RESUMO
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