| Objective: The correlation between maxillary sinus volume and root vertical movement before and after orthodontics in patients with different sagittal bone facets at different per capita angles was compared using cone-beam computed tomography(CBCT),and the contact relationship between the roots of maxillary posterior teeth and the floor of the maxillary sinus was evaluated to investigate the change of periapical bone height before and after orthodontic treatment of maxillary posterior teeth with apical protrusion into the maxillary sinus and to provide a reference for orthodontic clinic.Methods: According to the exclusion and inclusion criteria,adult patients attending the Department of Orthodontics of the Second Hospital of Dalian Medical University,from December 2019 to June 2023 were selected.Patients with homogeneous angles according to FH-MP angular cephalometric measurements were selected and divided into three groups according to the ANB angular cephalometric measurements: skeletal class I group,skeletal class II group and skeletal class III group.All patients underwent CBCT before and after orthodontic treatment.CBCT images before and after orthodontic treatment were reconstructed using Invivo Dental 5.0 software,and the maxillary sinus volume,the distance between the roots of the posterior maxillary teeth and the palatal plane.,the height of the periapical bone protruding into the maxillary sinus and the ratio of the posterior root of each maxilla teeth to the floor of the sinus were measured.All measurements were statistically analyzed using SPSS Statistics 26.0 to compare the variability of maxillary sinus volume and the distance from the tip of each root to the plane of the palate in maxillary posterior teeth groups with root tips of skeletal classes I,II and III,the change in periapical bone height before and after orthodontic treatment,and to analyze the relationship between maxillary sinus volume and vertical root movement before and after orthodontic treatment.Results:1.There was a significant positive correlation(P<0.05)between the amount of movement of the distal mesiobuccal roots of the maxillary second molars and the change in maxillary sinus size before and after orthodontic treatment in osseous Class II patients.The greater the distance the distal mesiobuccal roots of the maxillary second molars moved vertically toward the palatal plane,i.e.,the more the distal mesiobuccal roots of the maxillary second molars were depressed,the more the volume of the maxillary sinus increased.There was no significant correlation between the remaining apical orthodontic anterior and posterior movements and maxillary sinus volume(P>0.05).2.The difference in cavity volume between the two sexes was statistically significant(P<0.05),with a mean cavity volume of 25334.40±7064.390 mm~3 in males and 16161.88±5680.27 mm~3 in females,In addition,the mean cavity volume was significantly larger in males than females,and there were no significant differences(P>0.05)in the distance of the tip of the root of each posterior maxillary tooth from the palatal plane between males and females.3.There was no statistically significant difference in maxillary sinus volume and the distance of each root tip of the maxillary posterior teeth from the palatal plane between different sagittal bone facial types and between the left and right sides.4.A total of 59.61% of the roots in all samples were in contact with the floor of the maxillary sinus,with the largest proportion of the maxillary first molar distal mesiobuccal root in contact with the floor of the maxillary sinus(78.33%),followed by the maxillary second molar proximal mesiobuccal root(75.00%)and the maxillary second molar distal mesiobuccal root(75.00%).In addition,the tooth root with the highest percentage of access to the maxillary sinus was the palatal root of the maxillary first molar(33.33%),followed by the distal mesiobuccal root of the maxillary first molar(30.00%)and the proximal mesiobuccal root of the maxillary first molar(20.00%).5.When the root tip protruded into the sinus,i.e.the root tip protruded into the floor of the jaw,and the length of the protrusion was less than or equal to one third of the root length,the difference between the distance of the lowest bone point around the root tip from the palatal plane before and after orthodontic treatment was not statistically significant(p>0.05).Conclusions:1.In patients with skeletal Class II with an adult per capita angle,the greater the vertical movement of the distal mesiobuccal root of the maxillary second molar toward the palatal plane,i.e.,the more the distal mesiobuccal root of the maxillary second molar was depressed,the greater the increase in maxillary sinus volume;in patients with skeletal Class I and skeletal Class III,the vertical movement of the posterior maxillary teeth did not correlate with maxillary sinus volume.2.The mean maxillary sinus volume was significantly greater in males than in females,and there was no significant difference between the volumes of the left and right maxillary sinuses.3.The palatal root of the maxillary first molar was most closely related to the floor of the maxillary sinus,followed by the distal mesiobuccal root of the maxillary first molar and the proximal mesiobuccal root of the maxillary first molar.4.When the root tip protruded into the sinus cavity and the length of the protruding root was less than or equal to one-third of its total length,the difference in the change of bone tissue around the root tip before and after orthodontics was not statistically significant. |
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