Radicular Dentin Remaining, Risk of Perforation and Canal Transportation in Manual Versus Rotary Instrumentation in Primary Molars

Background: Root canal preparation techniques using manual instruments have found to be time-consuming and may lead to iatrogenic errors such as ledging, zipping, canal transportation, and apical blockage. To overcome this, much attention has been directed toward root canal preparation using nickel-titanium (NiTi)-rotary instruments. The flexibility and the instrument design of NiTi-rotary files allow it to closely follow the original root canal path. Aim: This in vitro study aims to compare the amount of dentin removal in primary molars instrumented with hand versus rotary files and the root canal transportation and risk of perforation using cone beam computed tomography (CBCT). Materials and Method: ( 20 ) extracted discarded mandibular second primary molars were selected to contribute in the study, having minimal apical resorption with presence of at least two-third remaining root structure with absence of visual perforating resorption. The teeth included in the study were stored in water or saline till the experimental time. The extracted primary molars were divided into two groups of the study: Group I was prepared with rotary instrumentation using ProTaper Next (Dentsply, Switzerland) and Group II was prepared by manual instrumentation using K type files. All the root canals (n=40) were prepared up to size 35 using the step-back technique. The teeth were subjected to CBCT scans for the evaluation of thickness of radicular dentin remaining, risk of perforation and canal transportation before and after instrumentation in the two groups at three different locations (2, 4 and 7 mm from the apex) . Dentin removal was calculated by superimposing images using the InVivo 5.1 software. Data were statistically analyzed using independent samples t test.