CBCT Study On Root And Root Canal Morphology Of Maxillary And Mandibular Second Permanent Molars In Guangfu Population In Lingnan Area

ObjectiveTo observe and statistics the root and root canal morphology of maxillary and mandibular second permanent molars in Guangfu population of Lingnan area by cone beam computed tomography(CBCT)5 so as to provide an anatomical basis for improving the root canal treatment,also provides a reference for anthropologists to understand the morphological characteristics of teeth in Guangfu people.Materials and methodsThe CBCT data of Guangfu population patients in Zhaoqing stomatological hospital were collected.1220 maxillary second permanent molars and 1279 mandibular second permanent molars with complete crown and root development,no dental pulp and periodontal disease,and without any treatment were selected as the study objects.The root and root canal morphology were observed and statistically analyzed,and the detection rate of each root and root canal morphology in different genders and ages was compared and analyzed,as well as the bilateral symmetry rate,through the Galileos CBCT equipment produced by SIRONA company in Germany.The data have been tested by standard consistency and analyzed by SPSS 22.0 statistical software.ResultAmong 1220 maxillary second permanent molars,there were 26 four roots type(2.13%),709 three roots type(58.12%),417 double roots type(34.18%)5 and 68 single root type(5.57%).Among double roots type,109 were proximal and distal buccal root fusion type(26.14%),106 were proximal buccal root palatal root fusion type(25.42%),202 were distal buccal root palatal root fusion type(48.44%).There was no significant difference in the detection rate of root types between different genders and age groups(P>0.05).The root canal morphology of each root of four roots type were all type Ⅰ(1-1),so are the palatal and distal buccal roots of three roots type.The main type of root canal morphology of proximal buccal root of three roots type was type Ⅰ(1-1)(78.84%),which was higher in females than in males(P<0.01),and that in the elderly than in the young(P<0.05).The root canal morphology of three fused roots of double roots type was significantly different(P<0.01).The most common root canal morphology of single root type was type(3-3),accounting for 63.25%.Bilateral symmetry rates of the root and root canal of maxillary second permanent molars were 75.86%and 73.64%,which both were no significant difference between different genders and age groups(P>0.05).Among 1279 mandibular second permanent molars,there were 3 three roots type(0.23%),731 double roots type(57.16%),420 C-Shaped root type(32.84%),and 125 conical fusion root type(9.77%).The detection rate of double roots type in males was higher than that in females(P<0.05),and that in older females was higher than that in younger females(P<0.01).The detection rate of C-Shaped root type in females was higher than that in males(P<0.05),and that in younger females was higher than that in older females(P<0.01).The root canal morphology of mesial root of the double roots type was type IV(2-2)38.58%,type Ⅱ(2-1)28.73%and type Ⅰ(1-1)22.98%,while type Ⅰ(1-1)was the main root canal morphology of distal root,accounting for 81.67%.The continuity of the upper 1/3 of the C-shaped root canal morphology was higher,the more it moved to the apical direction,the worse the continuity was.The C-shaped root canal morphology was significantly different in root canal orifice,middle part and apex(P<0.01).The continuity of the same level of C-shaped root canal morphology was worse with the increase of ageand,and the detection rate of root canal morphology in different parts of the root canal was also significantly different in different age groups(P<0.05).The root canal morphology of conical fusion root was C-shaped root canal type 62.40%,multiple root canal type 20%and single root canal type 17.60%.Bilateral symmetry rates of the root and root canal symmetry rates of mandibular second permanent molars were 68.10%and 62.93%,which both were higher in males than that in females(P<0.05),so both were higher in older females than that in younger females(P<0.05).ConclusionRoot and root canal morphology of maxillary and mandibular second permanent molars in Guangfu population in Lingnan area are complex and diverse,which was different from the data of 47 similar studies at home and abroad in recent 10 years,and also has certain morphological characteristics and rules.1.Three roots type is the most common type of the maxillary second permanent molars,and the root canal morphology of proximal buccal root is mainly but not all single root canal.Double roots type is the most common type of the mandibular second permanent molars,and there are many root canal moiphology in mesial root while distal root was mainly but not all single root canal.In the above mentioned roots,females are more inclined to single root canal than males.2.The fusion roots of maxillary and mandibular second permanent molar accounted for 39.75%and 42.61%,both of which are higher than that of most countries and regions at home and abroad.There are many root canal morphology and significant differences among all kinds of fusion roots,generally,the detection rate of single root canal is low,and there is no matching rule between root canal morphology and root morphology3.The detection rate of C-shaped root canal of mandibular second permanent molar was 38.94%.C-shaped root and C-shaped root canal are mostly found in young females.The continuity of C-shaped root canal morphology decreased with the downward movement of root canal level and the increase of age.4.The bilateral symmetry rate of root and root canal morphology of mandibular second permanent molar is lower than that of maxillary second permanent molar.The higher the detection rate of fusion root and C-shaped root canal,the lower the bilateral symmetry rate.