Microleakage of Class V composite restorations prepared conventionally with those prepared with an Er:YAG laser: a pilot study.

Since the advent of acid etching, composite resin technology has improved. 1 Composite resins are bonded mechanically to acid-etched enamel, relying on a large interlocking area between the two to form an effective bond. Bonding of composite resin to dentin is attained by chemical means, either to the organic or inorganic part of the dentin. Polymerization shrinkage, however, still plagues the longevity of direct resin restoration2, -~ Although the mechanical bond with enamel is sufficiently strong to withstand this contraction, the same cannot be said for the dentin. The result is marginal leakage at the junction of the composite resin and dentinal margin.3 Past experiments demonstrating leakage are performed with conventional highspeed drilling and acid etching either with gel or liquid. None of the traditional restorative materials used in dentistry provide adhesion to tooth structure. 5 Thus a microscopic space always exists between the restoration and prepared cavity. Staining, which sometimes is seen at the margin of resin restorations, is caused by the penetration of substances or their degradation products into these microspaces at the resin restorationtooth interface. Although some of the newer restorative materials, such as those systems based upon polyacrylic acid and possibly certain dentin bonding resin systems, have significantly reduced the microspaces, gaps may occur as a result of the material. Many materials shrink on setting, creating a gap at the tooth-restorative interface. The Er:YAG laser (Aesculap Meditec--Heroldsberg, Germany) currently is undergoing clinical trials in Europe that are directed toward cutting efficiency and patient comfort.4 Little information is available as to the quality of the restoration when the cavity preparation is prepared by and etched with an Er:YAG laser. The purpose of this paper is to compare microleakage when cavity preparations are prepared conventionally with a high-speed drill and acid etched or prepared and etched with an Er:YAG laser.