Prevention of neurological injuries during mandibular third molar surgery: technical notes

Surgery to the mandibular third molar is common, and injuries to the inferior alveolar nerve and the lingual nerve are well-recognized complications of this procedure. The aim of these technical notes is to describe operative measures for reducing neurological complications during mandibular third molar surgery. The following procedure should be used to prevent damage to the inferior alveolar nerve: a well-designed mucoperiosteal flap, to obtain appropriate access to the surgical area; a conservative ostectomy on the distal and distal-lingual side; tooth sectioning, to facilitate its removal by decreasing the retention zones; tooth dislocation in the path of withdrawal imposed by the curvature of the root apex; and careful socket debridement, when the roots of the extracted tooth are in intimate contact with the mandibular canal. To prevent injury to the lingual nerve, it is important (I) to assess the integrity of the mandibular inner cortex and exclude the presence of fenestration, which could cause the dislocation of the tooth or its fragment into the sublingual or submandibular space; (II) to avoid inappropriate or excessive dislocation proceedings, in order to prevent lingual cortex fracture; (III) to perform horizontal mesial-distal crown sectioning of the lingually inclined tooth; (IV) to protect the lingual flap with a retractor showing the cortical ridge; and (V) to pass the suture not too apically and from the inner side in a buccal-lingual direction in the retromolar are

The assesment of relationship between the angulation of impacted mandibular third molar teeth and the thickness of lingual bone : a prospective clinical study

Our purpose was to investigate the relationship between the angulation of mandibular third molars and the thickness of the lingual bone, which can affect the risk of lingual nerve damage during lower third molars surgical extraction. This study consisted of 104 patients (42 males and 62 females), aged between 18-42 years (24.67 ± 6.11 years). Cone Beam Computed Tomography (CBCT) images were taken for preoperative assessment. The teeth were divided into four groups according to their positions: mesioangular, distoangular, vertical and horizontal. Lingual bone thickness around impacted teeth were measured at three points: cementoenamel junction (CEJ) of the mandibular second molar, mid-root of the impacted third molar, and apex of the impacted third molar root. Two predisposing factors of lingual nerve damage were recorded: lingual bone perforated by the impacted tooth and lingual bone thinner than 1 mm. Additionally, buccolingual angulations of the teeth in each group were measured. Impacted mandibular third molars were removed in usual way. One week after surgery, the patients were evaluated regarding lingual nerve paresthesia. None of the 104 patients experienced paresthesia, including the ones who had teeth with close proximity with lingual nerve. The mean thickness of bone was 1.21±0.63 mm at CEJ of the second molar; 1.25±1.02 mm at the mid-root; and 1.06±1.31 mm at the apex. Horizontally impacted teeth had thinner lingual bone at mid-root level (p=0.016). Buccolingual angulated teeth were more often associated with perforated lingual bone (p=0.002). Buccolingual and mesial/distal angulation had negative correlation with lingual bone thickness (p<0.05). As the buccolingual and mesiodistal angulations increase, lingual bone thickness decreases. Horizontally impacted teeth seemed to compromise the integrity of the lingual bone more than impacted teeth in other positions. During the surgery, thin or perforated lingual bone may result in displacement of the impacted tooth lingually

Frequency of Lingual Nerve Injury after the Removal of Impacted Mandibular Third Molar

Objective: to determine the frequency of lingual nerve injury after the removal of impacted mandibular 3rd molar. Study Design: Cross sectional study Place and duration: outdoor patient department of Oral and Maxillofacial Surgery Hitec Dental College, Foundation College of Dentistry Peace Gernal Hospital, Nishtar Institute of  Dentistry,Multan from January 2018 to January 2019 in one year duration. Results: Study included 335 patients with mean age of 20.86+ 1.95 yrs. Males were 190(56.7%) and females were 145(43.3%).lingual nerve injury was found in 28 patients(8.4%)while it was absent in 307 patients(91.6%).There was no significant effect was found on the frequency of lingual nerve injury for age or gender of the patient population. Conclusion: Lingual nerve injury is a commonly encountered complication among those undergoing extraction of impacted third molar. It should be carefully sought in all the patients undergoing the surgical procedure and improvement in surgical skills and techniques needs to be emphasized to further reduce the incidence and risk of this complication. Keywords: Impacted third molar, Lingual nerve, OPG (orthopantomogram), Dentistry, Mandible. DOI: 10.7176/JMPB/57-01 Publication date: July 31st 201

Clinical outcomes of lingual nerve repair

Lingual nerve injury, a well-described complication of third molar removal, may result in permanent lingual sensory deficit leading to symptoms including lost or altered sensation, inadvertent tongue biting, and the development of unpleasant neuropathic pain, with consequent impaired quality of life. We analysed outcomes of a prospective case series to determine whether direct anastomosis of the lingual nerve results in improved sensory recovery and reduced neuropathic pain, and whether delayed surgery is worthwhile. In 114 patients who underwent nerve repair at our nerve injury clinic following damage sustained during mandibular third molar removal, sensory deficit was assessed before and after surgery using a questionnaire and visual analogue scales (VAS) to assess pain, tingling, and discomfort. Neurosensory tests were utilised to evaluate light touch, pin-prick, and two-point discrimination thresholds. Subjectively, 94% patients felt their sensation had improved following nerve repair, with significant reductions in the incidence of tongue biting (p 40) showed highly significant reductions in pain (p < 0.0001). No correlation was found between surgical outcome and patient’s age or delay until surgery. Lingual nerve repair results in good sensory outcomes and significant improvements in the incidence and degree of neuropathic pain, even when delayed

Correlation of miRNA expression with intensity of neuropathic pain in man

Background Peripheral nerve injury causes changes in expression of multiple receptors and mediators that participate in pain processing. We investigated the expression of microRNAs (miRNAs) – a class of post-transcriptional regulators involved in many physiological and pathophysiological processes – and their potential role in the development or maintenance of chronic neuropathic pain following lingual nerve injury in human and rat. Methods We profiled miRNA expression in Sprague-Dawley rat and human lingual nerve neuromas using TaqMan® low-density array cards. Expression of miRNAs of interest was validated via specific probes and correlated with nerve injury-related behavioural change in rat (time spent drinking) and clinical pain (visual analogue scale (VAS) score). Target prediction was performed using publicly available algorithms; gene enrichment and pathway analysis were conducted with MetaCore. Networks of miRNAs and putative target genes were created with Cytoscape; interaction of miRNAs and target genomes in rat and human was displayed graphically using CircosPlot. Results rno-miR-138 was upregulated in lingual nerve of injured rats versus sham controls. rno-miR-138 and rno-miR-667 expression correlated with behavioural change at day 3 post-injury (with negative (rno-miR-138) and positive (rno-miR-667) correlations between expression and time spent drinking). In human, hsa-miR-29a was downregulated in lingual nerve neuromas of patients with higher pain VAS scores (painful group) versus patients with lower pain VAS scores (non-painful). A statistically significant negative correlation was observed between expression of both hsa-miR-29a and hsa-miR-500a, and pain VAS score. Conclusions Our results show that following lingual nerve injury, there are highly significant correlations between abundance of specific miRNAs, altered behaviour and pain scores. This study provides the first demonstration of correlations between human miRNA levels and VAS scores for neuropathic pain and suggests a potential contribution of specific miRNAs to the development of chronic pain following lingual nerve injury. Putative targets for candidate miRNAs include genes related to interleukin and chemokine receptors and potassium channels

Sensibility and taste alterations after impacted lower third molar extractions. A prospective cohort study

Objectives: To determine the incidence, severity and duration of lingual tactile and gustatory function impairments after lower third molar removal. Study Design: Prospective cohort study with intra-subject measures of 16 patients undergoing lower third molar extractions. Sensibility and gustatory functions were evaluated in each subject preoperatively, one week and one month after the extraction, using Semmes-Weinstein monofilaments and 5 different concentrations of NaCl, respectively. Additionally, all patients filled a questionnaire to assess subjective perceptions. Results: Although patients did not perceive any sensibility impairments, a statistically significant decrease was detected when Semmes-Weinstein monofilaments. This alteration was present at one week after the surgical procedure and fully recovered one month after the extraction. There were no variations regarding the gustatory function. Conclusions: Lower third molar removal under local anesthesia may cause light lingual sensibility impairment. Most of these alterations remain undetected to patients. These lingual nerve injuries are present one week after the extraction and recover one month after surgery. The taste seems to remain unaffected after these procedures

An anomalous neural interconnection between the Lingual and Mylohyoid Nerves

ABSTRACT The interconnection between the lingual nerve (LN) and the hypoglossal nerve, the LN and the inferior alveolar nerve (IAN), and the LN and the mylohyoid nerve (MHN) has already been documented in the literature. Despite the fact that variations in the course of the MHN in regard to the mandible are regularly observed, they have yet to be well documented in the anatomical or surgical literature. This anatomical variety necessitates that surgeons and anesthesiologists who routinely perform oro-surgical interventions and nerve blocks in the face for various neuralgias enhance their knowledge and awareness in order to avoid unintended nerve injury. In the present case report, we observed an aberrant neural loop connecting LN and MHN, as well as anatomical insight into an integrated component of MH along with LN in addition to the motor component.Keywords             : Lingual nerve, Mylohyoid nerve, Interconnection, Neural Loop Correspondence    [email protected]

Sensory disturbances of buccal and lingual nerve by muscle compression: a case report and review of the literature

Introduction: several studies on cadavers dissection have shown that collateral branches of the trigeminal nerve cross muscle bundles on their way, being a possible etiological factor of some nerve disturbances. Case Report: a 45-year-old man attended to the Temporomandibular Joint and Orofacial Pain Unit of the Master of Oral Surgery and Implantology in Hospital Odontològic of Barcelona University, referring tingling in the left hemifacial región and ipsilateral lingual side for one year, with discomfort when shaving or skin compression. Discussion: several branches of the trigeminal nerve follow a path through the masticatory muscles, being the lingual nerve and buccal nerve the most involved. The hyperactivity of the muscle bundles that are crossed by nerve structures generates a compression that could explain certain orofacial neuropathies (numbness and / or pain) in which a clear etiologic factor can not be identified

Sensory disturbances of buccal and lingual nerve by muscle compression: a case report and review of the literature

Introduction: Several studies on cadavers dissection have shown that collateral branches of the trigeminal nerve cross muscle bundles on their way, being a possible etiological factor of some nerve disturbances. Case Report: A 45-year-old man attended to the Temporomandibular Joint and Orofacial Pain Unit of the Master of Oral Surgery and Implantology in Hospital Odontològic of Barcelona University, referring tingling in the left hemifacial región and ipsilateral lingual side for one year, with discomfort when shaving or skin compression. Discussion: Several branches of the trigeminal nerve follow a path through the masticatory muscles, being the lingual nerve and buccal nerve the most involved. The hyperactivity of the muscle bundles that are crossed by nerve structures generates a compression that could explain certain orofacial neuropathies (numbness and / or pain) in which a clear etiologic factor can not be identified

Inferior alveolar and lingual nerve injuries: An overview of diagnosis and management

Oral and maxillofacial surgery operations are susceptible to cause injury to terminal branches of the trigeminal nerve. The mandibular division is more prone to injury than ophthalmic and maxillary nerves. Inferior alveolar branch of the trigeminal nerve is the most commonly injured branch, followed by the lingual nerve. These nerves may be subjected to neurosensorial disturbance during third molar surgery, followed by sagittal split ramus osteotomy, endodontic therapy and dental implant placement. Local anesthetic injections, pre-prosthetic surgery, various other types of orthognathic surgery, ablative tumor surgery involving mandibular resections, osteoradionecrosis, osteomyelitis or maxillofacial trauma are among other potential etiologic factors. If an inferior alveolar or lingual nerve injury occurs, a timely diagnosis and a proper management are key factors to avoid further or permanent damage. A wide range of therapeutic modalities are available in managing nerve injuries, ranging from simple observation to complex grafting, depending on various factors. Data regarding nerve injuries may not always be reliable since most are based upon personal experience and in a retrospective nature. It is also challenging to draw proper conclusions from studies on nerve injuries due to the differences in outcome criteria and assessment methods. Still, an accurate knowledge of anatomy should be combined with both clinical and radiological data to avoid any nerve-related complications. Thus, this article will present a narrative review of the current literature on the inferior alveolar and lingual nerve injuries, focusing on the functional assessment methods, factors influencing recovery, the contemporary management protocols as well as future trends in nerve repairs