A Comparative Study On 3D Reconstruction Of Cortex Density In Zygomatic Alveolar Ridge Of Adults And Teenagers

Objective:Cortex density in zygomatic alveolar ridge of adults and teenagers were measured by 3D reconstruction to disclose impacts of age,gender and layer on cortex density in zygomatic alveolar ridge.Research results can provide some references for mini screw planting in zygomatic alveolar ridge of orthodontic patients at different ages.Method:A total of 80 patients with maxillofacial spiral CT scan were selected in Qingdao municipal hospital.According to the patient's age,it was divided into groups of adults and adolescents.There were 40 cases in the adult group.Age 18?30 years old.There were 40 cases in the adolescent group,age 12?16 years old.Each group has 20 males and 20 females.Specific inclusion criteria:(1)diseases that can't affect bone metabolism.(2)taking drugs affect bone metabolism not for a long time.(3)without Craniofacial deformity,in a word,Basic facial symmetry.(4)withoutr the maxillary fracture or large defects.(5)all teeth in the posterior teeth of bilateral upper maxillary(except for the third molar)have been cued,no supernumerary teeth,no missing teeth.(6)no severe crowding.(7)no obvious bone absorption.(8)no obvious abrasion of teeth,no periapical disease in the measuring area.(9)the pitch curve of the upper jaw were normal.Input the scan data into the Simplant software in DICOM format.3D model was constructed with SimPlant.Six measuring planes,based on the reconstruction of total dental surface layer,were selected successively on the coronal sequence diagram of left maxillary posterior tooth area.Three horizontal lines were marked in the reconstructed image at 13mm,15mm and 17mm above the mesiobuccal top of the first molar in the left upper jaw.Cortex densities at zygomatic alveolar ridge in the intersection between these three lines and buccal bone were measured in 6 selected coronal layers.Using SPSS17.0 statistical analysis software to process data.A statistical analysis on measurement results was carried out.Results:1.Comparison of cortical bone density in the zygomatic alveolar ridge area between different gendersThere's no statistically significant difference between genders in term of cortex density in zygomatic alveolar ridge.2.The cortical bone density of zygomatic alveolar ridge in adultsThe cortical bone density of the zygomatic alveolar ridg of the adult group was(1067.69±228.71)HU?(1392.83 ± 205.90)HU.In addition to the 17mm height,the comparison found that the difference in cortical density between different layers at the same height was statistically significant,both of them were the highest in the third layer and the lowest in the sixth layer.3.The cortical bone density of zygomatic alveolar ridge in adolescentsThe cortical bone density of the zygomatic alveolar ridge of the adolescent group was(833.43±408.85)HU?(1147.00±309.02)HU.The comparison found that there was no statistically significant difference in cortical density between different layers at the same height.Except the third and forth layers of 15mm height,in all measurement heights the cortical bone density at different layers had the same distribution trend that the density of cortical bone gradually decreased from mesial to distal.4.Comparison of the cortical bone density in the zygomatic alveolar ridge area between the adult group and the adolescent groupThe comparison of 18 measurement sites in the zygomatic alveolar ridge area between the adult group and the adolescent group found that the difference was statistically significant.In addition to the sixth layer of 13mm height,there were significant difference in the remaining 17 measurement sites.Conclusions:1.Mini screw implanting is applicable to zygomatic alveolar ridge in both adults and teenagers viewed from bone density,adults have higher stability than adolescents.2.From the point of view of bone density,the optimal implanting position of adults lies between mesiobuccal root and distobuccal root of the first molar in the upper jaw,and the optimal implanting position of teenagers is between the second premolar and the first molar in the upper jaw.