Study On The Anatomic Structure Of Maxillary Sinus In Middle-aged And Elderly People With Edentulous Site In The Posterior Maxillary Based On CBCT

Objective In this retrospective study,we analyzed the CBCT imaging data of middle-aged and elderly patients with maxillary posterior tooth loss.By measuring the anatomical structures,including the morphology of the maxillary sinus wall,sinus width,thickness of the sinus lateral wall,and the PNR,we obtained the general characteristics of the above anatomical structures and explored its relationship with maxillary sinus floor elevation,in order to provide reference for clinical work.Methods The CBCT imaging data of 500 patients with at least one missing tooth except the first premolar in the maxillary posterior region were selected from the CBCT database of Ninth people’s Hospital affiliated to the Medical College of Shanghai Jiaotong University,with a total of 782 edentulous sites.According to the edentulous site,they were divided into three groups,which were P2 group(maxillary second premolar site),M1 group(maxillary first molar site)and M2 group(maxillary second molar site).The CBCT images were processed by Mimics Medical 20.0 software.The morphology of the maxillary sinus wall of each edentulous site in the coronal plane was observed and divided into five types:narrow tapered type,tapering type,ovoid type,flat type and irregular type.The incidence of each type was calculated,and the correlation between sex,age,edentulous site and the morphology of the maxillary sinus wall was analyzed by Spearman correlation test.60 cases were randomly selected from each of the three groups of edentulous sites.The sinus width and the thickness of the sinus lateral wall at 3mm,7mm,10mm and 13mm above the sinus floor were measured.One-way ANOVA was used for intra-group and inter-group comparison.At the same time,the height and angle of the PNR were measured and compared between groups by One-way ANOVA.All data were analyzed by SPSS 25.0 statistical software.Results 1.The incidence of each type in the edentulous sites was different among the three groups.On the whole,the narrow tapered type accounted for the least,only 3.71%,followed by irregular type,flat type,tapering type and ovoid type,accounting for 4.47%,5.37%,28.52%and 57.93%,respectively.There were no statistical correlation between age,sex,edentulous site and the morphology of the maxillary sinus wall(P>0.05).2.There was significant difference in the sinus width among the three groups(P<0.05).In the 3mm,the sinus width was the second molar,the first molar and the second premolar from large to small,while in the 7mm,10mm and 13mm,the first molar site was the largest and the second premolar site was the smallest.3.There was significant difference in the thickness of the sinus lateral wall among the three groups(P<0.05).At the same measuring height,the first molar site was the thickest and the second molar site was the thinnest In addition,the thickness of the sinus lateral wall in each group showed that it was the largest at 3 mm,the smallest at 7mm,and increased slowly at 10mm and 13mm,showing a concave upward curve.4.The incidence of the PNR was higher in the three groups,and there were significant differences in the height and angle among the three groups(P<0.05).The height and angle of the PNR at the second premolar site were the lowest,which were(7.75 ± 1.67)mm and(107.15± 17.46)°,respectively.Conclusion 1.The morphology of the maxillary sinus floor varies greatly,it must be determined by imaging examination,rather than judged by gender,age,or edentulous site when maxillary sinus floor elevation is performed in clinical practice.2.In most cases,the sinus width was the largest at the first molar site,while the second premolar and second molar sites were smaller.3.The thickness of the sinus lateral wall was the thinnest at the 7mm above the sinus floor and the thickest at 3mm.The first molar site was larger than the second premolar and second molar sites while at the same height.It has guiding significance for the design of bone window in lateral window sinus floor elevation.4.At the second premolar site,the PNR angle is the smallest and the distance from the sinus floor is the smallest.The risk of SMP during the maxillary sinus floor elevation is higher than that of the molar site,so more care should be taken in clinic.5.The results of this study are helpful for clinicians to be familiar with and master the anatomical characteristics of the maxillary sinus in middle-aged and elderly people with edentulous sites in the posterior maxillary,and guide them to choose a reasonable mode of operation so as to improve the success rate of operation.