Microleakage of direct gold restorations: An in vitro study

Abstract

lhe adaptation of restorative materials to the walls of cavity preparations has been considered clinically important for many years.’ A chemical bond between a restorative material and tooth structure with no marginal leakage would be ideal. However, at the present time no available material possesses this criterion. Early studies of the microleakage of conventional amalgam alloys, using autoradiographs, showed that the initial sealing properties of amalgam were greatly improved by the use of copal resin cavity liner.‘> ’ More recently, it has been reported that corrosion-resistant amalgam restorations placed after coating the cavity walls with cavity varnish showed no leakage at 48 hours and after 3 months.4 These same authors reported similar results in a study using dogs as experimental animals5 The most recent study of leakage of direct gold restorations used a crystal violet dye technique.” In this study amalgam and compacted gold were found to have less leakage than composite resins using an acid-etch technique. Cohesive gold restorations have long been considered the epitome of clinical restorations in a general practice. Textbooks list adaptation to cavity walls and cavosurface margins as one of the attributes of cohesive direct gold restorations. Pure gold foil, electrolytically deposited mat gold, powdered gold encased in gold foil, and alloyed filling gold are in current use for conservative restorations. The purpose of this study was to evaluate the adaptation to cavity walls of four types of direct filling golds by studying the microleakage around restorations placed with and without a copal resin liner.