COMPARISON OF SURFACE-ROUGHNESS OF ORAL HARD MATERIALS TO THE THRESHOLD SURFACE-ROUGHNESS FOR BACTERIAL PLAQUE RETENTION - A REVIEW OF THE LITERATURE

Objectives. The roughness of intraoral hard surfaces can influence bac terial plague retention. The present review evaluates the initial surf ace roughness of several intraoral hard materials, as well as changes in this surface roughness as a consequence of different treatment moda lities. Methods. Articles found through Medline searches were included in this review if they met the following criteria: 1) stated threshol d surface roughness values and reputed change in surface roughness due to different manipulation techniques; or 2) included standardized sur face conditions that could be compared to the treated surface. Results . Recently, some in vivo studies suggested a threshold surface roughne ss for bacterial retention (R-a = 0.2 mu m) below which no further red uction in bacterial accumulation could be expected. An increase in sur face roughness above this threshold roughness. however, resulted in a simultaneous increase in plaque accumulation, thereby increasing the r isk for both caries and periodontal inflammation. The initial surface roughness of different dental materials (e.g., teeth, abutments, gold, amalgam, acrylic resin, resin composite, glass ionomer or compomer an d ceramics) and the effect of different treatment modalities (e.g., po lishing, scaling, brushing, condensing, glazing or finishing) on this initial surface roughness were analyzed and compared to the threshold surface roughness of 0.2 mu m. The microbiological effects of these tr eatment modalities, if reported, are also discussed and compared to re cent in vivo data. Significance. Based on this review, the range in su rface roughness of different intraoral hard surfaces was found to be w ide, and the impact of dental treatments on the surface roughness is m aterial-dependent, Some clinical techniques result in a very smooth su rface (compressing of composites against matrices), whereas others mad e the surface rather rough (application of hand instruments on gold). These findings indicated that every dental material needs its own trea tment modality in order to obtain and maintain a surface as smooth as possible.