Effect of Camphoroquinone Contents on the Shear Bond Strength of Experimental Composites to Bovine Enamel

A purpose of this study was to confirm the influence of camphoroquione contents on the shear bond strength of experimental light curing composite resins to bovine enamel. Five experimental composites were manufactured experimentally with varying the concentrations of camphoroquinone as 0.2%, 0.3%, 0.4%, 0.5%, 0.6%. Basic composition of experimental composites were monomer (a mixture of Bis-GMA 3 parts and TEG-DMA 1 part) 25% and filler (25micron crushed silica treated with 1% silane at 80°) 75% by weight. Amine were added as 0.2% to total weight. Then camphoroquinone were incorporated with various concentrations. Experimental groups were five including control group. 0.2% camphoroquinone containing composites was considered as a control group. Bovine enamel embedded in resin blocks were flattened on 600# emory paper and etched with 37% phosphoric acid for one minute. After rinse and dry, on etched enamel surface, 3mm dia. and 1mm thick mold was attached as cavity, and filled with each composites. 60 seconds illumination was done. Bonded specimens were immersed in 37° water for 1 day, and shear bond strengths were measured with 1mm/min speed in Instron 4467. 10 measurements were done for each group. Non-linear regression analysis was done between camphoroquinone concentrations and shear bond strength. One-way ANOVA test for Duncan's grouping was done between groups. Results: Results are presented as means and s.d. with MPa. * is a control group.

Correlation equation between camphoroquinone contents and shear bond strength was y=-155.14x²+129.81x+11.476 (r²=0.9278). However p-value between groups was 0.3718(p>0.05) which means no statistical differences. Conclusion: These results indicate that although the statistical differences was not confirmed, the optimal concentrations of camphoroquinone for highest shear bond strength may be 0.4%. Kisslee@khu.ac.kr