Effectiveness of Rotary Endodontic Instruments on Smear Layer Removal in Root Canals of Primary Teeth: A Scanning Electron Microscopy Study.

AIM: The present SEM study was undertaken to evaluate the effect of root canal instrumentation using both manual and rotary files in the root canals of primary anterior teeth. STUDY DESIGN: Thirty freshly extracted primary maxillary incisors were divided into 3 groups of 10 teeth each. In Group I, root canals were instrumented with rotary NiTi files; in Group II, the root canals were instrumented using manual NiTi K files and; in Group III, manual instrumentation was done with stainless steel K files. Longitudinal sections were prepared and processed for observation under SEM at the coronal, middle and apical thirds. Scoring of smear layer was done according to Hulsmann and the data obtained was subjected to statistical analysis. RESULTS: Rotary files cleaned the coronal and middle thirds of root canals more effectively. Statistically there was no significant difference between the groups. Lowest score of 2.6 in the apical third of root canals was seen with hand NiTi files. CONCLUSION: Rotary instrumentation was as effective as manual instrumentation in removal of smear layer in the root canals of primary anterior teeth.

Microbiological assessment of root canals following use of rotary and manual instruments in primary molars.

AIM: To assess the microflora of root canals in primary molars following use of rotary NiTi files and conventional hand NiTi and stainless steel files. STUDY DESIGN: This randomized clinical trial consisted of a total of 60 first and second primary molars requiring root canal treatment, who were selected from children aged 5-9 years. Based on type of root canal instrumentation, the teeth were randomly assigned to three groups of twenty teeth each; Group A: Rotary NiTi files, Group B: Hand NiTi files and Group C: Hand stainless steel files. Following administration of local anesthesia, isolation with rubber dam was carried out. For the purpose of instrumentation and sampling, the palatal canal of maxillary molars and the distal canal of mandibular molars were selected. Prior to sampling, the orifices of other canals in these teeth were sealed, so as to prevent any contamination. Instrumentation was carried out in each group using respective instruments along with intermittent saline irrigation. Root canal samples were obtained both before and after instrumentation, using sterile absorbent paper points and transferred to a sterile vial with transport fluid. Serial dilutions were prepared and cultured on suitable agar media. Both aerobic and anaerobic microbial counts were made. Data obtained was subjected to statistical analysis using Wilcoxon signed rank test and one-way Analysis of variance. RESULTS: In all three groups, there was a significant reduction in both aerobic and anaerobic mean microbial count following root canal instrumentation. (p < 0.001). CONCLUSION: Rotary NiTi files were as efficient as conventional hand instruments in significantly reducing the root canal microflora.