Effect of three di̇fferent maxi̇llary expansi̇on appli̇ences on root resorpti̇on

The aim of this study was to examine the skeletal and dentoalveolar effects of rapid maxillary expansion (RME), semi rapid maxillary expansion (SRME) and slow maxillary expansion (SME) and also assess and compare the root resorptions occurring in the supporting upper first premolar teeth during treatment by using the Micro-CT scan method. Thirty individuals that required maxillary expansion and upper first premolar tooth extraction were divied into three groups consisting of 10 individuals for rapid, semi rapid an slow expansion. Lateral and PA radiographies were taken at the beginning of treatment (T1), at the end of expansion (T2) and at the end of retention period (T3). In the RME group, the first premolar and the first molar teeth with hyrax screw were activated ¼ tour per twice a day with the banded expander apparatus. In SRME group, acrylic bonded hyrax apparatus was activated ¼ tour per every morning and night until the opening of suture. Upon the opening of the suture, it was activated ¼ tour per every two days until the sufficient maxillary expansion was gained. In SEM group, quad helix apparatus was applied and activated per every 20 days when subjects came to the clinic. After 12 weeks of retention period, the upper first premolar teeth were extracted. The teeth were scanned with Micro-CT (SkyScan 1172, Kontich, Belgium) and the images were analysed in a high capasity-workstation (Dell Precision T5500) to determine the resorption crater volumes. The mean activation duration lasted 20±5 days in the RME group. It was 43±7 days for SRME group and 87±4 days for the subjects of SEM group. Root surface was investigated in 8 groups as total volume and 12 groups as regional volume. In all samples, the resorption craters were concentrated on the buccal surfaces of the tooth roots. The highest resorption craters volume in the total resorption volume was observed in the RME group, followed by the SRME group and the least resorption crater volume was detected in the SEM group. There were 21 parametres in the cepholometric examination, there were no significant difference between the sagittal cahanges of three groups. There were 8 parametres in PA graphic examination, enlargement in the transversal direction were observed in all three groups and they were significantly different between groups. Since the supporting teeth were exposed to more force on the root surfaces, the most resorption was seen in the RME group. It was followed by SRME and SEM groups, respectively. The sites where resorption was most seen were the buccal, palatinal, distal and mesial surfaces of the roots, respectively.