Comparative Evaluation of Dimensional Stability

An in vitro study was conducted to evaluate time dependent dimensional stability of four interocclusal record materials( bite registration wax, polyether, PVS & ZOE). A stainless steel die , made according to modified ADA specification No.19, loaded with different interocclusal recording materials. These materials were separated from die 3 min after their respective setting time, which results in discs of standard diameter with two parallel lines and three perpendicular lines on the surface , at different time intervals ie: 1 hour,24,48and 72 hours. These lines observed under travelling microscope (magnus) & graded for length criteria to find out the dimensional stability of the material. The distance between the two parallel lines then measured at different time intervals to find out the dimensional stability of the material. The result on comparison showed that polyether presented the least linear changes of all the material tested, at all time intervals followed by PVS, Aluwax respectively , ZOE is least stable.