Systematic review of the incidence of inferior alveolar nerve injury in bilateral sagittal split osteotomy and the assessment of neurosensory disturbances

Politis C., Sun Y., Lambrichts I., Agbaje J.O.

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.

Button K.S., Ioannidis J.P., Mokrysz C., Nosek B.A., Flint J., Robinson E.S., Munafò M.R.

Low-powered studies lead to overestimates of effect size and low reproducibility of results. In this Analysis article, Munafò and colleagues show that the average statistical power of studies in the neurosciences is very low, discuss ethical implications of low-powered studies and provide recommendations to improve research practices. A study with low statistical power has a reduced chance of detecting a true effect, but it is less well appreciated that low power also reduces the likelihood that a statistically significant result reflects a true effect. Here, we show that the average statistical power of studies in the neurosciences is very low. The consequences of this include overestimates of effect size and low reproducibility of results. There are also ethical dimensions to this problem, as unreliable research is inefficient and wasteful. Improving reproducibility in neuroscience is a key priority and requires attention to well-established but often ignored methodological principles.

Baas E.M., Horsthuis R.B., de Lange J.

The present retrospective cohort study compared the subjective inferior alveolar nerve (IAN) function after distraction osteogenesis (DOG) and bilateral sagittal split osteotomy (BSSO) in mandibular advancement surgery.Treatment consisted of correction of a retrognathic mandible using DOG (30 patients) or BSSO (35 patients). Subjective IAN function was recorded using a questionnaire 1 year after surgery. A total of 130 IANs were evaluated.In 37 nerves (28.5%), an IAN disturbance was observed. In this group of 37 nerves, BSSO had been performed in 26 (70.3%) and DOG in 11 (29.7%). After eliminating confounders (eg, age, amount of advancement, gender), no significant difference (odds ratio 0.652, 95% confidence interval 0.221 to 1.920) was found. Age was significantly related to subjective IAN disturbances for women but not for men. This was seen in women older than 22 years and increased for women older than 36 years to an odds ratio of 22.8 (95% confidence interval 2.580 to 201.488). Satisfaction also correlated with age, independent of gender.No difference was found in subjective IAN disturbances after 1 year between DOG and BSSO for lengthening the mandible.

Yamauchi K., Takahashi T., Kaneuji T., Nogami S., Yamamoto N., Miyamoto I., Yamashita Y.

The aim of the present study was to evaluate the potential morphologic risk factors for postoperative neurosensory disturbance (NSD) after bilateral sagittal split osteotomy.The study subjects were 30 skeletal Class III patients (9 males and 21 females), with a mean age of 22.0 years (range, 16-39 years). All patients underwent bilateral sagittal split osteotomy for setback to correct mandibular prognathism. The bone marrow space between the outer mandibular canal and the lateral cortex of the ramus was measured on transaxial computed tomography images, and the length at the mandibular angle between the retromolar and gonion was measured on the lateral cephalograms. The NSD was tested bilaterally using discrimination to touch with the sharp head of a mechanical probe. Each patient was evaluated at 1, 3, and 6 months postoperatively.The median bone marrow space was 1.96 mm (range, 0-4.5 mm), and median length of the mandibular angle was 30.93 mm (range, 23-37 mm). Neurosensory disturbance was present on 15 sides (25.0%) at 1 month postoperatively, 9 sides (15.0%) at 3 months postoperatively, and 7 sides (11.7%) at 6 months postoperatively. The difference in the incidence of NSD with a small bone marrow space and a long mandibular angle from that with a large bone marrow space and short mandibular angle was highly statistically significant (P = .006 and P < .01, respectively).The frequency of NSD after bilateral sagittal split osteotomy in Class III cases was dependent not only on the position of mandibular canal, but also on the length of the mandibular angle. A lateral course of the mandibular canal and a long mandibular angle appeared to result in a high risk of injury to the inferior alveolar nerve, resulting in NSD owing to a compromised splitting procedure.

Hanzelka T., Foltán R., Pavlíková G., Horká E., Šedý J.

Bilateral sagittal split osteotomy (BSSO) aims to correct congenital or acquired mandibular abnormities. Temporary or permanent neurosensory disturbance is the most frequent complication of BSSO. To evaluate the influence of IAN handling during osteotomy, the authors undertook a prospective study in 290 patients who underwent BSSO. The occurrence and duration of paresthesia was evaluated 4 weeks, 3 months, 6 months, and 1 year after surgery. Paresthesia developed immediately after surgery in almost half of the patients. Most cases of paresthesia resolved within 1 year after surgery. A significantly higher prevalence of paresthesia was observed on the left side. The authors found a correlation between the type of IAN position between the left and right side. The type of split (and IAN exposure) did not have a significant effect on the occurrence or duration of neurosensory disturbance of the IAN. The authors did not find a correlation between the occurrence and duration of paresthesia and the direction of BSSO. Mandibular hypoplasia or mandibular progenia did not represent a predisposition for the development of paresthesia. In the development of IAN paresthesia, the type of IAN exposure and the split is less important than the side on which the split is carried out.

Yoshioka I., Tanaka T., Khanal A., Habu M., Kito S., Kodama M., Oda M., Wakasugi-Sato N., Matsumoto-Takeda S., Fukai Y., Tokitsu T., Tomikawa M., Seta Y., Tominaga K., Morimoto Y.

To elucidate the relationship between the anatomic position of the inferior alveolar nerve (IAN) at the mandibular second molar and the occurrence of neurosensory disturbances of the IAN after sagittal split ramus osteotomy (SSRO) in patients with mandibular prognathism. Also, the present study evaluated the difference in anatomic position of the IAN between patients with and without mandibular prognathism.Computed tomography images were taken of 28 patients with mandibular prognathism and 30 without prognathism. On these scans, the IANs from the mandibular second molar region to the mandibular foramen in the mandibular ramus were identified. The present study was designed as a cross-sectional study. The distance from the buccal aspect of the IAN canal to the outer buccal cortical margin of the mandible in the mandibular second molar regions was measured on the computed tomography images. Also, the linear distance between the superior aspect of the IAN canal and the alveolar crest in these regions was calculated. In addition, we investigated the presence or absence of contact between the IAN canal and the inner buccal cortical margin of the mandible from the mandibular second molar to the mandibular foramen in the mandibular ramus. Next, we examined whether neurosensory disturbances occurring after SSRO were related to the position of the IAN at the mandibular second molar.A significant difference was found in the occurrence of neurosensory disturbances of the IAN after SSRO between men and women (χ(2) test, P < .05). For the distance from the buccal aspect of the IAN canal to the outer buccal cortical margin of the mandible in the mandibular second molar region, a significant difference was found between groups with and without neurosensory disturbances (Student's t test, P < .01). The shorter the distance from the buccal aspect of the IAN canal to the outer buccal cortical margin, the more frequent the occurrence of neurosensory disturbances of the IAN.The present results have demonstrated that gender and the anatomic position of the IAN canal at the mandibular second molar are significantly related to the occurrence of neurosensory disturbances of the IAN after SSRO. Therefore, surgeons should clearly inform patients of the increased possibility of neurosensory disturbances after SSRO when the patients are female and are found to have a shorter distance from the buccal aspect of the IAN canal to the outer buccal cortical margin.

D'Agostino A., Trevisiol L., Gugole F., Bondí V., Nocini P.F.

This study analyzes permanent paresthetic disorders regarding the inferior alveolar nerve (IAN) after mandibular ramus sagittal osteotomy procedures. Fifty patients (ie, 100 nerves) who underwent mandibular bilateral sagittal split osteotomy between 2003 and 2007 were evaluated to detect sensorial disorders of the IAN. The evaluation was performed for each patient at least 1 year after surgical intervention. The sagittal osteotomy of the mandible ramus was performed according to Epker-Hunsuk technique. The method of fixing through titanium plates and monocortical screws and the displacement width of the osteotomized stumps were also considered. The evaluation of the IAN functionality was performed both subjectively, by means of a questionnaire, and clinically, by using 4 types of tests: light-touch sensation, pinprick sensation, Weber test, and Dellon test.The clinical test analysis revealed that no nervous lesion was detected in 52% of the tested sites, whereas 24% reported significant nervous lesions. In the subjective evaluations, 74% of the patients described the discomfort related to the neurologic alteration as "absent to mild" or "mild to moderate," 10% as "moderate to serious," and 4% as "serious."We observe that the percentage of significant nervous lesions is relatively low and that it matches the mean described in literature. The central nervous system capacity to hide or compensate for functional deficits due to peripheral nervous lesions was confirmed by the comparison between the results of the clinical tests and the patients' subjective evaluations.

Phillips C., Kim S., Tucker M., Turvey T.

Wijbenga J.G., Verlinden C.R., Jansma J., Becking A.G., Stegenga B.

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.

Frey D.R., Hatch J.P., Van Sickels J.E., Dolce C., Rugh J.D.

The possible effects of orthognathic surgery on signs and symptoms of temporomandibular disorder (TMD) are still controversial. We prospectively investigated the association between the amount of advancement and rotation of the mandible during bilateral sagittal split osteotomy (BSSO) and the development of TMD signs and symptoms.Class II patients (n = 127) received mandibular advancement with BSSO. We used factorial analysis of covariance to assess whether the magnitude (< or > or = 7 mm) and the direction (clockwise or counterclockwise) of the movement were associated with the onset or worsening of TMD signs and symptoms during 2 years of follow-up.Counterclockwise rotation of the mandible was associated with more muscle tenderness, especially in patients receiving long advancements. The combination of long advancement with counterclockwise rotation was also associated with increased joint symptoms. All symptoms declined over the 2-year follow-up period.Counterclockwise rotation of the mandible is related to a slight increase in muscle symptoms after BSSO. The combination of counterclockwise rotation with long advancement also might increase joint signs and symptoms. All symptomatology tended to decline over time, suggesting that the amount of advancement and mandibular rotation should not be considered as risk factors for the development of TMD in patients without preexisting conditions.

Colella G., Cannavale R., Vicidomini A., Lanza A.

The evaluation of neurosensory disturbance of the inferior alveolar nerve (IAN) can be performed by purely subjective, relatively objective, or purely objective methods. The aim of this study was to provide a systematic review of the incidence of inferior alveolar nerve sensory disturbance after bilateral sagittal split osteotomy, as well as the frequency of recovery of sensory function using objective methods of evaluation only.Searches were conducted employing MEDLINE, Scirus, and the Cochrane Central Register of Controlled Trials (CENTRAL). Seven studies were included in this review.This systematic review has shown that the frequency of nerve impairment evaluated by subjective methods was higher than that indicated by studies adopting objective methods at each time of follow-up considered. In particular at the seventh postoperative day the frequency obtained using the objective methods was 63.3% while that obtained with subjective methods was 83%. At 1 year follow-up a frequency of sensory impairment of 12.8% was obtained using objective methods and a frequency of 18.4% when subjective methods were used. The data were analysed using the index of inter-rater reliability (Cohen's Kappa) with the degree of nerve damage evaluated by objective methods considered the "gold standard." The value of Cohen's Kappa at 1 week follow-up is 0.53; at 1 year follow-up it increased to 0.90.On the basis of these results, objective methods provide the most sensitive diagnostic tests at early controls-within 3 months of the operation. At later control points the sensitivity increases and the inter-rater reliability is satisfactory.

Pahkala R.H., Kellokoski J.K.

Surgical-orthodontic treatment is a common treatment approach for adult patients with skeletal maxillomandibular discrepancy. Some patients report improvement in signs and symptoms of temporomandibular disorder (TMD) after surgery. Whether the correction of malocclusion is responsible for the improvement of TMD symptoms after orthognathic surgery is still controversial. The objectives of this prospective study were to evaluate subjective treatment outcomes in patients with bilateral sagittal split osteotomy (BSSO) and to find out whether signs and symptoms of TMD and changes in occlusion are related to patient satisfaction.Eighty-two patients (53 female, 29 male) with a mean age of 32 years (range, 16-53 years) treated with BSSO in the Oral and Maxillofacial Department at Kuopio University Hospital in Finland were examined; 64 had mandibular advancement, and 18 had mandibular setback. Occlusion and signs and symptoms of TMD were registered pre- and postoperatively. At the postoperative examination (mean, 1.8 years after BSSO), the patients were asked to fill out a questionnaire about the influence of treatment on their masticatory function and symptoms of TMD, as well as their satisfaction with the treatment outcome.TMD symptoms were significantly reduced after treatment. Improvements were also reported in facial appearance (82%) and chewing ability (61%); also, facial (56%) and temporomandibular joint (40%) pain disappeared. However, in 12% of the patients, temporomandibular joint problems were worse after treatment. Most patients (73%) were very satisfied with the outcomes; no one expressed dissatisfaction. Multiple logistic regression analysis showed that subjects with improved mastication and self-confidence, and those without long-term neurosensory deficits, expressed high satisfaction with the treatment outcome. Patients with mandibular setback were more pleased with the outcome than those with mandibular advancement.Orthognathic patients generally experience functional and psychosocial benefits after surgical-orthodontic treatment. In addition to functional and morphological reasons, the psychosocial factors should be more emphasized when making the treatment decision and comparing the alternative treatment approaches.

Boutault F., Diallo R., Marecaux C., Modiga O., Paoli J.-., Lauwers F.

Ding Y., Xu T., Lohrmann B., Gellrich N., Schwestka-Polly R.

The aim of the present study was to evaluate the long-term skeletal and dento-alveolar stability 15 years after combined orthodontic and surgical correction of skeletal anterior open bite. Ten (8 female, 2 male) anterior openbite patients who had undergone orthodontic treatment in combination with bimaxillary surgery at Hanover Medical School were examined. Each patient had undergone Le Fort I osteotomy combined with bilateral sagittal split osteotomy (BSSO); osteosynthesis with plates and screws was carried out in the maxilla, and wire-osteosynthesis in the mandible. Cephalometric records of these patients were examined immediately before the start of the orthodontic treatment (T1), before surgery (T2), immediately after surgery (T3), medium-term after surgery, averaging 1.5 years (T4), and long-term after surgery, averaging 15 years (T5). Hasund cephalometric analysis was performed for which skeletal and dental cephalometric measurements had been taken. Moderate skeletal relapse was observed 15 years after surgery. Overbite remained quite stable 15 years after surgery, which is mainly due to the upper and lower incisors' eruption over the long-term period. Treatment of skeletal open bite via Le Fort I and bilateral sagittal split osteotomy appears to be a clinically successful procedure providing stable results.

Jääskeläinen S.K., Teerijoki-Oksa T., Forssell H.

This study investigated the utility of neurophysiologic examination and thermal quantitative sensory testing (QST) in the diagnosis of trigeminal neuropathy and neuropathic pain. Fifty-eight patients (14 men), 34 with sensory deficit within the inferior alveolar nerve (IAN) and 24 within the lingual nerve (LN) distribution, were included. Twenty-six patients (45%) reported neuropathic pain. Patients underwent blink reflex (BR) test and thermal QST; sensory neurography was done to the IAN patients. Results of clinical sensory testing were available from the charts of 48 patients revealing abnormal findings in 77% of the IAN and in 94% of the LN patients. The BR test was abnormal in 41%, neurography in 96%, and QST in 91% of the IAN patients. In the LN group, BR was abnormal in 33%, and QST in 100% of the patients tested. Neurophysiologic tests and QST verified the subjective sensory alteration in all but 2 IAN patients, both with old injuries, and 4 LN patients who did not undergo QST. When abnormal, thermal QST showed elevation of warm and cold detection thresholds (hypo/anesthesia), hypoalgesia was less marked, and heat allodynia was only occasionally present. Contralateral thermal hypoesthesia after unilateral injury was found in 14 patients. It was associated with the occurrence of neuropathic pain (P=0.016). Axonal Abeta afferent damage was less severe in the IAN patients with pain than in those without pain (P=0.012). Neurophysiologic tests and thermal QST provide sensitive tools for accurate diagnosis of trigeminal neuropathy and study of pathophysiological features characteristic to human neuropathic pain.

Topan C., Bilge S., Demirbas A.E.

Shinozaki K., Kobayashi T., Seki N., Iwanaga J., Kusukawa J.

Neurosensory disturbances (NSD) are the most widely recognized complication of bilateral sagittal split ramus osteotomy (BSSRO), but predictors of NSD remain unclear. The aim of this study was to identify factors predicting NSD following BSSRO. A retrospective cohort study of 129 consecutive patients with dentofacial deformities (median age 24.0 years; 76.0% female), who underwent BSSRO (95 without genioplasty, 34 with genioplasty), was conducted. The presence of NSD was evaluated at 6 months postoperatively and was found in 97 patients (absent in 32 patients). Potential NSD-related factors investigated were age, sex, genioplasty, mandibular canal type, inferior alveolar nerve (IAN) exposure, mandibular movement, and laterality. Multivariate binary logistic regression analysis was conducted to elucidate factors predicting NSD, with calculation of odds ratios (OR) and 95% confidence intervals (CI). The dependent variable was defined as NSD after BSSRO. Independent variables were those with P < 0.100 in the univariate analysis. In the multivariate binary logistic regression analysis, NSD showed a significant association with BSSRO with genioplasty (adjusted OR 3.87, 95% CI 1.21-12.26; P = 0.022) and left IAN exposure (adjusted OR 4.69, 95% CI 1.49-14.73; P = 0.008). The study findings may lead to enhanced clinical outcomes for BSSRO.

Alali Y.S., Aldokhi H.D., Alayoub R.A., Mohammed (Bin) W.A., Alshehri S., Alshayban M.

Background/Objectives: Le Fort I maxillary osteotomy (LF1-MO) is associated with a risk of infraorbital nerve neurosensory deficiency (NSD). This study aimed to evaluate post-operative subjective numbness and objective NSD after LF1-MO and assess the impact of these outcomes on overall patient satisfaction. Methods: A retrospective cross-sectional study was conducted among adult LF1-MO patients, who were evaluated for treatment satisfaction using a 10-item patient satisfaction questionnaire. In addition, subjective and objective NSDs were assessed post-operatively for six months. Overall patient satisfaction was compared against different variables (patient age, sex, and type of LF1-MO) and NSD. The proportion of subjective and objective NSDs were statistically correlated and compared against these variables, assuming a 95% significance level (p < 0.05). Results: A total of 58 LF1-MO patients in the age range of 20–38 years (mean–29.79 ± 4.62 years) were included in this study. Most patients were females (n = 48; 82.8%) and aged 30 years and older (n = 32; 55.2%). The overall mean patient satisfaction score was 27.38 ± 3.94 (range 12–30), which did not significantly differ based on patient age or sex. Patients who had advanced LF1-MO had significantly higher satisfaction scores (28.27 ± 1.85) compared to those who had impaction (24.61 ± 7.34) (p < 0.05). Subjective numbness and an abnormal “Level A” response to objective neurosensory testing were associated with poor patient satisfaction. There was significant statistical correlation between subjective and objective NSDs (Spearman’s rho–0.441; p < 0.01). Based on a chi-squared test, patients undergoing maxillary setback (subjective–88.9%; objective–44.5%) had significantly higher NSDs (p < 0.05). Conclusions: Most patients reported satisfaction after LF1-MO, particularly among females, those aged 30 and older, and those without NSD. However, residual infraorbital NSDs persisted, with about two-thirds experiencing subjective numbness and 25% showing abnormal responses in “Level A” objective neurosensory tests six months post-operatively. Moreover, subjective numbness correlated with abnormal objective testing results, leading to lower patient satisfaction.

S. Al Qooz F., S. Al Olaimat M., Alzoubi Z.R., Alkhawaldeh M.A., Al Najada L.A.

Sagittal split osteotomy is a standard procedure performed by maxillofacial surgeons. Patients usually present with either aesthetic or functional concerns. Surgical landmark identification is crucial to a successful surgical procedure. Various diagnostic preoperative tools have been used to identify these landmarks, such as imaging studies or cadaveric dissections. The cone-beam computed tomography (CBCT) is currently the most common preoperative tool used. This study aims to identify whether the deepest part of the ascending ramus (coronoid notch) distance to the mandibular lingula can be used as a safe reference prior to performing medial horizontal osteotomies. Data were extracted from a database of patients who underwent CBCT scanning for various reasons. A total of 313 CBCT scans were included in this study. Patients younger than 18 years, with a history of mandibular pathology, or whose scans were suboptimal were excluded. Statistical analysis was performed via IBM SPSS v29 (IBM Corp., Armonk, NY, U.S.), and the predetermined p-value was < 0.05. Statistical significance was present in both the right and left measurements. A total of 313 (626 sides) CBCT were included in this study. Most patients were of the female gender, with 171 scans (54.6%) and 142 scans (45.4%) from males. Our study focused on the distance from the specific reference point, the coronoid notch (the most concave point at the ascending ramus in the retromolar area), to the anterior part of the mandibular lingula. For the total sample, the standard deviations for each side were 2.25 (p-value = < 0.001) and 2.07 (p-value = 0.003), left and right, respectively. This finding indicated that the distances on each side were statistically significant. The authors suggest that the anterior aspect of the ramus can be used as a reference point for horizontal medial osteotomy, as both distances were statistically significant. This finding has important implications for the safety and efficiency of bilateral sagittal split osteotomy procedures, as it provides a reliable reference point for surgeons to use during the procedure, potentially reducing the risk of complications, surgical time, and improving patient outcomes.

Kim S., Kwon T.

This chapter demonstrates the potential complications associated with orthognathic surgery, which is a cornerstone treatment in maxillofacial surgery aimed to correct dental and skeletal irregularities. Potential complications include spectrum of complications, ranging from minor, transient issues to more significant, long-term challenges. Based on comprehensive review of current literatures and clinical practices, the chapter emphasizes the importance of a thorough preoperative assessment, patient education, and informed consent in mitigating these risks. It also highlights the role of cutting-edge surgical techniques and a multidisciplinary approach in enhancing patient outcomes. The chapter concludes with a call for ongoing research and innovation to refine surgical methods further and improve patient care, advocating for the integral balance between achieving surgical objectives and minimizing postoperative complications.

Charoenvicha C., Sirikul W., Thaweethanasit D., Kongmebhol P., Madla C., Wongtriratanachai P.

Background The inferior alveolar nerve (IAN), a crucial branch of the trigeminal nerve, innervates the mandible. Precise knowledge of IAN positioning ensures surgical safety. Methods This cross-sectional study analyzed head and neck computed tomography scans from Maharaj Nakorn Chiang Mai Hospital. Inclusion criteria comprised dentate adults. Exclusion criteria included mandibular trauma/pathology or prior surgery. The study aimed to determine IAN positioning relative to key surgical landmarks: the first molar, lingula, and mental foramen. Results A total of 450 Thai mandibles (900 hemimandibles) with a mean age of 36 years (58.2% male) were included. No significant differences were observed in IAN positioning relative to the first molar between the left and right sides in superior and inferior landmarks. However, the buccal distance was significantly closer on the left. The lingula distance was higher on the left, whereas that to the mental foramen was lower. Conclusion Surgical implications suggest maintaining a 15-mm distance from the lower mandibular border during osteotomy and upper plate placement, restricting horizontal cuts within this 15-mm range from the lingula, and ensuring screws do not extend more than 7 mm from the buccal surface. This study provides valuable guidance for minimizing the risk of iatrogenic injury to the IAN.

Cheung C., Huang L., Zhu Z., Liu Z., Liu Y., Luo E.

Joseph B., Anirudhan A., Krishnan Kutty D., Ummer N., Anjana C.M.

Sagittal split osteotomy is still considered as a difficult procedure though there are many modifications to make it safer, more reliable, and more predictable with less relapse. Currently the most accepted technique of sagittal split osteotomy is the modification described by Epker in 1957. In Epker's modification, the medial ramus osteotomy is the most difficult to perform and may cause bad split at times, especially if the ramus is thin and/ or lingula is placed at a higher level. In this article, the authors describe a novel sublingula technique of medial ramus osteotomy, which makes the osteotomy easier and predictable with less risk of bad split without additional risk of damage to inferior alveolar nerve. Fifteen patients (30 sides) underwent surgery using the sublingula osteotomy technique. CBCT was taken for all patients as a guide to locate lingula, mandibular foramen, and inferior alveolar nerve. This novel modification of sagittal split osteotomy makes the medial ramus osteotomy easier to perform and reliable as the cut is low and short with less risk of bad split without additional risk of damage to inferior alveolar nerve. The use of CBCT to locate anatomical structures helps in precise planning of the osteotomy, and hence, this modification works well with less experienced surgeons.

Shaik K.V., Mohan A.P., Kumar K.A., Haripriya C.

The bilateral sagittal split osteotomy is a crucial aid in the correction of dentofacial abnormalities. The technique has been in practice since the late 1800s. In 2007, a study was published, in which the author performed bilateral sagittal split osteotomy on 26 patients with severe skeletal malocclusion. The article aims in displaying the follow-up of previous study at the intervals of three months, six months, one year, two years, three years, four years, five years using objective assessment of neurosensory responses. Preoperatively the anatomic location of inferior alveolar nerve was estimated using CT scans, the information derived from it was used intraoperatively, due to which the author and his team were successful to avoid damage to the inferior alveolar nerve during the procedure, hence reducing the risk of postoperative paresthesia. The article concludes by providing that preoperative evaluation of the anatomic location of the inferior alveolar nerve via CT scan, has helped to preserve inferior alveolar nerve completely during the surgery, thus displaying postoperative paresthesia in all the subjects of the study for as long as five years.

Vachirarojpisan T., Srivichit B., Vaseenon S., Powcharoen W., Imerb N.

Peripheral nerve injuries (PNIs) are prevalent conditions mainly resulting from systemic causes, including autoimmune diseases and diabetes mellitus, or local causes, for example, chemical injury and perioperative nerve injury, which can cause a varying level of neurosensory disturbances (NSDs). Coenzyme Q10 (CoQ10) is an essential regulator of mitochondrial respiration and oxidative metabolism. Here, we review the pathophysiology of NSDs caused by PNIs, the current understanding of CoQ10's bioactivities, and its potential therapeutic roles in nerve regeneration, based on evidence from experimental and clinical studies involving CoQ10 supplementation. In summary, CoQ10 supplementation shows promise as a neuroprotective agent, potentially enhancing treatment efficacy for NSDs by reducing oxidative stress and inflammation. Future studies should focus on well-designed clinical trials with large sample sizes, using CoQ10 formulations with proven bioavailability and varying treatment duration, to further elucidate its neuroprotective effects and to optimize nerve regeneration in PNIs-induced NSDs.

Govaers L., Beckers R., Politis C.

Several studies have described the outcomes and complications following orthognathic surgery. However, the average patient age in these studies is 20–40 years. It is unclear whether results from these age groups can be extrapolated to older patients. This retrospective observational study included 54 patients over 50 years of age, who underwent orthognathic surgery. From these patients' medical records, we retrieved data regarding patient characteristics, surgery characteristics, outcomes, and complications. The patients' mean age was 56 years (range, 50–69 years), and mean ASA score was 2. A bad split occurred in one patient, and immediate postoperative complications occurred in two patients. There were no long-term sequelae. Neurosensory disturbances (NSD) occurred in 30 patients. Preoperative temporomandibular dysfunction (TMD) was present in 9 patients—among whom, five were cured after surgery. Four patients postoperatively developed de novo TMD. Hardware removal was performed in 22 patients. The mean length of stay was two days for monomaxillary procedures, and three days for bimaxillary procedures. This study demonstrated apparent differences between patients over 50 years of age and the general orthognathic population. In particular, neurosensory disturbances and hardware removal were more prevalent in our study population.

de Castro R.W., Marlière D.A., Haiter Neto F., Groppo F.C., Asprino L.

To evaluate the positions of the mandibular foramen (MF) and mandibular canal (MC) between different skeletal classes to highlight the implications for bilateral sagittal split osteotomy (BSSO). A cross-sectional study was performed using cone-beam computed tomography on 90 patients classified into classes I, II and III. Linear measurements were performed on multiplanar reconstructions as follows: from the MF to the edge of the mandibular ramus (1), to the mandibular notch (2), to the ramus width (3) and to the occlusal plane (4); and from the MC to the alveolar crest (A), to the lower border of the mandible (B) and to the mandibular buccal cortical bone (C). Mandibular thickness (D), width (E) and height (F) of the MC were measured. Intra-class correlation coefficient (ICC) checked the reliability. Two-way ANOVA and Tukey’s test were used to compare measurements and classes. Linear measurements 2 presented a statistically significant difference between classes I and II. There was no statistically significant difference between the classes and measurements B, C, D, E and F. Linear measurements A were shorter in class III than in class II. Although most measurements suggest that the BSSO technique does not need to be modified for each skeletal class, measurements from the MF to the mandibular notch in class II and from the MC to the alveolar crest on distal of the second molars in class III could help surgeons to recognize critical regions.

Pourdanesh F., Tabrizi R., Alam M., Farzan A., Moslemi H., Farzan A., Khorsand A., Mohammadikhah M., Farzan R.

Background: The present study aims to determine the effect of Transcutaneous Electrical Nerve Stimulation (TENS) on neuro-sensory disturbance after orthognathic surgery. Materials and methods: In a randomized clinical trial, the participants via split-mouth sampling were randomly divided into two intervention (n=27) and control (n=27) groups. In the intervention group, participants received TENS physiotherapy. TENS physiotherapy was performed on the day after surgery, 1, 2, 3, and 4 weeks after surgery, along with prescriptions for the use of painkillers. On the control group, no physical therapy was performed and the patients only used painkillers (immediately after the operation). Paresthesia was evaluated using the 2-point discrimination (TPD) test and the semi-quantitative sensory-neural disorders test called brush stroke 6 months after the surgical procedures. Self-reported sensory-neural disorders were measured and reported for each patient before and 6 months after surgery using the visual analog scale (VAS). Results: A total of 54 patients participated in this study. The mean TPD score in the TENS group and the control group 6 months after the operation were 5.76 (SD=0.73) and 6.14 (SD=0.54), respectively (P=0.003). The mean VAS score in the TENS group and the control group 6 months after the operation was 6.48 (SD=0.50) and 5.80 (SD=0.63), respectively (P=0.005). Also, 66.7 and 38.9% in the TENS and control groups, respectively, performed the brush stroke test correctly (P=0.007). Conclusion: In sum, the benefits of TENS physiotherapy can be effective in reducing complications such as pain in dental surgery treatments or orthognathic surgeries.

Keykha E., Tahmasebi E., Hadilou M.

Abstract Background The present systematic review intended to evaluate the current evidence on the modalities used for treating iatrogenic late paresthesia in the oral tissues innervated by the mandibular branch of the trigeminal nerve. Main text As a common side effect of dental procedures, paresthesia can exert a profound adverse effect on patients’ quality of life. The inferior alveolar nerve (IAN) and lingual nerve (LN) have the highest chance of injury during several dental procedures, including mandibular orthognathic surgeries, implant placement, extraction of the third molar, anesthetic injections, flap elevation, and endodontic treatments. Moreover, several methods have been proposed for treating iatrogenic late paresthesia, including photobiomodulation (PBM), microsurgery, medication, and close observation until achieving spontaneous recovery of sensation. However, no gold standard treatment for iatrogenic paresthesia has been agreed upon up to now. The present study included a comprehensive search of the databases of PubMed, Embase, Scopus, and Web of Science up to December 04, 2023, resulting in a total of 3122 related studies. Then, the titles, abstracts, and full texts of the studies were evaluated. Ultimately, seven controlled randomized trials (RCTs) were included in the final analysis. Also, the risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. Among all fields, randomization, allocation concealment, and data analysis were found to have the highest chance of bias in the included studies. Conclusions In conclusion, PBM, vitamin B12, and corticosteroids could accelerate the recovery of late paresthesia. However, considering the low sample size of the included studies and the high risk of methodological bias, it is recommended to perform further RCTs with robust study designs following Good Clinical Practice (GCP) guidelines to achieve more reliable results.

Bhagat M.J., Thennarasu A.R., Durairaj D., Kumar G.S., Sakthi S., Rizqiawan A.

BSSO is a technically sensitive procedure, especially in terms of causing iatrogenic damage to the inferior alveolar nerve (Roychoudhury et al. in J Oral Biol Craniofac Res 5(2):65–68, 2015 and Agbaje et al. in Int J Oral Maxillofac Surg 44(4):447–451, 2015) and obtaining a desired sagittal split of mandible. Split Spider Splint (SSS) is a newly designed digital surgical guide based on tracking the course of inferior alveolar nerve and intraoperatively helps to make precise osteotomy cuts. This technical note describes the design concept and clinical application of this surgical Splint/ Guide.