Comparison of the Effects of Four Pre-Bonding Preparation Methods on the Bond Strength between a Multilithic Tooth and Denture Base Resin

Introduction: With introducing composite teeth, their wear resistance has been well investigated, but there are few papers about their bonding to acrylic denture base resins. The aim of this study was to compare the four pre-bonding preparation methods on the ridge lap surface of one multilithic denture tooth by determining its bond strength to denture base resin.Materials and Methods: In this experimental laboratory study, 84 maxillary anterior teeth were divided into four groups based on four different pre-bonding methods (untreated, grinding, 2 retention grooves and diatorics). The teeth were mounted on 2 sides of triangular shaped wax models. Then, the laboratory procedures (wax elimination and resin packing) were done. Each of the specimens was tested by universal testing machine with cross head speed of 5 mm/min. The data were analyzed by Kruskal-Wallis and Mann- Whitney tests.Results: The mean bond strength in untreated group was 287.38 ± 51.82 N, in grinding group was 301.52 ± 113.65 N, in retention grooves group was 374.38 ± 88.22 N and in diatorics group was 415.19 ± 226.37 N. The highest mean bond strength was seen in diatorics group (P=0.009). The percentage of cohesive fractures in this group(90.5%) was significantly more than that in other groups (P<0.001).Conclusion: The results of this study showed that creating retention hole in the ridge lap surface of the multilithic tooth can increase its bond strength with denture base resin.