Effects of apical stop integrity and different root canal preparation techniques on apical sealing ability in straight root canals

Objective:To investigate the effects of apical stop integrity and three different root canal preparation techniques on apical sealing ability in straight root canals. Methods:64 upper anterior extracted teeth with straight root canals were collected, 60 of them were randomly assigned to 6 groups(n=10) by 2×3 factorial design, GroupA1B1: stainless steel file conventional root canal preparation technique with apical stop; GroupA2B1: stainless steel file conventional root canal preparation technique without apical stop; GroupA1B2: Gate-Glidden drill coronal preflaring + stainless steel file conventional root canal preparation technique with apical stop; GroupA2B2: Gate-Glidden drill coronal preflaring + stainless steel file conventional root canal preparation technique without apical stop; Group A1B3: ProTaper for hand crown-down technique with apical stop; Group A2B3: ProTaper for hand crown-down technique without apical stop. The other 4 samples were divided into two groups, negative control group and positive control group. All the prepared canals were obturated with cold lateral condensation. In order to evaluate the apical sealing ability, apical microleakage length was measured by dye penetration. Results:Apical stop integrity and different root canal preparation techniques have effect on apical sealing ability in straight root canals. There were interaction between the two factors. Root canal preparation technique has obvious effects on it. Microleakage of group A1 was fewer than that of group A2(P0.05). Microleakage of group B1 was larger than that of group B3 (P0.05). Conclusion:Crown-down technique and integrity apical stop can increase apical sealing ability in straight root canals.