with one of three treatments. Adhesive Bond II and Twinlook cements were used to bond a phosphoric acid-etched disk of P50 to the treated surface. Analysis of variance and Scheffé tests were used to assess the bond strength data. Scanning electron microscopy and microscopic analysis of the fractured and treated surfaces were also performed., Results: Bond strengths for all surface treatments did not significantly differ. Hybrids had a higher bond strength with etching than microfills, and mechanical roughening produced the greatest bond strengths with microfills. Microetching with orthophosphoric acid produced higher bond strengths than microetching with hydrofluoric acid on hybrids., Conclusions: Acid etching alone is not sufficient to produce effective bond strengths, and hydrofluoric acid treatments are detrimental to the resin composite.