بررسي تاثير زمان نگهداري و تكنيك resin coat روي استحكام كششي باند سمان panavia F به عاج

Evaluation of effects of storage time and resin coat technique on the tensile bond strength of panavia F dentin cement

Objective: Fabrication of indirect onlays and inlays and their cementation with resin cements have become increasingly popular. Resin cements used in indirect restoration cementations provide weaker bonds when compared with the bond strength supplied in a dentin bonding used for direct composites. This results in debonding of indirect restorations and consequent problems. Resin coat technique has been advocated as a solution. It is claim to increase the bond strength of resin cements to dentin using this technique .The purpose of this study was to evaluate the effects of storage time and resin coat technique on the panavia F cement tensile bond strength to dentin. Methods and Materials: Sixty extracted human third molars were divided into six groups of ten. The occlusal surfaces were trimmed to the exposure of the very first dentin layer, the specimens were placed under the following experimental conditions: Group 1: control group 1, no surface treatment on dentin with storage under distilled water for 24 hours. Group 2: control group 2, no surface treatment on dentin with storage under distilled water for 7 days Group 3: Resin coated dentin with clearfil liner bond 2V and storage under distilled water for 24 hours. Group 4: Resin coate dentin with clearfil bond 2V and storage under distilled water for 7 days. Group 5: Resin coated dentin with clearfil bond 2V and flowable composite and storage under distilled water for 24 hours Group 6: Resin coated dentin with clearfil bond 2V and flowoble composite and storage under distilled water for 7 days . Nickel chrome rod was bonded to the above surfaces using panavia F. Tensile bond strengths were evaluated with instron machine Paired t-test was used to detect differences among experimental groups and ANOVA test for comparison between the 6 groups. Results: The mean tensile bond strengths ± standard deviations were as following: Group 1: 15.94 ± 5.27, Group 2: 12.43 ± 4.75, Group 3 : 15.36 ± 5.41, Group 4 : 10.61 ± 3.53, Group 5: 18.45 ± 6.18 and Group 6: 13.34 ± 4.4 PMa. Statistical analysis showed no significant differences between groups 1 and 2. However, there was a significant difference between the highest strength was found in group 5, and the lowest one in group 4. ( P< 0.05). a7- day storage, to 1 day storage reduced paravia F bond strength to resin coated dentin ( P< 0.05). In all groups, inter facial failure was an adhesive failure between cement and dentin or resin coated dentin. Conclusion: Bonding strength was not improved by using resin coat technique. Usage of flow able composite in combination with clearfil liner bond 2V had not effect on bonding strength. Decrease in bonding strength after 7 days storage of resin-coated dentin was seen.