CBCT Measurement And Analysis Of Different Sagittal Orthodontic Aesthetic Regions

Objective: Orthodontic treatment aims at balance,stability and beauty.To achieve this goal,oral and maxillofacial soft and hard tissues need to coordinate with each other.The differences of alveolar bone morphology and lip soft tissue morphology in aesthetic region(lower 1/3 anterior teeth area)in different sagittal bone facial types and their relationship with gender were studied by CBCT measurement and analysis.To explore the changes of alveolar bone shape and lip soft tissue shape in different sagittal bone facial patterns in aesthetic region,and to guide the diagnosis of Orthodontics and the formulation of orthodontic treatment programs.Methods: 200 patients(70 males and 130 females)were selected from the orthodontic Department of Shenyang Stomatological Hospital Hospital from 2014 to 2018.The age ranged from 15 to 35 years,with an average age of 17.29±5.65 years.According to sagittal Osteofacial type,the patients were divided into three groups: skeletal class ?(0 degree < ANB < 5 degree,80 cases);skeletal class II(ANB < 5 degree,60 cases);and skeletal class III(ANB < 0 degree,60 cases).According to gender,they were divided into two groups: male group(70 cases)and female group(130 cases).To exclude the influence of growth and development on soft tissue,200 patients over 15 years old were selected for soft tissue measurement.Anterior teeth were measured with 11 and 41 as reference planes,maxillary palate and mandibular planes as reference planes.DICOM data were obtained by CBCT.DICOM data were imported into INVIVO DENTAL 5 software for three-dimensional reconstruction.Palate and mandibular planes were used as reference planes,maximum sagittal sections of 11 and 41 were used as bone tissue measurement planes,and sagittal planes of midface were used as soft tissue.The height of alveolar bone in the apex of upper and lower incisors,the height of alveolar bone in the cheek and palate(lingual)sides of upper and lower incisors,the height of incisor-alveolar bone in upper and lower incisors,the width of buccal-palatal(lingual)cortex in the middle point between the apex of upper and lower incisors and enamel-dential boundary,the width of buccalpalatal(lingual)cortex in the apex of upper and lower incisors,and the root apex of upper and lower incisors and palatal(mandible)were measured.Bone cortex width between buccal and palatal sides at midpoint between planes;thickness of alveolar bone from upper and mandibular apex to buccal side;thickness of alveolar bone from upper and mandibular apex to palatal(lingual)side;total thickness of alveolar bone between buccal and palatal(lingual)sides at upper and mandibular apex;A-point lip thickness;upper lip protrusion lip thickness;B-point lip thickness;and lower lip protrusion lip thickness were measured.SPSS 21.0 software package was used to statistics the data,and normal distribution and homogeneity of variance test were carried out on the data of sagittal bone surface grouping.If the data conformed to normal distribution and homogeneity of variance,LSD method was used to compare the two data.The data with uneven variance were compared and analyzed by Dunnet T3 test.Independent sample ttest was used to analyze the measured data of sex grouping.P < 0.05 indicates that the difference has statistical significance.Result: According to sagittal bone surface type,the height of alveolar bone of upper incisor root cusp,palatal side of upper incisor and lower incisor-alveolar bone were lower than those of skeletal class II,and the height of upper incisor-alveolar bone,upper incisor-alveolar bone,upper incisor-upper incisor buccal alveolar bone and lower incisor root cusp were lower than those of skeletal class III and lower incisor-alveolar bone.The mandibular lingual alveolar bone height was the highest in skeletal class II and the smallest in skeletal class III,with statistical significance(P < 0.05);there was no statistical difference in alveolar bone width between different sagittal bone surface types.As for alveolar bone thickness,the maxillary palate and apical lip-palate-toalveolar bone thickness of skeletal class II was the largest,with statistical significance(P < 0.05);there was no statistical difference between sagittal bone surface types with different mandibular alveolar bone thickness.In soft tissue,There was no statistical difference in the measured values of lip thickness between the bony groups..The thickness of Ls-Ls' in skeletal class III was smaller than that in skeletal class II and skeletal class I,and the thickness of A-A' in skeletal class III was larger than that in skeletal class I and skeletal class II,with statistical significance(P < 0.05).Grouped by gender: between different genders,the height of the mandibular buccal and lingual alveolar bone and the height of the inferior incisor-alveolar bone,the width of the cortical bone between the buccal and lingual sides of the inferior incisor,the maxillary root tip to the buccal alveolar bone The thickness and the thickness of the maxillary root tip to the temporal alveolar bone,the thickness of the cortical bone between the apex of the inferior incision and the buccal lingual side at the midpoint of the mandibular plane,and the thickness of the labial lip of the upper lip,the male measurements are greater than the female measurements,both have Statistical significance(P<0.05);the buccallingual cortical width,the buccal-lingual cortical width,the total alveolar bone thickness and the A-point lip thickness between the apex of upper incisor and the midpoint of the enamel-cementum boundary,the middle point between the apex of lower incisor and the enamel-cementum boundary were larger in males than those in females,and there was a significant difference between them.There was statistical significance(P < 0.01);there was no statistical difference between men and women in other soft and hard tissue measurement items.Conclusion: CBCT measurements of alveolar bone morphology and lip thickness in different sagittal bone profiles and aesthetic orthodontic regions of different sexes showed that some measurement items had statistical significance in alveolar bone height,alveolar bone thickness and lip thickness.According to the differences of different types of individualization,the anatomical characteristics of soft and hard tissues in different sagittal bone profiles and aesthetic regions of different sexes were fully understood.Before treatment,patients' alveolar bone and soft tissue morphology should be fully assessed,anterior teeth torque should be preventively controlled,indications of extraction should be strictly defined,treatment risks should be avoided purposefully,and clinicians should make more systematic diagnosis for different types of patients and make personalized treatment plans to achieve better treatment effect.