Trigeminal nerve injuries. Four years' experience at a single Argentine referral center and a literature review / Lesiones del nervio trigémino. Cuatro años de experiencia de un servicio quirúrgico odontológico en Argentina y revisión bibliográfica

ABSTRACT The aim of this retrospective study was to describe the etiology and characteristics of trigeminal nerve injuries referred to a specialized center in Buenos Aires, Argentina. A retrospective analysis was performed of patients referred from February 2016 to January 2020. Age, sex, intervention performed, nerve affected, time elapsed from injury, diagnosis, location, and whether patient had signed informed consent were recorded. A descriptive analysis of the data was made, and 95% confidence intervals were calculated for prevalence. The study sample consisted of 30 subjects (31 nerve injuries), 19 female and 11 male, average age (±SD) 40 ± 17 years. The inferior alveolar nerve was the most frequently injured nerve (74%,) while the lingual nerve accounted for 26%. The most common etiologies were inferior molar extractions (47%), dental implants (20%), and local anesthesia (13%). Other etiologies were autologous mandibular bone grafts for dental implants, removal of cysts associated with the inferior third molar, and endodontic treatment. Dental Institutions at which treatment was provided were found to be significantly associated with patients being warned and asked to sign informed consent (p<0.05), while dentists working at private offices requested fewer consents. The most frequent symptom was paresthesia, and 5 patients suffered spontaneous or evoked pain. Only 2 patients intended to file legal claims. Dentists should be aware of the debilitating effects resulting from trigeminal injuries, the complexity of their resolution and the importance of carefully planning dental procedures to prevent them.

RESUMEN El objetivo de este estudio fue describir la etiología y características de las lesiones del nervio trigémino remitidas a un servicio de referencia especializado en Buenos Aires, Argentina. Se realizó un análisis retrospectivo de los pacientes remitidos desde febrero de 2016 a enero de 2020. Se registraron edad, género, intervención recibida, nervio afectado, tiempo transcurrido desde la lesión, diagnóstico, ubicación y firma del consentimiento informado previo a la intervención Se realizó un análisis descriptivo de los datos y se calcularon intervalos de confianza del 95%. La muestra del estudio consistió en 30 sujetos (31 lesiones nerviosas), 19 mujeres y 11 hombres, con una edad promedio (± DE) de 40 ± 17 años. Aproximadamente 3 de cada 4 lesiones correspondieron al nervio alveolar inferior, representando el resto al nervio lingual. Las etiologías más frecuentes fueron la extracción dentaria (47%), los implantes dentales (20%) y la aplicación anestesia local (13%). Otras etiologías fueron la regeneración ósea para la colocación de implantes mandibulares, la extirpación de quistes asociados al tercer molar inferior y el tratamiento endodóntico. Se encontró que el tipo de establecimiento donde se realizó el procedimiento odontológico que generó la lesión, se asoció significativamente con los pacientes a los que se les advirtió y se les pidió que firmen el consentimiento informado (p<0.05); los odontólogos que trabajan en consultorios privados obtienen una menor proporción de consentimientos que los de las instituciones. El síntoma más frecuente fue la parestesia y 5 pacientes sufrieron dolor espontáneo o evocado. Solo 2 pacientes tenían intención de iniciar acciones legales. Teniendo en cuenta que son lesiones potencialmente permanentes, y de resolución compleja, la comunidad odontológica debe realizar especiales esfuerzos para disminuir esta complicación.

Management and prevention of third molar surgery-related trigeminal nerve injury: time for a rethink

Trigeminal nerve injury as a consequence of lower third molar surgery is a notorious complication and may affect the patient in long term. Inferior alveolar nerve (IAN) and lingual nerve (LN) injury result in different degree of neurosensory deficit and also other neurological symptoms. The long term effects may include persistent sensory loss, chronic pain and depression. It is crucial to understand the pathophysiology of the nerve injury from lower third molar surgery. Surgery remains the most promising treatment in moderate-to-severe nerve injuries. There are limitations in the current treatment methods and full recovery is not commonly achievable. It is better to prevent nerve injury than to treat with unpredictable results. Coronectomy has been proved to be effective in reducing IAN injury and carries minimal long-term morbidity. New technologies, like the roles of erythropoietin and stem cell therapy, are being investigated for neuroprotection and neural regeneration. Breakthroughs in basic and translational research are required to improve the clinical outcomes of the current treatment modalities of third molar surgery-related nerve injury.

Trigeminal somatosensory evoked potential test as an evaluation tool for infraorbital nerve damage

BACKGROUND: Neurosensory changes are frequently observed in the patients with mid-face fractures, and these symptoms are often caused by infraorbital nerve (ION) damage. Although ION damage is a relatively common phenomenon, there are no established and objective methods to evaluate it. The aim of this study was to test whether trigeminal somatosensory evoked potential (TSEP) could be used as a prognostic predictor of ION damage and TSEP testing was an objective method to evaluate ION injury. METHODS: In this prospective TSEP study, 48 patients with unilateral mid-face fracture (only unilateral blow out fracture and unilateral zygomaticomaxillary fracture were included) and potential ION damages were enrolled. Both sides of the face were examined with TSEP and the non-traumatized side of the face was used as control. We calculated the latency difference between the affected and the unaffected sides. RESULTS: Twenty-four patients recovered within 3 months, and 21 patients took more than 3 months to recover. The average latency difference between the affected side and unaffected side was 1.4 and 4.1 ms for the group that recovered within 3 months and the group that recovered after 3 months, respectively. CONCLUSION: Patients who suffered ION damage showed prolonged latency when examined using the TSEP test. TSEP is an effective tool for evaluation of nerve injury and predicting the recovery of patients with ION damage.

Morphometric relationships between the mandibular canal and the molar teeth: a tomographic analysis report / Relaciones morfométricas entre el canal mandibular y los dientes molares: reporte de un análisis tomográfico

Some dental treatments that are performed in the mandibular teeth involve manipulation of anatomical structures near the dental periapex, so it is likely to cause nerve damage due to the proximity of the inferior alveolar nerve with the apices of the mandibular teeth, mainly in the molar area. The aim of this study was to determine through Computed Tomography (CT) scan the existing distance between the mandibular canal and the anatomical structures adjacent to its path which will help to reduce the risk of injury to the inferior alveolar nerve during the different dental treatments developed in this zone. A cross-sectional study was performed where the study population consisted of 50 patients of both sexes, between 20 and 30 years with a full dentition mandible. Patients underwent a CT study of the mandible with coronal planes at 1.5 mm, the right side and the left side of each jaw were considered for the analysis and millimetric measuring was held of the distances of the mandibular canal (MC) from different anatomical structures. Subsequently, a statistical analysis was performed to obtain the mean and standard deviation of the distances between the mandibular canal and some adjacent anatomical structures. The distance from the alveolar nerve canal to the apex of the lower third molar in average was 1.49 mm on the right side and 1.69 mm on the left side, the distance between the mandibular canal and lingual cortical at the lower first molar level on average was 3.54 mm on the right side and 4.02 mm on the left side and the distance between the lingual cortical at the second molar level was on average 2.86 mm on the right side and 3.6 mm on the left side.

Algunos tratamientos dentales que se realizan en los dientes mandibulares implican la manipulación de estructuras anatómicas cercanas al periapice dental, por lo que existe la probabilidad de causar lesiones nerviosas debido a la cercanía del canal mandibular con los ápices de los dientes mandibulares, principalmente los molares. El objetivo de este estudio fue determinar a través de tomografía computarizada la distancia existente entre el canal mandibular a las estructuras anatómicas adyacentes a su trayecto lo que ayudará a disminuir el riesgo de lesiones del nervio alveolar inferior durante los diferentes tratamientos dentales desarrollados en esta zona. Se realizó un estudio transversal en donde la población de estudio estuvo compuesta por 50 pacientes de ambos sexos, entre 20 a 30 años con dentición completa en mandíbula. A los pacientes se les realizó un estudio de Tomografía Computarizada (TC) en mandíbula con cortes coronales a 1.5mm, se consideraron para el análisis el lado derecho y el lado izquierdo de cada mandíbula, y se realizó la medición milimétrica de las distancias que existen desde el CNAI a diferentes estructuras anatómicas. Posteriormente, se realizó un análisis estadístico para obtener Medias y Desviación Estándar de las distancias que existen entre el canal mandibular y algunas estructuras anatómicas adyacentes. La distancia del canal mandibular al ápice del tercer molar inferior en promedio fue de 1,49 mm del lado derecho y de 1,69 mm del lado izquierdo,la distancia entre el canal mandibular y la cortical lingual a nivel del primer molar inferior en promedio fue de 3,54 mm del lado derecho y de 4,02 mm del lado izquierdo y la distancia entre la cortical lingual a nivel del segundo molar fue en promedio de 2,86 mm del lado derecho y de 3,6 mm del lado izquierdo.

Distribution of the lingual foramina in mandibular cortical bone in Koreans

OBJECTIVES: The interforminal region, between the mandibular foramen, is known as a relatively safe area that is free of anatomic structures, such as inferior alveolar nerve, submandibular fossa, and lingual side of the mandible is occasionally neglected for its low clinical importance. Even in the case of a severely constricted alveolus, perforation of the lingual cortical bone had been intended. However, anterior extension of the inferior alveolar canal, important anatomic structure, such as concavity of lingual bone, lingual foramina, and lingual canal, has recently been reported through various studies, and untypical bleeding by perforation of the lingual plate on implantation has also been reported. Therefore, in this study, we performed radiographic and statistical analysis on distribution and appearance frequencies of the lingual foramina that causes perforation of the mandibular lingual cortical bone to prevent complications, such as untypical bleeding, during surgical procedure. MATERIALS AND METHODS: We measured the horizontal length from a midline of the mandible to the lingual foramina, as well as the horizontal length from the alveolar crest to the lingual foramina and from the lingual foramina to the mandibular border by multi-detector computed tomography of 187 patients, who visited Dankook University Dental Hospital for various reasons from January 1, 2008 to August 31, 2012. RESULTS: From a total of 187 human mandibles, 110 (58.8%) mandibles had lingual foramina; 39 (20.9%) had bilateral lingual foramen; 34 (18.2%) had the only left lingual foramen; and 37 (19.8%) had the only right lingual foramen. CONCLUSION: When there is consistent bleeding during a surgical procedure, clinicians must consider damages on the branches of the sublingual artery, which penetrate the lingual foramina. Also, when there is a lingual foramina larger than 1 mm in diameter on a pre-implantation computed tomography, clinicians must beware of vessel damage. In order to prevent these complications and progress with a safe surgical procedure, a thorough radiographic examination before the surgery is indispensable. Further, clinicians should retract lingual flap definitely to confirm the shape of the lingual bone and existence of the lingual foramina.