ABSTRACT
PURPOSE: The purpose of this study was to investigate the influence of certain defined variables on color and opacity of silicone elastomers for maxillofacial prostheses. MATERIALS AND METHODS: Three condensation-type and five addition-type silicone elastomers were tested for their changes in color and opacity as a result of aging. The specimens were aged under a xenon light source, dry or wet, and in darkness, also dry (control specimens) or wet. The aging times were 24, 96, 168, 336, 504, 840, 1176, and 1512 hours. The changes in appearance were measured with a spectrophotometer. RESULTS: The condensation-type polymers increased in opacity in an aqueous environment, while the addition-type polymers, as a group, showed the smallest color changes. Although the addition-type polymers generally had a higher filler content than the condensation types, they had a lower opacity. However, because of their higher viscosity, the condensation-type polymers offer better possibilities for intrinsic coloring of the prosthesis. CONCLUSION: Under the experimental conditions studied, significant differences between the silicone elastomers regarding color and opacity changes were demonstrated. However, for a proper choice of material in a given case, these factors have to be related to biologic and mechanical properties of the material.
Subject(s)
Maxillofacial Prosthesis , Silicone Elastomers/chemistry , Analysis of Variance , Color , Humans , Light , Materials Testing , Prosthesis Coloring , Signal Processing, Computer-Assisted , Spectrophotometry , Time Factors , Viscosity , WaterABSTRACT
The increasing use of ceramic crowns and inlays in posterior teeth has highlighted the clinical difficulties involved in achieving a good surface finish after corrective grinding. In the present work several polishing systems and techniques were compared, initially using only one dental ceramic, Vita Mark I. The two systems that produced the best results were then further used for the polishing of several different dental ceramics, mainly newer types. The initial surface roughness and the surface condition attained after various polishing stages were evaluated by using a surface roughness analyzer. In the initial test series the SofLex system and the Shofu Porcelain Laminate Polishing Kit produced the best results; they were therefore chosen for the second part of the investigation. In this the two polishing systems concerned produced a satisfactory surface finish in a clinically acceptable time for all the ceramics tested. The use of a diamond-containing polishing past did not improve the surface smoothness obtained with the SofLex system but gave a more varied result for the Shofu system.
Subject(s)
Aluminum Silicates , Dental Polishing/methods , Dental Porcelain , Aluminum Oxide , Analysis of Variance , Ceramics , Dental Alloys , InlaysSubject(s)
Face , Maxillofacial Prosthesis , Prostheses and Implants , Acrylates , Adult , Aged , Biocompatible Materials , Female , Humans , Male , Prosthesis Design , SiliconesABSTRACT
The cytotoxic potential of four different and potentially interesting RTV-silicones was evaluated using an in vitro cell culture technique. Both human epithelial cells and mouse fibroblasts were used in this study and the results indicate that all materials tested were cytotoxic. Treating the surface of the discs with talc appeared to decrease the cytotoxic effects of the materials.
