Postoperative Neurosensory Disturbance Research Articles

Changes in the position of the inferior alveolar nerve after sagittal split ramus osteotomy and its effect on postoperative neurosensory disturbances

Aim of the studyTo analyze the positional changes of the inferior alveolar nerve after sagittal split ramus osteotomy (SSRO) and assess the impact of these changes on postoperative sensory nerve disturbances. Material and methodsPreoperative and postoperative (one year) spiral CT scans were used to categorize the inferior alveolar nerve into the extended side (n = 30) and retrogressive side (n = 30). Measurement software was used to observe and measure positional changes of the mandibular nerve canal, followed by a comparative analysis. ResultsPost-surgical analysis revealed that the inferior alveolar nerve was displaced laterally and superiorly on the extended side, and medially and inferiorly on the retrogressive side, with statistically significant differences (p<0.05). Correlation analysis demonstrated a significant association between nerve displacement in the first molar region and sensory nerve impairment (p<0.05). ConclusionSignificant positional changes in the inferior alveolar nerve were observed post-surgery, particularly on the extended migration side, with these changes being correlated with the occurrence of neurological symptoms.

Risk Factors Associated With Inferior Alveolar Nerve Injury After Extraction of Impacted Lower Mandibular Third Molars: A Prospective Cohort Study

BackgroundInferior alveolar nerve (IAN) injury is one of the complications of impacted lower mandibular third molar (LM3) extraction. Given the unknown prognosis of IAN injuries and limited treatment options, it is critical to understand the risk factors of IAN injury before LM3 extraction. PurposeThe study purpose was to identify risk factors associated with IAN injury after LM3 extraction. Study design, setting, sampleThis was a prospective cohort study including patients who underwent LM3 extraction from May to December in 2021 at authors’ institution. Patients with systemic diseases, previous maxillofacial surgeries or sensory abnormalities were excluded. Predictor variable(s)The predictor variable is composed of several risk factors. The variables were grouped into four categories: demographic, radiographic, procedure-related, and surgeon experience. Main outcome variable(s)The outcome variable was postoperative neurosensory disturbance coded as present or absent and was measured as one-month (transient) and one-year (permanent). CovariatesNot applicable. AnalysesThe measurement data were represented by mean and standard deviation (SD). The association of each variable with the presence of IAN injury was tested by the chi-square test. Statistical significance was accepted at p < 0.05. ResultsThe study sample was consisted of 705 patients (37.0% male) with an average age of 28.51 ± 6.51 years. A total of 17/705 (2.4%) and 4/705 (0.57%) patients developed transient and permanent IAN injury. The results demonstrated that the following factors were associated with higher rates of transient injury: use of chisels during surgeries (6.4%; 95% CI: 2.7-12.3; p=0.02; RR=11.4), LM3s located below the IAN canal (8.7%; 95% CI: 4.3-15.7; p<0.01; RR=7.3), compressed contact between LM3s and the IAN canal (36.4%; 95% CI: 12.3-78.2; p<0.001; RR=25.4), and not using corticosteroids after surgeries (3.8%; 95% CI: 1.9-6.5; p=0.03; RR=3.1). The only factor associated with permanent injury was compressed contact between LM3s and the IAN canal (18.2%; 95% CI: 2.2-62.3; p<0.001; RR=48.2). Conclusions and RelevanceClose proximity between LM3s and IAN canal, and the use of chisels, increase the risk of transient IAN injury. Corticosteroid treatment may promote nerve recovery. Compressed contact between LM3s and IAN canal is the only risk factor for permanent injury.

Evaluation of Intraoperative Inferior Alveolar Nerve Exposure During and Postoperative Neurosensory Disturbances after Bilateral Sagittal Split Osteotomy: A Prospective Cross-sectional Study in Iran

Introduction: Inferior Alveolar Nerve (IAN) exposure and neurosensory disturbances (NSDs) following bilateral sagittal split osteotomy (BSSO) of the mandible are paramount. We aimed to assess intraoperative IAN exposure during and NSDs after BSOO surgery using different clinical assessment methods in a prospective study in a local setting.&#x0D; Materials and methods: The present study was a prospective cross-sectional study. We monitored the nerve exposure status during the BSSO. Our time points were: before surgery, one day after, one month later, three months after and six months after the BSSO surgery. We performed two-point discrimination test, static light touch test and pinprick test on both mental regions of the cases.&#x0D; Results: We included seven women and eight men. The average age of the participants was 25.13 ± 3.27 years. The results of the two-point discrimination test showed the following: the day after the BSSO compared to before the surgery, the sensation is significantly impaired in both mental regions. In addition, it is noted that during our study, the two-point discrimination test results showed a gradient healing, though not reaching the point before the surgery (P&gt;0.05). The results of the Pinprick test also showed a gradual resolution of the NSDs; however, a significant sensation difference remained between six months after the BSSO and before the surgery.&#x0D; Conclusion: The BSSO surgery significantly impairs the IAN sensation, causing intraoperative IAN exposure and postoperative NSDs for the patients. A gradient resolution of the NSDs was observed in all the cases, though; the sensation of the mental region did not reach the pre-surgical levels.

Assessment of Mandibular Canal Using Cone-Beam Computed Tomography (CBCT) and Its Relevance in Post-Operative Neurosensory Disturbances Following Bilateral Sagittal Split Osteotomy Setback.

Damage to the inferior alveolar nerve (IAN) during bilateral sagittal split osteotomy (BSSO) causesneurosensory disturbances (NSD) of the lower lip and chin. The study aims to investigate the pre-operative position and course of the mandibular canal using cone-beam computed tomography (CBCT) and orthopantomogram (OPG) and compare if there is any difference in NSD following the BSSO setback procedure. This is an observational study. This study was conducted in the Department of Oral and Maxillofacial Surgery, Mar Baselios Dental College, Kothamangalam, from November 2017 to October 2019. Thirty patients undergoing BSSO setbacks are selected based on the inclusion and exclusion criteria and randomly grouped into two groups - group A (15) andstudy group B (15). OPG was done for both groups as it was required during surgical orthodontic evaluation and preoperative assessment of the mandibular canal was done using CBCT in group B. Neurosensory assessment was done in all the patients and compared the results. NSD were reported in all the patients on the first postoperative day. The correlation between subjective and objective evaluation showed absolute coincidence but nearly all the patients returned to their presurgical situation within six months in group B and one year in group A who had NSD problems. From the study, it can be concluded that a CBCT scan is a useful and reliable modality in the pre-operative evaluation of the mandibular canal in patients undergoing BSSO setback procedures, which helps to improve the patient's post-operative care and quality of life.

Do anatomical variations of the mandibular canal pose an increased risk of inferior alveolar nerve injury after third molar removal?

The present study aimed to assess whether anatomical variations of the mandibular canal are associated with neurosensory disturbances of the inferior alveolar nerve (IAN) following mandibular third molar removal. Two observers compared the detection of third molar root-nerve relations and bifurcations of the mandibular canal on panoramic radiographs and CBCT images of 201 patients undergoing removal of 357 mandibular third molars. Potential neurosensory disturbances of the IAN were surveyed ten days after surgery. Fisher's Exact was performed to correlate presence of canal variations to postoperative neurosensory disturbances. Positive and negative predictive values (PPV, NPV) and likelihood ratios (LR + , LR-) were calculated. Thirteen patients reported postoperative altered sensation of the lower lip, with 2 of them having mandibular canal bifurcations on the ipsilateral side of the injury. Fisher's Exact showed that the studied mandibular canal variations were not related to postoperative neurosensory disturbances. CBCT was superior in visualization of anatomical variations of the mandibular canal. Prevalence of bifurcations was 14% on CBCT and 7% on panoramic radiographs. In both imaging modalities and for all parameters, PPVs were low (0.04 - 0.06) and NPVs were high (0.92 - 0.98), with LR ranging around 1. In the present study, the assessed mandibular canal variations had limited predictive value for IAN neurosensory disturbances following third molar removal. While a close relation between the third molar and the mandibular canal remains a high risk factor, mandibular canal variations did not pose an increased risk of postoperative IAN injury after third molar removal.

Evaluation of Sagittal Curving Osteotomy vs Conventional Advancement Genioplasty in Retrogenia Patients: a Randomized Control Trial.

With increasing aesthetic awareness, in addition to the forehead, nose, and cheekbone prominence, the chin nowadays is seen as one of the most important parts of the facial skeleton. Position of the chin has a strong influence on the assessment of the facial harmony; its different types and forms dominate the appearance. Furthermore, the expression of the chin is equated with character traits, and thus, it is an important component of the profile forms. Genioplasty is a routine procedure for the correction of aesthetic and functional deformity of the chin region. It is therefore one of the contour-enhancing surgical methods. The purpose of the present study is to study the versatility of sagittal curving osteotomy for advancement genioplasty as an alternative to conventional technique. A total of 24 subjects were enrolled for the study who were randomly distributed into two groups: group 1(n-12) comprising of patients in whom sagittal curving osteotomy was done and group 2 (n- 12) comprising of patients in whom conventional osteotomy was done. Neurosensory disturbances and hard and soft tissue relapse were compared between the two groups. On comparison of all the variables, it was found that the conventional osteotomy technique had more hard tissue relapse and more neurosensory disturbance as compared to sagittal curving osteotomy technique. Results of this study suggest that the use of sagittal curving osteotomy may be helpful in reducing postoperative neurosensory disturbances and relapses following genioplasty. Hence, it is recommended that sagittal curving osteotomy can be used as an alternative osteotomy technique for advancement genioplasty.

Neurosensory Disturbances After Apical Surgery of Mandibular Premolars and Molars: A Retrospective Analysis and Case-Control Study.

Objective:Apical surgery is an intervention to treat teeth with persistent or recurrent endodontic infection. The proximity of the mental foramen and mandibular canal may pose a risk of altered sensation when performing surgical interventions in the posterior mandible. The objective of this study was to determine the rate of neurosensory disturbances after apical surgery of mandibular premolars and molars. The secondary objective was to evaluate whether the occurrence of altered sensation correlated with the distances from the apex or the periapical lesion to the relevant anatomical structures.Methods:The charts of patients treated from September 1999 to December 2015 were retrospectively evaluated if an apical surgery had been performed in mandibular premolars or molars, and a minimum period of 1-year follow-up was documented. Patients with trauma or other surgical interventions in the same hemimandible were excluded. Cases with postsurgical altered sensation were defined as the test group. From the pool of unaffected cases, patients were selected to serve as controls. Two- or three-dimensional radiographs of test and control cases were assessed with regard to the shortest distances from the root apices/lesions to the mental foramen or mandibular canal.Results:The study population included 243 patients with 249 apical surgeries, of which 12.9% led to postoperative neurosensory disturbances. Sensation returned to normal within 22 days on average. The most frequent findings were hyperesthesia or paresthesia. With regard to the treated type of tooth, second premolars resulted more frequently (22.6%) in altered sensation than the other teeth (11.2 to 13.0%; p=0.310). There were no significant differences when comparing test and control cases regarding the measured distances in radiographs from the apex/lesion to the relevant anatomical structures.Conclusion:Altered sensation may typically occur following apical surgery in posterior mandibular teeth. However, in all cases of the present study, skin sensitivity in the lip/chin region returned to normal. The clinician must be particularly careful when performing apical surgery of second premolars due to the proximity of the mental foramen.

Prediction of neurosensory disorders after impacted third molar extraction based on cone beam CT Maglione’s classification: A pilot study

BackgroundSurgical difficulty assessment in the extraction of impacted mandibular third molars is a constant challenge for oral surgeons. AimThe first aim was to apply Maglione's new classification on patients that needed surgical extraction of impacted mandibular third molars, and the second aim was to study the correlation of the classification classes with the occurrence of postoperative neurosensory disorders. Materials & methodsThe present prospective clinical trial pilot study was conducted on patients attending oral and maxillofacial surgery clinics from February 2017 until January 2018 for the surgical extraction of impacted lower third molars. ResultsFifty-one out of sixty-nine patients made the surgical removal of one impacted mandibular third molar. The most common subclass was 1B (24.6%), followed by subclass 3B (23.2%). Subclass 3A and 4B showed an equal distribution of (11.6%) each, and then subclass 2B (10%). The most significant subclass was 4B with (5.9%) neurosensory disturbance. None of the patients had a permanent disturbance. ConclusionMaglione's classification offers unique detailed description of the buccolingual relationship of MTM with IAC that could be used as a future reliable radiographic guide to reduce the risk of post-operative neurosensory disturbances after MTM surgical removal.

Patterns of lingual split and lateral bone cut end and their associations with neurosensory disturbance after bilateral sagittal split osteotomy

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.

Incidence of inferior alveolar nerve affection with and without nerve exposure during bilateral sagittal split osteotomy

Objective: The aim of this study was to determine the presence and severity of inferior alveolar nerve (IAN) affection during bilateral sagittal split osteotomy (BSSO) in two groups of patients with and without direct exposure and visualization of the nerve during surgical procedure.Patients and Methods: In this prospective randomized clinical study, 14 patients (28 sides) indicated for BSSO were included. The sides were randomly divided into two groups with equal number of sides (14 sides). Group I with wide soft tissue dissection of the medial side of the ramus and exposure of IAN above the ligula and group II with minimal soft tissue dissection of the medial side of the ramus without exposure of IAN. For evaluation of neurosensory function of IAN, two methods were used including subjective evaluation and two-point discrimination test.Results: According to the subjective evaluation, there was a statistically significant difference between both groups in favor of group II in all follow-up recalls except in the final one at 12 months postoperatively. Considering the results of two-point discrimination test, the improvement obviously continued during the successive follow-up periods in both groups, with a statistically significant difference in favor of group II until the ninth month, and then in the last follow-up at the 12th month, the records were almost equal.Conclusion: To markedly reduce the postoperative neurosensory disturbances of IAV and to accelerate the full recovery of sensation of the lower lip and chin regions following BSSO, limited exposure and dissection of the medial soft tissues of the ramus should be practiced with avoidance of direct exposure and manipulation of IAN.

A Modified Technique of Mandibular Ramus Sagittal Split Osteotomy for Prevention of Inferior Alveolar Nerve Injury: A Prospective Cohort Study and Outcome Assessment.

Postoperative functional impairment of the inferior alveolar nerve (IAN) has been a common and well-recognized complication. Our study introduced a modified Obwegeser-Dal Pont bilateral sagittal split osteotomy (BSSO) technique and evaluated the subsequent incidence of postoperative neurosensory disturbance of IAN. In this prospective cohort study, 57 patients receiving our modified BSSO during orthognathic surgery were enrolled. The technique contained opening the 2 ramus cortices and inserting the osteotome bypassing the IAN to avoid nerve injury. A 5-point scale self-assessment questionnaire was used to evaluate IAN neurosensory disturbance one week, six months and 12 months postoperatively. Differences between groups were analyzed using χ test for categorical and Wilcoxon signed-rank test for pairwise categorical data. Complete ramus splitting could be achieved in 109 (95.6%) sides. Lower lip or chin neurosensory disturbances presented in 72 (63.2%) sides 1 week postoperatively and gradually reduced to 9 (7.9%), and 4 (3.5%) at postoperative months 6 and 12, respectively. This BSSO technique could be safely performed with low rates of IAN exposure and injury and a low incidence of persistent neurosensory disturbance in 3.5% of patients 12 months postoperatively.

Radiographic features of anatomic relationship between impacted third molar and inferior alveolar canal on coronal CBCT images: risk factors for nerve injury after tooth extraction.

IntroductionThe present study was aimed to identify the radiographic signs between impacted third molar root and inferior alveolar canal (IAC) on cone-beam CT (CBCT) images as risk factors and prognostic predictors associated with inferior alveolar nerve (IAN) damage following tooth removal.Material and methodsA retrospective clinical study was performed involving 136 patients with 257 impacted lower third molars from January 2013 to December 2014. The neurosensory function of the lower lip and chin was subjectively evaluated and assessed by neurosensory tests before and after surgery. The preoperative CBCT data were retrieved and analyzed to identify the radiographic signs associated with postoperative IAN injury.ResultsThe overall incidence of IAN injury in our patient cohort was 13.2%. Multiple radiographic features on coronal CBCT images including contact between IAC and root, IAC position relative to root, IAC shape and cortication status were found to be significantly associated with IAN damage (p < 0.05, χ2 test). Furthermore, buccolingual position, teardrop/dumbbell shape and cortication status of IAC were identified as independent prognostic predictors for IAN damage.ConclusionsOur findings indicate that radiographic signs including direct contact between IAC and root, buccal/lingual IAC position relative to root, teardrop/dumbbell shape and cortication absence of the IAC on presurgical CBCT images are associated with high risk of IAN injury and postoperative neurosensory disturbance.

Abnormal Anatomical Location of Root of Second Premolar in Mental Foramen: A Very Rare Case

ABSTRACT Mental foramen is a key factor in many of the surgical procedures. While carrying out surgical procedures in premolar region, the knowledge of anatomy of mental nerve and its foramen is of utmost importance to avoid intraoperative neurovascular damage and to avoid postoperative neurosensory disturbances. The variations of mental foramen with respect to position, size, and number are very well documented. However, in very rare cases, length of the premolar roots may be abnormally long or abnormally positioned, which can impinge on the mental nerve or may enter mandibular canal or mental foramen. We present one such rare case where second premolar root was impinging on the mental nerve and producing symptoms. Extraction of second premolar was done and patient became asymptomatic postoperatively. How to cite this article Khandelwal P, Dubey S, Hajira N. Abnormal Anatomical Location of Root of Second Premolar in Mental Foramen: A Very Rare Case. Int J Experiment Dent Sci 2016;5(1):76-77.

Morphological features of the mandible as predictors for neurosensory disturbances after bilateral sagittal split osteotomy.

This retrospective study aimed to identify anatomical predictors of neurosensory disturbance (NSD) after bilateral sagittal split ramus osteotomy (BSSO) by evaluating the morphology of the mandible on lateral cephalograms (LCs) and orthopantomograms (OPTs). The LCs and OPTs of 142 patients who underwent BSSO were reviewed. The influence of the mandibular angle was assessed on LCs, while the following morphological landmarks and subsequent measurements were analysed on OPTs: vertical and horizontal positions of the lingula, ramus width, mandibular body height, mandibular canal position and mandibular angle length. Post-operative NSD (hypoaesthesia) was considered permanent when objective tests or subjective evaluations indicated altered sensation one year after BSSO. Generalised linear mixed models were used to take into account the repeated measurement design (left and right measurements within one patient). Hypoaesthesia was present in 10.6% of the patients (5.6% of sites). After adjusting for age, a small mandibular body height was found to significantly increase the risk of hypoaesthesia. The other measurements showed no significant association with hypoaesthesia. These findings show a relationship between mandibular morphology and hypoaesthesia after BSSO and can aid surgeons in pre-operative assessments of the risk of NSD. Further research is needed to identify risk factors for NSD based on mandibular morphology.

Neurosensory disturbance after bilateral sagittal split osteotomy: A retrospective study

AimTo retrospectively evaluate neurosensory disturbance (NSD) after bilateral sagittal split osteotomy (BSSO). Material and methodsA retrospective review was carried out to assess inferior alveolar nerve function in patients treated by BSSO from 2010 to 2013. All patients included in the study were assessed using objective (cotton swabs and pin prick testing) and subjective testing (questionnaire) for inferior alveolar nerve function after a minimum of 1 year of follow-up. Medical records of the patients were used to assess the incidence of NSD in the immediate post-operative period. Results15 patients (30 sides) had undergone BSSO during the specified time period. On subjective testing, NSD was reported in 22 operated sides (73.3%) in the immediate post-operative period, while 4 operated sides (13.3%) reported persistent NSD. On objective testing, immediate post-operative NSD was seen in 20 operated sides (66.7%). After a minimum of 1 year follow-up, recovery was seen in 18 operated sides while persistent NSD was seen in 2 operated sides (6.7%). ConclusionNSD of the inferior alveolar nerve is a common complication after BSSO in the immediate post-operative period. However in a long term, nerve function usually recovers.

Bilateral sagittal split osteotomy versus distraction osteogenesis of the mandible: a randomized clinical trial

A randomized clinical trial was performed to evaluate differences in postoperative neurosensory disturbance (NSD) between two methods of mandibular advancement surgery. A total of 66 non-syndromal class II patients with mandibular hypoplasia were randomized for either distraction osteogenesis (DO) or bilateral sagittal split osteotomy (BSSO). Twenty-nine patients in the BSSO group and 34 patients in the DO group were available for evaluation. Objective assessment was performed by Semmes–Weinstein (SW) monofilament testing preoperatively and at least 1 year after surgery. Six of the 34 patients (17.6%) in the DO group experienced objective NSD, compared to 5/29 patients (17.2%) in the BSSO group. In the evaluation of nerve function by individual nerves, 8/68 nerves (11.8%) revealed objective NSD in the DO group, compared to 7/58 nerves (12.1%) in the BSSO group. A subjective NSD was reported in 11/34 patients (32.4%) in the DO group, compared to 9/29 patients (31.0%) in the BSSO group. In the evaluation of nerve function by individual nerves, a subjective NSD was reported for 13/68 nerves (19.1%) in the DO group, compared to 13/58 nerves (22.4%) in the BSSO group. None of the differences was significant. No differences in neurosensory disturbance could be found between the two study groups. Objective WS monofilament testing appeared to underestimate NSD compared to subjective patient report.

Influence of BSSO surgical technique on postoperative inferior alveolar nerve hypoesthesia: A systematic review of the literature

ObjectiveThe aim of this study was to evaluate the influence of different splitting techniques, namely, “mallet and chisel” versus “spreading and prying”, used during bilateral sagittal split osteotomy (BSSO) on postoperative hypoesthesia outcomes. Study designWe systematically searched the PubMed and Cochrane databases (from January 1957 to November 2012) for studies that examined postoperative neurosensory disturbance (NSD) of the inferior alveolar nerve (IAN) after BSSO. ResultsOur initial PubMed search identified 673 studies, of which, 14 met our inclusion criteria. From these 14 studies, 3 groups were defined: (1) no chisel use (4.1% NSD/site), (2) undefined chisel use (18.4% NSD/site), and (3) explicit chisel use along the buccal cortex (37.3% NSD/site). ConclusionStudy heterogeneity and a frequent lack of surgical detail impeded our ability to make precise comparisons between studies. However, the group of studies explicitly describing chisel use along the buccal cortex showed the highest incidence of NSD. Moreover, comparison of the study that did not use chisels with the 2 studies that explicitly described chisel use revealed a possible disadvantage of the “mallet and chisel” group (4.1% versus 37.3% NSD/site). These results suggest that chisel use increases NSD risk after BSSO.

Systematic review of preoperative mandibular canal position as it relates to postoperative neurosensory disturbance following the sagittal split ramus osteotomy

Systematic review of preoperative mandibular canal position as it relates to postoperative neurosensory disturbance following the sagittal split ramus osteotomy

Evaluation of an innovative computer‐assisted sagittal split ramus osteotomy to reduce neurosensory alterations following orthognathic surgery: a pilot study

Sagittal split ramus osteotomy (SSRO) can be associated with postoperative neurosensory disturbances. This study aimed to evaluate the effectiveness of computer-assisted SSRO in reducing the incidence and severity of neurosensory alterations, using a surgical guide fabricated by computer-aided design and rapid prototyping (to guide bone cutting lateral to the inferior alveolar nerve). A prospective double-blind, randomized controlled, clinical trial of computer-assisted SSRO vs conventional SSRO (assigned in a split-mouth design) in eight patients, mean age 23 (range 18-30) years, who participated in one session preoperatively and three sessions at 1 week and 1, 3 and 6 months postoperatively. At each session, subjective oral sensation was scored and quantitative sensory tests were performed. Neurosensory changes were compared between the two sides. The results showed that on the computer-assisted SSRO sides, patients had lower postoperative abnormal thresholds for the Semmes-Weinstein monofilaments on lower lip and chin (p < 0.05 at 3 months) and for the two-point discrimination on lower lip (p < 0.05 at 1 week) and chin (p < 0.05 at 6 months), with fewer abnormal self-reported changes in lower lip sensation (p < 0.05 at 1 week) after surgery. These findings imply that computer-assisted SSRO is associated with better levels of neurosensory function after surgery.

Concomitant Removal of Mandibular Third Molars During Sagittal Split Osteotomy Minimizes Neurosensory Dysfunction

Inferior alveolar nerve (IAN) injury is 1 of the most important postoperative complications after sagittal split osteotomy (SSO). The purpose of our study was to investigate the effects of the presence or absence of a mandibular third molar on the neurosensory recovery of the IAN after SSO. A prospective cohort study enrolled a sample composed of patients who underwent SSO to correct mandibular deformities. The primary predictor variable was the status of the mandibular third molar at the time of SSO and it was divided into two levels, present at the time of SSO (Group I) or absent at the time of SSO (Group II). The primary outcome variable was neurosensory recovery of the IAN, assessed using the Medical Research Council scale, functional sensory recovery, and subjective evaluation. Neurosensory status was measured 3 times (preoperatively and 3 and 6 months postoperatively). Appropriate bivariate and multivariate statistics were computed, and the level of statistical significance was set at P < .05. A total of 120 SSOs were performed in 60 patients. Group I included 64 SSOs (mean patient age ± SD 19.3 ± 8.0 years) and group II, 56 SSOs (mean patient age 24.9 ± 10.0 years). The Medical Research Council scale scores showed that the presence of third molars during SSO was associated with a statistically significant decreased incidence of neurosensory disturbance of the IAN at 3 and 6 months postoperatively (all P < .01). Functional sensory recovery was achieved more frequently in group I, but this difference remained significant only at 3 months after adjusting (P = .01). A "normal sensation" was subjectively reported more frequently in group I at 3 and 6 months postoperatively (P ≤ .05). The presence of third molars during SSO minimizes postoperative neurosensory disturbance of the IAN.