[Comparative biomechanical study of surgically assisted rapid palatal expansion with tooth-borne and bone-borne expanders].

The study objective was to compare the biomechanics of surgically assisted rapid palatal expansion (SARPE) with tooth-borne and bone-borne expanders. Materials include a sample of 54 cone-beam CT of 27 patients who underwent SARPE (bone-borne, n=21; tooth-borne, n=6) before treatment and at expander removal. Expansion efficacy was estimated by interapecal and intercoronal distances between maxillary canines, premolars and first molars as well as Coronal-Apical Index (CAI = coronal expansion (mm)/apical expansion (mm)). CAI varied between 1.5 and 2.0 in the group of patients with bone-borne appliances, and from 2.3 to 2.6 in the tooth-borne appliances group. The maximal amount of vestibular coronal declination was revealed in premolars by the use of tooth-borne appliances. Bone-borne appliances allowed lateralization of maxilla and the most prominent effect of tooth shift in a vestibular direction, which may be seen as the most important factors in a relapse prevention.