Branching patterns and intraosseous course of the mental nerve.

PURPOSE: The purpose of this study was to clarify the branching patterns of the mental nerve (MN) and intraosseous courses of the MN branches, and to determine the clinical relevance of the various courses of the MN branches. MATERIALS AND METHODS: We investigated the topography of the MN by dissecting 31 hemifaces of Korean cadavers. Based on the distribution area of the MN, it was divided into angular (A), medial inferior labial (ILm), lateral inferior labial (ILl), and mental (M) branches. We classified the branching patterns of the 4 branches of the MN into 5 types. RESULTS: Type II, in which the MN divided into 3 branches (A, ILm, and M), with the ILl branch separating from the A branch, was the most common (35.4%). The MN was classified based on the shape of the anterior loop into loop, straight, and vertical patterns, which constituted 61.5%, 23.1%, and 15.4%, respectively. In the mandibular canal, the inferior alveolar nerve completely divided into the MN and the dental nerve, which supplies the teeth. In 17 cases (81%), the nerve bundles constituting the A branch were located at the superior aspect, whereas the nerve bundles of the inferior labial and mental branches were in the middle and inferior aspects within the mandibular canal, respectively, at the mental foramen region. CONCLUSION: These observations can help clinicians to predict the location or extent of paresthesia in the facial region according to the location and extent of nerve damage during dental implant surgery or genioplasty.

Soft-tissue and cortical-bone thickness at orthodontic implant sites.

INTRODUCTION: To obtain sufficient stability of implants, the thickness of the soft tissue and the cortical bone in the placement site must be considered. However, the literature contains few anatomical studies of orthodontic implants. METHODS: To measure soft-tissue and cortical-bone thicknesses, maxillae from 23 Korean cadavers were decalcified, and buccopalatal cross-sectional specimens were obtained. These specimens were made at 3 maxillary midpalatal suture areas: the interdental area between the first and second premolars (group 1), the interdental area between the second premolar and the first molar (group 2), and the interdental area between the first and second molars (group 3). RESULTS: In all groups, buccal soft tissues were thickest closest to and farthest from the cementoenamel junction (CEJ) and thinnest in the middle. Palatal soft-tissue thickness increased gradually from the CEJ toward the apical region in all groups. Buccal cortical-bone was thickest closest to and farthest from the CEJ and thinnest in the middle in groups 1 and 2. Palatal cortical-bone thickness was greatest 6 mm apical to the CEJ in groups 1 and 3, and 2 mm apical to the CEJ in group 2. Along the midpalatal suture, palatal mucosa remained uniformly 1 mm thick posterior to the incisive papilla. CONCLUSIONS: Surgical placement of miniscrew implants for orthodontic anchorage in the maxillary molar region requires consideration of the placement site and angle based on anatomical characteristics.