Relationship between tongue volume and dental arch and basal bone indicies in Cl I and Cl II patients by CBCT

Abstract

Introduction: Considering the importance of the effect related to the growth pattern of soft tissue on the treatment plan and relapse of orthodontic treatment, the present study sought to assess the relationship between tongue volume and basal bone and dental arch indices in Class I and II patients by using CBCT imaging. Method: The present cross-sectional study used the archive of the CBCT radiographies related to the patients referred to the radiology department of Tabriz Dental School (n=66). The data were primarily reconstructed in NNT viewer software. Regarding the measurement of tongue volume in Mimics software, cement-enamel junction to first molar and premolars was rotated on sagittal and axial dimensions, leading to determine the ventral portion of tongue. The vertical plane passing through posterior nasal spine (PNS) was regarded as the criterion of the posterior limit of tongue. Finally, the dental and bone indices of intercanine (IC) width and depth, intermolar (IM) width and depth, intercanine ratio and intermolar ratio in CBCT samples were assessed by using Romexis software. Spearman correlation coefficient was used to evaluate relationship between tongue volume and basal bone and dental arch indices in Class I and II patients in CBCT imaging modality. Further, regarding the comparison of basal bone and dental arch indices in Class I and II patients, independent t and Mann-Whitney U tests were utilized in data with normal and non-normal distribution, respectively. The values of possibility which were less than 0.05 were regarded as significant level. The results were analyzed in SPSS 23 software by using analytical-descriptive statistics methods. Results: The correlation results related to the patients in Class I represents that the maximum of correlation coefficient was obtained in intercanine width (ρ=0.83) and intermolar width (ρ=0.64) as dental arch indices and intercanine width (ρ=0.72) and depth (ρ=0.64) as basal bone indices, which represent a positive significant correlation with tongue volume. While, regarding Class II, the dental index of intercanine width (ρ=0.40) and basal bone index of intercanine width (ρ=0.38) were correlated with tongue volume positively and significantly. Conclusion: According to the results of this study, with increasing the tongue volume, dental and basal intercanine widths in both class I and class II patients were also increased. On the other hand the relationship between tongue volume and dental and basal indices was prominent in class I patients rather than class II patients. Regarding this results and the importance of tongue volume on relapse of orthodontic treatment, considering the tongue volume, particularly in class I patients, can be benefitional in prevention of relapse.