| Objectives 1 Multi-slice spiral CT(MSCT)was used to analyze the relationship between the root of impacted mandibular wisdom tooth and the adjacent mandibular nerve canal.2Objective:to investigate the influencing factors of nerve injury after extraction of impacted mandibular third molars.Methods All the patients who were admitted to our hospital from October 2019 to December 2019 and were diagnosed as impacted wisdom teeth were examined by MSCT before wisdom tooth extraction.General clinical data such as age,sex were recorded,the types of impacted wisdom teeth,the relationship between mandibular nerve canal and root,the distance between mandibular nerve canal and root,and the injury of inferior alveolar nerve were recorded by post-processing technique.SPSS26 was used for non-parametric test,chi-square test and logistic regression analysis,P<0.05 differences were statistically significant.Results A total of 248 MSCT images(average age 29.98 years)were screened out.There were 136 MSCT images in male group,and the average distance between the mandibular neural tube and the adjacent root was 1.45(0.00,3.80)mm,and 112 MSCT images in female group,and the average distance between the mandibular neural tube and the adjacent root was 0.50(0.00,1.87)mm.There was no significant difference in the distance between the mandibular neural tube and the root between males and females(Z=-4.194,P<0.001).There were 172 mandibular neural tubes located at the buccal side of the root of the tooth with an average distance of 1.80(0.70,3.20)mm;there were 32 mandibular neural tubes located at the lingual side of the root of the tooth with an average distance of 0.00(0.00,1.42)mm;there were 44 mandibular neural tubes located below the root or at the root tip.0.00(0.00,0.00)mm;The shortest distance of the mandibular neural tube in the buccal side of the tooth root was greater than that of the mandibular neural tube in the lingual side of the tooth root and the apical group,and the difference was statistically significant(P<0.001).The average distance between root and mandibular neural tube was 0.85(0.00,2.70)mm,the average distance between root and mandibular neural tube was 1.80(1.30,2.30)mm,the average distance between root and mandibular neural tube was 1.80(1.30,2.30)mm,and the average distance between root and mandibular neural tube was1.80(1.30,2.30)mm.The average distance between the root and the mandibular neural tube was 0.85(0.00,1.70)mm,and the average distance between the root and the mandibular neural tube was 1.00(0.00,2.60)mm for 100 horizontally impacted wisdom teeth.The average distance between root and mandibular neural tube of other types of impacted wisdom teeth was 2.30(0.00,9.85)mm.The results showed that the distance between root and mandibular neural tube of horizontal impacted wisdom teeth was smaller than that of vertical impacted wisdom teeth(P=0.018).There were 56 low impacted wisdom teeth,and the average distance between root and mandibular neural tube was 0.00(0.00,1.40)mm,132 middle impacted wisdom teeth,and the average distance between root and mandibular neural tube was 1.30(0.00,2.70)mm,and 60 high impacted wisdom teeth.The mean distance between root and mandibular neural tube was 0.70(1.00,4.00)mm.The results showed that the distance between root and mandibular neural tube of low impacted wisdom teeth was less than that of middle impacted and high impacted group(P<0.001).There were 18 patients with transient nerve injury.There were 13 males and 5 females,and there was no significant difference between genders(χ~2=0.308,P=0.579).There were 4cases of meso-middle impacted,1 case of distal impacted,12 cases of horizontal impacted,1 case of other types,6 cases of low impacted,9 cases of middle impacted,and 3 cases of high impacted wisdom teeth.There was no statistical significance between different types of impacted wisdom teeth and nerve injury after surgery(χ~2 impacted type 1=5.555,P impacted type 1=0.180;χ~2=0.591,P=0.763).A total of 92 mandibular neural tubes were in contact with adjacent tooth roots,and 156 were not.There was a significant correlation between the contact between mandibular neural tube and impacted wisdom tooth root and the occurrence of nerve injury(χ~2=17.781,P<0.001).Four mandibular neural tubes were located in the buccal side of the impacted wisdom teeth,six were located in the lingual side,and 10 were located in the root tip OR below the impacted wisdom teeth.Results showed that only mandibular neural tubes were located in the lingual side of the impacted wisdom teeth root(P=0.03,OR value was 0.142,95%confidence interval was 0.024-0.83).Conclusions 1 Among the different types of impacted wisdom teeth,female,horizontal and low impacted wisdom teeth had the closest root to the adjacent mandibular canal.2 In the relationship between the mandibular nerve canal and impacted wisdom teeth,the mandibular nerve canal is located on the buccal side of the adjacent root.3 Nerve injury is more likely to occur when the mandibular canal is in contact with the root of impacted wisdom tooth than when it is not.4 The location of the mandibular nerve canal on the lingual side of the root of impacted wisdom tooth is a protective factor for the occurrence of nerve injury.Figure10;Table13;Reference 89... |
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