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An over-representation of women in dental implant-related inferior alveolar nerve injuries (IANIs) is recognized in the literature but has not been investigated. Therefore, a nationwide retrospective register study was conducted to analyse how IANIs compare with other implant-related complications (infection, implant malposition, lack of bone at implant site, mechanical damage, or failed osseointegration) separately in women and men. Financially compensated malpractice claims related to dental implant surgery were collected from the Finnish Patient Insurance Centre for the years 1997-2013, while the total number of nationally placed implants was ascertained from the implant register held by the Finnish Institute for Health and Welfare. In the 242 complications, the following were analysed: age of subject, absolute risk for complication, and aetiological factor of IANI. Statistical tests applied include Mann-Whitney U-test, Chi-squared test, and Fisher's exact test. Women sustaining IANI were more likely older than those having infection, mechanical damage, or failed osseointegration (P < 0.05), while no significant differences emerged in men. Women were more likely at risk for IANI (P < 0.01) or implant malposition (P < 0.05) than men. The results support earlier propositions that women are more vulnerable than men to iatrogenic IANI.

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. ispartof: INTERNATIONAL JOURNAL OF ORAL AND MAXILLOFACIAL SURGERY vol:50 issue:1 pages:132-138 ispartof: location:Denmark status: published

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.

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 χ2 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.

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).

The purpose of this study was to assess the pre- and postoperative position and dimensions of the inferior alveolar canal (IAC) following sagittal split osteotomy (SSO) and identify any association with postoperative neurosensory deficit (NSD) at 1 year. This retrospective cohort study enrolled consecutive patients who had SSO performed to correct skeletal malocclusion. The pre- and postoperative cone beam computed tomography data were superimposed to visualize differences in IAC position and dimensions. Subjective and objective neurosensory tests were used to determine NSD in the inferior alveolar nerve distribution. A total of 20 subjects were included. The preoperative distance from the lateral cortex of the IAC to the inner aspect of the lateral cortex of the mandible was significantly greater in sides with NSD when compared to sides without NSD (P = 0.01). A significantly greater reduction in the postoperative distance measurement was seen in sides with NSD when compared to sides without NSD (P = 0.01). The magnitude of mandibular movement was significantly increased in sides with NSD (P = 0.02). The preoperative location of the IAC, as well as certain changes in the mediolateral and vertical positions as a result of SSO, are risk factors for postoperative NSD.

Little research has been conducted into hypoesthesia, and no studies have elucidated the risk factors for refractory hypoesthesia and compared treatment modalities. The purpose of this multicentre retrospective cohort study was to investigate the relationships between various risk factors, treatment modalities, and refractory hypoesthesia. Risk factors for refractory hypoesthesia after oral surgery were evaluated using univariate and multivariate analysis. To minimize the selection bias associated with a retrospective data analysis, a propensity score analysis was performed between the medication and non-medication groups (65 sites in each group). Moderate or severe hypoesthesia (odds ratio 13.42) and no or late administration of ATP/vitamin B12 (odds ratio 2.28) were significantly associated with refractory hypoesthesia. In the propensity score analysis, the incidence rate of refractory hypoesthesia in the medication group was lower than that in the non-medication group (P

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.

A retrospective cohort study was performed to assess the clinical usefulness of combination assessment using computed tomography (CT) images in patients undergoing third molar extraction. This study included 85 patients (124 extraction sites). The relationship between cortication status, buccolingual position, and shape of the inferior alveolar canal (IAC) on CT images and the incidence of inferior alveolar nerve (IAN) injury after third molar extraction was evaluated. IAN injury was observed at eight of the 124 sites (6.5%), and in five of 19 sites (26.3%) in which cortication was absent+the IAC had a lingual position+the IAC had a dumbbell shape. Significant relationships were found between IAN injury and the three IAC factors (cortication status, IAC position, and IAC shape; P=0.0001). In patients with the three IAC factors, logistic regression analysis indicated a strong association between these factors and IAN injury (P=0.007). An absence of cortication, a lingually positioned IAC, and a dumbbell-shaped IAC are considered to indicate a high risk of IAN injury according to the logistic regression analysis (P=0.007). These results suggest that a combined assessment of these three IAC factors could be useful for the improved prediction of IAN injury.

The objectives of this study were to evaluate the efficacy of additional cone beam computed tomography (CBCT) imaging on decreasing the risk of inferior alveolar nerve (IAN) injury during third molar removal in patients at high risk and to assess the surgical outcomes. The study sample included patients considered at high risk for IAN injury based on panoramic radiography (PAN) evaluation. The primary predictor was the type of imaging method (PAN only or with additional CBCT). The other variables were demographic and anatomical/radiographic factors. The primary outcome variable was IAN injury. The secondary outcome variables were the preoperative surgical plan and surgical results including IAN exposure and duration of surgery. The sample comprised 122 patients (139 teeth) aged 18-48 years. Postoperative temporary IAN injury was present in three (4.2%) cases in the CBCT group and 11 (16.4%) in the PAN group at 7 days after surgery. However, none of the patients had a permanent IAN injury at the 6-month follow-up. Additional CBCT imaging was not superior to PAN in reducing IAN injury after third molar surgery during long-term follow-up. Nonetheless, CBCT may decrease the prevalence of temporary IAN injury and improve the surgical outcomes in high-risk patients.

The aim of this study was to evaluate the diagnostic accuracies of cone beam computed tomography (CBCT) and panoramic techniques in predicting inferior alveolar nerve (IAN) exposure. The sample size was determined based on a pilot study. This prospective clinical series study included 59 third molar extraction sites with any of seven previously suggested panoramic signs of IAN exposure. The diagnosis of nerve exposure was done on panoramic and CBCT images. Molars were extracted and nerve exposure was evaluated clinically. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CBCT method, and sensitivity and PPV of panoramic method were estimated). The panoramic and CBCT methods correctly classified 67.7% and 93.3%, respectively, of 60 cases. This difference was statistically significant ( χ 2 =13.333, P =0.000). The sensitivity, specificity, PPV, and NPV for CBCT were 97.4%, 85.7%, 92.7%, and 94.7%, respectively. The sensitivity and PPV of panoramic radiography were 67.8% and 97.6%, respectively. The signs with the highest sensitivity were interruption of the mandibular canal border and abrupt canal narrowing. None of the Pell and Gregory criteria, molar angulations, or three-dimensional canal–apex relationships was significantly associated with clinically confirmed IAN exposure. Panoramic radiography may miss about one-third of exposure cases, but a positive panoramic diagnosis is most likely to be a real exposure and should be taken seriously.

The treatment dilemma provided by asymptomatic third molars in mandibular angle fractures remains controversial. This prospective randomized controlled trial was undertaken to determine whether there is an advantage to extraction or retention of the third molar whilst repairing a mandibular angle fracture. Sixty-four patients were allocated randomly to the two treatment groups. All underwent open reduction and internal fixation (ORIF) with standard postoperative care. The primary outcome measure was uncomplicated fracture healing. Secondary measures were surgical duration, malocclusion, wound healing, nerve injury, and return to theatre. All patients had uncomplicated fracture healing. The incidence of nerve injury was 16% for the retention group compared with 39% for the removal group (P=0.038). The average operating time for ORIF and third molar retention cases was 58.5min and for ORIF and third molar removal cases was 66.3min (P=0.26). There was no statistically significant difference between groups for wound healing, occlusion outcomes, or return to theatre. Given the additional risk of nerve injury and the additional operating time required for removal of a third molar, in the absence of an absolute indicator for removal of the third molar, it appears justifiable to advise retaining the tooth in the line of a mandibular angle fracture.

The objective of this study was to improve the accuracy of diagnosis of inferior alveolar nerve (IAN) injury by determining degrees of nerve disturbance using the sensory nerve action potential (SNAP) and sensory nerve conduction velocity (SCV). Crush and partial and complete nerve amputation injuries were applied to the IAN of rabbits, then SNAPs and histomorphometric observations were recorded at 1, 5, and 10 weeks. For crush injury, most nerves were smaller in diameter at 5 weeks than at 1 week, however after 10 weeks, extensive nerve regeneration was observed. The SNAP showed a decrease in SCV at weeks 1 and 5, followed by an increase at week 10. For partial nerve amputation, small to medium-sized nerve fibres were observed at weeks 1 and 5, then larger nerves were seen at week 10. Minimal changes in SCV were observed at weeks 1 and 5, however SCV increased at week 10. For complete nerve amputation, nerve fibres were sparse at week 1, but gradual nerve regeneration was observed at weeks 5 and 10. SNAPs were detectable from week 10, however the SCV was extremely low. This study showed SCV to be an effective factor in the evaluation of nerve injury and regeneration.

With the growing demand for dental work, trigeminal nerve injuries are increasingly common. This retrospective cohort study examined 53 cases of iatrogenic trigeminal nerve injury seen at the Department of Oral and Maxillofacial Surgery, University Hospitals of Leuven between 2013 and 2014 (0.6% among 8845 new patient visits). Patient records were screened for post-traumatic trigeminal nerve neuropathy caused by nerve injury incurred during implant surgery, endodontic treatment, local anaesthesia, tooth extraction, or specifically third molar removal. The patients ranged in age from 15 to 80years (mean age 42.1years) and 68% were female. The referral delay ranged from 1day to 6.5years (average 10months). The inferior alveolar nerve (IAN) was most frequently injured (28 cases), followed by the lingual nerve (LN) (21 cases). Most nerve injuries were caused during third molar removal (24 cases), followed by implant placement (nine cases) and local anaesthesia injuries (nine cases). Pain symptoms were experienced by 54% of patients suffering IAN injury, compared to 10% of patients with LN injury. Persistent neurosensory disturbances were identified in 60% of patients. While prevention remains the key issue, timely referral seems to be a critical factor for the successful treatment of post-traumatic neuropathy. ispartof: INTERNATIONAL JOURNAL OF ORAL AND MAXILLOFACIAL SURGERY vol:47 issue:6 pages:789-793 ispartof: location:Denmark status: published

To study the trigeminal nerve neuropathy prevalence after mandibular fractures and follow nerve recovery and to examine associations with clinical features.The files of 304 patients treated for 424 mandibular fractures in Hadassah Medical Center between 2001 and 2008 were analyzed. Twenty-five patients with paresthesia were examined by electro-diagnostic conduction test (quantitative sensory testing).The most common fracture sites were the symphysis (28.5%) and condyle (21.4%). A strong correlation between fracture severity and treatment modality was found. Nerve damage occurred in 13.4% of nondisplaced fractures and in 65.3% of5 mm displaced fractures. Patients who were treated by open reduction internal fixation demonstrated the biggest difference in quantitative sensory testing values between the affected and nonaffected sides. C nerve fibers were the most damaged and least regenerated. There was correlation between damage perception and objective test results.There is a correlation between fracture type and displacement severity on neurologic deficit and prognosis. The objective neurosensory damage was manifested by higher nerve excitation threshold on the injured side. Patients should be informed on the prognosis of neurologic deficit according to fracture type.

The aim of the present study was to compare two methods used in inferior alveolar nerve (IAN) repositioning to evaluate their effect on the vitality of intact teeth anterior to the mental foramen. Nerve lateralization (NL) is defined as the lateral reflection of the IAN without incisive nerve transection; nerve transposition (NT) involves sacrifice of the incisive nerve. Twenty-one patients were included in this study. Vitality tests for the teeth anterior to the mental foramen, including pulse oximetry and electric pulp testing, were evaluated at 1 week prior to surgery and at 1 week, 1, 3, 6, and 12 months after surgery. Lower lip and chin neurosensory changes were also recorded at the same time intervals by static light touch test with a cotton-tipped applicator and two-point discrimination test with sharp callipers. Vitality tests were negative after the operation in the NT group, while all had normal values at 1 week prior to the operation. In the NL group, only two patients (20%) had negative test results at 1 week after surgery. Lip and chin neurosensory changes in the total transpositions (28 operations) were seen in 7.1% at 1 year after the operation. It appears that NL is a more physiological procedure than NT.

The aim of this study was to determine the safest length of monocortical screws that can be inserted for the treatment of mandibular fractures following Champy's technique. Fifty cone-beam computed tomography (CBCT) scans of hemi-mandibles were studied. Linear measurements were taken from the buccal cortical plate to the tooth apex, from the canine to the second premolar, and from the buccal cortical plate to the tooth apex and the inferior alveolar canal in the molar area. The minimum values of the horizontal distances both at the level of the apex and the inferior alveolar canal at the second molar were found to be 4 mm, which is greater than those of the first molar. At the canine, first premolar and second premolars, the minimum values of the horizontal distances at the level of the apex was found to be 2 mm, 2.33 mm and 2 mm, respectively. Stabilizing miniplates using 4 mm screws both at the level of the apex and the inferior alveolar canal is safe in the second molar area, anterior to this, there is a risk of injury to tooth root and inferior alveolar nerve.

Trigeminal nerve injury is the most problematic consequence of dental surgical procedures with major medico-legal implications. This study reports the signs and symptoms that are the features of trigeminal nerve injuries caused by mandibular third molar (M3M) surgery. 120 patients with nerve injury following M3M surgery were assessed. All data were analysed using the SPSS statistical programme and Microsoft Excel. 53 (44.2%) inferior alveolar nerve (IAN) injury cases and 67 (55.8%) lingual nerve injury (LNI) cases were caused by third molar surgery (TMS). Neuropathy was demonstrable in all patients with varying degrees of paraesthesia, dysaesthesia (in the form of burning pain), allodynia and hyperalgesia. Pain was one of the presenting signs and symptoms in 70% of all cases. Significantly more females had IAN injuries and LNIs (p < 0.05). The mean ages of the two groups of patients were similar. Speech and eating were significantly more problematic for patients with LNIs. In conclusion, chronic pain is often a symptom after TMS-related nerve injury, resulting in significant functional problems. Better dissemination of good practice in TMS will significantly minimize these complex nerve injuries and prevent unnecessary suffering.

This study evaluated the differences in surgical changes and post-surgical changes between bi-cortical and mono-cortical osteosynthesis (MCO) in the correction of skeletal Class III malocclusion with bilateral sagittal split osteotomies (BSSOs). Twenty-five patients had bi-cortical osteosynthesis (BCO), 32 patients had mono-cortical fixation. Lateral and postero-anterior cephalometric radiographs, taken at the time of surgery, before surgery, 1 month after surgery, and on completion of orthodontic treatment (mean 9.9 months after surgery), were obtained for evaluation. Cephalometric analysis and superimposition were used to investigate the surgical and post-surgical changes. Independent t-test was performed to compare the difference between the two groups. Pearson's correlations were tested to evaluate the factors related to the relapse of the mandible. The sagittal relapse rate was 20% in the bi-cortical and 25% in the mono-cortical group. The forward-upward rotation of the mandible in the post-surgical period contributed most of the sagittal relapse. There were no statistically significant differences in sagittal and vertical changes between the two groups during surgery and in the post-surgical period. No factors were found to correlate with post-surgical relapse, but the intergonial width increased more in the bi-cortical group. The study suggested that both methods of skeletal fixation had similar postoperative stability.

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.

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. 2 h 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.

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).

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.

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.

金沢大学医薬保健研究域医学系, 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

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.

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 (p0.01). 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.

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 diagnostic value of several clinical, quantitative sensory tests (brush-stroke directional discrimination (BSD), touch detection threshold (TD), warm/cold (W/C) and sharp/blunt discrimination (S/B)), and electrophysiologic tests (mental nerve blink reflex (BR), nerve conduction study (NCS), cold (CDT), and warm (WDT) detection thresholds) in the recovery of inferior alveolar nerve (IAN) injury was evaluated in a prospective 1-year follow-up study of 20 patients after bilateral sagittal split osteotomy (BSSO). The subjective sensory alteration was assessed from patients' drawings. The predictive values of different tests at 2 weeks were determined in relation to the subjective sensory recovery at 12 months. The most pronounced recovery of the nerve damage occurred during the first 3 months according to all measures used. After 3 months, the electrophysiologic tests, especially the NCS, indicated significant further improvement. Except for the TD test, all other clinical test results were normal already at 3 months postoperatively. At early and late controls, the NCS and the thermal quantitative sensory testing could best verify the subjective sensory alteration, and most accurately assess the degree of thick and thin fibre dysfunction. At 1 year, the nerve dysfunction, as revealed by the NCS, corresponded with the figures of sensory alteration reported by the patients (35% R, 40% L). The W/C, BSD, S/B and WDT tests had the best early positive predictive values. Electrophysiologic tests had higher negative predictive values compared to clinical tests.

The biological mechanisms of nerve adaptation to distraction osteogenesis have not yet been elucidated. This study observed response of Schwann cells in the inferior alveolar nerve (IAN) following mandibular lengthening by electron microscopy and immunohistochemistry of S-100 protein, a specific marker of Schwann cells. Unilateral mandibular distraction (10 mm elongation) was performed in nine young adult goats. Three animals were sacrificed at 7, 14 and 28 days after completion of distraction, respectively. The distracted IAN specimens and control nerves (from the contralateral sides) were harvested and processed for histological, ultrastructural and immunohistochemical examinations. Wallerian degeneration was observed in the distracted IAN, and Signs of axonal regeneration, as well as many activated Schwann cells were seen in the lengthened nerves. The expression of S-100 protein increased significantly at early stage of distraction osteogenesis, but almost returned to the normal level at 28 days after distraction. This study suggests that Wallerian degeneration caused by mechanical stretching may stimulate Schwann cells to enter a proliferated and activated state. Schwann cells and S-100 protein appear to play crucial roles in axonal regeneration that contributes to nerve adaptation to gradual distraction. Therefore, the IAN injury caused by mandibular gradual distraction was not serious; it seems to recover totally through a complicated repair mechanism.

Minor surgical procedures to the inner (mucosal) aspect of the lower lip may occasionally cause numbness of the overlying skin. This study was designed to find, by means of dissection and computerized three-dimensional reconstruction, why surgical interference with nerve fibres in the deep aspect of the lip can cause neurological deficit in the superficial layers. Thirteen cadaveric lips were examined by dissection under a surgical microscope (9 lips) or serial sectioning and computerized three-dimensional reconstruction (4 lips). Muscle mass, minor labial salivary glands and nerve fibres were identified and traced. Three patterns of mental nerve distribution were seen on dissection and two on computerized reconstruction; these latter corresponded to two of the patterns seen on dissection. Fibres passing close to the labial minor salivary gland mass were seen to travel towards the superficial aspect of the lip, terminating in the dermis. It is clear that there is no safe anatomical space for minor surgical procedures to the inner (mucosal) aspect of the lower lip if avoidance of cutaneous numbness is an important consideration. However, we describe a technique that may minimize the possibility of cutaneous numbness.

There is little objective data about whether surgical technique or mandibular anatomy are a risk for inferior alveolar nerve (IAN) injury during bilateral sagittal split osteotomy (BSSO). Orthodromic sensory nerve action potentials (SNAPs) of the IAN were continuously recorded on both sides in 20 patients with mandibular retrognathia during BSSO operation. Changes in latency, amplitude, and sensory nerve conduction velocity (SNCV) at baseline and at different stages of the operation were analyzed. The SNAP latencies prolonged, the amplitudes diminished, and the SNCVs slowed down during BSSO (P = 0.0000 for all parameters). The most obvious changes occurred during surgical procedures on the medial side of the mandibular ramus. There was a clear tendency towards more disturbed IAN conduction with longer duration of these procedures (right side R = -0.529. P = 0.02; left side R = -0.605, P = 0.006). Exposure or manipulation of the IAN usually had no effect on nerve function, but the IAN conduction tended to be more disturbed in cases with nerve laceration. Low corpus height (R = 0.802, P = 0.001) and the location of the mandibular canal near the inferior border of the mandible (R = 0.52, P = 0.02) may increase the risk of IAN injury. There was no correlation between the age of the patients and the electrophysiological grade of nerve damage.

In a prospective study 1,106 impacted mandibular third molars were removed from 687 patients. Clinical, radiographic, and surgical factors were recorded. Postoperatively, we examined the modalities of common sensation in order to assess sensory deficit. The patients were followed up, until complete restitution occurred, or, if the sensibility failed to recover, for at least 6 months. A total of 3.6% of the operated sides demonstrated impairment of labial sensation, and 2.1% of lingual sensation. The vast majority of these disturbances subsided completely during the follow-up period. The incidence of persisting sensory diminution after 6 months was 0.91% for the inferior alveolar, and 0.37% for the lingual nerve. However, the degree of the persisting deficit was slight in most instances. The relationship between the recorded factors and the alteration of sensation was analysed by using the chi2 test. For the inferior alveolar nerve we found the patient's age, the development of the roots, the degree of impaction, and the radiographic position of the nerve canal to be significantly correlated to sensory deficit, as well as the surgical procedures in the depth of the socket and the intraoperative opening of the mandibular canal. As far as the lingual nerve is concerned, general anaesthesia and the individual operator were the main factors predictive of nerve damage.

Different methods of assessing functional impairment of the inferior alveolar nerve after sagittal split osteotomy were compared with subjective reports. Thirty patients were tested preoperatively as well as after four days, three weeks, three months, six months, and one year of follow up. All the patients underwent bilateral mandibular ramus sagittal split osteotomy. The sensation of the mandibular teeth was assessed by an electric vitality scanner. Other neurosensory assessments included light touch, two-point discrimination, tactile discrimination, and thermal discrimination. It was shown that electric sensibility-testing of mandibular teeth is a useful method for evaluating neurosensory disturbance after sagittal split osteotomy, and it correlated even better with the patient's subjective evaluation than the other tests used in this study.

A comparison of primary suturing and a new laser weld technique is described for the microsurgical repair of the inferior alveolar nerve in Wistar rats. A reliable method of exposure of the inferior alveolar nerve has been developed in order to allow intraosseous repairs of the nerve involving suturing with 10:0 nylon and a laser weld technique using an albumin-based solder, containing indocynine cardiogreen, plus an infrared (810 nm wavelength) diode laser. Seven cases of microsuture and laser weld repairs were performed with a 29.4% reduction in total operating time in the laser weld group. Histochemical analysis showed comparable mean neuron counts and mean tracer uptake by neurons for the microsuture and laser weld groups. Giant cell reactions were identified in two of the primary suture cases and axon deflection in three cases demonstrating possible advantages of the laser weld technique which showed no adverse reactions by axons or epineurium to the coagulative repair with the solder. The technique of laser weld repair, on inititial analysis, therefore appears comparable with traditional suture repairs and indeed may possess several advantages. Further studies are recommended.

Sagittal split osteotomy may result in sensory impairment of the inferior alveolar nerve; altered sensation in the lower lip varies from patient to patient. We evaluated individual and intraoperative risk factors of sagittal split osteotomy and correlated these findings with self-reported postoperative changes in lower-lip sensation. Follow-up data for 163 consecutive patients who underwent a bilateral sagittal split osteotomy were assessed for self-reported sensibility disturbances in the lower lip at the last follow-up visit. These self-reports were categorized as normal, hypoesthesia, hyperesthesia, or slightly diminished sensation in the central area of the chin. The overall rate of self-reported changed sensibility was 15.1% (49/324; 13.0% on the right side and 17.3% on the left side). Of 16 patients (9.9%) who experienced hypoesthesia on the right side and 25 patients (15.4%) who experienced hypoesthesia on the left side, 10 experienced bilateral hypoesthesia (31 patients total, 19.1%). Genioplasty and age at surgery were significant predictors of hypoesthesia; a 1-year increase in age at surgery increased the odds of hyposensitivity by 5%, and the odds of hypoesthesia in patients with concurrent genioplasty were 4.5 times higher than in patients without genioplasty. Detachment of the nerve at the left side, but not at the right side, was significantly correlated with hypoesthesia.

The PainDETECT questionnaire (PD-Q), originally developed and validated in a multicentre study of neuropathic pain (NeP) patients with back pain, is increasingly being applied to other pain conditions. The present study assessed whether the PD-Q would be a suitable screening tool for detecting NeP in patients with post-traumatic inferior alveolar nerve injury (IANI) and lingual nerve injury (LNI). A prospective cohort of patients with clinically diagnosed neuropathy was given the PD-Q at their clinic appointment, or it was sent to them after their consultation. Eighty-nine patients (IANI = 56, LNI = 33) were included in the study, 75 of whom suffered from painful neuropathy. Of the patients who completed the questionnaire fully (n = 56), allowing a summary score to be calculated, 34% were classified as having ‘likely NeP’ according to the PD-Q; 41% of patients scored in the uncertain classification range and the remaining quarter in the ‘likely nociceptive’ classification. There was a significant association between PD-Q scores and pain intensity levels across the sample, with those classified as likely NeP reporting high levels of pain. The results suggest that the PD-Q in its current format is not a suitable screening tool for NeP associated with IANI or LNI.

In this study we investigated the relationships among the risk factors for inferior alveolar nerve injury (IANI), and the difference between preoperative imaging findings on panoramic radiographs and computed tomography (CT), by univariate and multivariate analyses. We determined the following to be significant variables by multivariate analysis: panoramic radiographic signs, such as the loss of the white line of the inferior alveolar canal or the diversion of the canal; excessive haemorrhage during extraction; and a close relationship of the roots to the IAN (type 1 cases) on CT examination. CT findings of type 1 were associated with a significantly higher risk (odds ratio 43.77) of IANI. In addition, many panoramic findings were not consistent with CT findings (275 of 440 teeth; 62.5%). These results suggest that CT findings may be able to predict the development of IANI more accurately than panoramic findings. Panoramic radiography alone did not provide sufficiently reliable images required for predicting IANI. Therefore, when the panoramic image is suggestive of a close relationship between the impacted tooth and the IAN, CT should be recommended as a means of conducting further investigations.

Prediction of neurosensory deficit in the lower lip and chin after sagittal split ramus osteotomy (SSRO) is challenging. This study aimed to elucidate factors related to the development and improvement of neurosensory disturbance (NSD) after SSRO with respect to surgical procedure and the anatomical and structural characteristics of the craniomaxillofacial skeleton. Subjects comprised 50 patients treated by a single experienced surgeon. Anatomical data and landmarks were obtained by computed tomography (CT) imaging. There was a significant difference between patients with or without NSD for the surgical space on the medial side of mandibular ramus 1 week after SSRO (P=0.006). Less than 15.0mm between the lingula and mandibular notch (relative risk, 6.7; 95% CI, 1.7-33.8) and 195.0mm(2) or more space on the medial side of the mandibular ramus (relative risk, 17.2; 95% CI, 3.9-100.4) indicated a significant risk of NSD development at 6 months postoperatively. These results suggested that the development of NSD is related to the surgical space on the medial side of the mandibular ramus and subsequent manipulation of the inferior alveolar nerve (IAN) in that region. Limited periosteal degloving prevents excessive stretching of the IAN during SSRO, thus lowering NSD incidence.

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.

Injury to the inferior alveolar nerve (IAN) during surgery is an important complication of bilateral sagittal split osteotomy. With cone beam computed tomography, the course of the nerve and its relationship to the surrounding structures can be assessed in three dimensions. This study aims to determine whether tomography can predict attachment of the neurovascular bundle to the proximal segment of the mandible during sagittal split osteotomy (SSO). Bilateral linear measurements were taken on cross-sectional tomography images. During osteotomy, it was noted for each patient whether the neurovascular bundle was attached to the proximal segment during the split. If attached, a bone-cutting instrument or a blunt instrument was needed to free the nerve. The nerve was attached at more than one-third of operation sites (170 sites). Of these, over 65% of attached nerves (108 sites) required a bone-cutting intervention to free them from the mandible. After correcting for confounding factors, the linear distances from the buccal cortical margin of the IAN canal to the inner and outer buccal cortical margins of the mandible were important predictors of whether the IAN will be attached to the proximal segment of the mandible during SSO.

Intraoral transmental suction lipectomy (TMSL) is performed by entering the suction canula through the chin osteotomy/ostectomy gap into the sub- and/or supraplatysmal fat tissue layers. The aim of the study was to know patients' and operators' satisfaction with the procedure, and to know the kind and frequency of the complications. Twenty patients were consecutively treated and reviewed after a minimum of 5 years. All were satisfied with the overall results. It proved difficult to differentiate between the results of the liposuction and those of the genioplasty and/or orthognathic profile correction. From a surgeon's point of view, 11 showed excellent, nine good and one moderate results. Complications included one local subcutaneous infection, four transient neurosensory disturbances at the lower lip and two marginal branch weaknesses. All complications were resolved by the time of the long-term follow-up appointment. TMSL offers the psychological advantage of being performed without skin incision. Cosmetic results and complications are similar to those obtained with the transcutaneous liposuction techniques.

This retrospective study evaluated the effects of early extraction of immature lower third molar on preventing complications, particularly nerve injury following lower third molar removal. Patients were grouped according to age and radiographic results: group A (518 patients, ≤23 years, immature teeth with apical foramen not closed); group B (532 patients, >23 years, mature teeth with closed apical foramen). Group A included 230 males and 288 females (average age 17 years). In group A, 808 lower mandibular third molars were extracted bilaterally in 290 and unilaterally in 228 patients; the incidence of complications was 2.48% (20/808) (all were temporary), the incidence of nerve injury was 0%. Group B included 250 males and 282 females (average age 39 years). In group B, 810 lower third molars were extracted bilaterally in 278 and unilaterally in 254 patients; the incidence of complications was 10% (81/810), the incidence of nerve injury was 1.6% (13/810). All complications were temporary, except two removals of permanent inferior alveolar nerve numbness (>6 months). In this study, early removal of the lower third molar was effective in avoiding some postoperative complications, especially nerve injury. Early extraction of lower third molar in youngsters is recommended following a team consultation.

This study describes the management of 216 patients with post-traumatic iatrogenic lingual nerve injuries (LNIs; n = 93) and inferior alveolar nerve injuries (IANI; n = 123). At initial consultation, 6% IANI and 2% LNI patients had undergone significant resolution requiring no further reviews. Reassurance and counselling was adequate management for 51% IANI and 55% LNI patients. Systemic or topical medication was offered as pain relief to 5% of patients. Additional cognitive behaviour therapy (CBT) was offered to 8% of patients. Topical 5% lidocaine patches reduced pain and allodynia in 7% of IANI patients, most often used without any other form of management. A small percentage of IANI patients (4%) received a combination of therapies involving CBT, surgery, medication and 5% lidocaine patches. Exploratory surgery improved symptoms and reduced neuropathic area in 18 LNI and 15 IANI patients resulting in improved quality of life. In conclusion, the authors suggest a more diverse and perhaps holistic strategy for management of patients with iatrogenic trigeminal nerve injuries and recommend pragmatic assessment criteria for measurement of treatment success in these patients.