Surface topography of conventional restorative materials

Technical advances have made it possible to characterise surface topography of restorative materials in ways previously impossible. Objectives: This study examines and compares surface wave (W), profile (P) and roughness (R) of gold, amalgam and porcelain to obtain baseline data of these materials and determine whether such measures can give useful information on surface topography. Methods: Six 5mm diameter specimens were prepared for each material in Perspex discs using conventional clinical procedures. Surface topography was measured in a Form Talysurf Series 2 using three parallel traces 3.2mm in length. The trace was modified to an arc (A) or line (L). W, P and R readings were made for average (a), valley (v), peak (p) and total (t) surface features. The data was subjected to Tukey's Studentised range test with significance set at P<0.05. Results: Magnitude of surface features varied markedly between W, P and R eg. for porcelain Ra=1.5±0.41µm; Pa=10.0±2.55µm; Wa=7.89±2.54µm. Line was slightly more discriminating than arc producing 2 more instances of significant difference between the materials for [WPR(avpt)]. Profile was more discriminating between the materials compared with W and R. There was no significant difference for gold R, P and W values between L and A; porcelain differed significantly between L and A readings for P and W; R, P and W for amalgam showed significance (P<0.001) between A and L. Conclusions: The newer surface topography measures have the potential to yield valuable data which could explain previously contradictory experimental findings.