investigation into the effect of cavity varnish on microleakage of amalgam restoration

The purpose of the present work was to study the effect of cavity varnish upon microleakage of amalgam filled cavities. Butt-joint class V cavities were prepared on the buccal surfaces of human extracted teeth. Four cavity varnishes were used [Vocopal, Dorilac, Copal Plus and Voco]; while the amalgam filling was Dispersalloy. Immediately before filling, cavity walls were subjected to one of washing by distilled water, washing then varnishing, or washing, acid-etching, then varnishing. Teeth were thermal-cycled at a temperature changes between 50 and 10 +/- 2C. Afterwards, they were kept in methylene-blue, then sectioned. The degree of dye penetration at the interface was measured in microns. The results indicated that the cavity varnish reduced the dye penetration. On the other h and, acid-etching, followed by cavity varnish had no added effects over that produced by cavity varnish alone