Aim : the study compared three different rotary file systems: Kedo-S, M Pro Pedo , and ProTaper Gold Rotary in respect to Cleaning efficacy, Instrumentation time, Bacterial load, and Quality of obturation in pulpectomy of primary molars.

Methods: Seventy two maxillary primary molars were divided into three groups: Group I (Kedo-S), Group II (M Pro Pedo) Group III (ProTaper Gold) then each group was subdivided into two subgroups (A, B), subgroups IA, IIA, IIIA assessing cleaning efficacy and instrumentation time, subgroups IB, IIB, IIIB assessed bacterial load and obturation quality. India ink was injected into palatal canals before instrumentation, then teeth were decalcified, dehydrated and cleared, the post-instrumentation traces of ink were evaluated using stereomicroscope and teeth were scored according to the India ink remaining in each third of the canal separately to evaluate cleaning efficacy. A digital chronometer measured total active instrumentation time. Teeth in subgroups IB, IIB, IIIB were immersed in E. Faecalis suspension and bacterial colonies were counted after instrumentation to assess bacterial load reduction. Palatal canals were obturated using Metapex and postoperative radiographs were taken to assess obturation quality.
Results: : No significant differences were found between groups in cleaning efficacy in coronal and middle thirds, PTG showed the best cleaning efficacy at the apical third. M Pro Pedo consumed the least instrumentation time followed by Kedo-S then PTG . No significant difference between different groups regarding bacterial load reduction. PTG showed the best obturation quality
Conclusion: M Pro Pedo is a promising file system