Comparison of root resorption after bone-borne and tooth-borne rapid maxillary expansion evaluated with the use of microtomography.

INTRODUCTION: Root resorption was compared between bone-borne and tooth tissue-borne rapid maxillary expansion patients with the use of microtomography. METHODS: The study included 20 patients (ages 11-16 years) requiring fixed orthodontic treatment who underwent extraction of their first premolars after rapid maxillary expansion with the use of modified appliances. One side of the appliance covered the teeth with acrylic, while the other side was fixed to the palatal bone by means of a miniscrew. After 3 months' retention, the appliance was removed and teeth were extracted and examined with the use of microtomography. RESULTS: When the apical, middle, and cervical thirds, as well as the buccal and lingual sides, were compared, the volume loss was significantly higher in the tooth tissue-borne group than in the bone-borne group (P <0.01). The least volume loss occurred on the cervical third lingual surface in the tooth tissue-borne group and on the middle third buccal surface in the bone-borne group. In the former group, least resorption occurred on the cervical third and highest resorption on the buccal side. In the latter group, surfaces showed no significant changes. CONCLUSIONS: More root resorption occurred in the tooth tissue-borne group, mostly in the apical and middle thirds. The amount of resorption on the buccal surface was higher than that on the lingual surface.