Influence of Root Canal Instruments on Primary Molars' Canal Preparation

Objectives: To investigate the percentage of dentine thickness removed from root canal of primary molars after preparation using three instrumentation techniques. The time taken for canal preparation was also investigated.

Methods: Forty-five human primary molars were selected and randomly divided into 3 groups i.e. stainless steel hand instruments (K- Flexofile)(Dentsply Maillefer, Ballaigues, Switzerland), nickel-titanium hand instruments (NiTiFlex)(Dentsply Maillefer, Ballaigues, Switzerland) and nickel-titanium rotary instruments (Profile)(Dentsply Maillefer, Ballaigues, Switzerland). Only one root was chosen from each tooth. Pre-instrumentation radiograph for each specimen was taken with Vitapex™ as contrast medium using a special radiographic platform. Each group was prepared by one of the instrumentation techniques mentioned above. On completion of instrumentation, canal was again filled with Vitapex™ and post-instrumentation radiograph was then taken. Pre- and post-instrumentation images were traced from the radiographs. Measurement of dentine thickness removed was carried out by superimposition of the tracings using the image analyser.

Results: There is a significant difference in dentine thickness removed at the inner curve (p=0.043) between the stainless-steel hand and rotary groups, and for the outer curve (p=0.048) between the nickel-titanium hand instruments and rotary group (Kruskall-Wallis test). There is also significant difference (p=0.042) of the mean time taken for canal preparation between the stainless -steel hand instrumentation and rotary groups.

Conclusion: Instrumentation techniques affected the dentine thickness removed and the time taken for canal preparations.