In-vitro study on dimensional changes of composite cores

ABSTRACT

Dimensional changes for the composite cores, after using two types ofcomposite resin, caused by water sorption were measured. Three differenttechniques for the retention of composite cores were followed. Thesetechniques were slot technique, T.M.S. pins applied vertically on the dentinefloor and T.M.S. pins as before but were then bended. Measurements ofdimensional changes were done using a stereomicroscope for 1 day, 3 days and 7days after water immersion. The results of the present study showed that forboth types of composite resin investigated, bending the pin after beingapplied vertically on dentine floor showed the least values of dimensionalchanges. For all the variables included in this study, it was found thatafter three days storage in water, there were no dimensional changes. It isadvocated from the findings of this study to delay crown preparation in caseof composite cores a few days later to avoid discrepancy due to hygroscopicexpansion caused by water sorption