A Clinical Study On The Influence Of Maxillary Sinus Floor On Orthodontic Teeth Movement

Objective:To explore the movement of upper first molar in close relationship with the maxillary sinus under orthodontic loading,so that to clear the influence of the maxillary sinus on orthodontic tooth movement,which is of great significance for treatment planning and avoid complications.Method:Orthodontic patients underwent fixed orthodontic treatment with the maxillary second premolars extracted were selected for the study.The anatomical relationship between the maxillary sinus and the roots of upper first molar was observed according to the CBCT taken before treatment.A total of 20 upper first molars which had at least one root entered the maxillary sinus floor for each molar were selected as the experimental group.Other 15 maxillary first molars with no roots contact with the maxillary sinus floors were selected as the control group.After regular alignment of the upper and lower dentition,0.019×0.025 inch stainless steel wires were placed for 1 month and it was recorded as T0.Extraction gap were closed using 0.012 inch nickel-titanium spring with 200 g force.The patient was reviewed every 4 weeks,and the value of the nickel-titanium tension spring was measured.The force was continued for 20 weeks and recorded as T1.All patients underwent CBCT in T0 and T1,respectively.The CBCT data was exported in a digital imaging and communications in medicine(DICOM)format,and the reconstruction of the jaw and teeth was performed using Mimics l 5.0 three-dimensional processing software.Re-set the coronal interface C,the sagittal interface S,and the horizontal interface H.Distance between the setting points and specific plane and the changes in the inclination of the tooth long axis were measured,the absorption of the roots were observed by three-dimensional registration.Statistical analysis was performed using SPSS22.0 statistical analysis software using paired sample t test,independent sample t test,and one-way ANOVA.Results:1.The crown and root of the maxillary first molar in the experimental group and the controgroup all moved in the near direction with orthodontics,and the horizontal distance to the C plane decreased,and the difference was significant before and after the orthodontics (P<0.05).2.The moving distance of the maxillary first molars were larger than the horizontal distance of the root.The difference of the crown and root movement distance of the same molar was statistically significant(P<0.05)..3.In the two groups,the difference between the crown and root movement of the maxillary first molar was greater than that of the control group.The angle of the proximal tilt of the experimental group was larger than that of the control group,but the difference was not statistically significant(P> 0.05).4.During the observation period,the apex of the maxillary first molars in the two groups had only mild damage,and there was no serious damage to the roots.Conclusion:1.The maxillary first molar that enters the maxillary sinus floor during the orthodontic movement can effectively move in the proximal direction during the orthodontic movement.2.The movement of the maxillary first molar is that the crown and the root move in the same direction,and movement of the crown is more than that of the root,and the inclined movement of the tooth towards the mesial direction occurs.3.The maxillary first molar that enters the maxillary sinus floor does not cause severe root resorption during orthodontic movement.