Slow maxillary expansion: a comparison between banded and bonded appliances.

Various investigations have mentioned the use of a bonded maxillary expansion appliance. It was postulated that a full coverage of the occlusal surfaces by acrylic would remove interferences during the lateral displacement of the two maxillary bones and would lessen the resistance to maxillary expansion. The first objective of this study was to compare two appliances, a bonded and a banded Minne expander using a continuous force of two pounds, which would produce a slow maxillary expansion. The second objective was to evaluate the ratio between the skeletal and dental response to slow maxillary expansion, and to compare these results to those obtained with a rapid maxillary expansion procedure. Each experimental group consisted of 5 patients, aged between 8 and 12 years wearing the two different appliances. Prior to treatment they were implanted according to the Björk technique. The slow expansion period lasted 7 to 15 weeks followed by a retention period of 12 weeks. Post-retention observations followed 12 weeks after the end of retention. No significant difference was found between banded and bonded appliances in regard to dental and skeletal expansion and relapse. The amount of skeletal versus dental movements equalled results obtained with rapid maxillary expansion. The relapse tendency appeared lower than with rapid maxillary expansion.