Evaluation of the Lingual Canals of Mandible in Cone Beam Computed Tomography

This study aims to assess the frequency of the lingual foramina and canals relative to their location on the mandibular cortical plate and also to closely inspect the course of the lingual canals inside the mandibular body using 3D reconstruction of the evaluated area. A retrospective study was conducted with 55 cone bean computed tomography (CBCT) scans in order to analyze the location, number, course and anastomosing pattern of the lingual canals. A total number of 165 lingual canals (LCs) were recorded from 55 patients, as follows: 94 median (MLC), 16 paramedian (PLC) and 55 lateral lingual canals (LLC). MLCs were a constant finding in all 55 patients (100% of the cases), PLCs were present in 15 patients (27.3% of the cases), and LLCs were identified in 35 patients (63.3% of the cases). The anastomosing pattern of the MLC, in which a supraspinous canal anastomosed with an infraspinous canal, was found in 10.9% of the cases (6 of 55 patients),. The LLCs were anastomosed with the mandibular incisive canal (MIC) in 56.3% of the cases (31 of 55 LLCs) and with the mandibular canal (MC) in 3.6% of the cases (2 of 55 LLCs). CBCT revealed itself to be a reliable tool for evaluating the intramandibular topography of the LCs. The anastomosing pattern of the lingual canals might raise the question whether the LCs could be responsible for incomplete anesthesia after conventional mandibular block by carrying sensory innervation from the mylohyoid nerve to the inferior alveolar nerve.

Evaluation of the Lingual Canals of Mandible in Cone Beam Computed Tomography

This study aims to assess the frequency of the lingual foramina and canals relative to their location on the mandibular cortical plate and also to closely inspect the course of the lingual canals inside the mandibular body using 3D reconstruction of the evaluated area. A retrospective study was conducted with 55 cone bean computed tomography (CBCT) scans in order to analyze the location, number, course and anastomosing pattern of the lingual canals. A total number of 165 lingual canals (LCs) were recorded from 55 patients, as follows: 94 median (MLC), 16 paramedian (PLC) and 55 lateral lingual canals (LLC). MLCs were a constant finding in all 55 patients (100% of the cases), PLCs were present in 15 patients (27.3% of the cases), and LLCs were identified in 35 patients (63.3% of the cases). The anastomosing pattern of the MLC, in which a supraspinous canal anastomosed with an infraspinous canal, was found in 10.9% of the cases (6 of 55 patients),. The LLCs were anastomosed with the mandibular incisive canal (MIC) in 56.3% of the cases (31 of 55 LLCs) and with the mandibular canal (MC) in 3.6% of the cases (2 of 55 LLCs). CBCT revealed itself to be a reliable tool for evaluating the intramandibular topography of the LCs. The anastomosing pattern of the lingual canals might raise the question whether the LCs could be responsible for incomplete anesthesia after conventional mandibular block by carrying sensory innervation from the mylohyoid nerve to the inferior alveolar nerve. Keywords: mandible, lingual canal, intramandibular anastomosis, CBCT

DISSECTION AND DETAILED ANATOMY OF AN IMPACTED MANDIBULAR THIRD MOLAR. Disección y anatomía detallada de un tercer molar mandibular impactado

Los trastornos neurosensoriales del nervio alveolar inferior (IAN) o el nervio lingual (LN) se reportan comúnmente en casos del tercer molar inferior impactado. Los casos están documentados usualmente mediante estudios imagenológicos. Pruebas de disección de la anatomía detallada en estos casos son raras, sino inexistentes. Se informa aquí sobre un estudio de disección en un caso de un tercer molar inferior impactado (ángulo bucal), en un cadáver de un hombre adulto, 68 años de edad. Más allá de las “clásicas” relaciones del diente impactado con el IAN y el LN, también han sido encontradas estrechas relaciones con las ramas de LN, el ganglio de debajo de la mandíbula, el nervio milohioideo (MN) y la anastomosis del LN y MN. Estos detalles anatómicos deben considerarse también cuando tales casos están documentados en pacientes antes de procedimientos quirúrgicos. Los efectos de los daños del ganglio de debajo de la mandíbula deben ser analizados más. Neurosensory disturbances of the inferior alveolar nerve (IAN), or the lingual nerve (LN), are commonly reported in cases of third mandibular molar impaction. Cases are usually documented by use of imagistic methods. Dissection proofs of the detailed anatomy in such cases are rare, if not absent. It is reported here a dissection study in a case of an impacted (bucco-angular) third mandibular molar, in an adult male cadaver, 68 years old. Beyond the “classical” relations of the impacted tooth with the IAN and the LN, close relations were also found with the LN branches, submandibular ganglion, mylohyoid nerve (MN), and the anastomosis of the LN and the MN. These anatomical details should be also considered when such cases are documented in patients before surgical procedures. Effects of the submandibular ganglion damage should be further explored.

The Efficacy of Mylohyoid Nerve Anesthesia in Dental Implant Placement at the Edentulous Posterior Mandibular Ridge

The aim of this study is to evaluate the anesthetic efficacy of mylohyoid and buccal nerve anesthesia at the posterior edentulous mandible versus regional anesthetic block to the inferior alveolar nerve in dental implant surgery. The study was composed of 2 groups. In the first group (group A), 14 voluntary adults (7 female and 7 male) received local infiltrations of 1 mL articaine HCl 4% with epinephrine 1/200 000 to the ipsilateral mylohyoid and buccal nerves. In the second group (group B, control; 9 female and 5 male adults), the inferior alveolar and the buccal nerve blocks were performed. Visual analog scales were obtained from patients to determine the level of pain during incision, drilling, implant placement, and suturing stages of implant surgery. A combination of buccal and mylohyoid nerve block offered an acceptable level of anesthesia. Two patients from group A stopped the ongoing surgery and had extraregional anesthesia by inferior alveolar nerve block. In group B, patients were operated on successfully. Local anesthetic infiltrations of the mylohyoid and the buccal nerve may be considered alternative methods of providing a convenient anesthetic state of the posterior mandibular ridge.

A Unique Case of a Sublingual-Space Schwannoma Arising from the Mylohyoid Nerve

We describe a unique case of a sublingual-space schwannoma presenting as a painless, 3 × 2-cm enlarging mass in the oral cavity of a 63-year-old man. Computed tomography demonstrated a distinct, well-encapsulated mass in the right side of the floor of the mouth. Findings on fine-needle aspiration cytology were consistent with a pleomorphic adenoma. Transoral excision was performed. Intraoperatively, the mass appeared to involve the nerve to the mylohyoid muscle. Upon removal, the gross tumor measured 4.4 × 3.5 × 2.5 cm. On microscopic examination, the spindle-cell neoplasm was found to be consistent with a schwannoma. Schwannomas of the sublingual space are exceedingly rare. Moreover, to the best of our knowledge, this case represents the first published occurrence of a schwannoma that arose from the mylohyoid nerve.

Mylohyoid discharge of the in situ rat: a probe of pontile respiratory activities in eupnea and gasping

Our purpose was to characterize respiratory-modulated activity of the mylohyoid nerve. Since its motoneurons are in the trigeminal motor nucleus, mylohyoid discharge could serve as a probe of the role of pontile mechanisms in the generation of respiratory rhythms. Studies were performed in the decerebrate, perfused in situ preparation of the rat. Phrenic discharge was recorded as the index of the respiratory rhythm. In eupnea, the mylohyoid nerve discharged primarily during neural expiration, in the period between phrenic bursts. This expiratory discharge increased greatly in hypoxia and fell in hypercapnia. The hypoxia-induced increase in mylohyoid discharge was due, at least in part, to a direct influence of hypoxia on the brain stem. In ischemia, phrenic discharge increased, and then declined to apnea, which was succeeded by gasping. The mylohyoid nerve discharged tonically during the apneic period, but still declined during each of the phrenic bursts of gasping. This maintenance of a respiratory-modulation of the mylohyoid discharge in gasping supports the concept that a release of medullary mechanisms, rather than a ubiquitous suppression of pontile influences, underlies the neurogenesis of gasping. Results also provide additional support for our conclusion that activity of any single cranial nerve does not provide an accurate index of the type of respiratory rhythm, be it eupnea or gasping.