Vulnerability of the Inferior Alveolar Nerve and Mental Nerve During Genioplasty: An Anatomic Study

Abstract

Microgenia or "small chin" is corrected by various techniques, such as insertion of an alloplastic implant, cartilage or bone grafting, or horizontal advancement osteotomy. Horizontal recession osteotomy is used in macrogenia. Particularly in a microgenic mandible, the mental foramen is unexpectedly nearer to the inferior border of the body. During sliding horizontal osteotomy of the mentum, the inferior alveolar nerve (IAN) and mental nerve are vulnerable to an injury. Thirty fresh hemimandibles were used for a study of the IAN. The IAN course was traced by serial sections at intervals of 5 mm. In 50 dry specimens the direction of the mandibular canal was evaluated by the photographs with a stick put into the mental foramen. The IAN in mandibular canal runs above the lower one-third of the mandibular body. The terminal mandibular canal locates at an average of 4.5 mm under the mental foramen, advances 5.0 mm anteriorly, loops, and ends at the foramen. The direction of the mandibular canal at the mental foramen was 39.4 degrees lateral, 67.2 degrees superior, and 80.2 degrees posterior. It is advisable for surgeons to keep the level of sliding osteotomy of the mentum at least 4.5 mm below the mental foramen to spare the IAN.

Course and Topographic Relationships of Mandibular Canal: A Cone Beam Computed Tomography Study

“…in the molar area, the mandibular canal was either in contact with the lingual cortex or ran very close to the lingual cortex while in the premolar area, the mental nerve usually makes a sharp turn from lingual to buccal and exits through the mental foramen. Similar courses have been recorded by several other investigators [13,[19][20][21]. The buccolingual course of the MC becomes more important in cases of deficiency of the vertical dimension of the alveolar ridge.…”

“…For example, dry skull reports may have variable diseases and lack relevant data such as age, gender, or include edentulous mandibles, or use inconsistent and anatomically irrelevant landmarks [6].…”

Position of the Mental Foramen in Panoramic Radiography and Its Relationship to Age in a Selected Iranian Population

“…It is especially important to identify its boundaries and to preserve it during surgery, trauma, and local anesthesia (1)(2)(3). In this study, three variables were assessed to determine the location and appearance of the MF with panoramic radiography.…”

“…The exact position of the MF should be identified for nerve blocks (2,3). Mental nerve injury may lead to temporary or permanent changes in thermal and tactile sensation, and localizing the MF during surgical procedures helps prevent such injuries (4).…”

Mental Foramen Position Using Modified Assessment System: An Imperative Landmark for Implant and Orthognathic Surgery

“…During implants, periapical surgery, orthognathic surgery, mental nerves and vessels can be traumatized. Recently implant technique and frequency of orthognathic surgery have increased the chance of surgical procedure near MF area 4) , as well as increased the chance of injury to the mental bundle 5) , as a result it can cause temporary or permanent sensorial, tactile or thermal changes 6) .…”