The Study On The Movement Of The Maxillary Teeth Penetrated To The Maxillary Sinus Floor With CBCT

Objective: The aims of the present study were to analyse the movement statusand the root resorption of the maxillary teeth incident to orthodontics, which the teethwere penetrated to the floor of the maxillary sinus, then identify if the patients couldaccepted orthodontics.Methods:19patients (11men,8women, mean age,16.3years) with teeth rootpenetrated to the maxillary sinus scanned with cone beam computed tomography(CBCT) before and after orthodontics were selected. With the help of Invivo software,the plane was defined as A, which through the right and left orbitale and the rightporion. And the plane was defined as C, which through the right and left orbitale andperpendicular to the A plane. The plane was defined as S, which passing throughnasion (N) and perpendicular to the A plane and C plane. Distance between each roottips and the C plane were measured. Distance between the middle of the mesio-marginal ridge and the C plane were investigated. Angle between each root tips andthe mesio-marginal ridge and the C plane projected on the S plane were measured.All of the measurements were taken in the teeth penetrating to the sinus left and rightside before and after orthodontics. The CS Imaging software was used to observe therelation between the sinus floor and the teeth roots and the roots resorption. Thepaired t test and Wilcoxon signed-rank test was used to analysis the measurements.Results:1. On the CBCT images,89.47%of the mesio buccle root,92.11%of the distalbuccal root and97.37%of the palatine root showed contact with the floor of themaxillary sinus. Furthermore,15.79%of the mesio buccle root,10.53%of the distalbuccal root and39.47%of the palatine root showed classification Ⅳ.2. The distance between nasion and A plane was not significant differences in before and after orthodontics (P>0.05). The distance between nasion and C plane wasnot significant differences in before and after orthodontics too (P>0.05).3. The distance between each root tips and the C plane was significantdifferences before and after orthodontics. The distance between the middle of themesio-marginal ridges and the C plane was significant differences before and afterorthodontics too (P<0.05).4. The angle between each root tips and the middle of the mesio-marginal ridgeand the C plane projected on the S plane was significant differences before and afterorthodontics (P<0.05).5. On the CBCT images,7.89%of the teeth showed no resorption, whereas73.68%and18.42%showed mild resorption and moderate resorpption, respectively.Severe resorption and extreme resorption were not found.Conclusion：1. the palatine root has more closer relationship with the maxillary sinus floorthan the mesio buckle root and distal buccal root.2. The position of N was not significantly change before and after orthodontics.3. The position of teeth root tips and the middle of the mesio-marginal ridge weresignificantly moved before and after orthodontics.4. The angle was significantly different before and after orthodontics.5. Most of the teeth roots show mild resorption, and Severe resorption andextreme resorption were not found.