Root And Root Canal Morphology Of Mandibular First Premolars Of Chinese

Root canal therapy is a main method used in treatment of pulposis and periapical diseases.A thorough understanding of the internal and external morphologies of a tooth using accurate radiography is crucial to successful root canal treatment.In this study,mandibular first premolars of Chinese were selected as the research objects for exploring the root morphology,root canal morphology and associated influential factors.Meanwhile,advantages and disadvantages of CBCT in diagnosing the root and root canal morphology of mandibular first premolars were evaluated using micro-CT as “gold standard”.This work aims to provide reference for research on the anatomical structure of mandibular first premolars of Chinese,as well as for root canal treatment.The experimental results are provided as follows:Experiment 1:Research on root and root canal morphology in mandibular first premolars of ChineseAn exhaustive search was undertaken to identify associated literature and case reports of root and root canal morphology in mandibular first premolars of Chinese through domestic and foreign database,6201 of mandibular first premolars were selected.In the 1324 mandibular first premolars investigated for roots,cases of single roots accounted for 93.13%,cases of two roots accounted for 6.57%,cases of three roots accounted for 0.30%,and no case of four roots was found.In the 5745 mandibular first premolars investigated for root canals,cases of single root canals accounted for 75.25%,cases of multiple root canals accounted for 24.75%.Through Ⅴertucci classification of 4650 mandibular first premolars,it was found that cases of type Ⅰ accounted for 75.10%,cases of type Ⅱ accounted for 1.96%,cases of type Ⅲ accounted for 1.74%,cases of type Ⅳ accounted for 5.53%,cases of type Ⅴ accounted for 12.52%,cases of type Ⅵ accounted for 0.06%,cases of type Ⅶ accounted for 0.04%,cases of type Ⅷ accounted for 0.47%,cases of other root canal classification accounted for 2.58%.In 478 mandibular first premolars investigated for apical foramen,cases of single apical foramina accounted for 63.18%,cases of two apical foramina accounted for 25.73%,cases of three apical foramina accounted for 9.00%,cases of four apical foramina accounted for 2.09%.In 771 mandibular first premolars containing 946 apical foramina,cases of top apical foramina accounted for 56.55%,cases of lateral apical foramina accounted for 43.45%.Experiment 2:The root canal morphology in mandibular first premolars: a comparative evaluation of cone-beam computed tomography and micro-computed tomography136 mandibular first premolars in both micro-CT and CBCT were identified as type Ⅰ(n=104),type Ⅲ(n=5),type Ⅴ(n=20)and type Ⅸ(n=7),respectively.Out of the remaining 7 teeth,2 teeth were identified as type Ⅰ in micro-CT but misdiagnosed as type Ⅲ in CBCT,1 tooth was identified as type Ⅶ in micro-CT but misdiagnosed as type Ⅴ in CBCT and 4 teeth were identified as type Ⅸ(2 type 1-3 and 2 type 1-2-3)in microCT but misdiagnosed as type Ⅴ in CBCT.There was no significant difference between the two techniques in detecting the root canal configurations and the actual agreement was kappa=0.886.Experiment 3:A study of the root and root canal morphology of mandibular first premolars in a population from southwest China by using the Cone-bean computed tomographyIn the 2034 mandibular first premolars investigated for roots,cases of single roots accounted for 98.87%,cases of two roots accounted for 1.08%,cases of three roots accounted for 0.05%.In the 2034 mandibular first premolars investigated for root canals,cases of type Ⅰ accounted for 78.22%,cases of type Ⅱ accounted for 0.15%,cases of type Ⅲ accounted for 2.26%,cases of type Ⅳ accounted for 0.44%,cases of type Ⅴ accounted for 17.11%,cases of type Ⅵ accounted for 0.05%,cases of type Ⅶ accounted for less than 0.34%,cases of type Ⅸ accounted for 1.43%.In the perspective of sex,females had higher incidence of root canal configuration type Ⅰ and males had higher incidence of type Ⅴ and Ⅸ,both differences were of statistic significance;For other types of root canal configurations,there was no statistically significant difference in the incidence between female and male.In addition,there was no statistically significant difference in the incidence of the same root canal configuration between the right and left of the mandibular first premolars;It was known from the consistency comparison between right and left root canal configurations that the Kappa value was 0.665,suggesting that the right and left root canal configurations were of intermediate consistency.