[Effect of cavity liners on micro leakage of Cl V amalgam restorations]

ABSTRACT

There is no bonding between amalgams and restored cavity walls. Therefore, these restorations are prone to leakage despite the deposition of corrosion products. The aim of this in vitro study was to evaluate the effectiveness of three cavity liners in reducing micro leakage of class V amalgam restorations. Sixty-eight extracted intact human molar teeth were selected. Class V cavity preparations were performed in all teeth and they were randomly divided into four groups. Group one was used as a control group [no liner], and the rest were Varnish, Resin Cement [Panavia F], and Light-cured dentin bonding agent [Single Bond] groups. Or alloy amalgam was condensed into the prepared Cl V cavities. All teeth were immersed in distilled water at 37°C, for 24 hours. All restorations were subjected to 1000 thermal cycles at 5-55 degrees centigrade. For micro leakage test, all teeth were immersed in 0.5% Basic Fuchsine and sectioned. Dye penetrations were evaluated by stereomicroscope. The collected data were analyzed statistically by Kruskal-Wallis and Bonferroni test. The results showed significant differences between four groups [P< 0.05]. Control group showed the maximum and Panavia group revealed the minimum micro leakage. There was no significant difference between Panavia and Single Bond groups. On the other hand, no significant difference [P>0.008] was observed between occlusal and gingival margins in the control, Single Bond and Panavia groups. Although, the difference was statistically significant in varnish group [P=0.002]. When compared with control group, the dentin bonding agent, varnish and cement resin groups demonstrated significantly decreased micro leakage at the enamel margin [P=0.0001]. However, when compared with varnish and control group, the dentin bonding agent and cement resin groups demonstrated significantly decreased micro leakage at the cementum margin [P<0.008]. Findings of this investigation clearly demonstrate the advantage of using lining materials in amalgam restorations. Therefore, we can conclude that such materials may significantly increase the sealing ability and decrease the micro leakage in Class V amalgam restorations