A 3-dimensional evaluation of available retromolar space for the application of ramal plates.

INTRODUCTION: This study aimed to evaluate the available retromolar space for ramal plates in patients with Class I and III malocclusions and compare that space with and without third molars using cone-beam computed tomography. METHODS: Cone-beam computed tomography images of 30 patients (17 males, 13 females; mean age, 22.2 +/- 4.5 years) with Class III malocclusion and 29 subjects (18 males, 11 females; mean age, 24.3 +/- 3.7 years) with Class I malocclusion were analyzed. Available retromolar space at 4 axial levels of the second molar root and the volume of the retromolar bone were evaluated. Two-way repeated measures analysis of covariance (repeated measures analysis of covariance) was applied to compare the variables between Class I and III malocclusions and the presence of third molars. RESULTS: Patients with Class I and III relationships showed up to 12.7 mm of available retromolar space at 2 mm apical from the cementoenamel junction (CEJ). At 8 mm apical from CEJ, patients with Class III malocclusion had 11.1 mm of space, whereas those with a Class I relationship showed 9.8 mm of available space. When patients had third molars, the amount of available retromolar space was significantly greater in patients with a Class I and III relationship. However, patients with Class III malocclusion exhibited greater available retromolar space than those with a Class I relationship (P = 0.028). In addition, the bone volume was significantly greater in patients with Class III malocclusion than in patients with a Class I relationship and those with third molars than in those without them (P <0.001). CONCLUSIONS: Class I and III groups showed the availability of at least 10.0 mm of retromolar space 2 mm apical to the CEJ for molar distalization. Based on this information, it is suggested that clinicians consider available retromolar space for molar distalization in diagnosing and planning treatment for patients with Class I and III malocclusion.