ABSTRACT
Total seal in the root apex for healing of periodontium is an important goal of endodontic surgery that is obtained by application of various kinds of retrograde materials. The purpose of this study was to evaluate and compare marginal adaptation of two retrograde materials [Gray MTA and Portland cement], using SEM. In this invitro study, 50 extracted single-rooted human teeth with mature apices, without decay, absorption or root fracture were selected. The canals were instrumented by rotary system and filled with gutta-percha and then 3 mm of the root-end was resected. Then a cavity was prepared at the root-end with 3 mm depth and 1 mm width. Next, the teeth were divided into two groups of 25 teeth each. Each group was filled with one of the retrograde materials [Gray MTA or Portland cement]. After that, the teeth were resected longitudinally to create buccal and lingual sections. Finally, the gap was determined and recorded in millimeter in two dimensions. The data were analyzed using Mann-Whitney test and Fisher's Exact test. The mean gap in Gray MTA and Portland cement were 211.6micron and 326.3 micron, respectively. The difference was not statistically significant. There was no significant difference in marginal adaptation between Gray MTA and Portland cement