Mechanical properties of a light-polymerizing provisional restorative material with and without reinforcement fibers.

Interim restorations are vulnerable to inadvertent fracture during mastication. Autopolymerizing acrylic resins have traditionally been selected for fabrication of provisional restorations. Triad light-polymerizing tooth-colored acrylic resin was recently introduced as an alternative material for this procedure. This material does not contain methyl methacrylate monomer and permits an increased working time. Heavy occlusal forces may initiate cracks within these restorations, and propagation of these cracks may ultimately lead to failure. Various forms of reinforcement fibers are available and are marketed for strengthening dental resins used for provisional restorations. Investigators have demonstrated that the mechanical properties of acrylic resins may be improved with the incorporation of reinforcing fibers, but a published evaluation of fiber-reinforced light-polymerizing provisional restorative materials is lacking. This investigation recorded and compared two mechanical properties of one light-polymerizing provisional restorative material with and without incorporation of vertically and horizontally oriented woven, matted, polyethylene fibers. No significant difference in modulus of rupture was recorded between groups with and without fibers. The mean flexural elastic modulus of the group with the horizontally oriented fibers was significantly greater than the mean flexural elastic modulus of the specimens without incorporated fibers.

Rapid mixing of zinc phosphate cement for fixed prosthodontic procedures.

This study was done to determine the efficacy of rapidly mixing zinc phosphate cement in conjunction with fixed prosthodontic procedures. Properties measured included rate of pH change and temperature increase, film thickness, and setting time. The rapid mix technique in conjunction with the frozen glass slab resulted in a faster elevation of the pH but slightly greater temperature rise and film thickness. As was expected, the rapid mixing procedure resulted in an increased working time but decreased setting. On the basis of this study, it appears that the rapid mixing technique in conjunction with a frozen glass slab is an acceptable technique for preparing zinc phosphate cement for fixed prosthodontic procedures.

Application of silica coating technique for removable prosthodontics. A clinical report.

A technique for constructing a maxillary removable partial overdenture using the Silicoater system has been described.

SEM evaluation of the in-vitro effects of an air-abrasive system on various implant surfaces.

This investigation was conducted to determine the effects of an air-abrasive polishing system on various implant surfaces. Four each of the following types of implants were obtained from the manufacturer: Stryker DB (a titanium alloy implant), Denar Steri-Oss (a pure titanium implant), IMZ (pure titanium polished collar/plasma-sprayed body), and IMZ transmucosal implant extensions (highly polished pure titanium). Four samples of each type of implant material were placed in a group to be treated with an air-abrasive polishing system for 0.5, 1, 5, or 10 seconds, for a total of 16 samples. Scanning electron photomicrographs taken of each sample before and after treatment were analyzed by three examiners who were blind to the treatment conditions. They determined if the abrasion on the treated surface was greater than, equal to, or less than the pretreatment control. No perceptible difference was noted between the pretreatment and posttreatment photomicrographs regarding the surface integrity of the implant material surfaces.

Comparison of dye and ion microleakage tests.

Basic fuchsin has been established as an effective testing agent in determining the extent of microleakage present under restorations. Recently, the presence of microleakage in vivo has been studied through the use of hydroxyl ions as is present in proprietary cavity liners such as Dycal. The purpose of this study was to determine a correlation between the use of these two systems in measuring microleakage. A series of restored human teeth containing a calcium hydroxide liner were thermocycled and then tested with pH indicating paper. The same samples were then given additional thermocycles in 0.5% basic fuchsin dye. The teeth were sectioned in two planes and ranked as to the amount of dye penetration. Over an 18-week period the number of positive pH tests began to diminish while the dye penetration values remained relatively constant. The dye penetration method continued to record microleakage after the pH paper had ceased to detect hydroxyl ions. The dye penetration method appeared to be more dependable as the age of the restoration increased.

Fixed partial dentures opposing complete dentures.

When fixed partial dentures are indicated in an arch opposing a complete denture, it is best to develop the occlusal surfaces of the fixed restorations at the same time that the opposing denture teeth are arranged in wax to permit greater flexibility and reduce the compromise in developing bilateral balanced occlusion. This article describes the development of bilaterally balanced occlusion between casting patterns for fixed partial dentures and a complete denture. The technique emulates the ease of arranging maxillary and mandibular denture teeth and can be used to develop fixed restorations with metal or porcelain occlusal surfaces. Porcelain occlusal surfaces are described because the use of porcelain is more technique sensitive.

An in vitro comparison of two dowel and core techniques for endodontically treated molars.

A laboratory study was designed to compare the shear-compressive strength of two post and core systems in mandibular molars. A buildup with cemented posts and an amalgam core proved to have greater strength than a system in which only amalgam was used to create a dowel and core. The addition of crowns to the buildups did not produce a significant increase in the shear strength of the specimens. Most specimens prepared by a specific restorative technique fractured in a consistent predictable pattern. The dentist should be aware of the incidence of lingual wall fractures in planning the restorations for endodontically treated molars. Careful evaluation of the remaining amount of tooth structure should influence the selection of the dowel and core technique.