Comparison of shear bond strength of recementing debonded resin bonded prosthesis with two type of dual cured resin cement

Abstract

Debonding is the major problem of resin bonded restorations. However recementation would positively affect the longevity of these restorations. This study aimed at a evaluation of the shear bond strength of recemented resin bonded restoration and the effect of two cleansing protocol on it.Methods and materials: Buccal, incisal and proximal enamel of 52 central incisors were cut. Custom tray were constructed and final impression were made by using polyether impression material.52 metal castings were waxed individually and cast with Ni- Cr alloy using lost wax technique. Inside of each casting was air abraded and then cemented with either Panavia or RelyX Ultimate cement. Samples were mounted on universal testing machine and an axial load was applied on tooth casting interface. After debond, cement remnants were cleansed by pumice slurry or tungsten carbide bur. Castings were recemented again and shear bond strength was tested. The load which lead to the bond failure were recorded. Data were imported to SPSS software and analysed by ANOVA and Post Hoc Tukey test. The level of significance was set at 5%.Results: Initial shear bond strength of resin bonded restorations cemented by Panavia was higher than Rely Ultimate cement (p=0.002). Shear bond strength of RelyX Ultimate recemented restorations after cleaning with pumice slurry were significantly lower compared to panavia samples recemented after cleaning with both pumice slurry (p= 0.002) and tungsten carbide ( p=0.033).Conclusion: Panavia cement had the highest shear bond strength and cleansing dentin surface with tungsten carbide bur is more effective than pumice slurry.