Maxillary Expansion Via Palatal Mini-Implants: A Preliminary Study

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 6 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. (Turkish J Orthod 2014;27:16–27)