Comparison of short-term effects of mini-implant-supported maxillary expansion appliance with two conventional expansion protocols.

Objective: This study evaluates the dentoskeletal effects of a mini-implant-supported maxillary expansion (MISME) appliance in comparison with two types of conventional expansion methods.

Methods: Records of 42 patients with bilateral or unilateral posterior crossbite were included in this study. The patients were divided into three groups. In group 1, four miniscrews were placed to the palatal region and an acrylic expansion device was bonded on these screws. A bonded maxillary expansion appliance was used in group 2, while a banded expansion appliance was used in group 3. Measurements from cephalometric, postero-anterior radiographs, and dental casts taken before and after expansion were evaluated statistically.

Results: ANB angle increased significantly in group 1 and 3. MISME group also showed an increase of SNA angle. Measurements regarding the vertical dimension did not change with MISME but significant posterior rotation was found in group 2 and 3. Overbite value showed a significant decrease in group 2 and 3, but remained stable in group 1. The nasal, maxillary, maxillary intermolar widths showed significant increases in all groups. The difference between MISME group and other groups in maxillary width was significant indicating more skeletal expansion in MISME group. The maxillary molars showed significant buccal tipping in group 2 and 3, while lingual tipping of molars was found in MISME group.

Conclusions: MISME can be a better alternative to bonded expansion particularly in patients with vertical growth patterns and lack of anchorage teeth.