Microleakage of composite fillings in Er,Cr:YSGG laser-prepared class II cavities

If there is insufficient bonding to the enamel, the shrinkage of composites that occurs during polymerization can result in a gap between the filling material and the cavity wall. This gap permits the passage of bacteria or their metabolic products and also of various molecules and ions. This leads to hypersensitivity or secondary caries and is thus one of the causes of the failures encountered in composite restorations. The aim of this study was to examine the quality of the margins of composite fillings in Er,Cr:YSGG laser-prepared cavities by means of dye penetration. The results were compared with those of restoration in conventionally prepared and conditioned cavities.

To this end, 45 class II cavities in extracted molars were prepared. The teeth were divided into three groups. The first group served as a control group. The cavities were prepared in the classical manner by using a diamond, beveled and subsequently conditioned by the etching method. In group 2, the cavities were prepared and conditioned exclusively with the Er,Cr:YSGG laser. In group 3, laser preparation was supplemented by conditioning of the cavity with phosphoric acid.

No significant difference could be found between the classical preparation technique in combination with etching and the laser preparation method with supplementary etching (group 3). The degree of dye penetration was highest in the group undergoing laser-prepared restoration without additional etching (group 2) (Wilcoxon test, P < 0.017).

Although it was found in previous studies that there is no significant difference between bond strength of acid etched enamel and Er,Cr:YSGG laser etched enamel, the dye penetration rate differs. On the basis of the results of our study, the additional use of etching after Er,Cr:YSGG laser preparation is recommended as it is used in the classical cavity preparation technique.