Three-dimensional Measurement And Analysis Of Alveolar Bone Height And Root Surface Area In Periodontal Support Tissue

Objective: Simulating the process of periodontal support tissue destruction by surface modeling technology to observe the root surface area(RSA)distribution of each tooth types,to investigate the difference between attachment loss and RSA loss under specific conditions and evaluate the consistency of periodontal support capacity.Methods: We obtained 15 CBCT images,420 teeth were included.First,Mimics software was used to reconstructed the 3D models.Then import them respectively into Geomagic software for optimization.Finally,dividing the roots precisely to simulated 1mm~10mm periodontal support heights by Solidworks software.To measure root length and RSA,compare the differences of RSA at cervical 1/3,middle 1/3 and apical 1/3.Also we compare the percentages of bone loss height(Ph)and the percentages of RSA loss(Ps)at the same CRR and same attachment level to examine the consistency of the Ph and Ps results.Results: In incisors,canines and premolars teeth groups,RSA amount: cervical 1/3 > middle 1/3 > apical 1/3.In molars group,middle 1/3 > cervical 1/3 > apical 1/3.(P < 0.001).Except the upper molars,there was statistically significant differences in bone resorption(RL%)and actual RSA% loss at CRR levels of 1:1,5:4,3:2 and 2:1(P<0.001).And RL% is 0.71%~13.68% higher than RSA%.For upper molars,when CRR was less than 1:1 and greater than 2:1,the difference between RL% and RSA% was statistically significant(P<0.001),while when CRR was 5:4 and 3:2,there was no significant statistically difference between RL% and RSA%(P=0.734 or P=0.07).For incisor types and lower premolar types,the 95% confidence interval of the Ph-to-Ps difference was within the consistency limit value(-15%,15%).For other tooth types,the 95% confidence interval for the Ph-to-Ps difference was beyond the consistency limit value.Conclusions: For single tooth and fusion tooth types,RSA were concentrated in the cervical 1/3,and for multiple tooth types,RSA was concentrated in the middle 1/3.Multiple clinical parameters of Ph,Ps and CRR should be used to evaluate the prognosis of the affected teeth.The bone resorption height may lead to overestimate severity at the 1:1 CRR level and it may caused underestimation at the 2:1 CRR level for maxillary molars.For upper and lower incisors,lower canines and lower premolars,Ph and Ps changes are consistent.Oppositely,the other teeth types is inconsisitent.