Classification Of Osseous Housing And Incidence Of Labial Bone Perforation For Virtual Implant Surgery By CBCT In The Edentulous Maxillary

Objective:This cone beam computed tomography(CBCT)was used to measured and analysed the related anatomy of edentulous maxillary alveolar ridge by unified measurement.The aim of this study was to classify alveolar ridge of the maxillary anterior missing teeth,was to investigate the incidence of fenestration and associated risk factors with virtual placement of an implant in the maxillary missing teeth region.Methods and materials:85 adults were screened who missing single tooth in maxillary anterior region according to the defied inclusive criterion from Fujian Medical University Union Hospital.They divided into two groups(male 55,female30);three groups(young 34,middle-aged 37,older-aged 14);six groups(right center incisor 16,right lateral incisor 15,right canines 8,left center incisor 26,left lateral incisor 16,left canines 4).Acquire the image by applicating of Koda CBCT imaging system and combining with CS 3D imaging V3.Measured the width of the residual crest alveolar bone(LP),the height of the area lack of alveolar bone resorption(LL’,PP’),and classify alveolar rigde.Root-form implants(3.3mm*10mm and 3.3mm*12mm)were placed virtually in the edentulous space following the axis of the ipsilateral crown.Buccolingually,the implants were placed in the ideal prosthetic cingulum position.Measured the angulation of the alveolar bone with reference to the implants(∠LR,∠PR,∠IR),the difference between them △=∠LP-∠IR,the thickness of the alveolar bone that is 10 mm and 12 mm the top of implants in the sagittal plane,the thickness of the concavity depth of the alveolar ridge.The incidence of fenestration were recorded.The data were analyzed and compared by SPSS 19.0.P<0.05 for the difference was statistically significant.Results:Results in 85 adult patients:(1)The frequency distribution of the alveolar bone morphology of the maxillary anterior missing teeth indicated that,of the 85 samples,2.4%,30.6%,9.4%,15.2%,27.1%,15.3% were classified as Class Ⅰa,Ⅰb,Ⅱa,Ⅱb,Ⅲ and Ⅳ,respectively.(2)The statistically significant differences(P<0.05)between each specific tooth type and the classification.(3)There was significant differences(P<0.05)between the concavity thickness of the alveolar ridge.(4)The overall probability of labial bone perforation was 56.5%,which presented statistically significant differences(P<0.05)in each specific tooth type and the alveolar bone classification.(5)The discrepancy between the ∠ LP and ∠ IR was statistically significantly larger in the fenestration sites than in the nonfenestration sites.Conclusions:Within the limitations of this study: the long axes of the maxillary bone in the tooth deficiency tend to palate;the height and width of residual alveolar ridge will reduce obviously after teeth missing;the most classification of alveolar bone isⅠtype,the least is Ⅲ type;and it can be concluded that the occurrence of labial bone perforation is common;labial bone perforation is found in Ⅱ type and lateral incisor.When a clinician performs implants in the anterior esthetic zone,they should be aware that the specific tooth type,the alveolar bone classification,and morphologic features of concavity are associated with a risk of experiencing labial bone perforation.