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The aim was to present expert-based guidelines on the management of trigeminal nerve injuries. A two-round multidisciplinary Delphi study was conducted amongst international trigeminal nerve injury experts with a set of statements and three summary flowcharts using a nine-point Likert scale (1 = strongly disagree; 9 = strongly agree). An item was deemed appropriate if the median panel score was within the range of 7-9, undecided if the score was 4-6, and inappropriate if the score was 1-3. Consensus was achieved if at least 75% of panelists scored within one range. Eighteen specialists from dental, medical, and surgical specialties participated in both rounds. Consensus was reached on most statements related to training/services (78%) and diagnosis (80%). Statements related to treatment were mainly undecided due to a lack of sufficient evidence for some of the proposed treatments. Nevertheless, the summary treatment flowchart reached consensus with a median score of eight. Recommendations on follow-up and opportunities for future research were discussed. None of the statements were deemed inappropriate. A set of recommendations and accepted flowcharts are presented; these will aid professionals involved in managing patients with trigeminal nerve injuries., Competing Interests: Competing interests John Zuniga is a consultant for Axogen Inc. and a member of the board of directors at the Global Nerve Foundation., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Neurosensory disturbance of the inferior alveolar nerve (IAN) is an adverse effect associated with sagittal split osteotomies (SSO). The purpose of this work was to evaluate neurosensory recovery of the IAN when SSOs were performed with piezoelectric (PZ) versus reciprocating (RP) saws. This was a prospective split-mouth study of patients undergoing bilateral SSO using a PZ saw on one side and an RP saw on the other. The primary outcome of interest was neurosensory recovery, as assessed using the functional sensory recovery (FSR) scale defined by the UK Medical Research Council. Descriptive, bivariate, and regression statistics were computed. Twenty patients (40 SSOs) with a mean age of 19.9 ± 3.2 years were included. The mean mandibular movement did not differ significantly (P = 0.50) between the PZ and RP groups. All patients achieved FSR within 1 year of surgery (range 34-249 days). The median time to FSR overall was comparable between the PZ and RP groups (94.5 days and 101.5 days, respectively; P = 0.20). However, at the time FSR was achieved, PZ SSO sites were more likely to have higher neurosensory scores when compared to RP SSO sites (hazard ratio 2.3, 95% confidence interval 1.1-4.9, P = 0.04)., (Copyright © 2021 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

This systematic review and exploratory meta-analysis of the available evidence was performed to examine whether early nerve repair of lingual nerve (LN) and inferior alveolar nerve (IAN) injuries has an effect on neurosensory recovery. A literature search was conducted to identify relevant studies meeting the inclusion criteria. Two reviewers independently evaluated the methodological quality of the included studies and the risk of bias using the ROBINS-I quality assessment tool. For the quantitative analysis, data were pooled using the Mantel-Haenszel random-effects method due to the clinical heterogeneity across the studies. Sensitivity and subgroup analyses were performed based upon the group definition of timing from injury to nerve repair, with breakpoints of 2, 3, and 6 months. A total 1236 citations were identified, with a final 13 studies included in the systematic review. A clear definition of 'early' versus 'late' repair was not reported in six studies, allowing only seven to be included in the meta-analysis. The effect of early repair on functional sensory recovery was found not to be significant in nine studies, while four studies found a significant effect of early intervention. The meta-analysis showed a combined success rate of 93.0% for the early group and 78.5% for the late group. The odds of improvement were 5.49 (95% confidence interval 1.40-21.45) in the 3-month breakpoint studies and 2.28 (95% confidence interval 1.05-4.98) in the 6-month studies. A trend towards early repair achieving better functional sensory recovery outcomes was observed, but the specific time period is unknown., (Copyright © 2020 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Post-traumatic trigeminal neuropathy (PTTN) is a known complication of common oral and maxillofacial procedures. The burden on the patient and society is often underestimated. This retrospective study included 29 patients with PTTN who underwent surgical treatment. Symptoms were differentiated, pre- and postoperatively, into neuropathic discomfort and loss of perceptive function. Clinical and patient-reported outcomes were recorded. The Brief Pain Inventory questionnaire was completed at the last follow-up. The effect of different variables was evaluated through subgroup analysis. The mean time interval between injury and surgery was 19 weeks. Overall, 20 patients (69%) showed improvement during a mean follow-up of 49 months. Neuropathic pain decreased in most patients (13/18; 72%) and two patients became pain-free. However, 16 patients reported persistent pain on the Brief Pain Inventory questionnaire. Medication use decreased postoperatively. Subgroup analysis showed a positive association between improvement and male sex (Fisher's exact test, P=0.033), and between improvement and the buccal fat nerve wrapping procedure (Fisher's exact test, P=0.02). In conclusion, surgery showed substantial benefit in the treatment of PTTN, even when neuropathic pain was present. The effect of different variables and the potential of buccal fat nerve wrapping should be evaluated further in future research., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

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<0.0001), impaired speech (p<0.0001), and neuropathic pain (p=0.0017). Quantitative neurosensory data showed highly significant improvements in light touch, pin-prick, and two-point discrimination (all p<0.0001), and VAS scores for pain (p=0.0145), tingling (p<0.0025), and discomfort (p<0.0001) were significantly reduced. Patients with high levels of pain preoperatively (VAS>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., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Coronectomy is an alternative surgical technique for the management of high-risk third molars. It involves the removal of the crown of a tooth and the deliberate retention of the roots, thereby avoiding injury to the inferior alveolar nerve (IAN). Previous studies have suggested that it reduces the risk of nerve injury when compared with surgical extraction. The purpose of this study was to systematically review the incidence of complications following coronectomy such as IAN injury, pain, dry socket, infection, root migration, and need for re-operation. A comparative cost analysis of coronectomy and surgical extraction was done based on the results of the review. This provides an insight into the economic implications of the two procedures. A search through the MEDLINE database via Ovid, PubMed, Scopus, EMBASE via Ovid, and Web of Science, was carried out to extract randomised and non-randomised controlled trials. Four studies fulfilled the inclusion criteria. A meta-analysis was conducted to measure the overall effect of each outcome. The pooled odds ratio (OR) for IAN injury was 0.16 (95% CI 0.01 to 0.39). Coronectomy reduced this risk by 84%. Dry socket may occur less frequently following coronectomy whereas infection did not show a higher incidence with either intervention. Root migration was found to occur in 13%-85% of cases and the average incidence of re-operation was 2.2%. The ratio of the average costs was 1.12 favouring coronectomy if cone-beam computed tomography (CBCT) was not done prior to the procedure. If a scan was taken routinely for coronectomy, the cost ratio marginally favoured extraction. Coronectomy reduced the risk of nerve injury in high-risk third molars. Definitive conclusions, however, cannot be made for outcomes such as the need for re-operation, which may alter the cost ratio of coronectomy:extraction, as higher quality studies with longer follow-up are needed., (Copyright © 2020 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

To the best of our knowledge there are no guidelines regarding the surgical management of dental implant-related injuries to the mandibular nerve. This review aims to investigate the success of different surgical interventions. Neurosensory injury to the mandibular branch of the trigeminal nerve can occur during administration of local anaesthetic, elevation of the flap, preparation for osteotomy, and placement of the implant. Surgical interventions include extraction of the implant, external decompression, internal neurolysis, excision of a neuroma, neurorrhaphy, nerve grafting, and low-level laser therapy. The following electronic databases were searched: MEDLINE, EMBASE, and the Cochrane Library. Primary outcome measures included patient-reported outcomes such as pain and altered sensation. A total of 185 publications were obtained, of which 21 were included in the qualitative synthesis (2 randomised controlled trials (RCT), 9 controlled cohort studies, and 10 case reports/series). They were all screened in consideration of the exclusion criteria and appraised using the Cochrane risk of bias tool, the Newcastle Ottawa scale, and the modified Newcastle Ottawa scale. Results were triangulated to evaluate their level of agreement. The extraction of dental implants less than 36hours after injury to the mandibular nerve results in the most successful resolution of neurosensory dysfunction. Various microsurgical techniques have shown less success in obtaining neurosensory recovery than extraction of the implant. However, microsurgery is worthwhile, as it improves neurosensory dysfunction and reduces dysaesthesia in the majority of patients. Direct suturing and external decompression can result in good neurosensory recovery, and nerve grafts are also successful whenever tension-free direct suturing is not possible. Low-level laser therapy has been shown to achieve some neurosensory improvement., (Copyright © 2020. Published by Elsevier Ltd.)

We have investigated the effect of photobiomodulation on the recovery of neurosensory function of the lip and chin after bilateral sagittal split osteotomy (BSSO). Laser irradiation was applied with a GaAs diode laser (continuous wave 980nm wavelength, power 100mW, and energy density 12J/cm 2 ). It was maintained within a 0.5cm 2 area in a total of 12 points for 60seconds at each visit on each point. Unilateral extraoral contact photobiomodulation treatment was applied the day before operation and then on days 1, 3, 7, 14, 21, and 28 postoperatively. One side of the mandible was the intervention side and the other the control side. On the control side, the laser probe was turned off and placed on the chosen area. Neurosensory evaluations were made before and immediately after operation, and 30 days and 60 days postoperatively. Twenty-five patients were screened, and 18 who met the inclusion criteria were included in the study; 14 were women and the mean (SD) age was 23 (5) years. Analysis of the visual analogue scales for general sensibility, pain discrimination, directional discrimination, and 2-point discrimination showed a significant difference between the intervention and control sides after 30 days (p=0.0011, 0.0034, 0.0023, and 0.0160, respectively). The difference was also significant after 60 days (p=0.0001, 0.0002, 0.0003, and 0.0010, respectively). The thermal discrimination rate was significantly higher in the laser group than the control group 30 days after surgery (p=0.002), but after 60 days the difference was not significant (p=1.000). We found no side effects from the laser radiation during the two-month follow up. The results suggest that photobiomodulation accelerated the patients' improvement from neurosensory disturbance after BSSO., (Copyright © 2020 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The purpose of this study was to characterize the patterns of lingual split and lateral bone cut end (LBCE) after bilateral sagittal split osteotomy (BSSO) in patients and identify their associations with postoperative neurosensory disturbance. This retrospective cohort study recruited 273 patients with skeletal malocclusion who received BSSO. The postoperative cone beam computed tomography data were reconstructed to three-dimensionally view the patterns of lingual split and LBCE. Associations between lingual split and LBCE and their effects on neurosensory disturbance in the lower lip and chin were determined. Six types of lingual split and three types of LBCE were defined based on three-dimensional images. Type I lingual split as a vertical fracture line to the inferior mandibular border was the most common (40.29%). Inferior LBCE was the most prevalent, followed by lingual and buccal types. Significant associations among lingual split, LBCE and skeletal deformities were found (P < 0.05). However, patterns of lingual split and LBCE were not associated with the incidence of neurosensory disturbance. Patterns of lingual split after BSSO significantly associated with types of LBCE and dentomaxillofacial deformities, but not with postoperative neurosensory disturbance., (Copyright © 2019 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

This survey of expert opinion regarding the management of mandibular third molar (M3M) impaction and its clinical sequelae was circulated to all members of the British Association of Oral and Maxillofacial Surgeons (BAOMS). It was completed by 289 clinicians who reported treating 60003 patients annually. Respondents included 199 (69%) specialists and 58 (20%) primary care clinicians. Most (99%) of the clinicians treated at least one M3M with complete surgical removal (CSR) annually. Only 69% performed one or more coronectomies (COR). Advocates of coronectomy reported lower rates of inferior alveolar nerve (IAN) injury, but IAN, lingual nerve, and adjacent second molar damage were rare, occurring in less than 0.5% of cases, with small differences between the COR and CSR groups. Although these differences are not statistically significant, they are likely to be clinically important. Also, the COR group would have comprised mainly high-risk teeth, while the CSR group would include many teeth at low risk of complications. This might have skewed the results. Those clinicians performing no coronectomies cited three main reasons for being low adopters of COR: the lack of irrefutable evidence to support its benefit, the increased need for a second operation, and more non-IAN complications. Although COR may prevent permanent IAN damage in high-risk cases, this paper highlights clinicians' views that there is a gap in evidence and knowledge to support COR. As a result, 47% of the clinicians surveyed recommended, and were prepared to participate in, further studies to determine the effectiveness and safety of COR., (Copyright © 2020 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The aim of this study was to introduce a method to evaluate the risk of inferior alveolar nerve (IAN) injury following the extraction of impacted lower third molars. Two hundred impacted lower third molars adjacent to the IAN were evaluated. These were divided into four classification groups according to preoperative cone beam computed tomography (CBCT) findings: AR, apical region; LT, lateral region of the tapered root; LE, lateral region of the enlarged root; AE, adjacent to the enlarged root. All teeth were dislocated along the long axis or arc of the root by tooth sectioning technique and extracted by a single surgeon. The primary outcome variable was postoperative neurosensory impairment of the IAN. The χ 2 test was used to evaluate differences in postoperative IAN injury between the classifications. Logistic regression analysis was used to evaluate the risk factors for postoperative IAN injury. The overall incidence of postoperative IAN injury was 7%. Specifically, most injuries involved classification AE (AE 36%, LE 8.6%, LT 3.6%, AR 0%), and the difference was statistically significant (P< 0.05). Logistic regression showed that classification AE was the only risk factor for postoperative IAN injury (P< 0.001). According to preoperative CBCT, the risk of postoperative IAN injury is higher when the IAN is adjacent to the enlarged part of the root., (Copyright © 2019 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Our aim was to evaluate neurosensory symptoms after lateralisation of the inferior alveolar nerve (IAN). We studied a retrospective case series with one-year follow up that included 139 procedures in 123 patients. After the IAN had been located it was deflected from the mandibular body and the implant placed. Sensitivity was mapped 24hours, one month, six months, and one year after the intervention by gently pressing the skin and lips with the tip of a probe. A total of 337 implants were placed in 123 patients aged between 44 and 68 years. There were 33 men and 90 women and they all recovered. The IAN was mobilised by one of two procedures, one that involves the nerve directly (transposition) and one that does not (lateralisation). During lateralisation the nerve is deflected laterally through a mandibular osteotomy, while the mental nerve and mental foramen are not manipulated. The resulting hypoaesthetic area was drawn on a graph to assess its extension. Although different techniques are available for placing implants in atrophic jaws, mobilisation of the IAN is indicated in certain cases in which other techniques are not feasible or have a high risk of complications., (Copyright © 2019 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The extraction of mandibular third molars can lead to injury to the inferior alveolar nerve. Hence, it is important to assess the proximity of the root to the inferior alveolar canal before extraction. The classification system of Pell and Gregory and the Winter classification are commonly used to evaluate the positional relationship of the third molar based on radiographs. This retrospective study involving 105 mandibular third molars was performed to assess whether these systems reflect the proximity of the root to the canal (based on computed tomography images), and to identify risk factors for nerve injury. Regarding the prediction of computed tomography-verified canal invasion, the sensitivity, specificity, and positive and negative predictive values were high for each Pell and Gregory category when there was radiographic evidence. The mean distance of invasion was significantly greater in class III than in class I. However, there were no significant differences between the Winter inclination categories. The mean distance differed significantly between a horizontal inclination angle to the buccal side of >5° and an angle of ≤5°. Thus, a horizontal inclination angle >5° represents a novel risk factor for nerve injury., (Copyright © 2017 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Coronectomy is gaining popularity for the management of mandibular third molars that pose a risk of injury to the inferior dental nerve, as it considerably reduces the risk when compared with extraction. The technique could also be beneficial to other teeth. We report 17 patients who had coronectomy of mandibular teeth that were not third molars. Clinical and radiographic follow up for a median (range) of 12 (1-79) months showed satisfactory healing and no transient or permanent injury to the nerve. None of the retained roots have required retrieval., (Copyright © 2016 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The purpose of this study was to evaluate the relationship between third molars and the inferior alveolar canal using panoramic radiographs and cone beam computed tomography (CBCT) scans and to assess clinical outcomes after third molar removal retrospectively. The degree of superimposition, buccolingual position (buccal, central, and lingual) and physical relationship (separation, contact, and involved) were measured using CBCT scanning. Post-extraction complications were recorded. Based on radiographic evaluation, 45.9% of third molar roots were inside the inferior alveolar canal, 21.3% were in contact with the inferior alveolar canal, and 32.8% were separated from the canal. The frequency at which the mandibular canal was separated from the root apex was significantly higher when the canal was in the buccal position (80.0%) than in the central (20.0%) and lingual positions (0.0%). Although on panoramic radiographs all third molars were directly superimposed on the inferior alveolar canal, CBCT showed direct contact or canal involvement in 67.2% and separation of the canal from the root apex in 32.8%. Complications occurred in nine patients: eight had third molar root apices inside or in contact with the inferior alveolar canal. The prevalence of post-extraction complications correlated with the absence of cortication around the inferior alveolar canal., (Copyright © 2012 International Association of Oral and Maxillofacial Surgeons. All rights reserved.)

Bilateral sagittal split ramus osteotomy (BSSO) is widely used to treat mandibular prognathism. Several methods have been described for fixation of the bony segments. This study compared two methods of rigid fixation (bicortical screws and monocortical miniplates) to identify differences in postoperative masticatory function and neurosensory disturbance after 5 years of mandibular set-back correction. 77 women who had undergone BSSO for Class III malocclusion were reviewed, and masticatory functions and neurosensory recovery were examined with the appropriate indicators pre- and postoperatively (at approximately 1 month, and 1, 2, 3, 4, and 5 years). Masticatory function exhibited similar recovery patterns in both groups. Orthognathic surgery improved occlusal force and occlusal contact area, but longer than 4 years after surgery may be required for postoperative occlusal functions in prognathic patients to reach the level of healthy subjects. The groups showed no significant differences in the recovery of parameters of masticatory functions and neurosensory disturbance even 5 years after surgery. In the evaluation of temporomandibular joint function using the Helkimo index, the score was significantly higher for the screw group than for the miniplate group. This suggests that BSSO fixed with miniplates may offer a relatively safe and reliable procedure yielding adequate results and high patient satisfaction., (Copyright © 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The sensitivity of teeth anterior to a fracture between the mental and mandibular foramina has been tested and followed up until reinnervation or 3 years has passed. This study assessed the reinnervation period, the number of denervated teeth, and their clinical importance. Fifty patients and 459 teeth were examined. Two hundred and seventy-three teeth were affected and had potentially impaired innervation. Tests after injury showed non-responsive teeth in 81% of affected teeth. Six weeks after injury, 19% of teeth were reinnervated; by 1 year after injury, 92% of initially non-responsive teeth were reinnervated. Most teeth (34%) were reinnervated from 6 weeks to 3 months. All 23/186 initially non-responsive, unaffected, contralateral corresponding teeth were reinnervated within 6 weeks. A year after injury, 95% of incisors, 91% of canines, 94% of premolars, and 82% of molars were reinnervated. Three years after injury, 8% of teeth remain denervated. During the second and third years, no reinnervation occurred, but clinical signs of pulp devitalisation of denervated teeth occurred in 18% or 1% of the initially non-responsive affected teeth. The results revealed the stability of pulp 1 year after injury. Denervated teeth should not be treated if no clinical or radiological signs of devitalisation exist., (Copyright © 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The treatment of midfacial fractures depends on the dislocation of the fracture and patient-related limitations. Surgical treatment risks iatrogenic complications. In 740 patients with midfacial fractures, the age, sex, fracture type, concomitant injuries, cause of accident and the decision to use operative or non-surgical treatment were recorded. Follow-up was performed 6 and 12 months after the injury. In 41% the fractures were isolated; they were multiple in 59%. Initially, hypaesthesia of the infraorbital nerve was present in 10% of the single and 16% of the multiple fracture patients. Surgical treatment was performed in 57% of the single and in 75% of the multiple fracture patients. Women underwent surgical treatment considerably less frequently than men. After 6 and 12 months, significantly more complications were present in the surgically treated cohort. Nerve disturbances and 'meteorosensitivity' were most prominent. These results, together with previous findings, indicate that there is a need for prospective clinical investigations that fulfil the criteria of evidence-based medicine to generate guidelines for decision making in trauma surgery. In the meantime, the decision to use surgical treatment for midfacial fractures has to be made carefully., (Copyright © 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Bell's palsy is an idiopathic and acute, peripheral nerve palsy resulting in inability to control facial muscles on the affected side because of the involvement of the facial nerve. This study describes a case of Bell's palsy that developed after dental anaesthesia. A 34-year-old pregnant woman at 35 weeks of amenorrhea, with no history of systemic disease, was referred by her dentist for treatment of a mandibular left molar in pulpitis. An inferior alveolar nerve block was made prior to the access cavity preparation. 2h later, the patient felt the onset of a complete paralysis of the left-sided facial muscles. The medical history, the physical examination and the complementary exams led neurologists to the diagnosis of Bell's palsy. The treatment and results of the 1-year follow-up are presented and discussed. Bell's palsy is a rare complication of maxillofacial surgery or dental procedures, the mechanisms of which remain uncertain., (Copyright © 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The aim of this study was to conduct a prospective clinical trial comparing the neurosensory function of the inferior alveolar nerve (IAN) after mandibular advancement surgery with either bilateral sagittal split osteotomies (BSSO) or mandibular distraction ostoegenesis (MDO). 23 Class II mandibular hypoplasia patients requiring mandibular advancement were randomized into two groups for either BSSO or MDO. Subjective and objective neurosensory evaluations were performed preoperatively and at the following postoperative times: 2 weeks (TBD1), 6 weeks (TBD2), 12 weeks (TBD3), 6 months (TBD4) and 12 months (TBD5). Subjective evaluation included the use of a visual analogue scale (VAS). Objective evaluation included the use of light touch (LT), two-point discrimination (2PD) and pain detection threshold (PD) tests. Intra-operative or postoperative complications were recorded. Using a mixed model, no significant differences were reported in subjective VAS scores and objective LT, 2PD and PD scores between the BSSO and MDO groups over 12 months (p>0.05). Common postoperative complications included localized wound infection (BSSO=2, MDO=6) and condylar resorption (BSSO=1, MDO=1)., (Copyright 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

This study compares the effects of bilateral sagittal split osteotomy (BSSO) and distraction osteogenesis (DO) for lengthening the mandible regarding loss of function of the inferior alveolar nerve (IAN). In a retrospective cohort study design, the function of the IAN was tested with a Weinstein monofilament 3.22, 1 year after the surgical procedure in 65 patients (35 BSSO; 30 DO). This was defined as the upper limit for normal function. Of 130 IAN studied (70 BSSO, 54%; 60 DO, 46%), nerve function was disturbed in 23 (18%). In this group, 14 cases (61%) had undergone BSSO and 9 (39%) DO. One-hundred and seven nerves had no neurosensory IAN changes; of these BSSO had been performed in 56 cases (52%) and DO in 51 cases (48%). After eliminating confounding factors, there was no significant difference in the occurrence of neurosensory changes between the treatment options (DO versus BSSO, odds ratio: 1.254 with 95% CI: 0.366-4.300). In conclusion, there was no difference in IAN function between patients treated with BSSO or DO for lengthening the mandible.

This prospective cohort study investigates the types and duration of neurosensory disturbances (NDs) related to mandibular nerve (MN) lateralization for placement of implants. From March 2001 to March 2007, 87 patients underwent implant placement surgery with MN lateralization. All patients had panoramic radiograph and CT scans taken preoperatively. Patients completed questionnaires to report NDs 1 week after surgery, and at the end of each month within the year after surgery. All 87 patients (110 posterior segments, 23 bilateral and 64 unilateral) participated in the study. All patients reported NDs in the first week: anaesthesia in 81 sites, hypoesthesia in nine sites, burning in nine sites, pain in eight sites, pinching in two sites, and tickling in one site. The sites with NDs decreased to 29 sites (26%) at the end of first month, and to three sites (3%) at the end of the sixth month with no changes to the end of the year. 82 patients were satisfied with the result of nerve lateralization after 1 year. The mean time for full recovery of MN was 37+/-15 days. These findings indicate that concerning NDs, MN lateralization is a useful method for placing implants in the atrophic posterior mandible., (Copyright 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The authors present a case of inferior alveolar nerve morbidity attributable to use of bone wax to control haemorrhage during third molar surgery. The patient presented after 11 symptom-free years with parasthesia and, eventually pain in the cutaneous distribution of the right inferior alveolar nerve. Radiographs revealed a 1cm radiolucency consistent with a neuroma. Pathological examination of the surgically resected lesion revealed a foreign body reaction to bone wax. The case illustrates the poor resorption qualities of bone wax and the need for other haemostatic agents to achieve haemostasis in dentoalveolar surgery., (Copyright 2010. Published by Elsevier Ltd.)

A prospective study of all lower third molar surgery performed in the outpatient extraction clinic of a teaching dental hospital was conducted from January 1998 through October 2005 to determine the incidence of subsequent neurosensory deficit due to inferior alveolar nerve (IAN) and lingual nerve (LN) injury, to examine possible contributing risk factors and to describe the pattern of recovery. 3595 patients were included (61% female, 39% male; age range, 14-82 years). Of the 4338 lower third molar extractions performed by various grades of operators, 0.35% developed IAN deficit and 0.69% developed LN deficit. Distoangular impaction was found to increase the risk of LN deficit significantly (p<0.001). Depth of impaction was related to the risk of IAN deficit (p<0.001). Undergraduates caused more LN deficits (p<0.001). Sex, age, raising of a lingual flap, protection of LN with a retractor, removal of distolingual cortex, tooth sectioning and difficulty in tooth elevation were not significantly related to IAN or LN injury. Postoperative recovery from IAN and LN deficits was noted most significantly at 3 and 6 months, respectively. By the end of the follow-up period, 67% of IAN deficits and 72% of LN deficits had recovered completely., (Copyright (c) 2009 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Damage to the cutaneous branch of the mylohyoid nerve (CBMN) during genioplasties is possible but rare. The aim of this cadaveric study was to demonstrate possible mechanisms of injuring the CBMN during genioplasties. Mandibulotomy access was used to carry out sublingual and lateral cervical dissections on 10 formalinized cadavers with a mean age of 65 years. The length of the mylohyoid nerve was measured at three sections on the mandible. The posterior section of the mylohyoid nerve was 8.7+/-0.5 mm; the middle section was 14.5+/-0.9 mm and the anterior section was 15.6+/-1.2 mm in length. The submental skin island of 7 specimens had unilateral innervation by the CBMN. The bilateral innervation pattern was detected in 3 of the specimens. Damage to the sensory and the motor branches of the mylohyoid nerve can occur during genioplasties by transaction of the soft tissue pedicle attached to the mental spine and inferior border of the symphis. Surgeons should pay attention during dissection and osteotomy of the chin to avoid complications of the mylohyoid nerve and its branches.

The authors evaluated changes in position and angle of the proximal segment, including the condyle, after intraoral vertical ramus osteotomy (IVRO) with and without a Le Fort I osteotomy to verify whether displacement of the proximal segment could induce postoperative complications. Changes in condylar angle, ramus angle, and displacement of proximal segment were measured pre- and postoperatively. The position of the temporomandibular joint (TMJ) disc was examined pre- and postoperatively. Trigeminal nerve hypoesthesia in the lower lip was assessed bilaterally. The postoperative horizontal condylar angle was significantly smaller than the preoperative one on the deviated and non-deviated sides (P<0.0001). The postoperative coronal condylar angle was significantly larger than the preoperative one on the deviated side (P=0.0483). The postoperative sagittal ramus angle was larger than the preoperative one on the deviated (P<0.0001) and non-deviated (P=0.00005) side. Most joints with an anteriorly-displaced disc with and without reduction improved on the non-deviated side; 5 of 16 joints improved on the deviated side. Results suggest the position and angle of the proximal segment, including the condyle, could change after IVRO. This could be associated with symptomatic improvement in TMJ, and extreme medial displacement of the proximal segment could delay recovery from lower lip hypoesthesia.

This study investigated the diagnostic accuracy of cone beam computed tomography (CBCT) compared to panoramic radiography in determining the anatomical position of the impacted third molar in relation with the mandibular canal. The study sample comprised 53 third molars from 40 patients with an increased risk of inferior alveolar nerve (IAN) injury. The panoramic and CBCT features (predictive variables) were correlated with IAN exposure and injury (outcome variables). Sensitivity and specificity of modalities in predicting IAN exposure were compared. The IAN was exposed in 23 cases during third molar removal and injury occurred in 5 patients. No significant difference in sensitivity and specificity was found between both modalities in predicting IAN exposure. To date, lingual position of the mandibular canal was significantly associated with IAN injury. CBCT was not more accurate at predicting IAN exposure during third molar removal, however, did elucidate the 3D relationship of the third molar root to the mandibular canal; the coronal sections allowed a bucco-lingual appreciation of the mandibular canal to identify cases in which a lingually placed IAN is at risk during surgery. This observation dictates the surgical approach how to remove the third molar, so the IAN will not be subjected to pressure.

Neurosensory disturbance (NSD) of the inferior alveolar nerve (IAN) is the most common complication after bilateral sagittal split osteotomy (BSSO) and distraction osteogenesis (DO) of the retrognathic mandible. It is suggested that the risk is lower after DO than after BSSO. This retrospective study compared both techniques with regard to long-lasting NSD and overall patient satisfaction. 91 patients (representing 182 IANs) were included, they completed a questionnaire and underwent an objective neurosensory test. In the BSSO-group (90 nerves), long-lasting NSD was reported in 27 cases (30%) versus 21 cases (23%) in the DO group (92 nerves). In 39 cases (24 BSSO, 15 DO) the long-lasting NSD was reported in the lower lip, the chin or both. Of these cases, 9 (5 BSSO, 4 DO) were objectively tested positive. The overall prevalence was 8% in the BSSO group and 10% in the DO group. There was no significant difference in subjectively reported and objectively measured NSD between the groups. In this study patients seemed to over-report the NSD compared with the objective findings. For both procedures, overall patient satisfaction was high.

Operations to the face and skull can obscure the landmarks that are required to locate the position of the foramen ovale. We describe the use of three-dimensional computed tomography (3D-CT) to guide the approach to the foramen ovale to block the mandibular nerve in a patient with a mandibular deformity that had been caused by segmental mandiblectomy. Successful blockage of the mandibular nerve controlled the pain, contributed to the relief of physical and mental stress, and avoided the side effects of analgesics and pain from inserting the blocking needle.

The aim of the present survey was to assess neurosensory disturbances and/or tooth-pulp sensitivity losses after mandibular parasymphyseal bone-harvesting procedures. Twenty-eight harvesting areas in 16 patients were surveyed. Mucosal and skin sensitivity of the chin/lower lip, divided into four regions, were determined via Pointed-Blunt and Two-Point-Discrimination Tests. Pulp sensitivity of the mandibular teeth from the left second bicuspid to the right second bicuspid was tested by cold vitality preoperatively and 12 months postoperatively. Teeth were grouped according to sensitivity alterations and distance from the harvesting defects, as measured on CT scans, and statistically significant differences sought. At 12 months, 29% of preoperatively vital cuspids overlying the harvesting defects revealed pulp-sensitivity losses; no patient reported anaesthesia or analgesia; hypoaesthesia was present in 4% (8 sites; 2 patients), hypoalgesia was present in 3% (5 sites; 2 patients) and Two-Point-Discrimination Tests yielded pathologic responses in 5% of tested areas (10 sites; 4 patients). Teeth with and without pulp sensitivity changes were statistically indistinguishable regarding distances between root apices or mental foramen and the harvesting defect. The loss of pulp sensitivity in any tooth cannot be predicted simply on the basis of the distance between its apex and the harvesting osteotomy line.

Total replacement of the temporomandibular joint (TMJ) has been done in the UK since 1987. The three currently available systems are the Christensen system, the TMJ Concepts system and the Lorenz (BMF) system. Data from surgeons who replace TMJ were collated up to May 2007. There were nine units (eight NHS, one private) offering replacement. The TMJ Concepts system is the most popular of the three systems. Units are treating between five and 12 patients each year with an estimated total annual workload of 60-65 patients. The current total costs range from pound 15 000 to pound 19 000 for bilateral replacement. The most worrying complication is infection, which may affect up to 2.6% of patients.

Distraction osteogenesis (DO) is widely used in deformities and defects of the craniofacial bone. Accelerating inferior alveolar nerve (IAN) recovery would aid the process. Nerve growth factor (NGF) plays a vital role in peripheral nerve regeneration. In this study, the ability of locally applied human NGF beta (hNGFbeta) to enhance the morphological recovery of the IAN in a rabbit model of mandibular DO was studied. Rabbits underwent bilateral DO with a rate of 0.5mm per 12h. Two doses of 40 microg hNGFbeta in buffer were injected into callus at the beginning the of consolidation time. The contralateral side received injections of placebo. Rabbits were killed at 14 and 28 days. IAN specimens were subjected to histological and histomorphometric analysis. In both 14 and 28 days consolidation experiments, nerve histological analysis showed less degeneration and more regeneration in nerve fibers on the hNGFbeta treated side than the control side. Histomorphometric analysis showed that the myelinated fiber density on the hNGFbeta treated side was significantly higher than on the control side (p<0.01). The data indicate that locally applied hNGFbeta can accelerate the morphological recovery of the IAN and may play a role in reducing nerve injury in mandibular DO clinically.

Unlabelled: Trigeminal nerve damage often leads to chronic pain syndromes including trigeminal neuralgia, a severely debilitating chronic orofacial pain syndrome. Options for treatment of neuropathic pain are limited in effectiveness and new approaches based on a better understanding of the underlying pathologies are required. Partial ligation has been shown to effectively mimic many of the qualities of human neuropathic pain syndromes. We have devised a mouse model of trigeminal neuralgia using a partial infraorbital nerve ligation (pIONL) that induces persistent pain behaviors and morphological changes in the brainstem. We found that the pIONL effectively induced mechanical allodynia lasting for more than 3 weeks. Cell proliferation (bromodeoxyuridine), activation of astrocytes and microglia in the ipsilateral caudal medulla, and persistent satellite cell reaction in the ipsilateral ganglion were observed. Neurochemical markers calcitonin gene-related peptide, substance P were decreased in medullary dorsal horn ipsilateral to the injury side, whereas substance P receptor NK1 expression was increased after 8 days. Nerve injury marker ATF3 was markedly increased in ipsilateral trigeminal ganglion neurons at 8 days after pIONL. The data indicate that partial trigeminal injury in mice produces many persistent anatomical changes in neuropathic pain, as well as mechanical allodynia., Perspective: This study describes the development of a new mouse model of trigeminal neuropathic pain. Our goal is to devise better treatments of trigeminal pain, and this will be facilitated by characterization of the underlying cellular and molecular neuropathological mechanisms in genetically designed mice.

This study is a randomized control split-mouth non-blinded prospective trial, the aim of which was to evaluate clinically the frequency and type of injury to the inferior alveolar nerve (IAN) following mandibular third molar surgery using or not using the tooth section technique. The sample consisted of 50 lower third molars in 25 patients, in the control group the tooth section technique was not used, and it was used in the experimental group. The outcomes have shown a frequency of 8% of IAN injury for both groups (in both genders), and there were no statistically significant associations between the use of the tooth section technique and a diminished incidence of IAN injury or the presence of radiographic signs of a direct relationship between the tooth/nerve/mandibular canal and IAN injury. There was no association between deformities of the tip of dental needles and nerve injury. Temporary hypoesthesia and paresthesia were the commonest nerve injuries. All patients recovered from these injuries within six months.

The purpose of this prospective, non-randomised, descriptive study is to characterise the neurosensory deficit and associated neurogenic discomfort in 52 patients with iatrogenic injury to the inferior alveolar nerve (IAN). All patients were examined and followed up according to a protocol assessing tactile, thermal, and positional perception as well as two-point discrimination and pain. In 48 patients with IAN injuries of differing etiologies who did not undergo surgery, 32 patients with injury associated with third molar surgery exhibited significant spontaneous improvement of sensory function. Recovery improvement of sensory function was insignificant in the patients with other etiologies. In most patients the level of sensory perception was such that microsurgical repair was only occasionally indicated. Four patients had microsurgical repair; the outcome was favourable in three. IAN injuries associated with third molar surgery, other dento-alveolar surgery or implant surgery occur sufficiently often to render prevention a key issue.

During mandibular distraction osteogenesis (DO), the inferior alveolar nerve (IAN) is damaged during distractor activation, but spontaneously recovers during consolidation. Although many neurotrophic factors are known to play critical roles, there have been few studies on the mechanism of peripheral nerve recovery after DO. The aim of this study was to observe the expression pattern of p75NGFR (low-affinity receptor of NGF) and to detect autocrine growth activity in IANs following mandibular DO. Unilateral mandibular distractions (0.5mm each, twice per day for 10 days) were conducted on eight mongrel dogs. Two each were killed at 7, 14, 28 and 56 days after completing distraction. The distracted IAN and contralateral control nerve were harvested. Immunohistochemical staining was performed to determine p75NGFR expression, and double immunofluorescent staining to detect NGF and p75NGFR co-expression. Levels of p75NGFR expression were found to be significantly elevated at 7 and 14 days in Schwann cells located in the outer layer of axon, but were almost undetectable at 28 and 56 days. In double immunofluorescent images, the co-expression of NGF and p75NGFR was also detected at 7 and 14 days. p75NGFR plays an important role in remyelination due to its abundant expression in Schwann cells of damaged nerves, and NGF is an autocrine growth factor present in distracted IANs during the early consolidation period after mandibular DO.

The aim of this retrospective study was to determine the aetiology and characteristics of trigeminal nerve injuries referred to a university centre with nerve injury care. Fifty-nine patients with 73 injured trigeminal nerves were referred in 10 months. The most common aetiologies were odontectomy (third molar surgery) (52.1% of nerves), local anaesthetic (LA) injections (12.3%), orthognathic surgery (12.3%) and implant surgery (11.0%). The inferior alveolar nerve (IAN) was most commonly injured nerve (64.4%), followed by the lingual nerve (LN) (28.8%). About a quarter of IAN injuries (27.3%) and half of LN injuries (57.1%) from odontectomy had severe sensory impairment. There were twice as many LN than IAN injuries from local anaesthetic injections, but all had mild or no sensory impairment. Nerve injuries from implant surgery occurred only in IAN injuries; none had severe sensory impairment. Neuropathic pain occurred in 14.9% of IAN injuries and only in those with mild or no sensory impairment. Nerve surgery was offered to 45.8% of patients; a third underwent surgery.

The objective of this study was to assess the anatomical variation of the marginal mandibular nerve, and evaluate the risk of nerve malfunction after neck dissection. The method involved clinical assessment of the anatomy and function of the marginal mandibular nerve in 133 neck dissections. When the neck was extended the nerve was displaced in an anterior and downward direction with the lowest point 1.25+/-0.7 cm below the mandible between the posterior and anterior facial veins. The nerve was >1cm below the lower border of the mandible in 54% of dissections. When the intent was to preserve the nerve, dysfunction was observed in 16 of 101 dissections (16%). The incidence of marginal mandibular nerve dysfunction following neck dissection is comparable to that observed following submandibular gland excision for benign disease. Placement of incisions 2 cm below the lower border of the mandible will put the nerve at risk in a significant number of patients.

Ultrasound osteotomy is a new surgical technique used in dentistry to section hard tissues without damaging adjacent soft tissues. It was hypothesized that this could also be useful in craniofacial and orthognathic surgery. An ultrasonic device was employed in the following craniofacial surgical procedures: 144 Le Fort I osteotomies, 140 palatal expansions after Le Fort I osteotomies and 140 bilateral sagittal osteotomies; 2 Le Fort III osteotomies for treatment of Crouzon syndrome in two patients; 12 cases of unicortical calvarial bone grafting; removal of superior orbital roof in 25 cases of craniofaciostenosis; removal of external wall of the orbit in 10 cases of orbital cavity tumour; removal of anterior and posterior walls of the frontal sinuses in four cases of orbital cavity tumour. Integrity of soft tissues and surgical time were evaluated. Functional results were good without any soft-tissue damage being observed, but the overall operative time was increased. Ultrasound osteotomy is a new technical procedure that is advantageous for bone cutting in multiple situations, with minimal to no damage in adjacent soft tissues such as brain, palatal mucosa and the inferior alveolar nerve.

We evaluated the facial nerve function in 136 patients who had had retrograde nerve dissection during parotidectomy for benign disease. One week after the operation 90 patients (66%) had some weakness of the facial nerve. After 1 month 52 (38%) had facial nerve paresis. After 3 months 114 (84%) had recovered fully and 21 (16%) had minor nerve paresis. After 6 months 135 (99%) had normal nerve function. One patient had persistent marginal mandibular nerve paresis.

Bilateral sagittal split osteotomy is commonly used to treat mandibular prognathism. Several fixation methods for bony segments have been described. The present study compared masticatory function and neurosensory recovery patterns after mandibular correction between two methods of rigid fixation, bicortical screw (n = 38) and monocortical miniplate (n = 32). Patients who had undergone bilateral sagittal split osteotomy for Class III malocclusion were reviewed, and masticatory function and neurosensory recovery were studied with the appropriate indicators at 1, 3, 6 and 12 months postoperatively. Minimal differences were seen between groups at 1-year postoperatively, and although patients treated with miniplate fixation tended to recover faster, with regard to masticatory function and neurosensory disturbance, than those treated with screw fixation, no significant differences were identified. As the two methods seem to provide equal comfort and reliability, the choice should be made by the individual surgeon.

Bilateral sagittal split osteotomy (BSSO) and distraction osteogenesis (DO) are the most common techniques currently applied to surgically correct mandibular retrognathia. It is the responsibility of the maxillofacial surgeon to determine the optimal treatment option in each individual case. The aim of this study was to review the literature on BSSO and mandibular DO with emphasis on the influence of age and post-surgical growth, damage to the inferior alveolar nerve, and post-surgical stability and relapse. Although randomized clinical trials are lacking, some support was found in the literature for DO having advantages over BSSO in the surgical treatment of low and normal mandibular plane angle patients needing greater advancement (>7 mm). In all other mandibular retrognathia patients the treatment outcomes of DO and BSSO seemed to be comparable. DO is accompanied by greater patient discomfort than BSSO during and shortly after treatment, but it is unclear whether this has any consequences in the long term. There is a need for randomized clinical trials comparing the two techniques in all types of mandibular retrognathia, in order to provide evidence-based guidelines for selecting which retrognathia cases are preferably treated by BSSO or DO, both from the surgeon's and the patient's perspective.

The purpose of this study was to evaluate hypoesthesia of the lower lip using trigeminal somatosensory-evoked potential following 2 types of sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO). There were 30 patients with mandibular prognathism, with and without asymmetry, who were divided into three groups: the Obwegeser method (Ob) group, the Obwegeser-Dal Pont method (ODP) group and the intraoral vertical ramus osteotomy (IVRO) group. The trigeminal somatosensory-evoked potential was recorded in the region of the lower lip and evaluated preoperatively and postoperatively. The average recovery periods from lower lip hypoesthesia in the IVRO and the Ob group were significantly shorter than in the ODP group (P<0.05). In conclusion, IVRO showed the earliest recovery from hypoesthesia or an absence of hypoesthesia, and lower lip hypoesthesia was less with the Ob method than the ODP method.