Evaluation of the effect of root canal flaring on bacterial microleakage

Given controversies over the extent of root canal preparation and the importance of root canal preparation and flaring in microleakage and its effect on the preservation of teeth, the aim of this study was to evaluate the effect of the root canal flaring extent on bacterial microleakage in vitro. In this in vitro study 126 human single canal teeth were selected using simple sampling technique. After decoronation with a diamond disk, access cavities were prepared and the root canals were prepared with step-back technique up to file #30. Then the teeth were divided into three groups randomly for root canal flaring up to files #45, #55 #70 after the master apical file. After the preparation, the root canals were obturated with lateral condensation technique. To evaluate microleakage every 3 days Enterococcus faecalis solution was injected to the samples and microleakage was evaluated for 90 days by turbidity of the antiserum solution around the root. Data were analyzed with SPSS 20 using chi-squared test and survival analysis (α=0.05). The results showed that during the 90-day study period microleakage was significantly lower in group 2 compared to the other two groups (p value = 0.025 and p value = 0.036), and maximum survival rate was observed in this group. However, the survival analysis did not reveal any significant differences between group 1 and group 3 (p value = 0.717). The results showed that root canal preparation up to different file sizes affected microleakage and preparation up to file #55 resulted in the least microleakage.