CBCT Evaluation Of Interadicular Space In The Molar Region Of Different Vertical Facial Patterns In Class Ⅲ Subjects

Objective: To compare and analyze the interadicular space between the distal of the first premolar and the mesial of the second molar region in adolescent class Ⅲ patients with different vertical facial patterns.Materials and Methods: 15 patients(7 males and 8 females)aged 12-16 years(mean 13.1 ± 1.2 years)with skeletal Class Ⅲ were selected from the Department of Orthodontics,Dalian Stomatological Hospital Affiliated to Dalian Medical University.Inclusion criteria: excluding the 3rd molars,no history of dental trauma,no congenital absence,no tooth abnormalities,no supernumerary teeth,no impacted teeth,no obvious crowding in the molar area,and complete CBCT data before and after treatment.The skeletal class Ⅲpatients were divided into three groups according to different vertical facial patterns(high angle n = 5,normal angle n = 5,low angle n = 5),All cases were scanned by CBCT(cone beam computed tomography)of Ka Vo company(USA).Using CS image analysis software,The interadicular distances at right and left sides between the distal of the first premolar and the mesial of the second molar were measured at three different height(3,6 and 9 mm)from the alveolar ridge.SPSS 25.0 statistical software was used to analyze all measurements,and 95% confidence interval was used to evaluate the reliability of the data.The differences of interadicular spaces between low angle,normal angle and high angle groups were tested for normality and homogeneity of variance.One way ANOVA performed when the data is normally distributed and homogeneity of variance were met.Kruskal Wallis test was used when the data is abnormally distributed and homogeneity of variance was not met.Multiple comparisons were analyzed by LSD test.Statistical significance was considered at P < 0.05.Remarkable Statistical significance was considered when p < 0.01.Result: 1.The interadicular spaces of low angle,average angle and high angle groups were 1.22-3.74 mm,1.36-3.67 mm and 1.55-3.88 mm,respectively.2. The interadicular space between the maxillary 1st and 2nd molars at 3 mm from the alveolar ridge in the low angle group was significantly larger than that in the normal angle group(P < 0.05).The interadicular space between the second premolar and the first molar was the largest in all groups.There was no significant difference in the interadicular spaces between the other measured teeth of different vertical facial patterns(P > 0.05).3.The interadicular spaces between the maxillary 1st and 2nd molars at 6 mm from the alveolar ridge showed a significant difference between males and females(P < 0.05).Conclusion: 1.The interadicular space of the maxillary 1st and 2nd molars at 3mm from the alveolar ridge in the low angle group were significantly greater than those in the normal angle group.2.The interadicular space between the maxillary 1st and 2nd molars at 6 mm from the alveolar ridge was different between males and females.3.There was no statistical significance in the interadicular spaces between the other measured teeth of different vertical facial patterns.The results of this study showed that the interadicular space between the maxillary 2nd premolar and 1st molar was the largest in all groups,which suggested that in class Ⅲ patients with different vertical facial patterns,the safest region to insert miniscrwes in the maxillary molar region,if more anchorage is needed,is between the maxillary 2nd premolar and 1st molar.