Influence Of Different Gutta-percha Cones On The Sealing Ability In Oval Canals

Objectives:The purpose of this study was to compare the sealing ability of continuous-wave condensation technique in oval canals, when using different gutta-percha cones, in order to provide experimental basis for clinical treatment.Methods:73single-rooted premolars which satisfied the definition of oval canals were selected for this study and were randomly divided into six test groups and one positive control group of10each and one negative control group of3. All teeth were prepared with ProTaper instruments to F2and were cleaned with2%sodium hypochlorite and17%EDTA using ultrasonic instrument. Teeth in both positive and negative control groups were not obturated. The continuous-wave condensation technique were used to fill the teeth in all test groups. The study consisted of three parts.The first part was to evaluate the sealing ability in oval canals when the gutta-percha cones were cut off different lengths. In group A, the gutta-percha cones were cut off0.5mm from the apex while in group B, the gutta-percha cones were cut off1.0mm. After obturation, the teeth were placed in1%methylene blue solution for one week to perform dye penetration tests. Then the teeth were made transparent so the apical microleakage could be measured by vernier calipers under a stereomicroscope. ANOVA and LSD tsets were used to analyze the microleakage lengths in different groups.The second part was aim to analyze the influence of AH-PLUS sealant on the sealing ability. AH-PLUS sealant was used while obturation in group C, but was not used in group D. The measurement and statistic tests were the same as in the first part.The third part was to analyze whether two different types of gutta-percha master cones have different influences on the sealing ability in oval canals. In group E, Protaper matched gutta-percha-points were used as the master cone while in group F,06taper gutta-percha-points were used. The measurement and statistic tests were the same as in the first part.Results:1.The microleakage lengths were shorter when the gutta-percha cones were cut off0.5mm from the apex than when the gutta-percha cones were cut off1.0mm (P<0.05). Thus the sealing ability of the former was better than the latter.2.The microleakage lengths were shorter when AH-PLUS sealant was used than when AH-PLUS sealant was not used (P<0.05). Thus the sealing ability of the former was better than the latter.3.The microleakage lengths were shorter when the Protaper matched gutta-percha-points were used as the master cone than when06taper gutta-percha-points were used (P<0.05). Thus the sealing ability of the former was better than the latter.Conclusions:1.When obdurating oval canals by continuous-wave condensation technique, the master cones which were cut off0.5mm from the apex would get a better sealing ability than the master cones which were cut off1.0mm.2.The AH-PLUS sealant could enhance the sealing ability in oval canals.3.For oval canals which were prepared by ProTaper instruments, using Protaper matched gutta-percha-points as the master cone could achieve better sealing ability than06taper gutta-percha-points.