ABSTRACT

Objective:

To examine the treatment effects of a miniscrew assisted memory screw system supported by piezoincision for the noncompliance molar distalization of maxillary first molars in patients with Class II malocclusion.

Materials and Method:

Nine subjects with skeletal Class I dental Class II malocclusion were treated. An anchorage unit was prepared using two miniscrew that were placed just behind a line connecting the first premolars at the mesial contact point. The memory expansion screw (500 g), and two miniscrews placed parallel to the occlusal plane provided stable, 4-point support for the appliance. Piezoincision was performed immediately after the appliance as cemented. Four midlevel incisions were made under local anesthesia between the roots of the teeth on the buccal side of the maxillary alveolar bone from the mesial first premolar to the second molar. A 3-mm piezoelectrical corticotomy was then performed by inserting the tip of Piezotome into each of these openings. Screw activation was started the following day. Skeletal and dental changes were measured on cephalograms, and dental casts were obtained before and after distalization.

Results:

Upper first molars were successfully distalized in approximately 4.6 months and the mean distalization at the end was 4.98 mm. The average distal tipping of the upper first molars was 7.75°. No statistically significant changes were noted in the sagittal position of the maxilla or in the position of the upper incisors as a result of treatment. The maxillary first molars also moved palatinally (1.13 mm), but no significant distal rotation occurred.

Conclusion:

This system provided an efficient distalization method for posterior teeth and showed no anchorage loss. Molar tipping and palatal movement were observed as side effects in the patients.