The longevity of restorative procedures is related to, among other factors, a perfect adaptation and a strong, long-term union between dental restorative materials and teeth structures. The knowledge of the factors causing marginal leakage is Essential to develop procedures and materials in order to minimize the problem. In the same manner, the importance of choosing a standardized technique is necessary to analyze microleakage and to relate and discuss the results presented in literature. There are many laboratory tests to measure the marginal adaptation between tooth and restorative material, and each one has its own characteristics and properties. Once there is no standardization of techniques to analyze marginal leakage at literature, the aim of this review was to perform a critical evaluation related to factors influencing some techniques and consequently the results. The subject is of interest to researchers of the methodologies presented in literature.

KEY WORDS: microleakage; microleakage tests; dental structures