Aim and Objectives: The aim of the study was to determine and compare the effects of force delivered through rapid maxillary expansion and semi rapid maxillary expansion on the Buccal bone plate thickness using imaging.

Material and Method: The study was conducted among 20 patients reporting to the OPD of Orthodontics department, RUHS College of Dental Science, Jaipur with transverse maxillary deficiency requiring expansion of maxilla. The sample was then divided into two groups, RME and SRME with 10 subjects in each group. A hyrax expansion screw was customized and bonded with an acrylic splint on the maxillary first premolars and first molars in both the groups. The appliance activation protocol of 4-quarter turn per day was followed in RME group whereas protocol of 2-quarter turns per day for the first week, followed by one- quarter turn every other day was followed in SRME group. After completion of expansion process, the screws were stabilized by tying ligature wire in hyrax opening hole. The same hyrax expansion screw was used for retention forat least 3 months after expansion. CBCT scans of each subject were done prior to the delivery of the expander (T1) and 3 months after the last activation of the expansion appliance (T2). DICOM images were obtained & Image analysis was performed to measure the thickness of the buccal bone corresponding to the maxillary first molars on the mesiobuccal root for the left sides at 3- & 6-mm distance from CEJ. The change in buccal bone thickness is then evaluated in pre & post CBCT in both the groups. Data obtained was compiled on to a MS Office excel worksheet & subjected to statistical analysis using SPSS software. Paired t test was used for the comparisons between the groups. For all the statistical tests, P0.05). In case of RME the mean difference in buccal bone plate thickness at 3mm was 0.66 ±0.12mm and at 6 mm it was 0.82 ±0.19 mm and the mean difference at 3mm and 6 mm point was found to be 0.16 mm which was statistically significant (P<0.05) was considered to be statistically significant.

Result: The result showed that the mean difference in buccal bone plate thickness before & after the treatment with SRME at 3mm was 1.05±0.12 mm and at 6 mm it was1.09 ±0.16 mm and the mean difference at 3mm and 6 mm point was 0.04 mm, which was statistically insignificant (P>0.05). In case of RME the mean difference in buccal bone plate thickness at 3mm was 0.66 ±0.12mm and at 6 mm it was 0.82 ±0.19 mm and the mean difference at 3mm and 6 mm point was found to be 0.16 mm which was statistically significant (P<0.05). On comparing the mean difference between the buccal bone plate thickness after treatment with Semi RME and RME at 3 and 6 mmwas found to be 0.12 mm which was statistically significant (p≤0.05).

Conclusion: In case ofRME the difference in buccal bone thickness before & after procedure at 3 & 6mm was non uniform suggestive of more tipping movement whereas in case of SRME the difference in buccal bone thickness before & after procedure at 3 & 6mm was more uniform suggestive of less tipping movement and more bodily movement. Thus, it can be concluded from the study that SRME can be a better alternative in adult patients with transverse discrepancies.