Técnicas de reposición del nervio alveolar inferior: transposición y lateralización / Techniques for the reposition of the inferior alveolar nerve: transposition and lateralization

La rehabilitación de los sectores mandibulares con atrofias óseas severas utilizando implantes es objeto de desafío para cualquier profesional debido a las dificultades que presentan. Existen dos técnicas quirúrgicas para llevar a cabo la reposición del nervio dentario que son relativamente seguras y ofrecen una alta tasa de supervivencia de los implantes: la transposición y la lateralización. El objetivo de este trabajo es llevar a cabo una actualización sobre las técnicas de reposición del nervio alveolar inferior, y para ello se ha efectuado una búsqueda de estudios sobre humanos empleando las bases de datos PubMed y Scopus, utilizando como palabras clave: "transposition", "alveolar nerve", "atrophic mandibles" y "nerve complications". Se revisan para ello un total de 22 artículos de casos clínicos y estudios in vitro; 9 de ellos sobre lateralización, 8 sobre transposición y 5 sobre ambas técnicas. Tanto la lateralización como la transposición del nervio dentario presentan riesgos relacionados con complicaciones neurosensoriales y fractura mandibular. Se observa una alta tasa de éxito en la supervivencia de los implantes sin discriminación significativa de la técnica. Las técnicas de reposición del nervio dentario no están exentas de complicaciones. La inserción de los implantes combinados con la técnica de transposición presenta un comportamiento similar a cualquiera de las otras técnicas empleadas en el campo de la implantología, siendo su pérdida ósea marginal similar a la de otras superficies implantarias

The use of dental implants for the rehabilitation of the atrofic posterior mandible has been a challenge due to the complications they may carry. There are two surgical techniques for the reposition of the inferior alveolar nerve which are relatively sure and offer a high survival rate of the implants: transposition and lateralization. A research of studies about human beings is carried out, using PubMed and Scopus data bases. The key words were: "transposition", "alveolar nerve", "atrophic mandibles" and "nerve complications". It is performed a total review of 22 articles of clinical cases and in vitro studies; 9 about lateralization, 8 about transposition and 5 about both techniques. Both lateralization and transposition of the inferior alveolar nerve present risks related with neurosensorial complications and mandibular fracture. A high survival rate of the implants without discrimination of the technique is observed. Complications may appear when reposition technique of the inferior alveolar nerve is performed. It is observed a similar behavior between the use of dental implants with a reposition technique and any other, especially in terms of marginal bone loss

Lateralização do nervo alveolar inferior em mandíbula atrófica / Lateralization of the lower alveolar nerve in atrophic mandible

A atrofia óssea fisiológica decorrente da perda dentária associada a doenças sistêmicas como osteoporose limita a reabilitação oral. Pacientes acometidos por estes defeitos e que utilizam por longo prazo bifosfonatos possuem risco aumentado de osteonecrose. São debilitados funcionalmente, aparentam fragilidade, podendo elevar o índice de fratura patológica da mandíbula. Nesse sentido, os sistemas de fixação com placas mais rígidas são indicadas como opção terapêutica capaz de suportar as forças biomecânicas. Aliada a esta, a lateralização do nervo alveolar inferior poderá ser efetuada para evitar dano ao mesmo quando forem colocadas as placas e os parafusos de fixação. O objetivo deste trabalho foi descrever um caso clinico de tratamento de lesão de grande extensão em mandíbula atrófica decorrente da osteonecrose induzida por uso de bifosfonatos com placa de reconstrução pré-modelada com recurso de prototipagem e lateralização do nervo alveolar por meio de acesso intraoral. Conclui-se que, a técnica de lateralização do nervo alveolar inferior permitiu a utilização da placa de reconstrução, sendo considerado um método terapêutico com baixo índice de morbidade, sem evidência de parestesia após quatro meses, repercutindo de forma positiva na qualidade de vida do paciente(AU)

Physiological bone atrophy due to dental loss associated with systemic diseases such as osteoporosis limits oral rehabilitation. Patients affected by these defects and who use long-term bisphosphonates have an increased risk of osteonecrosis. They are functionally weakened, appear brittle, and may elevate the index of pathological fracture of the mandible. In this sense, the fixation systems with more rigid plates are indicated as a therapeutic option capable of withstanding the biomechanical forces. Allied to this, the lateralization of the inferior alveolar nerve can be effected to avoid damage to it when the plates and the fixing screws are placed. The objective of this work was to describe a clinical case of treatment of a large lesion in the atrophic mandible due to the osteonecrosis induced by the use of bisphosphonates with a pre-shaped reconstruction plate with prototyping and lateralization of the alveolar nerve by means of intraoral access. It was concluded that the technique of lateralization of the inferior alveolar nerve allowed the use of the reconstruction plate, being considered a therapeutic method with low morbidity index, without evidence of paresthesia after four months, positively affecting the quality of life of the patient(AU)

Unusual array of neural communications in the infratemporal fossa: Useful for skull base surgery.

Variations in the branching pattern of the mandibular nerve frequently accounts for failure to obtain adequate local anesthesia in routine oral and dental procedures, and also for unexpected injury to the nerves during surgery. The knowledge of the neurovascular relationships of the infratemporal region is relevant in odontostomatology practice. In this article we present a rare case of atypical communication between the inferior alveolar nerve and lingual nerve and the mylohyoid and lingual nerves. Further, the clinical implications of these communications on the development of the supplementary innervation and their possible role in anesthesia is discussed in detail. The communication between mylohyoid and lingual nerve was found in this case near the submandibular ganglion after the lingual nerve passes in close relation to third molar tooth, which makes it more susceptible to injury during third molar extractions. The communicating branch between the mylohyoid nerve and lingual nerve may also innervate the tongue, and surgeons should be aware of this variation to avoid post- operative complcations after oral surgeries. Thus the precise anatomy of structures of infratemporal region and its variations may prove beneficial to clinicians, especially to oral and maxillofacial surgeons.

Bifurcation of the inferior dental nerve canal: an anatomical study.

The aims of this study were to find the incidence of bifurcation of the inferior dental nerve (IDN) canal, to describe the characteristics of this variant, and to examine the sensitivity and specificity of dental panoramic tomography to identify it. We classified bifurcations by size and position relative to the main canal and the lower third molar using cone-beam computed tomography (CT) and dental panoramic tomography. In our study of 281 patients, 106 (38%) had bifurcations, and in one quarter, these were classified as large accessory canals. Bifurcations were most commonly found posterior to the lower third molar (n=64, 57%) or within 2mm of the roots of the third molar (n=40, 38%). The sensitivity and specificity of dental panoramic tomography to identify all bifurcations was 11% (95% CI: 5.67 to 17.97) and 91% (95% CI: 85.58 to 94.68), respectively; this was 33% (95% CI: 15.63 to 55.32) and 94% (95% CI: 90.34 to 96.50), respectively, for large bifurcations. Our use of cone-beam CT suggested an incidence of bifid canals of 38%, with a variation in size and distribution in relation to the lower third molar. It also showed that the sensitivity of panoramic radiography to identify them was poor.

Accessory Mental/Buccal Foramina: Case Report and Review of Literature.

The presence of the additional mental foramen of the mandible is considered to be a rare anatomical occurrence. Only a few cases have been reported. In these cases, only 1 foramen is called the mental foramen and the others are termed either accessory mental foramen or accessory buccal foramen. The purpose of this article was to present a case with computed tomography images and suggest that preoperative cone beam computed tomography should be performed to detect any anatomical variation. In addition, we present all reasonable terminology to ease the communication through unique terminology among surgeons.

Anastomosis between the transverse cervical nerve and marginal mandibular nerve: how often does it occur?

Anastomoses in the neck between the sensory transverse cervical nerve (C2,3) and the cervical branch of the facial nerve are common, but communications with more superior branches of the facial nerve are rare. After we had identified a case where the transverse cervical nerve joined the marginal mandibular branch of the facial nerve in the submandibular triangle during a selective neck dissection, we searched for this variant in 86 neck dissections to see if it occurs more often than expected. We found it in one further patient. As this anastomosis of the nerve could easily be confused with the marginal mandibular branch itself, particularly during a more limited exposure (such as excision of a submandibular gland), our findings remind surgeons to be vigilant when dissecting in this area to minimise the risk of weakness of the lower lip postoperatively.

Anterior loop of the inferior alveolar nerve: Averages and prevalence based on CT scans.

STATEMENT OF PROBLEM: The treatment of edentulous patients by using a complete implant-supported fixed prosthetic with distal extension has been widely studied; success is mainly dependent upon the placement of the distal implants. The location of the inferior alveolar nerve determines implant placement, but the length, prevalence, and symmetry between the left and right side of the anterior loop of the alveolar nerve are unknown. PURPOSE: The purpose of this clinical study was to measure the anterior loop of the inferior alveolar nerve, which determines the placement of distal implants, in a group of 55 Mexican participants. The study expected to ascertain the average length, prevalence, and symmetry between left and right side and any sex differences. To differentiate the inferior alveolar nerve path, a new technique was applied using Hounsfield unit (HU) thresholds. The null hypothesis was that no significant differences would be found between the left and right sides or between men and women for the anterior loop of the inferior alveolar nerve. MATERIAL AND METHODS: Fifty-five computed tomography (CT) scans were made (Somatom Sensation 16; Siemens Healthcare) and were visualized with InVesalius software. Anterior loop measurements were made on 3-dimensional surfaces. To determine statistical differences between the left and right side and between the sexes, the t test was used. The interclass correlation coefficient test was also applied to verify the reliability of the measurements. RESULTS: Ninety percent of participants showed the anterior loop of the inferior alveolar nerve. The length of the anterior loop ranged between 0 and 6.68 mm, with a mean of 2.19 mm. No significant differences were found between the left and right sides or between men and women. CONCLUSIONS: The mean length for the anterior loop in the sample was 2.19 mm. As the anterior loop length shows a high degree of variability, these findings suggest that a CT scan for each patient is recommended in order to visualize a safety zone before placing implants close to the mental foramen.

Avaliação da ocorrência de ramificações dos canais mandibulares em regiões afetadas ou não por inflamação por meio de tomografia computadorizada de feixe cônico / Mandibular canal branching and dental inflammation assessed through cone beam computed tomography

O canal mandibular precisa ser considerado em diversos procedimentos odontológicos, com vistas a evitar injúrias do nervo alveolar inferior. A ocorrência de variações anatômicas do canal mandibular aumenta o risco de lesões neurovasculares. Sensibilidade aumentada e falhas em procedimentos anestésicos em mandíbulas, especialmente em casos com inflamação, também podem estar relacionadas com alterações da inervação local. Este estudo visou avaliar a ocorrência de ramificações dos canais mandibulares em regiões afetadas por inflamação dentária, por meio de tomografia computadorizada de feixe cônico (TCFC), com o intuito de verificar se há algum relacionamento entre ramificações e inflamação. Uma base de dados de 2.484 TCFCs foi revisada para identificar ramificações dos canais mandibulares e inflamação dentária. A amostra final foi pareada para idade e gênero. As ramificações próximas aos dentes posteriores foram consideradas como variável dependente. A ocorrência e localização de inflamação dentária, assim como as medidas dos níveis de cinza nas mesmas regiões, foram consideradas como variáveis independentes. Os testes de Kolmogorov-Smirnov, Qui-quadrado, teste-T e análise por regressão logística foram aplicados para verificar o relacionamento estatístico dos dados (P<0,05). As lesões mais relacionadas às ramificações foram lesões endoperio e lesões apicais. Gênero (P=0,308) e idade (P=0,728) não mostraram associação com a ocorrência de ramificações dos canais mandibulares. A ocorrência de inflamação aumentou o risco para a ocorrência de ramificações dos canais mandibulares próximas aos dentes posteriores. (P<0,001; OR=11,640; IC-95%: 4.327-31.311). As lesões mais frequentemente associadas com as ramificações apresentaram origem endodôntica. Foi verificada associação entre as ramificações dos canais mandibulares e inflamação dentária na região dos dentes posteriores

The mandibular canal must be considered in several dental procedures in order to avoid injuries of the alveolar inferior nerve. The occurrence of anatomical variations of the mandibular canal increases the risk of neurovascular injuries. An increased sensitivity and failed anesthetic procedures in mandibles, especially in cases with inflammation, can be also related with alterations of the local innervation. This study aimed to assess the occurrence of mandibular canal branching (MCB) in alveolar ridges affected by dental inflammation by means of cone beam computed tomography (CBCT), in order to verify if there is some relationship between MCB and dental inflammation. A database of 2,484 CBCTs was reviewed for identifying mandibular canal branching (MCB) and dental inflammation in mandibular alveolar ridges. The final sample was matched by age and gender. MCB nearby the posterior teeth was considered as the dependent variable. Dental inflammation occurrence and location as well as measurements of gray levels at the same region were assessed as independent variables. The Kolmogorov-Smirnov, Chi-square, T-test and multiple logistic regression analysis were applied to verify the statistical relationship of the data (P<0.05). The most frequent inflammatory lesion was apical radiolucency with endodontic origin. The lesions mostly related to MCB were combined endodontic and periodontal lesions and apical lesions. Gender had no influence on mandibular canal branching (P=0.308), not did age (P=0.728). The occurrence of dental inflammation increased the risk for occurrence of the MCB nearby posterior teeth (P<0.001; OR=11.640; CI-95% 4.327-31.311). The gray levels had a minor role on the presence of MCB (P=0.002; OR=1.002; CI95% 1.002-1.003). The lesions most often associated with the branches had endodontic origin. An association between MCB situated around the posterior teeth and dental inflammation was found

Intraparotid Location of the Great Auricular Nerve: A New Anatomical Basis for Gustatory Sweating Syndrome.

BACKGROUND: Gustatory sweating syndrome (also known as Frey syndrome or auriculotemporal nerve syndrome) is thought to result from a lesion of the auriculotemporal nerve. A lesion of this nerve can lead to aberrant regeneration of nerve fibers to the sweat glands and blood vessels. The occurrence of signs outside the region of the auriculotemporal nerve prompted the author to search for another anatomical basis for this syndrome. METHODS: The author dissected 46 great auricular nerves from their origin to the parotid gland and in the infratemporal fossa. The author investigated the different connections of the great auricular nerve with the facial nerve and the auriculotemporal nerve. RESULTS: The great auricular nerve was found to essentially be a parotid nerve. There was a set of intraparotid nerve connections on 14 of the 46 half-heads that were dissected. The author was able to discern three types of parotid great auricular nerve connections, which he designates as either type 1, connection with the trunk of the facial nerve and its branches; type 2, connection with the auriculotemporal nerve; or type 3, connection with the auriculotemporal nerve and the facial nerve with the formation of an intraparotid nerve circle. CONCLUSIONS: Having clearly established the nerve connections of the great auricular nerve, the author believes that it is primarily this nerve that is responsible for gustatory sweating syndrome. This allows for a better understanding of the sympathetic nervous system features and the manifestation of the syndrome outside the region of the auriculotemporal nerve.

Frequency and anatomy of the retromolar canal - implications for the dental practice.

The retromolar canal (RMC) is an anatomical variant of the mandibular canal. Apart from blood vessels it also contains accessory nerve fibers and is clinically important, because its presence can account for failures of mandibular block anesthesias and in rare cases, injuries of its neurovascular bundle can lead to complications such as hemorrhages and dysesthesias. The aim of this retrospective case study was to analyze the frequency and anatomy of the RMC using cone beam computed tomography (CBCT) in order to draw conclusions for the dental practice. A total of 680 CBCT scans comprising 1,340 mandibular sides were evaluated. A total of 216 RMCs (16.12%) were found. The most common appearance of the canal (39.82%) corresponded to type Al (vertical course), whereas type C (horizontal course) occurred least often (6.02%). Mean measured values were 1.03 mm (SD=0.27mm) regarding the RMC diameter, 10.19 mm (SD=2.64mm) regarding the RMC height and 15.10 mm (SD=2.83 mm) regarding the distance of the RMC to the second molar. Neither demographic factors nor the spatial resolution of the CBCT had a statistically significant impact on the frequency of the RMC. Since the present study revealed a frequency of RMCs amounting to 16.12% (corresponding approximately to every sixth retromolar area), we recommend to spare it during surgery or to consider an additional locoregional anesthesia in the retromolar region. For preoperative diagnosis the CBCT has proved suitable, offering the possibility to select the spatial resolution depending on the indication, so that radiation exposure is reduced without a decrease in validity.

Anatomical study of the course of the inferior alveolar nerve in craniofacial microsomia using three-dimensional computed tomography: correlation with the Pruzansky classification.

Dysmorphogenesis of the mandible complicates assessment of the course of the inferior alveolar nerve in patients with craniofacial microsomia. Our aim in the present study was to correlate the anatomical description of the course with the Pruzansky classification (which indicates the severity of hemifacial microsomia), in the mandibles of 22 affected patients using 3-dimensional computed tomography (CT). We measured the distance between fixed landmarks on the normal and the microsomic sides. The normal sides served as controls. In the group of five patients with type I disease, we found no significant differences between the unaffected and the microsomic side. In the nine patients with Pruzansky type II disease morphological views of the course showed a between-side difference in the length of the bony canal and the height of the mandibular ramus. In the five patients with Pruzansky type III disease, there was no bony canal. Three-dimensional CT analysis may be of value in plotting the course of the inferior alveolar nerve and assisting the surgeon in mandibular osteotomy or distraction osteogenesis.

Variations in the branching pattern of posterior division of mandibular nerve: a case report.

PURPOSE: Abnormal communications among the branches of mandibular nerve especially the posterior division are significant due to various procedures undertaken in this region. These variations are worth reporting as they pose serious implications in several interventions in this region, and may even lead to false diagnosis. METHODS: During routine dissection, the mandibular nerve and its branches were dissected in the infratemporal fossa. The branches from the posterior division of the mandibular nerve namely the inferior alveolar and auriculotemporal nerves were carefully dissected, and their abnormal branching pattern was noted. RESULTS: There was a communicating branch between left inferior alveolar and auriculotemporal nerve. There was also a variant recurrent branch from the left inferior alveolar nerve that supplied the lateral pterygoid muscle. CONCLUSIONS: Such variant branches and communications between the branches of mandibular nerve as seen in this case have an embryological basis and are clinically important in this region especially for dental surgeries and anesthesia.

Accessory mandibular foramen during dental implant placement: case report and review of literature.

Accurate knowledge of vital anatomical structures, such as the inferior alveolar nerve, mental nerve, and mental foramen, is critical to achieve favorable results during oral surgical procedures and dental implant placement. Although uncommon, variations in mandibular foramina have been reported and if unnoticed and, as a result, injured, may lead to patient morbidity, neurosensory disturbances, and other undesired complications. We present a case report of identification of an accessory mandibular foramen (AMF) encountered during placement of 2 dental implants for a mandibular implant-retained overdenture and demonstrate appropriate management. In addition, we propose a more reasonable terminology for such accessory foramina so as to facilitate communication through common terminology among health care providers. As conventional radiography (periapical and panoramic films) may not allow for proper identification of such anatomical variations, cone-beam computed tomography may be useful in the diagnosis of AMF during treatment planning of dental implants in the mandible.

Bilateral anomalous high position of the mandibular foramen: a case report.

The inferior alveolar nerve block is one of the most common techniques for delivering dental anesthesia. Its success depends on placing the needle tip in close proximity to the mandibular foramen (MF). In certain cases, however, this nerve block fails, even when performed by the most experienced clinician. Anatomical variability may be one source of local anesthetic failure and includes bone and nerve variations. A case is presented of a bilateral anomalous high position of the MF, identified from the panoramic radiograph. An adjusted anesthetic technique (the Vazirani-Akinosi technique) was used to achieve local anesthesia before extraction of a lower second molar following an unsuccessful conventional indirect technique with a higher entry point. A description of the embryological basis for the anomalous high positioned MF and its impact from a practical and clinical perspective, with particular reference to local anatomy, is included.

Pain caused by a dental implant impinging on an accessory inferior alveolar canal: a case report.

This report presents a case history of intractable facial pain following the placement of a posterior mandibular implant. The pain was resistant to all medical management, but a cone beam computed tomography (CBCT) scan showed that the implant impinged on an unusual accessory inferior alveolar nerve. The decision to remove the implant led to significant pain reduction. This clinical example underscores the need for scrupulous imaging prior to implant placement.

Extramandibular position of the inferior alveolar nerve. Analysis and review of the literature.

We report a highly unusual case of unilateral absence of the mental foramen, with the inferior alveolar nerve exiting the mandible via an orifice situated on the lateral surface of the angle of the mandible. However, the teeth on this side of the dental arch had normal sensitivity, and the mandible had grown correctly. Despite the absence of intraosseous course, the inferior alveolar nerve seems to keep its neural and guide roles.

A case report of developmentally missing mental foramen.

The inferior alveolar nerve is the mandibular division of the trigeminal nerve. Studies have documented variations in the course and branching pattern of the nerve. Here the author reports a case of developmentally missing mental foramen in an individual with normal sensory function. Identification of variations in the nerve pathway is essential for treatment planning in the area.

The clinical relevance of bifid and trifid mandibular canals.

BACKGROUND: Bifid mandibular canals (BMC) and trifid mandibular canals (TMC) are variations on the normal anatomy with incidences ranging from 0.08% to 65.0%. Such aberrations have an important clinical impact. For example, an extra mandibular canal may explain inadequate anesthesia, especially when two mandibular foramina are involved. Furthermore, during mandibular surgery, a second, or even third, neurovascular bundle may be damaged causing paresthesia, neuroma development, or bleeding. CASE REPORT: Two cases are presented in this article. One patient had a BMC on both sites, and the other patient had a TMC on one site and a BMC on the other site. DISCUSSION: Initial screening for the presence of a BMC or TMC can be executed by conventional panoramic radiography. BMCs or TMCs are diagnosed, before executing mandibular surgery; additional CBCT scanning is indicated.