Does the timing and method of rapid maxillary expansion have an effect on the changes in nasal dimensions?

The aim of this study was to assess the effects of rapid maxillary expansion (RME) and surgical assisted rapid maxillary expansion (SARME) on nasopharyngeal area. The study group consisted of 30 subjects in the permanent dentition who had both maxillary constriction and a posterior cross-bite. The patients were divided into two groups, RME and SARME. The subjects in the RME group consisted of 15 patients (eight girls, seven boys) whose average age was 12.1 +/- 1.1 years. The SARME group also consisted of 15 patients (eight boys, seven girls) whose mean age was 18.4 +/- 1.4 years. An acrylic bonded RME appliance was used in both groups. Surgery was performed using lateral cortical osteotomies in the SARME group. The nasopharyngeal and respiratory area was determined using a digital planimeter on lateral cephalometric radiographs taken before and after RME. Nasal cavity width was evaluated on postero-anterior radiographs. Nasal dimension was measured using planimeter measurements of the respiratory and nasopharyngeal areas before and after treatment. The data obtained were analyzed using SPSS. Comparisons within the groups were carried out with paired t-tests and comparisons between the groups were with a Student's t-test. In both groups, the respiratory area and the ratio of the respiratory area to nasopharyngeal (RA/NA) area increased following RME. There were no statistically significant differences between the groups. Nasal cavity width and maxillary width also increased, but the difference between the groups was not significant. Following RME, various differences in both the maxilla and surrounding bones occurred and nasal width increased with a decrease in nasal airway resistance. At the end of treatment there were increases in the width of the nasal floor near the midpalatal suture and nasal cavity. As the maxillary structures separated, the outer walls of the nasal cavity moved laterally resulting in an increase in internasal volume. Nasal resistance decreased and respiratory area increased in patients treated with RME.

Unilateral distal molar movement with an implant-supported distal jet appliance.

With the guidance of the basis of the distal jet appliance, we present a new implant-supported distal jet appliance. In this case, we used a modified distal jet appliance that was supported by a palatal implant placed at the anterior edge of the rugae region of the palate for molar distalization. The treatment results were evaluated from lateral cephalometric and panoramic radiographs and dental casts. We conclude that an implant-supported modified distal jet appliance is effective in the correction of a Class II molar relationship.

Effects of a modified acrylic bonded rapid maxillary expansion appliance and vertical chin cap on dentofacial structures.

The aim of this study was to determine the sagittal, transverse, and vertical effects of a modified acrylic bonded rapid maxillary expansion (RME) device used with a vertical chin cap on dentofacial structures. The study group consisted of 34 patients (25 girls and 9 boys) who were selected without regard to their skeletal class and gender. All subjects had permanent dentition (mean age, 12.7 years) and needed maxillary expansion. Study Group I (RME only) was composed of 17 subjects, and study Group II (RME with vertical chin cap) was composed of 17 subjects. Twenty-nine measurements were made on the patients' cephalometric films and plaster models. The means and standard deviations for linear and angular cephalometric measurements were analyzed statistically, and intra-group and inter group changes were evaluated by paired and Student's t-tests using SPSS 10.1 for windows. We found that the maxilla moved anteriorly relative to the anterior cranial base. The nasal width, maxillary width, intercanine width, mandibular intermolar width, maxillary intermolar width, and overjet all increased, while the upper molars tipped buccally in both groups. In Group I, the mandible rotated posteriorly, the lower anterior facial height increased, and the overbite decreased. These effects were reduced in Group II. We conclude that the vertical chin cap is an effective appliance for preventing the adverse vertical effects of RME in patients with a crossbite and a vertical growth pattern.