effect of tooth preparation on microleakage of stainless steel crowns placed on primary mandibular first molars with reduced mesiodistal dimension.

incomplete adaptation of stainless steel crown margins leads to microleakage. the aim of this study was to evaluate the effect of tooth preparation on microleakage of stainless steel crowns (sscs) placed on mesiodistally reduced primary mandibular first molars.in this in vitro study, 60 primary mandibular first molars with reduced mesiodistal dimension were selected. pulp cavities were filled with amalgam and occlusal surfaces were reduced. the samples were randomly divided into two groups (groups p and blp). standard preparation was done in group p with only proximal reduction. in group blp, after reducing the proximal undercuts, buccal and lingual surfaces were slightly reduced. occlusal one-third of the buccal surfaces was beveled in both groups. then, the sscs of the primary maxillary and mandibular first molars were fitted and cemented in p and blp groups, respectively. after immersing the samples into deionized water, thermo-cycling, and immersion in 2% basic fuchsin, the samples were sectioned buccolingually. the mesial halves were evaluated microscopically for microleakage in both buccal and lingual margins. data were analyzed using mann-whitney u test in spss 19 at the significant level of 0.05.there was a significant difference in microleakage of the buccal margin (p=0.003); whereas, the difference observed in the lingual margin was not significant (p=0.54).we suggest reduction of buccal and lingual surfaces of mesiodistally reduced primary mandibular first molars and placing lower (mandibular) crowns.