Measurement Of Cortical Bone Thickness In The Maxillary Posterior Region Of Orthodontic Patients With Mild Chronic Periodontitis By Using CBCT

Object:CBCT imaging data were used to study the cortical thickness of the alveolar bone in the different parts of the posterior maxillary posterior teeth area for the adult mean angle orthodontic patients who had entered the stationary phase after periodontal treatment.This provides a reference for the design of orthodontic orthodontics and the selection of implant anchorage sites.Method:This study selected patients who came to the Department of Orthodontics from the Stomatological Hospital of Nanchang University from July 2015 to December2017.Screening age between 18 and 30 years old and cephalometric measurement of patients with 27.3°<GoGn-SN<37.7 °,0.7°?ANB ?4.7°,diagnosed as mild chronic periodontitis by a dental laboratory in our hospital Twenty patients(10 males and 10 females)were included in the experimental group and 20 patients(10 males and 10 females)with periodontal health as the control group.The CBCT images were taken according to uniform standards and DICOM data were obtained.UR and UL are used to represent the right and left regions of the maxilla,respectively,45 represents the first and second premolar interproximal regions,56 represents the second premolar,the first molar interdental region,and 67 represents the first molar,the first In the interdental area of the two molars,B and L represent the buccal and lingual sides of the alveolar bone,and 5mm,7mm,and 9mm represent three levels of the measured height respectively.This experiment used InvivoDental 5.1 analysis software to perform three-dimensional reconstruction.After adjusting the head position,the alveolar bone and cortical bone of the posterior maxilla was measured.The study area included UR45,UR56,UR67,UL45,UL56,and UL67.5mm,7mm,9mm)Buccal lingual alveolar bone cortical thickness.SPSS 19.0 statistical software was used for data entry and analysis.An independent sample t-test was performed on the cortical thickness of the same site(the same height level,the same tooth position,and the same bone surface)in the experimental group and the control group.A paired t-test was performed on the buccal and lingual cortical bone thickness at the same level.One-way analysis of variance(LSD)was used to compare the levels of different heights of the same tooth site in the experimental group(5,7,9 mm)and different tooth levels at the same height level.Differences in bony and lingual cortical bone thickness.Result:(1)Comparison between the experimental group and the control group: In the three height planes connecting the neighboring two enamel cementum boundaries,5mm,7mm,and 9mm,the measurement values of the buccal and lingual cortical bone thickness in the control group were all greater than The experimental group,and the data between the two groups were statistically significant(p<0.05,viewing the Table 1 for details).(2)Comparison within experimental group:1.Comparison of cortical bone thickness at the same buccal and lingual alveolar bone: Except for UL67,the thickness of buccal cortical bone was greater than that of lingual cortical bone,and the difference was significant(p<0.05).The differences of other sites were not statistically significant.(p>0.05,viewing the Table 2-4 for details).2.Comparison of buccal and lingual cortical bone thickness at different heights of the same measurement: 45 cortical bone thickness of alveolar bone> 56 cortical bone thickness of alveolar bone > 67 cortical bone thickness of alveolar bone at 5mm,7mm and 9mm.The regularity on the height level plane was consistent with that on the lingual and buccal sides,but the difference was not statistically significant(p>0.05,viewing the Table 5-6 for details).3.Comparison of buccal and lingual bone cortical thickness at different measurement heights of the same tooth: The lingual cortical bone thickness at the buccal side shows that 9mm >7mm >5mm.The difference was statistically significant(p<0.05);While the buccal side shows that UL45,7mm cortical bone thickness> 9mm cortical thickness> 5mm,and UL56 shows 7mm cortical bone thickness>9mm > 5mm,the difference was not statistically significant(p>0.05).The rest of the teeth shows that thickness of bone cortical thickness 9mm >7mm >5mm.The difference wasstatistically significant(p<0.05,viewing the Table 7-8 for details).Conclusion:1.In patients with mild chronic periodontitis,the thickness of the posterior maxillary and lingual cortex is thinner than that of healthy periodontitis,and the absorption of periodontal tissue is more likely to occur when treated with orthodontic force.Therefore,light force should be used in orthodontic treatment of this kind of patients.Control torque to avoid bone fenestration and dehiscence.2.The greater the thickness of the cortex is in the vertical direction,the thinner the thickness of the cortical is in the lingual and the sagittal direction of the lingual cortex.Therefore,the microscrew anchorage is used in the above part,and the thickness of the cortex is thinner in the sagittal direction.The implantation site should be far away from the enamel cementum boundary and select the proximal middle region of dentition to obtain a large bone cortex retention.