The Relationship Between The Maxillary Posterior Teeth And The Maxillary Sinus Floor In Skeletal Class Ⅱ Patients With Different Vertical Facial Types

Objective The aim of this study was to evaluate the relationship between the maxillary posterior teeth and the maxillary sinus floor in skeletal Class Ⅱ patients with different vertical facial types by using cone-beam computed tomography(CBCT)Methods Cone-beam computed tomographic images of 61 patients were collected and divided into 3 types according to the vertical facial type.The distances and relationship between the maxillary posterior teeth and the maxillary sinus floor were recorded.Data were correlated with the vertical facial typeResults There was no significant difference in the distance from the maxillary posterior teeth to the maxillary sinus floor between the left and right sides and different sexes(P>0.05).The mesiobuccal roots of the maxillary second molar were closest to the maxillary sinus floor(0.18 ±1.41 mm),followed by the palatinal roots of the maxillary first molar(0.46 ± 1.75 mm)and the distobuccal roots of the maxillary second molar(0.66 ± 1.41 mm);The maxillary first premolars had the maximum distance to the maxillary sinus floor(4.63±2.29mm).The distance from the maxillary posterior teeth to the maxillary sinus floor was different in different vertical facial types(P<0.05).The measurement in the high angle group was lower than that in the low angle group Except the mesiobuccal roots of the second molar were dominated by type H-Ⅱ(43.44%),the frequency of type H-Ⅲ in other roots of the maxillary posterior teeth were higher(40%-89%).The frequency of type H-Ⅲ was different among patients with different vertical facial types,and the distribution in high angle group was significantly higher than that in low angle group.The horizontal relationship between the roots of maxillary molar and the maxillary sinus floor was dominated by type Ⅴ-Ⅲ(93.44%for the first molars and 80.33%for the second molars)Conclusion The vertical relationship between the maxillary sinus floor and the maxillary posterior teeth root is different according to the vertical facial type in skeletal Class Ⅱ patients.If vertical control is necessary in the orthodontic treatment of high angle patients,the limitation of maxillary sinus on molars should be considered and should not be depressed blindly.Using CBCT can accurately analyze the anatomical structure of the maxillary posterior region.