A Study On The Root Canal Taper Of 33 Mandibular Second Premolars Of Chinese With Single-canal

Objective The aim of this study was to obtain young people mandibular second premolar root canal sections of the original taper value for clinical selection of suitable root canal instruments, and discuss its age-related changes.Methods The root canals of 33 extracted single-root mandibular second premolar were divide into two groups by age. 13-23 years of which as a youth group had 23 ,35-80 years as a middle-aged group had 10. Using micro CT, specimens respectively from the tip to the coronal scaned carried and obtainsd a number of root canal cross-section. Each root canal was divided into 3 - Apical 1 / 3, Middle third1 / 3 and Cannal orifice 1 / 3, Through 3D-DOCTOR Trial Version measured the mesio-distal and the bucco-lingual diameters corresponding to each section in the upper and lower root canal cross-section, calculated the three Corresponding root canal tapers. Comparison of two different directions of each root canal taper and the difference between horizontal taper in and between the two groups were made.Result1.23 mandibular second premolar teeth from ages 13-23 years which bucco-lingual diameters are greater than the distance from the mesio-distal's, but the more near the tip, the smaller the gap between the two tracks, the root canal's cross section tend to become more circular. The root canal tapers in bucco-lingually are greater than the mesio-distal's. The average taper of cervical, middle and apical third were 0.32,0.21,0.25 bucco-lingually and 0.06,0.08,0.07 mesio-distally. There was significant difference (P <0.05) between the bucco-lingual taper of three sections, while the mesio-distal direction changes in the taper was no difference (P> 0.05).2. 10 teeth in middle-aged group (35-80 years old),with age increase, the root canal diameter decrease while the root canal taper is a decreasing trend too. The elderly group showed apical foramen oval, the diameter between the bucco-lingual and mesio-distal difference decreases in the middle and apical 1 / 3, and the root canal cross-sectional shape often appears oblong changes elliptical shape. The average taper of cervical, middle and apical third were 0.09,0.18,0.34 bucco-lingually and 0.06,0.06,0.02 mesio-distally. There was significant difference (P <0.05) between the bucco-lingual taper of three sections, while the mesio-distal direction changes in the taper was no difference (P> 0.05). All directions, the level of taper root canal in different age groups showed no significant difference (P> 0.05).Conclusion23 mandibular second premolar teeth from ages 13-23 years1 The results showed that long oval canal in common in the mandibular second premolar. The bucco-lingual diameter of root canals were greater than the mesio-distal diameter, while the buccolingual taper was also far greater than mesio-distal taper. In root canal therapy should be near its mesio-distal diameter and taper as the reference for instrument choice;2 The root canal is not a continuous taper,the bucco-lingual taper changed significantly. The smallest is in the middle 1 / 3 of the root canal.The mesio- buccal taper,which is smaller than the bucco-lingual's ,but not very different, showing a continuous change in uniform.10 mandibular second premolar teeth from ages 35-80 years With age, the root canal diameter decrease, the root canal taper is also a decreasing trend; the root canal taper in some parts (such as bucco-lingual apical 1 / 3) have obviously difference compared with which in the youth group.