An evaluation of the surface changes in PMMA biomaterial formulations as a result of toothbrush/dentifrice abrasion.

Objectives. The objective of this study was to evaluate the abrasion resistance and surface roughness of two injection-molded poly(methylmethacrylate) denture base materials (SR-Ivocap 'Plus', Ipsyl 60 RV), and also one compression- molded material (Trevalon). A fourth group of specimens (prepared from Trevalon using the injection-molding procedure) was compared to the compression-molded specimens.

Methods. Ten specimens were prepared according to manufacturers' instructions. An experiment involving toothbrush and dentifrice abrasion was performed on all specimens from each of the materials and the cumulative percentage weight-loss was calculated after 100,000 brushstrokes. A series of surface roughness profile measurements were also obtained from each specimen within the groups. The data were analysed by using the Kolmogorov-Smirnov test. A level of significance of 0.017 was set in order to adjust for multiple comparisons between the three sets of materials.

Results. There was found to be no statistically significant difference between the three groups of materials in terms of percentage weight-loss, and no statistically significant difference between the Trevalon specimens when injection-molded or compression-molded. In terms of surface roughness, however, SR-Ivocap 'Plus' recorded the Lowest surface roughness profile of the three groups. It was found that there was a statistically significant difference (P < 0.017) between this material and Ipsyl RV 60 (producing the highest roughness), and compression-molded Trevalon. Furthermore, there was found to be no statistically significant difference between injection-molded and compression-molded specimens of Trevalon with regard to surface texture.

Significance. From a clinical standpoint, the surface roughness results suggest SR-Ivocap 'Plus' to be the material most likely to produce the least suitable substrate for the accumulation of denture plaque. (C) 2003 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.