Abstract: Objective：To compare clinical and radiographic success rates of a modified primary root canal filling (ingredients: zinc oxide-eugenol, iodoform and calcium hydroxide, MPRCF) vs. zinc oxide-eugenol cement (ZOE) and calcium hydroxide/iodoform paste (Vitapex) in pulpectomized primary molars at the end of 6 and 12 months, and to evaluate the degradation of materials in the root canals and in apical area. Methods: In the study, 160 primary molars from 155 children ( the average age: 5.88±1.27 years) that met the inclusion criteria were allocated to one of the three materials via block randomization. A two-visit pulpectomy was performed by an investigator. The clinical and radiographic diagnoses were blindly assessed by other two investigators. Results: At the end of 6 and 12 months, the ZOE and MPRCF success rates were 100% both in clinical and radiographic evaluation. The Vitapex group showed the clinical success of 100% at the end of 6 months and 94.5% at the end of 12 months. Radiographic evaluation for the Vitapex group showed 80.4% success at the end of 6 months and 60.7% at the end of 12 months. No statistically significant differences were noted at the end of 6 months in the three groups both in clinical and radiographic evaluation. The success rates in clinical and radiographic evaluation at the end of 12 months for ZOE and MPRCF groups were not significantly different, and better than those for Vitapex group with statistically significant difference. The completely resorb rate of excess extruded extraradicularly were 14.3%, 100% and 71.4% for ZOE, Vitapex and MPRCF at the end of 12 months. The rates of resorption of material at the same rate of the root were 5.8%, 7.2% and 40.9% for ZOE, Vitapex and MPRCF at the end of 12 months. Conclusion: MPRCF, a mixture of zinc oxide eugenol and iodoform with calcium hydroxide can be used as a root canal filling material in primary teeth, taking account of the success rate and resorbing at a similar rate with the roots of the primary teeth.

Key words: Tooth, deciduous, Root resorption, Root canal filling materials, Zinc oxide, Calcium hydroxide