A comparison of pulpectomies using ZOE and KRI paste in primary molars: a retrospective study

Maintaining a successfully root-treated primary molar has the advantage of preserving the natural tooth--the best possible space maintainer. The purpose of this study was to compare the success of endodontic treatment of nonvital primary molars using ZOE with that of KRI paste. Of 78 necrotic primary molars, 34 were filled with ZOE and 44 with an iodoform-containing paste (KRI). The canals were prepared with files, rinsed with saline and filled with one of the resorbable pastes, using a spiral Lentulo on a low-speed handpiece. A radiograph was exposed immediately postoperatively to observe whether the root filling was flush, underfilled, or overfilled. The effect of length of fill on the treatment outcome also was evaluated. Teeth were examined periodically clinically and radiographically to assess success of the treatment. Follow-up interval varied from 12 to more than 48 months. Overall success rate for KRI paste was 84% versus 65% for ZOE, which was statistically significant (P < 0.05). Overfilling with ZOE led to a failure rate of 59% as opposed to 21% for KRI (P < 0.02). Conversely, underfilling led to similar results, with a failure rate of 17% for ZOE and 14% for KRI. These results support the clinical efficacy of root filling with KRI paste as a treatment option for nonvital primary molars.