Effect of primers on wear resistance of composite-titanium interface

Objectives: The aim of this study was to evaluate effect of primers on resistance to toothbrush-dentifrice abrasion of composite-titanium interface. Methods: Rectangular specimens were cast from titanium metal (T-Alloy H, GC Corp.) and were air-borne particle abraded with 50 µm alumina. The castings were either unprimed or conditioned with a combination of two primers (Alloy Primer and Estenia C&B Opaque Primer, Kuraray Medical). An opaque and a tooth-colored indirect composites (Estenia C&B OA3 and E1) were layered on the titanium castings, polymerized, and stored in 37˚C distilled water for 14 days. Toothbrush abrasion test was performed with a 3.4 N vertical load for 20,000 reciprocal strokes using the Crest dentifrice (P&G). Wear depth was determined by means of a scanning laser microscope (1LM21, Lasertec), and the results were analyzed by Mann-Whitney U test (P=0.05 level). Worn surfaces were also observed by scanning electron microscope (S4300, Hitachi High-Technologies). Result: The average wear depths in µm (n=8) with standard deviations in parentheses were 3.5 (0.5) for the primed group and 8.0 (1.4) for the unprimed group. Significant difference was found between the two groups. Scanning electron micrographs demonstrated considerable worn surface for the unprimed opaque composite, whereas primed specimens did not show apparent worn pattern. Conclusion: It can be concluded that application of the two primers was effective for enhancing wear resistance of the bonded specimens at the composite-titanium interface. Supported in part by a Grant-in-Aid for Scientific Research B(2) 16390566 from the JSPS, and by a Grant-in-Aid for Young Scientists B(2) 16791210 from the MEXT-Japan.