Comparison of buccal and palatal cortical bone thickness changes during en-masse retraction using skeletal anchorage- a CBCT study

Introduction: To evaluate and compare the labial and lingual cortical bone thickness in maxillary anterior segments during en masse retraction using skeletal anchorage aided by micro implants. Methods: The study was done in-vivo on 10 subjects, with angle’s class i bi-maxillary protrusion and/or angle’s class ii div 1 protrusion patients between the age group of 18-30 years in the permanent dentition.pre-treatment and post treatment CBCT’s were taken for all the patients. titanium small head micro implants, were used as anchor units for en-masse retraction. changes in cortical bone thickness were measured at cervical(s1),middle(s2)and apical(s3)regions. Results:One-way Anova test and Paired t test were performed on the given data which stated that statistically significant increase in cortical bone thickness was seen in at s2&s3 on the buccal aspect with a p value of <0.001,whereas on the palatal aspect there was significant decrease in s1 s2 and s3 after retraction. Conclusion-This current study concluded that orthodontic retraction force causes significant change in the thickness of cortical plates ie: reduction in thickness along the direction of force and differential remodelling at s1,s2 &s3.Increase in labial cortical plate thickness was seen after correction of inclination and retraction of maxillary anterior segment.