The International Journal of Prosthodontics, 02/1992

The strength of resin-bonded, all-ceramic fixed partial dentures with different framework and prosthesis designs was evaluated. Metal dies were fabricated from a cast of a patient missing the left central incisor and the adjacent teeth were prepared to receive an all-ceramic, resin-bonded prosthesis. Framework designs were standardized and at least 10 samples were made for testing each design. Labial veneering of the pontic with Vitadur-N significantly decreased the stability compared with that of the unveneered In-Ceram framework. Circumferential veneering of the pontic and additional proximal box preparation yielded the strongest units.

A brief history of electrical discharge machining (EDM) is given and the process is discussed. A description of the application of EDM for fabricating precision attachment removable partial dentures, fixed-removable implant prostheses, and titanium-ceramic crowns is presented. The advantages and disadvantages of the EDM process for the dental profession are evaluated. Although expensive, the procedure has merit.

To investigate the chewing patterns of patients with TMJ disorders, analysis of mandibular movement was performed in 25 normal subjects and 150 patients with stomatognathic dysfunction using the Sirognathograph analyzing system. Patients with TMJ disorders demonstrated different chewing patterns than those of normal subjects. Chewing patterns in the frontal, horizontal, and sagittal projections were classified into four, two, and two different patterns, respectively, and each distinct chewing pattern appeared to be associated with a specific TMJ disorder.

The effect of porcelain veneer opacity on the resultant shade of a veneer-substrate system was evaluated colorimetrically. Three groups of porcelain discs were fabricated using shade A1 Ceramco G veneer porcelain diluted with 0%, 25%, or 50% translucent porcelain. The discs were luted to a shade C4 substrate using an untinted resin composite luting agent. A custom shade guide was fabricated. All samples were analyzed with a Chrome Meter using Munsell and CIE LAB notation. ANOVA showed significant differences (P less than .05) for each coordinate in both the Munsell and CIE LAB color space for all groups. The smallest delta E*ab for all groups was noted with shade tab C2. The resultant shade was neither the shade of the porcelain (A1) nor the substrate (C4). The data indicate that the translucent porcelain has as great or greater effect on the color coordinates of the veneer-substrate system as the substrate material.

Studies reporting the influence of finish-line configuration on the fit of cemented crowns have had conflicting conclusions. This study examined the effect of finish-line configuration on the fit of cemented complete crowns. Three identical tooth preparations were made, each with a different facial finish line: shoulder, shoulder-bevel, and chamber. The prepared teeth were replicated to produce 45 epoxy resin teeth, 15 for each finish-line design. Thirty cast crowns were fabricated and seated on their respective epoxy resin teeth - fifteen without cement and fifteen with zinc phosphate cement. An additional set of fifteen castings, seated on their working dies, was used for control measurements. All specimens were embedded, sectioned, and measured at predetermined sites. Results showed that finish-line form does not affect the fit of cemented crowns.

The purpose of this study was to determine whether wear of two resin composite materials and contacting I-bar clasp tips would occur within a simulated RPD placement and removal period of 2 years. The data were compared to enamel with contacting I-bars. Cast I-bar clasps were passed over each specimen in the resin composite and tooth experimental groups (n = 10). Computer digitized image analysis of SEM photomicrographs of the specimens provided data for analysis of wear. Results indicated a statistical difference in the amount of mean wear between the two resin composites and between the I-bar groups. The results from this study suggest that the selection of a resin composite for use as a RPD retentive undercut must be carefully undertaken to avoid excessive wear and loss of retention.

This article reviews the methods currently used for making provisional restorations for endosseous dental implants. With the requirements for osseointegration in mind, a simple and aesthetic alternative is suggested. The clinical and laboratory stages for the fabrication of the prosthesis are outlined.

Mandibular rest position, swallowing occlusal position, and maximum opening were evaluated in a sample of healthy young adults (52 male, 27 female) using a mandibular kinesiograph. It was found that males have a significantly greater vertical dimension of rest than do females, while there were no gender differences in the maximum opening. Most of the subjects had a swallowing occlusal position that coincided with or was very near to the position of maximum intercuspation. Reported data allow the definition of a three-dimensional normal range of variability of maxillomandibular positions during the functional tests most frequently used.

A computerised system has recently become available to assist in occlusal analysis. An evaluation of this system is described, with particular emphasis on the measurement of bite force. A hand-held testing device and a Nene universal testing machine were used to apply force. A limited clinical trial was carried out on two volunteers with known occlusal interferences present. It was concluded that the system does not measure bite force accurately, but is useful as a clinical tool if used with care.

The purpose of this study was to test the adherence strength of oxides to some silver-free high-palladium alloys, and to compare the results to values obtained from Au-Pd and Ni-Cr metals. The results showed that the adherence strengths of the oxides were greater than the reported cohesive strength of opaque porcelain. This would indicate that the oxides formed on the alloys examined in this study are sufficiently adherent to their substrates to produce adequate porcelain bonds.

A vehicular accident resulted in a total maxillectomy for the patient compromising deglutition, mastication, speech, and appearance. Bone grafting provided a site for the placement of endosseous implants. The implants were used as stabilization for a prosthesis that resolved these problems. The prosthesis consisted of a multipart substructure attached to the implants. The superstructure was in intimate contact with the substructure, obturated the defect, and provided occlusal contacts, palatal form, and lip support.