Correlation Analysis Of Maxillary Molars Inclination With Impacted Position And Growth Direction Of Maxillary Third Molars

Objective:Based on the results of Cone-beam computed tomography（CBCT）before orthodontic treatment in Angle class I homogenous patients,the mesio-distal inclination of maxillary molars was investigated and grouped and analyzed to explore the maxillary molars.Correlation between inclination and impacted depth,impacted angle and growth direction of maxillary third molars in order to provide reference for orthodontic clinical diagnosis and treatment.Methods:Cone-beam computed tomography（CBCT）data of 67 patients（40females and 27 males,with an average age of 23.24 years）before orthodontic treatment were collected.According to the impacted depth of the maxillary third molar,they were divided into three groups:normal eruption group,middle impacted group and low impacted group;Using the palatal plane as the reference plane,the mesio-distal inclination of the maxillary molars was measured,and the measurement data were statistically analyzed.The correlation analysis between the inclination angle of the maxillary molar and the impacted depth,impacted angle and growth direction of the maxillary third molar was carried out respectively.SPSS 25.0 software was used for statistical analysis,and the data conforming to the normal distribution were expressed in the form of x^—±s.The differences of different genders in the inclination of maxillary molars,the impacted depth of the third molars,the impacted angle and the growth direction of patients were determined by independent samples t test.The difference of maxillary molars inclination among normal eruption group,the median impacted group and the low impacted group was compared using ANOVA and SNK-q for post-hoc test.The numerical difference of maxillary molars inclination between the mesial and distal groups was compared using independent samples t test.Finally,Pearson was used to analyze the correlation between the maxillary molar inclination and the impacted depth,impacted angle and growth directionof the maxillary third molars（P<0.05 means the difference is statistically significant）Results:1.There was no significant difference in the maxillary molar inclination,the impacted angle of the maxillary third molar,and the impacted depth of the maxillary third molar between different gender groups（P>0.05）;2.When the impacted depth and impacted direction of the maxillary third molar were different,there were significant differences in the inclination of the maxillary first molar and the second molar（P<0.05）;3.The inclination of the maxillary first molar and the second molar was significantly positively correlated with the impacted depth of the third molar（P<0.05）,but not significantly correlated with the growth direction of the third molar（P>0.05）.The maxillary first molar was inclined There was a significant positive correlation between the angle of the third molar and the impacted angle of the third molar（P<0.05）.Conclusion:1.The lower the impaction of the third molar,the more the distal inclination of the maxillary molar;The more mesial the impacted direction of the third molar,the more distally inclined the maxillary first molar.2.The impaction depth and angle of the third molar should be considered when evaluating the influencing factors of the compensatory change of maxillary molar inclination in clinic.The influence caused by the change of maxillary molar inclination should also be considered,when estimating whether the maxillary third molar can erupt smoothly.