Maxillary Expansion Via Palatal Mini-Implants: A Preliminary Study

Abstract

Objective: This study evaluates the skeletal and dental effects of a mini-implant supported maxillary expansion (MISME) appliance that applied forces directly to the maxilla.

Materials and Method: Records of 9 patients (5 female and 4 male patients; mean age = 12 years 8 months) with indications of maxillary expansion were included in this study. After insertion of four miniscrews (1.6 mm in diameter, 7 mm in length), an acrylic expansion device was bonded on the screws. Two miniscrews were placed in the anterior palate bilaterally, 3-4 mm lateral to the suture and 3-4 mm posterior to the incisive foramen. Two miniscrews were placed bilaterally between the second premolar and first molar roots in the palatal alveolus. The MISME appliance was activated with a semi-rapid protocol until the desired expansion was achieved. The average treatment duration was 97.1 +/- 62.2 days. Measurements from cephalometric, posteroanterior radiographs and dental casts taken before and after expansion were evaluated statistically. The nonparametric Wilcoxon test was used for not normally distributed parameters (i.e., Nperp-A), and the parametric paired t test was performed for normally distributed parameters. A finding of p < 0.05 was considered to be statistically significant.

Results: Forward movement of the maxilla (p<0.05) as well as an increase in nasal and maxillary skeletal and dental widths (p<0.001) were observed in the sample group. Maxillary intermolar, intercanine, and palatal widths also increased (p<0.001) without buccal tipping of molars. A slight posterior rotation of the mandible was seen. Dentoalveolar measurements did not show any significant changes.

Conclusion: The MISME appliance showed successful expansion of the maxilla without such side effects as buccal tipping of molars and bite opening. This appliance, which provides parallel expansion, can be a simple and economic alternative to transpalatal distraction.