Specimen Fabrication Method Impacts 3-D Surface Topographies Of Restorative Resins

Objectives: To compare the effect of four specimen fabrication methods on 3-dimensional topographies of selected adhesive- and composite-resins.
Methods: Unpolished specimens of composite-resins PTF (Point 4, Kerr Corp.) and TPH (TPH Spectra HV, Dentsply Caulk), and adhesive-resin ASB (Adper Scotchbond Multi-Purpose, 3M ESPE) were fabricated against glass slides (G), mica (M) or silicon (S) wafers, or sequentially wet-polished (P; 180-1200grit SiC-disks, and 1.00-0.50μm polycrystalline-diamond suspensions). Specimens were stored (ultra-pure water @37°C) before scans were acquired in air (n=15/resin for all methods except P, where n=24/resin; scan-size 1,025x850μm) using a Profilm3D optical-profilometer. Topographical parameters calculated using ProfilmOnline software and Plane-Least-squares-fit-of-shape Flatten operation were: Mean roughness (Sa), Root mean square roughness (Sq), Maximum peak to valley height (St) and Kurtosis (Sku). Data were analyzed using General-Linear-Models and post-hoc Student-Newman-Keuls (SNK) tests (α=0.05; SAS software).
Results: Mean value ranges were: Sa (0.16μm [PTF-P] to 0.61μm [ASB-M]), Sq (0.21μm [PTF-P] to 0.75μm[ASB-M]), St (1.16μm [ASB-P] to 6.03μm [ASB-M]) and Sku (3.44 [ASB-P] to 108.63 [TPH-G]). Statistically significant differences existed among the resin-fabrication method combinations for all parameters (p<0.0001). For ASB, method P produced the lowest mean St value, whereas S, G and P produced the lowest mean Sa and Sq values. Method M produced the highest mean St, Sa and Sq values. For PTF, methods S and P showed the lowest mean Sa values, whereas G and M produced the highest mean values for both parameters. The highest mean Sku value was with method S. Mean St values did not vary by method. For TPH, method M showed the highest mean Sa and Sq values, whereas P had the lowest mean Sq value.
Conclusions: Wet-polishing produced the smoothest 3-D topographies and mica wafers produced the roughest topographies in the resins tested. Choice of specimen fabrication method has profound implications for future studies on the long-term analysis of resin biodegradation and biofilm formation.