Study On The Root And Root Canal Morphology Of Permanent Teeth Of Different Tooth Position

Objective:To investigate the root and root canal morphology of maxillary premolars of the elderly、mandibular anterior teeth and mandibular second molars of different age groups in PLA General Hospital,using cone-beam computed tomography(CBCT),and provide some substantial clinical value in guiding endodontic treatment.Method:All CBCT images of maxillary premolars、mandibular anterior teeth and mandibular second molars were selected according to inclusion and excluding criteria.And the results were statistically analyzed.Result:Experiment 1 studied on root and root canal morphology of maxillary first and second premolars in the elderly.57.9%of maxillary first premolars from male patients were single-rooted,and the remaining had two(40.3%)or three roots(1.8%).On the other hand,70.2%of female patients presented single-rooted teeth,whereas the remaining presented two-rooted teeth.Moreover,90.6%and 9.4%of maxillary second premolars from male patients were single-and two-rooted,respectively.And 98.4%of female patients presented single-rooted whereas the remaining presented two-rooted teeth.Marked differences in number of roots and gender were observed in both maxillary first and second premolars.Moreover,among the maxillary first premolars,60.9%,37.8%,and 1.3%were single-,two-,and three-rooted teeth,respectively,with no statistical relationship between number of roots and tooth position.Furthermore,among the maxillary second premolars,92.5%and 7.5%were single-and two-rooted teeth,respectively(no three-rooted teeth),with no statistical relationship between number of roots and tooth position.In addition,some special morphologies,such as 2-1-2-1,4-4,1-3 and 2-1-2-1-2,were noted in maxillary first premolars.Experiment 2 studied on root and root canal morphology of mandibular anterior teeth.All the mandibular central incisors and lateral incisors were single-rooted,and 1.65%of canines had two roots.19.14%of mandibular central incisors,33.20%of lateral incisors,12.37%of canines had multiple root canals.The rate of double root canals of mandibular incisors between 51 and 60 years old was the highest.The higher the age after 30,the higher the rate of multi-rooted canals of mandibular incisors.The highest frequency of symmetry of root canals was in mandibular lateral incisors(91.67%).Vertucci type Ⅰ(1-1)canal morphologies was most common in mandibular anterior teeth,the second was type Ⅱ(2-1).All types except Ⅷ(3-3)were showed and there was a special morphology showed as 2-1-2-1.Experiment 3 studied on root and root canal morphology of mandibular second molars.Single-、double-and three-rooted teeth were all observed in mandibular second molars,and C-shaped root in mandibular molars were 34.95%,C2 was the most common(70.31%)type.The incidence of males and females was 31.16%and 43.75%respectively.The frequency of symmetry of root canals was 86.49%.Conclusion:1、The root canal morphology of maxillary premolars is complex,and CBCT is helpful to observe the root and root canal morphology.2、The probability of multiple canals among mandibular anterior teeth is great.The multi-canals is most common in mandibular lateral incisors.The highest incidence of symmetry of root canals is also observed in mandibular lateral incisors.Using CBCT before treatment can reduce the occurrence of missing root canals.3、The variations of root canal morphology of mandibular second molar are great,C-shaped root is common.The incidence of C-shaped root of female is higher than male,and the incidence of symmetry of root canals is high.