Evaluation of Fracture Resistance of Zirconia Modification/Polishing Around Implant Abutments.

Subcrestal placement of implants may have interproximal bone proximity issues that interfere with the submucosal contour of implant-supported zirconia restorations during delivery of the restorations. Modification of the mesial distal submucosal areas may be necessary to fully seat the restoration without impingement of the interproximal bone. Our aim was to determine if modification of submucosal cervical contour of implant supported zirconia-titanium base (Zi-Ti base) restorations resulted in a significant change in fracture strength compared with Zi-Ti base restorations without any modification near the cervical submucosal area. Implant Zi-Ti base restorations designed in the form of a maxillary premolar were made for the Straumann implant lab analog. Zirconia samples were cemented onto the Ti-base and the test group (N = 20) underwent recontouring and polishing at the junction of the Zi-Ti base cervical areas. The control group (N = 20) did not undergo any modifications. All 40 samples underwent fracture testing with an Instron machine. We assessed differences between modified and unmodified implants restorations using a 2-tailed t test for independent samples. Fracture strength values (N) ranged from 4354.68 to 6412.49 in the test group (N = 20) and from 5400.31 to 6953.22 in the control group (N = 20). The average fracture strength in the control group (6154.84 ± 320.50) was higher than in the modified group (5593.13 ± 486.51; P < .001). Modification of submucosal contour significantly decreased fracture strength. However, the average fracture strength exceeded the masticatory forces of humans.

Dental students' ability to evaluate themselves in fixed prosthodontics.

Self-evaluation is an essential skill for dental professionals for lifelong learning and improvement through the course of their careers. Students taking a preclinical fixed prosthodontics course were studied. The students were asked to assign themselves a grade upon completion of their timed preparation examination (teeth preparations and provisional restorations), and these were compared with grades given by the faculty. The poorer performing students tended to be less critical with their examination and to overrate their performance whereas the higher performing students were more critical of themselves and underrated their performance.

Distortion of disposable plastic stock trays when used with putty vinyl polysiloxane impression materials.

STATEMENT OF PROBLEM: Impressions are made using high-viscosity putty vinyl polysiloxane impression materials in conjunction with disposable plastic stock trays. The impression materials have been shown to be dimensionally stable. However, it remains unclear if the disposable plastic stock trays are rigid enough to resist deformation thus yielding potentially unreliable results. PURPOSE: This study evaluated the rigidity and ability to resist deformation of 6 commercially available disposable plastic stock trays and 1 metal stock tray when used in conjunction with a high-viscosity vinyl polysiloxane impression material. MATERIAL AND METHODS: Ten impressions were made with 1 putty vinyl polysiloxane material (Reprosil Putty) using each of the 6 tested disposable plastic stock trays, Sani-Trays (perforated), Sani-Trays (nonperforated), COE Disposable Spacer Tray (perforated), COE Disposable Spacer Tray (nonperforated), Bosworth Tray-Aways (perforated), Track-it Trays (perforated), and 1 metal stock tray (nonperforated), Cadco Dental Products, as a control on a mandibular plastic model. The dimensions of the tray in cross section at the mandibular right first molar area were measured before, during, and after the impression procedures with an electronic digital caliper. The cross-arch dimensions of the tray were measured at similar intervals. One examiner made all measurements and each measurement was repeatable within +/-0.01 mm. A split plot repeated measures analysis of variance (ANOVA) was performed and 2-sided P -values were calculated (alpha=.05). RESULTS: The results indicated that the disposable plastic trays tested were not sufficiently rigid to resist deformation when used with very high-viscosity putty material. Metal stock trays showed significantly less change in cross-arch dimension than plastic trays (F(1.68)=11.25, P =.001). Metal stock trays also showed significantly less change in cross-sectional arch dimension than plastic trays (F(1.68)=15.15, P<.001). CONCLUSION: When disposable plastic stock trays were tested in conjunction with very high-viscosity impression materials there was distortion of the tray both across the arch and in cross section.

Evidence-based approach for treatment planning options for the extensively damaged dentition.

Restoring the extensively damaged dentition has always been a difficult decision-making process for the dental practitioner. Decisions to restore these teeth were primarily based on the fact that "fixed" teeth are typically better functionally than "removable" teeth and better esthetically than "no" teeth. Prior to dental implants, restoring missing teeth and extensively damaged teeth utilizing traditional therapy such as crown lengthening, root hemisection/amputation, endodontic therapy, apical surgery, post and cores and splinting were the options available to our patients. These teeth typically required the expertise of additional specialist, however their prognosis and success rates were typically guarded at best. Presently, dental implant success rates have been clearly identified and documented in the literature which now questions the survivability and success rates of the traditional mode of therapy for extensively damaged teeth. This paper will attempt to review the dental literature for various traditional modes of therapy for restoring the extensively damaged to provide a consensus of their survivability to help the practitioner to present options and prognosis for their patients.

Esthetic considerations with removable partial dentures.

The reduction in partial edentulism that has occurred due to successful preventive procedures and the predictable use of osseointegrated implants has reduced the need for removable partial dentures. However, for a variety of reasons, many patients can continue to benefit from partial denture therapy; and these patients deserve the best esthetic result possible. The primary esthetic objection to removable partial denture therapy is the unsightly display of the clasp assemblies. This article describes three strategies that can be used by the discriminating clinician to eliminate the display of the clasp assembly and provide an esthetic and functional removable prosthesis.

The role of all-ceramic crowns in contemporary restorative dentistry.

A large number of all-ceramic alternatives to metal-ceramic restorations are being marketed aggressively to the dental profession. Most of these all-ceramic alternatives have little or no scientific evidence to support their use. This article present guidelines for clinicians to analyze new ceramic systems and specific indications and contraindications for use. It is suggested that before practitioners consider using an all-ceramic system, they make sure that published clinical trials document a survival rate of at least 95 percent over five years. In addition, each system should be evaluated to determine whether it delivers the esthetic results anticipated.