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

Therapeutic modalities for iatrogenic late paresthesia in oral tissues innervated by mandibular branch of trigeminal nerve: a systematic review

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.

The online attention analysis on orthognathic surgery research

OBJECTIVES

Altmetrics is one of the fields of bibliometrics that seeks to assess the impact and interest of a given subject through Internet users. The aim of this study is to make an altmetric analysis of the orthognathic surgery literature.

METHODS

A literature search was conducted using Dimensions app up to December 2023. A list of the 100 most mentioned articles on the topic was compiled. A Google Trends search was performed with same strategy to visualize important data regarding internet search. Charts and tables were created using Microsoft Excel and VOSviewer software to allow bibliometric visualization.

RESULTS

There was a very poor correlation between the number of mentions and the number of citations (r = 0.0202). Most articles discussed on technical innovations associated to orthognathic surgery, majority related to virtual planning (n = 26). Other topics considered interesting to internet readers were complications (n = 18), surgical technique (n = 14), and psychological aspects/quality of life (n = 13).

CONCLUSION

Online interest in orthognathic surgery closely aligns with the level of academic interest but is also influenced by factors such as location and economic status. The internet is a powerful tool for disseminating scientific research to a broad audience, making it more accessible and engaging than traditional academic channels.

Relationship of the Degree of Nerve Exposure and Surgical Manipulation and Short-Term Neurosensory Disturbance Following Sagittal Split Ramus Osteotomy: A Prospective Study

BACKGROUND

Neurosensory disturbance (NSD) is a common complication after sagittal split ramus osteotomy (SSRO) due to inferior alveolar nerve (IAN) injury. The impact of intraoperative nerve manipulation on NSD remains debated.

PURPOSE

The purpose of this study was to evaluate the influence of IAN exposure and manipulation during SSRO on functional sensory recovery (FSR).

STUDY DESIGN

This was a single-center, prospective cohort study of 40 patients undergoing SSRO at Mahidol University from December 2020 to December 2021. The inclusion criteria were patients aged 20-34, ASA Class I-II. The exclusion criteria were patients with systemic bone disease, history of head and neck or neurological pathology, previous SSRO, or incomplete data collection.

PREDICTOR VARIABLE

Degree of intraoperative nerve manipulation was divided by the attending surgeon as follows; 1) Nerve fully encased in distal segment and not visible (NS); 2) Nerve encased in distal segment but partially visible (DS); and 3) Nerve partially encased in proximal segment and fully dissected free (PS).

OUTCOME VARIABLES

The area of interest was divided into the lip and chin. The primary outcome was time to FSR. The secondary outcome was subjective patient report, using a visual analogue scale, compared to FSR.

COVARIATES

The covariates were sex, age, skeletal diagnosis, degree of movement, and concomitant genioplasty/subapical procedure.

ANALYSES

Kaplan-Meier survival analysis, Cox proportional hazards regression, and Mcnemar test were utilized. P-value < .05 was significant.

RESULTS

In the lip, the median times to FSR were NS, 2 days; DS, 45 days; PS, 102 days. (Interquartile range: 77,127, 114, respectively) In the chin, the median times to FSR were NS, 23 days; DS, 92 days; PS, 87 days. (Interquartile range: 77, 161, 101, respectively.) Nerve manipulation significantly affected FSR in the lip and chin (P = .001, <0.001, respectively. Cox hazard ratios for DS and PS were lower compared to NS. Patients consistently reported more NSD compared to FSR as per Mcnemar test.

CONCLUSION AND RELEVANCE

After SSRO, FSR in the lip is prolonged when the IAN is partially encased in the proximal segment and released. This raises the question of the efficacy of surgically releasing a partially encased IAN.

Exploring the relationship between the number of systematic reviews and quality of evidence: an orthognathic surgery-based study

OBJECTIVE

We analyzed the quality and quantity of systematic reviews (SRs) of orthognathic surgery, the most frequently published topic in maxillofacial surgery.

STUDY DESIGN

We searched the PubMed database for SRs of orthognathic surgery with no restriction on the language of publication date. We assessed the certainty of evidence presented according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol and the Leiden Manifesto using the Grading of Recommendations Assessment, Development, and Evaluation approach. We analyzed the data using descriptive statistics, Pearson´s correlation test, and linear regression.

RESULTS

Of the 171 SRs evaluated, approximately one fifth presented evidence with a high level of certainty. The number of orthognathic surgery SRs has been increasing, and many SRs were published after very similar topics had already been published. There is no relationship between the impact factor and the certainty of evidence.

CONCLUSIONS

An excessive number of SRs of orthognathic surgery are published, and many SRs are superfluous, simply reporting previous findings. Clinicians should not base treatment decisions solely on the evidence presented in SRs, and journal editors and reviewers should evaluate these SRs more critically, particularly when they address topics that have already been covered in the literature.

Effect of betamethasone injection into the pterygomandibular space on the neurosensory disturbance after bilateral sagittal split ramus osteotomy: a pilot study

AIM

The aim of this study was to evaluate the effect of local betamethasone injection into the pterygomandibular space on postoperative neurosensory deficits.

MATERIALS AND METHODS

A prospective controlled clinical study was conducted on 16 patients (6 male, 10 female; mean age, 24.95 ± 9.22 years) who underwent bilateral sagittal ramus osteotomy for mandibular discrepancies. One side of each patient's mandible was randomly selected as the control side, and the opposite side as the experimental side. On the experimental side, a solution of betamethasone (6 mg/1 ml) was injected into the pterygomandibular space after the completion of wound closure. Neurosensory tests, including light touch, two-point discrimination, direction of movement, thermal sensitivity, and pin-prick discrimination, were performed. The follow-up period ranged between 6 and 12 months, according to the particular sensory test. The Fisher exact test was used to analyse the data.

RESULTS

The light touch sensation was abnormal in 75% of the control side and 31% of the study side, with the difference being significant (p = 0.03). However, at 6 months, all the study cases regained touch sensation, compared to 69% of the control side. No significant difference in direction movement discrimination was seen; however, at 3 months, the study side showed significantly less direction sensation (19%) compared to the control side (56%) (p = 0.02). There was no significant difference in the two-point discrimination; however, at 3 months, the study side had a significantly less abnormal two-point sensation (13%) than the control side (56%) (p = 0.02). In addition, no significant difference was noted in thermal sensitivity or pin-prick sensation.

CONCLUSION

Betamethasone injection into the pterygomandibular space reduces neurosensory disturbances after bilateral sagittal split ramus osteotomies nd leads to faster recovery of sensations.

Investigation of the efficacy of two different laser types in the treatment of lower lip paresthesia after sagittal split ramus osteotomy

Orthognathic surgery involves invasive and major surgical procedures commonly used to correct maxillofacial deformities. Bilateral sagittal split ramus osteotomy (BSSO) is often used to treat dentofacial anomalies related to the mandible, but it can result in various complications, the most common of which is inferior alveolar nerve damage. Nerve damage-induced paresthesia of the lower lip significantly affects patient comfort. Medical treatments such as steroids and vitamin B, low-level laser therapy (LLLT), and platelet-rich fibrin (PRF) can be used as supportive therapies for nerve regeneration after damage. This study aimed to investigate the effectiveness of two different types of lasers in treating lower lip paresthesia after BSSO. This clinical trial was a controlled, single-center, prospective, single-blind, randomized study. Thirty patients were included in the study and randomly assigned to three groups: Group I (laser GRR, n = 10) received transcutaneous and transmucosal GRR laser treatment, Group II (Epic10 laser, n = 10) received transmucosal and transcutaneous Epic10 laser treatment, and Group III (vitamin B, n = 10) received B-complex vitamin tablets orally once a day. Two-point and brush tests were performed six times at specific intervals, and a visual analog scale was used to evaluate pain and sensitivity. Both vitamin B and laser therapies accelerated nerve regeneration. The contribution of the laser groups to the healing rate was better than that of the vitamin B group. Although there was no statistically significant difference between the two laser groups, clinical observations indicated better results in the GRR laser group.

Radiological evaluation of inferior alveolar nerve displacement after removal of impacted mandibular third molars prior to sagittal split osteotomy

INTRODUCTION

We hypothesize that the removal of mandibular third molars (M3) 6 months prior to a bilateral sagittal split osteotomy (BSSO) could allow the displacement of the inferior alveolar nerve (IAN) in a favorable lingual position. This study aimed to radiographically compare the position of IAN before and after M3 removal in patients with Class II malocclusion.

MATERIALS AND METHOD

The CBCT images of 30 randomly selected patients (mean age 15.5 years, 19 females and 11 males) were segmented regarding the mandibular bone and the IAN canal. Mandibles were then superimposed and compared using 3D slicer (www.slicer.org). An orthonormal system was constructed, and the coordinates of IAN were assessed in the x- (horizontal axis), y- (depth axis), and z- (vertical axis) directions.

RESULTS

The mean changes in x- and z-values were 0.37 %, -0.09 % for the right IAN, 0.07 %, and -0.10 % for the left IAN, respectively. Y-axis was the dimension the most impacted by the M3 removal with a mean variation of -11.96 % for the right IAN, and 0.45 % for the left nerve (p1=0.74 and p2=0.04, respectively). Three patients presented a change in the IAN position superior to 1 mm on at least one coordinate axis. We observed a more important change in x-values of the right IAN in male than in female (p = 0.04), and no significant modifications regarding the other dimensions. Finally, there was no correlation between the age of the patients and the changes in IAN position.

CONCLUSION

This study confirms the absence of influence of mandibular third molar removal on the inferior alveolar nerve route prior to BSSO.

Does osteotomizing the lower border of the mandible affect the lingual split pattern in a sagittal split ramus osteotomy?

AIM

The purpose of this study was to evaluate the effect of adding a fourth osteotomy at the lower border of the mandible on the lingual cortical fracture pattern in bilateral sagittal split ramus osteotomies.

PATIENTS AND METHODS

The sample of the study consisted of 20 patients (12 male and 8 female, with a mean age of 26.79 ± 7.12 years) with mandibular deformities who needed bilateral sagittal split ramus osteotomy. One side underwent a traditional sagittal split ramus osteotomy, and the procedure was modified on the other side by adding a 1 cm horizontal osteotomy at the lower border of the mandible, just distal to the caudal end of the vertical buccal osteotomy cut. A 3D CBCT was used to identify the split pattern.

RESULTS

In the total sample, 40% of the lingual splits ran vertically toward the lower border of the mandible (LSS1), 20% of the splits passed horizontally to the posterior border of the mandible (LSS2), 32.5% of the splits took place along the inferior alveolar canal (LSS3), and 7.5% of the splits were unfavourable fractures (LSS4). On the inferior border osteotomy sides, the distribution of LSS1, LSS2, LSS3, and LSS4 was 10 (25%), 6 (15%), 4 (10%), and 0 (00), respectively. Their distribution on the sides without inferior border osteotomy was 6 (15%), 8 (20%), 13 (32.5%), and 3 (7.5%), respectively. Statistical analysis revealed a significant difference between the two groups (p < 0.05).

CONCLUSION

Inferior border osteotomy tends to direct the lingual split fracture line toward the lower and posterior borders of the mandible and minimizes bad splits; however, further studies are needed to confirm our findings.

Clinical Analysis of Patients who Underwent Reoperation After Orthognathic Surgery: A 14-Year Retrospective Study

PURPOSE

The purpose of this study was to analyze the patients clinically who underwent reoperation after certain Orthognathic procedures, and to assess the reoperation rate. Furthermore, the authors also evaluated the incidence of intraoperative and postoperative complications that led to the need for reoperation.

METHODS

Total 526 patients were selected who underwent Orthognathic surgery between July 2008 and February 2022 at the Department of Oral and Maxillofacial Surgery in Pusan National University Dental Hospital by single surgeon. All the patients information were extracted from electronic database of our university. Demographic, radiologic, intraoperative, and postoperative data were recorded and compiled.

RESULTS

Out of 526 patients, 265 (50.3%) were males and 261 (49.6%) were females. The total number of patients who showed complication is 89 (16.9%) and the patients who underwent reoperation are 17 (3.2%). The common complications that occurred were postoperative sensory disturbance (31; 5.8%), unwanted fractures (17; 3.2%), intraoperative nerve injury (11; 2%), wound dehiscence (11; 2%), infection (10; 1.9%), tooth injury (2; 0.3%), and others (18; 3.4%). The serious complications that led to reoperation include severe bleeding (6; 1.1%), unesthetic results (5; 0.9%), non-union of maxilla (4; 0.7%), and failed osteosynthesis (2; 0.3%). After 2018, all the orthognathic surgeries were performed with the help of virtual surgical planning. After application of virtual surgical planning, the number of patients with complications statistically decreased.

CONCLUSION

The present study showed that the reoperation rate after orthognathic surgery was low, this rate was more decreased after applying 3-dimensional virtual surgery and 3-dimensional printed plate, especially in unesthetic cases.

Avoiding Inferior Alveolar Nerve Injury During Sagittal Split Ramus Osteotomy

Orthognathic surgery is highly effective in improving overall facial esthetics, in addition to achieving an ideal occlusion. Sagittal split ramus osteotomy (SSRO) of the mandible is the mainstay of modern orthognathic surgery, but intraoperative injury to the inferior alveolar nerve (IAN) remains one of the common complications. The authors report a case of 19-year-old male patient with left cleft lip and palate who received orthognathic surgery involving SSRO. The patient's right IAN ran close to the outer cortex of the mandible, but SSRO was successfully performed without injuring the nerve. Detailed preoperative evaluation using computed tomography images is essential. Blind splitting maneuvers during SSRO may cause IAN injury, and direct visualization inside the ramus helps to prevent injury to the nerve. Sagittal split ramus osteotomy could be considered as a viable option even when the IAN runs close to the outer cortex. This article describes SSRO procedures, highlighting the methods to avoid nerve injury.

The effectiveness of photobiomodulation therapy on inferior alveolar nerve injury: A systematic review and META-analysis

OBJECTIVE

The aim of this META-analysis was to evaluate the efficacy of photobiomodulation (PBM) therapy in the treatment of inferior alveolar nerve (IAN) injury due to orthognathic surgeries, extraction of impacted third molars and mandibular fractures.

METHODS AND MATERIALS

A electric search was conducted by a combination of manual search and four electric databases including Pubmed, Embase, Cochrane library and Web of Science, with no limitation on language and publication date. Gray literature was searched in ClinicalTrials.gov and googlescholar. All retrieved articles were imported into ENDNOTE software (version X9) and screened by two independent reviewers. All analysis was performed using the REVMAN software (version 5.3).

RESULTS

Finally, 15 randomized controlled trials met the inclusion criteria for qualitative analysis and 14 for META-analysis from 219 articles. The results showed that PBM therapy had no effect on nerve injury in a short period of time (0-48h, 14 days), but had significant effect over 30 days. However, the effect of photobiomodulation therapy on thermal discrimination was still controversial, most authors supported no significant improvement. By calculating the effective rate of PBM, it was found that there was no significant difference in the onset time of treatment, whether within or over 6 months.

CONCLUSIONS

The results of this META-analysis show that PBM therapy is effective in the treatment of IAN injures no matter it begins early or later. However, due to the limited number of well-designed RCTs and small number of patients in each study, it would be necessary to conduct randomized controlled trials with large sample size, long follow-up time and more standardized treatment and evaluation methods in the future to provide more accurate and clinically meaningful results.

The inferior alveolar nerve at the proximal fragment during bilateral sagittal split osteotomy - Is there need to reposition to distal fragment?

Inferior alveolar nerve (IAN) injury is most common in bilateral sagittal split osteotomy (BSSO) cases. The present standard is to always reposition the IAN from the proximal fragment to the distal fragment during surgery. This study aims to assess the severity and incidence of postoperative injury and the recovery of the inferior alveolar nerve in proximal fragment entrapment.

Methods

- A total of 35 patients (70 BSSO osteotomies) with mandibular deformities requiring movements equal to or less than 6 mm were selected. Twenty out of 70 osteotomies had IAN on the proximal fragment (Group 1) while splitting. Group 2 included 20 osteotomies with IAN on the distal segment in the same patients. Therefore, 15 patients who had IAN on distal segments on both sides were excluded from this study. All the BSSO procedures were performed by the same surgeon. Postoperative recovery and follow-up were performed on the immediate 1st postoperative day and at 3-, 6- and 12-month intervals. The nociception (pin-prick discrimination) test and mechanoreceptive tactile skin test with cotton fibrils were performed by a third clinician who was blinded to the procedure to assess IAN sensation.

Conclusion

There was no significant difference between the groups in the recovery of IAN sensation after 6 months and the 1-year period. Hence reposition of IAN from the proximal segment to the distal segment during BSSO surgery may not be mandatory if the required movement is within 6 mm. This avoids unnecessary manipulation of the IAN over the proximal fragment.

Effects of sagittal split osteotomy on brainstem reflexes

OBJECTIVES

This prospective study was designed to assess whether patients with skeletal deformities show characteristic masseter inhibitory reflex (MIR) and blink reflex (BR) patterns. A secondary aim was to investigate whether these reflexes change following bilateral sagittal split osteotomy (BSSO).

MATERIALS AND METHODS

Fourteen consecutive patients who underwent single-jaw BSSO and 14 class I subjects who constituted the control group were enrolled into the study. MIR and BR, obtained by the stimulation of supraorbital (SBR) and mental nerves (MBR), were electrophysiologically recorded. Sensory impairment in the mental nerve distribution was clinically tested. Three evaluation periods were specified as immediately before (T0), 1 month (T1) and 6 months (T2) after surgery.

RESULTS

MIR early silent period duration was significantly shorter in the patients at T0 (p < 0.001). Sensory deficits developed on 23 sides after BSSO, of which, 17 recovered after 6 months. At T1, MBR was inelicitable bilaterally in 3 patients and unilaterally in 2 patients. These responses were still unrecordable bilaterally in 1 patient, and unilaterally in 4 patients at T2. MIR were unrecordable on 18 sides at T1 and recovered on 11 sides at T2. There were no parallels between the clinical sensory deficits and the abnormal results of the reflexes.

CONCLUSIONS

Shorter MIR in patients with dentofacial abnormalities may be a reflection of an adapted trigeminal reflex mechanism. Although MBR and MIR abnormalities do not develop parallel to the clinical sensory deficits, their course might provide insights into the disturbed trigeminal reflex pathways.

Influence of Inferior Alveolar Nerve Exposure During Sagittal Split Osteotomy on the Rate and Timing of Baseline Sensory Recovery

PURPOSE

Neurosensory disturbance is the most common consequence of sagittal split osteotomy (SSO). The purpose of this study is to quantitatively assess neurosensory deficiency and recovery to the preoperative status when the inferior alveolar nerve (IAN) was exposed versus unexposed during SSO.

METHODS

This is a single-center, prospective, cohort study of all patients undergoing bilateral SSO between August 2018 and July 2019. Patients were included in the study sample if they underwent bilateral SSO with an intact intraoperative IAN and were received follow-up assessment for at least a year. The predictor variable was the intraoperative IAN status (exposed vs unexposed). The outcomes of interest were the rate and timing of recovery to the preoperative status. The covariates were age, sex, and the magnitude and direction of surgical movements. Neurosensory function was quantitatively evaluated using the Semmes-Weinstein monofilament test at follow-up intervals of 1, 3, 6, and 12 months. Descriptive statistics, bivariate statistics, Cox proportional hazards regression, and Kaplan-Meier analyses were performed. P value <.05 was considered statistically significant.

RESULTS

Of 90 patients, 86 patients who underwent 172 SSOs were included in this study. The mean age was 22.95 ± 3.34 years (range, 17 to 30), 65 were women, and the range of surgical movements was 3 to 8.3 mm of advancement and 2 to 12 mm of setback. Eighty-five nerves (49.4%) were allocated to the unexposed group, and 87 (50.6%) to the exposed group, with statistically significant differences in the rate and timing of recovery (hazard ratio = 2.368; 95% confidence interval, 1.662 to 3.376; P < .001). Among those with recovered nerves, the median time to recovery was 90 days in the unexposed group and 364 days in the exposed group (P < .0001).

CONCLUSIONS

IAN exposure during SSO is associated with an increased risk of neurosensory deficiency and an increased time of sensory recovery to the baseline threshold in patients aged 17 to 30 years. When the IAN remained fully enclosed in the canal of the distal segment, only 11% of patients had a measurable sensory deficit 1 year after surgery. In those patients with any degree of IAN exposure, 36% had a residual sensory deficit 1 year after surgery.

Development of an oral health-related quality of life questionnaire on neurosensory disturbances after orthognathic surgery - a pilot study

OBJECTIVE

Development of a new questionnaire, Oral Health-Related Quality of Life - Neurosensory Disturbances after Orthognathic Surgery (OHRQL-NDO), designed to measure the effects of neurosensory disturbance (NSD) on patients' oral health-related quality of life (OHRQL) and to evaluate reliability and validity of this questionnaire.

MATERIALS AND METHODS

A questionnaire including 11 items was constructed. Thirty patients with NSD affecting the lower lip and/or chin following orthognathic surgery were included. Convergent validity was assessed by comparing OHRQL-NDO with OHIP-14 and two global questions. Test-retest reliability was assessed by asking the patients to complete OHRQL-NDO at two different occasions with an interval of two to three weeks.

RESULTS

The internal consistency, measured with Cronbach's alpha, was 0.84. The test-retest reliability, measured with ICC, was 0.89 (95% CI 0.77-0.95). The correlation between the mean sum score for the OHRQL-NDO and the mean sum score for the OHIP-14 was r = 0.75, using Pearson correlation coefficient. The correlations between the mean total score for the OHRQL-NDO and the global questions 1 and 2 were r = 0.74 and r = 0.72, respectively.

CONCLUSIONS

The current instrument OHRQL-NDO is a promising test, but needs further development to better capture the different aspects of OHRQL. Further tests of the questionnaire must follow in other samples to finalize the instrument.

Comparison of two surgical techniques (HOO vs. BSSO) for mandibular osteotomies in orthognathic surgery-a 10-year retrospective study

PURPOSE

To retrospectively compare the high-angled sagittal split osteotomy (HOO) and the bilateral sagittal split osteotomy (BSSO) for the correction of skeletal dysgnathias regarding intra- and postoperative complications.

METHODS

The electronic medical records of all patients treated with an orthognathic surgery at the Department for Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Frankfurt, Germany, between the years 2009 and 2019 were retrospectively reviewed.

RESULTS

Two hundred ninety-one patients were included. The overall complication rates were 19.78% (BSSO) compared to 12.5% (HOO) (p = 0.14). Significant differences were found regarding the operation time (HOO < BSSO, p = 0.02), material failure (HOO > BSSO, p = 0.04), and early recurrence requiring revision surgery (HOO < BSSO, p = 0.002). The use of a ramus plate significantly reduced the risk of plate failure (2.8% < 13.6%, p = 0.05). More bad splits (p = 0.08) and early sensory disorders (p = 0.07) occurred in the BSSO group.

CONCLUSION

The HOO presents a possible alternative to the BSSO since newly developed osteosynthesis material significantly reduces the risk of material failure. The BSSO is accompanied by higher risks of developing complications like a bad split and sensory disorders but, however, remains the standard for large anterior-posterior transpositions of the mandible.

Reliability of radiographic findings in large FOV CBCTs of mandibular third molars as basis for pre-operative patient information

OBJECTIVE

The aim of this study was to assess the relation between radiographic findings in large field of view (FOV) cone beam computed tomography (CBCT) exams and clinical findings of mandibular third molars in relation to the pre-operative patient information.

MATERIAL AND METHODS

Two hundred and nine mandibular third molars in 134 orthognathic patients examined with CBCT were removed. Three observers assessed tooth- and mandibular canal-related variables in CBCT images, and the findings were correlated to clinical findings during surgery for all observers: tooth angulation, number and morphology of roots and close relationship between the tooth and the mandibular canal. Moreover, positive (PPV) and negative (NPV) predictive values and positive (LR+) and negative (LR-) likelihood ratios were calculated for the canal-related variables. Inter- and intra-observer reproducibility was expressed as percentage accordance and kappa-statistics.

RESULTS

Generally, there was high correlation between radiographic and clinical tooth-related variables. The opposite was true for the canal-related variables, since the PPV and LR + were low. The highest PPV and LR + were found when the mandibular canal was positioned between the roots of the third molar.

CONCLUSIONS

Tooth-related findings in CBCT are reliable, whereas mandibular canal-related findings should not affect the information provided to the patient pre-operatively.

Complications related to orthognathic surgery: A 10-year experience in oral and maxillofacial training center

This article aimed to review adverse events and complications to orthognathic surgery based upon 10 years. This study was a retrospective investigation between 2009 and 2018. Independent variables such as sex, age, pre-operative conditions, diagnosis, type of surgery, bleeding volume, surgery duration, and hospitalization were recorded. The data regarding orthognathic surgery adverse events and complications were evaluated and statistically analyzed with a significance level of p < 0.05. A total of 891 patients were included in this study (male 39.1%, female 60.9%) with a mean age of 26.4 ± 6.09 years. A neurosensory disturbance was found as immediate post-operative sequelae as 93.5%. The four most frequent complications had a relapse (6.4%), post-operative TMD (5.7%), unfavorable osteotomy (5.5%), and infection (4.9%), which seem to be more common in males. An average blood loss was 497 ± 371 ml and the average operative time was 401 ± 109.3 min. Complication rates were statistically affected by bleeding volume (p-value = 0.01), operative time (p-value = 0.03), and type of skeletal deformity (p-value = 0.01). Although numerous complications were recorded, no fatal complications were experienced. Bleeding time, operative time, and skeletal classification have significant influence on orthognathic surgery complications. However, a multitude of factors could be modified to reduce the complication rate and improve the result of the treatment. One of the most significant factors was the operative time.

The Assessment of Neurosensory Disturbance Following Bilateral Sagittal Split Osteotomy With Subjective and Three-Dimensional Evaluation

PURPOSE

Inferior alveolar neurosensory disturbance (IAND) is the most common complication of bilateral sagittal split osteotomy (BSSO). The aim of the present study was to evaluate IAND with subjective tests postoperatively and assess the relationship between three-dimensional measurements of the mandibular canal (MC) and IAND.

METHODS

Eighteen patients (Mean age: 24.05 ± 5.85 years) treated with BSSO were retrieved from the archive. Subjective tests (light touch, tactile sensitivity, 2-point discrimination, brush-stroke directional discrimination, sharp/blunt discrimination, dental vitality, questionnaire) and three-dimensional measurements related to MC and fixation screws were done postoperatively (on average 20.43 ± 8.76 months after surgery). Statistical significance was set at P < 0.05.

RESULTS

Subjective test results were found compatible with each other except brush-stroke directional discrimination test. According to the questionnaire, IAND was apparent in all patients immediately after surgery, and recovery after 1 to 2 years was statistically significant (P < 0.05). Preoperative ramus width, medial and lateral cancellous bone lengths, the decrease in MC length, and the presence of screw in MC were not related to IAND (P < 0.05).

CONCLUSIONS

There is a high incidence of IAND following BSSO, and the subjective tests are efficient to evaluate the disturbance. Spontaneous recovery of the nerve occurs during the follow-up periods. Instead of preoperative measurements of bone thickness, MC length, and the position of fixation screws, the surgical procedure seems to be more important in IAND occurrence.

Orthognathic Surgery of the Mandible

Orthognathic surgery performed in conjunction with orthodontic treatment is commonly performed to correct skeletal irregularities and realign the maxillomandibular relationship to improve occlusal function and facial esthetics. A thorough understanding of soft tissue esthetics, skeletal and occlusal relationships, and surgical techniques is required to obtain successful results. Surgical techniques have evolved greatly throughout history, as technological advances such as virtual surgical planning have become available and widely used to obtain predictable movements with minimized complications. The aim of this article is to review the orthognathic surgical procedures of the mandible, with particular attention to the indications, contraindications, preoperative assessment, surgical technique, and possible complications encountered.

Quantitative Morphometric Analysis of Anatomical Landmarks Involved in Bilateral Sagittal Split Osteotomy in Different Skeletal Malocclusions Using Cone-Beam Computed Tomography

BACKGROUND

To assess and compare the anatomical landmarks involved in bilateral sagittal split osteotomy (BSSO) in different skeletal malocclusions quantitatively using cone-beam computed tomography (CBCT).

METHODS

This retrospective study evaluated 63 CBCT scans of the three malocclusion classes (n = 21). Twenty-one quantitative variables were measured and compared between different malocclusion classes. One-way ANOVA, Welch test, Kruskal Wallis test and the Mann-Whitney test with Bonferroni adjustment were used for data analysis. The level of significance was set at ≤0.05.

RESULTS

The patients had a mean age of 26.35 years (range 18-58 years). The width of the lateral cortex in the posterior third (T1-P) of ramus in the left side, and the mean value in the right and left sides were significantly different between different classes of malocclusion (P = 0.049) such that class II patients had significantly thinner lateral cortex. No other significant differences were noted between different malocclusion classes in other variables.

CONCLUSION

The quantitative morphological assessment of the mandible in BSSO of different malocclusion classes did not reveal significant differences. There is no superiority in the dimensions of discussed landmarks involved in BSSO among different malocclusion classes. So the risk or the safety of this kind of surgery is similar for these classes. Thus, diagnostic preoperative workup by CBCT is imperative for selection of a surgical approach with minimal postoperative complications.

The neurosensory deficit of inferior alveolar nerve following bilateral sagittal split osteotomy: a prospective study

OBJECTIVES

Investigation in Saudi Arabia or the Arab Gulf States to assess the unfavorable impacts of the bilateral sagittal split osteotomy (BSSO) is non-existent, so questions have been raised about the success rate of this operation and the frequency of unwilling outcome. To address these worries, we directed a case series study to evaluate the hypoesthesia, a type of neurosensory deficit (NSD) of the inferior alveolar nerve (IAN) after BSSO, and if the hypoesthesia outcome will improve if the surgeries performed by a single surgeon.

PATIENTS AND METHODS

This was a prospective case series study for the patient who underwent BSSO in a medical complex that is considered one of the largest in Saudi Arabia (Riyadh). The inclusion criteria include patient aged 18-40 years, any gender, and American Society of Anesthesiologists (ASA) class I. They will undergo BSSO for either mandibular, retrognathia, prognathic, or to follow the maxilla. The outcome will be measured after evaluating the neurosensory by four means light touch (LT), pinprick (PP), 2-point discrimination (2PD), and thermal sensations (TT) in four repeated measurements (preoperatively, 1 week, 1 month, 3 months postoperatively) as the primary outcome. Other confounding factors were the secondary outcome (age, gender, visualization of the I.A.N, the type of mandibular movement, split favorability, mandibular canal location, and patient reports about paresthesia or dysesthesia on any given side); these data analyses were carried out using SPSS ver. 25 data processing software.

RESULTS

The nerve was visible in 93% of cases. During the operation, none of the nerves was transected. Hypoesthesia on the first follow-up was 94% of cases for LT, 92% for PP, 82% for TT, and 100% for the 2PD. On the last follow-up, the patients still had hypoesthesia for the LT 51%, PP 35%, TT41%, and 2PD 55%; age and sex did not significantly affect hypoesthesia outcomes. Nerve visibility and inferior alveolar nerve canal (IAC) distance did not influence the results. The level of confidence for all tests was set at p < 0.05.

CONCLUSIONS

The 2PD sensation was the most affected sense on the last visit, and the right side of the chin and lower lip was affected most both on early and long-term follow-up due to several reasons. A 3-month period was enough as a recovery time to restore 100% of neurological sensation for 45% of the sample, which is similar to several studies in the literature. A single surgeon did not show superior result compared to two surgeons' literature papers. Advancement movement was associated with a high percentage of hypoesthesia.

Postoperative Pain Management Using Supplemental Bupivacaine After Mandibular Orthognathic Surgery: A Triple-Blind Randomized Controlled Clinical Trial

PURPOSE

The objective of this triple-blind, randomized, placebo-controlled trial was to assess the clinical analgesic efficacy of 0.5% bupivacaine in acute postoperative pain management after bilateral sagittal split ramus osteotomy (BSSO).

METHODS

Patients were randomly allocated into the experimental (0.5% bupivacaine with 1:200000 epinephrine) or control group (normal saline - placebo) using block randomization. The interventions were administered at the inferior alveolar nerve block and buccal nerve block sites bilaterally after the BSSO surgery. Analgesic efficacy was assessed in terms of the patient's pain perception measured by a numerical rating scale (0 to 10), rescue drug requirement, and duration of analgesia for 24 hours after the surgery. The statistical analysis was blinded to the allocation groups, and P-value of <.05 was considered as a significant difference for all tests.

RESULTS

In total, 28 patients underwent BSSO (ie, 14 in each group). There was no significant difference in pain perception of patients injected with 0.5% bupivacaine and those administered with placebo during the 24 hours after the surgery (P > .05). Three patients in the bupivacaine group took the rescue drug after the surgery (mean duration - 268 minutes) and 1 patient in the placebo group took the rescue drug after 27 minutes.

CONCLUSIONS

Postoperative use of bupivacaine did not show a superior analgesic efficacy when compared with normal saline in controlling acute postoperative pain after BSSO.

Does the use of a piezoelectric saw improve neurosensory recovery following sagittal split osteotomy?

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).

Penetration of inferior alveolar nerve canal increased by bicortical fixation after bilateral sagittal split osteotomy in mandibular prognathism

The purpose of this three-dimensional cone beam computed tomography (CBCT) study was to identify the difference between monocortical fixation (MCF) and bicortical fixation (BCF) in mandibular canal penetration after bilateral sagittal split osteotomy (BSSO) to correct mandibular prognathism, where interosseous fixation was done by BCF or MCF. CBCT was performed 1 week postoperatively and Dolphin 3D software was used to assess direct penetration of the mandibular canal by either type of screw. The primary outcome variable was the presence or absence of mandibular canal penetration and was categorized as a binary coded variable. The BCF and MCF groups were compared by χ² test, and the odds ratio for canal penetration was estimated. Multiple logistic regression was performed to identify factors related to canal penetration. A total of 118 patients were included. The MCF group had only 6% canal penetrations (3/50 patients) and the BCF group had 58.8% canal penetrations (40/68 patients). The regression model showed that BCF was the only factor causing mandibular canal penetration, with an adjusted odds ratio of 52.5. Awareness of the increased risk of canal penetration with BCF and potential nerve injury might influence case selection.

Position of the mandibular canal before and after bilateral sagittal split ramus osteotomy: a cone beam computed tomographic study

The aim of this study was to evaluate the position of the mandibular canal (MC) before and after bilateral sagittal split ramus osteotomy (BSSRO) using cone-beam computed tomography (CT), and to compare the position of the MC in Class II and Class III patients in the preoperative period. Patients were divided into two groups: Class II (n = 38) and Class III (n = 41). Measurements of the superior, inferior, buccal, and lingual distances of the MC in relation to the cortical bone were taken at three levels in the proximal segment of the mandible. Results were analysed using the Kruskal-Wallis test (p < 0.05). In the Class II group the superior distance of the MC at levels 2 and 3, and the inferior distance at level 3 significantly decreased after BSSRO. In the Class III group, no significant differences were found at any level, and the inferior distances at all levels were smaller preoperatively than those in the Class II group. In the Class II group the position of the MC altered in relation to superior and inferior cortical bone after BSSRO. However, the position of the MC remained stable in the Class III group. Our results also suggest a deeper cut in inferior cortical bone in Class III patients.

Buccal corticotomy using piezosurgery as a surgical approach for removal of deeply impacted mandibular teeth: An alternative procedure to avoid pitfalls associated with the conventional technique

PURPOSE

To describe and evaluate the use of buccal corticotomy (BC) using a piezosurgical approach for the removal of deeply impacted mandibular teeth.

PATIENTS AND METHODS

The charts of all patients who underwent BC for the removal of impacted mandibular teeth between 2011 and 2019 at the University Hospital of Geneva were reviewed. The primary outcome variables were (1) the indication for the removal of impacted mandibular teeth by BC, (2) complications. Other variables included age, gender, teeth involved, indication for tooth removal and radiological features. Follow-up was at 1, 3, 6 and 12 months, and we noted the status of healing and complications, if any.

RESULTS

Twenty-three mandibular-impacted teeth in 6 patients were extracted using BC (8 third molars, 6 second molars, 1 first molar, 4 second premolars and 4 first premolars). The indications for using the BC approach included (1) deeply impacted teeth closely related to the inferior alveolar nerve (IAN) that runs either lingually or inferior to the dental roots (4 patients); or (2) deeply impacted teeth closely related to the IAN and located anterior to the second molar region (2 patients). No complications were observed during the follow-up period.

CONCLUSION

The present study showed that the BC approach is a valuable method for removing deeply impacted teeth in close proximity to the mandibular canal and is associated with no complications and sound bone healing.

Orthognathic surgery complications: The 10-year experience of a single center

The retrospective cohort study aimed to assess the incidence and characteristics of these complications in patients who underwent orthognathic procedures. Data on the intraoperative and the postoperative complications were extracted from the patients' medical files. Procedures were further subdivided into single-jaw procedures and bimaxillary procedures. A total of 209 orthognathic procedures were carried out in 190 patients. 184 (88%) were performed to treat angle class III malocclusion, while 25 (12%) aimed to treat class II malocclusion. A total of 94 complication events were observed (44.9% of 209 procedures). 22 of them occurred in single-jaw procedures (28.2% of 78 single jaw operations), and 72 occurred in bimaxillary procedures (55% of 131 bimaxillary operations). When compared regarding the type of complication, complication rates were comparable between the study groups with the exception of late-stage malocclusion. A significant difference (p-value = 0.028) in malocclusion incidences between the bimaxillary and single-jaw groups were observed (9 events, 4.3% and zero events, 0%, respectively). The majority of the complications during and following orthognathic surgical procedures are temporary or minor and require little or no treatment at all.

Anatomical Variation in the Mandibular Foramen in Non-Atrophic and Atrophic Mandibles

Objectives

Previous studies of variation in mandibular foramen characteristics with age have involved comparison in different populations, but few data, between non-atrophic and atrophic mandibles are available. The aim of this original article was to compare the position, shape and area of the mandibular foramen between non-atrophic and atrophic mandibles.

Material and Methods

Morphometric methods were used to study the mandibular foramen variation. Fifty adult dry mandibles from the laboratory of anatomy were selected. Mandibles were considered non-atrophic if the distance between the base and alveolar ridge was homogeneous and greater than 25 mm in the anterior region and 20 mm in the posterior region. Conversely, mandibles were considered atrophic if that distances were lower than those described to a minimum of 11 mm in all areas. All measurements were performed with a digital caliper. For statistical analysis, the admitted level of significance was 5%.

Results

When non-atrophic mandibles were compared to atrophic ones, the mandibular foramen shifted significantly to an anterior position (mean difference [MD]: 4.81 mm; P < 0.0001) and to an inferior position (MD: 3.04 mm; P < 0.0001) and changed from an elliptical shape to round one, with a significant decrease in its area (MD: 3.66 mm²; P < 0.05).

Conclusions

The results indicate that there are significant differences in the position, shape and area of the mandibular foramen between non-atrophic and atrophic mandibles. These data should be considered in anaesthetic techniques and surgical procedures to prevent vascular and nervous lesions.

Effectiveness of low-level laser therapy on recovery from neurosensory disturbance after sagittal split ramus osteotomy: a systematic review and meta-analysis

Background

Orthognathic surgery such as bilateral sagittal split ramus osteotomy (BSSRO) for the treatment of mandibular deformities is one of the most common procedures in maxillofacial operations that may lead to neurosensory disturbance. In this study, we aimed to evaluate the effectiveness of low-level laser therapy (LLLT) on augmenting recovery of neurosensory disturbance of inferior alveolar nerve (IAN) in patients who underwent BSSRO surgery.

Methods

A comprehensive literature search was conducted by two independent authors in PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, Embase, and Google Scholar electronic databases. Besides, a manual search of all textbooks and relevant articles were conducted. Searches took place in August 2020 and were limited to published and peer-reviewed articles from 2000 to 2020. All analysis was performed using the comprehensive meta-analysis (CMA) and the STATA MP (version:16) software. The weighted mean difference (WMD) using the inverse variance method and the standard mean difference (SMD) was considered for continuous variables.

Results

Seventy-four papers were retrieved after removing duplicate studies and finally, eight studies were assessed for qualitative synthesis and five for meta-analysis. Totally, 94 patients were included in the meta-analysis. Based on the meta-analysis, it was shown that LLLT was not effective in a short interval (0 to 48 h) after surgery, but in a period of more than 1 month after surgery, the positive results of treatment can be observed strikingly. Also, LLLT side/group showed no significant difference in some aspects of neurosensory recovery such as thermal sensation compared to the placebo side/group.

Conclusions

The meta-analysis of randomized controlled trials revealed that LLLT generally improves IAN sensory disturbance caused by BSSRO. Further high-quality clinical trials with longer follow-up periods and larger sample sizes are recommended.

Stress distribution is susceptible to the angle of the osteotomy in the high oblique sagittal osteotomy (HOSO): biomechanical evaluation using finite element analyses

AIM

This computational study aimed to evaluate the influence of the angle of the osteotomy when performing a high oblique sagittal osteotomy over the distribution of stress to the osteosynthesis plates and mandibular segments. Material and methods: For this purpose, a finite element analysis of different combinations was carried out based on the osteotomy angle and mandibular mobilization using Autodesk Inventor® resulting in a total of 72 simulations. To check the correlation between the osteotomy angles with respect to the tension in the mandibular structure in different mobilizations, a student t-test was used. Results: The results of the advancement mobilizations (2.5 mm to 5.5 mm) reported increasing values for tension in the probe of the fourth screw and in the probe of the plate surface as the osteotomy angle increased (p-value <10-8). The results of the setback mobilizations (-2.5 mm to -5.5 mm) show comparable values (p-value <10-8). The resulting contact surface between bone segments varies depending on the osteotomy angle, increasing 44.67% from 45° to 70° and decreasing 22.05% when the angle is reduced to 30°. Conclusion: The angle of the osteotomy is a very relevant parameter in the design of the studied mandibular osteotomy, since the distribution of the reported stresses is substantially susceptible to its variation.

The relationship between neurosensory disturbance of the inferior alveolar nerve and the lingual split pattern after sagittal split osteotomy

OBJECTIVE

The aim of this study was to evaluate the relationship between neurosensory disturbance (NSD) and the different types of bilateral sagittal split osteotomy (BSSO) lingual fracture created.

STUDY DESIGN

The study group consisted of 45 patients with mandibular deformities (90 sides; 14 males and 31 females). Computed tomography (CT) scans were obtained preoperatively and 1 week postoperatively. All patients were divided into lingual fracture line groups on the basis of their postoperative scans. NSD was tested preoperatively and 1, 3, and 12 months postoperatively by using a sensory touch Semmes-Weinstein (SW) test and the 2-point discrimination (TPD) test.

RESULTS

Patients were divided into 2 groups on the basis of their lingual fracture lines after mandibular BSSO; among the 45 patients, 39 sides (43.3%) had short-splits, and 51 sides (56.7%) had long-splits. The short-split group was less affected at all tested times, and the difference between the 2 groups was significant 1 month postoperatively on TPD test but not at other times on the both tests.

CONCLUSIONS

The split type did not affect the NSD incidence at 3 and 12 months postoperatively.

Long-term neurosensory disturbances after modified sagittal split osteotomy

We have investigated the long-term incidence of neurosensory disturbances after modified bilateral sagittal split osteotomy, and identified associated risk factors. We prospectively studied 376 patients, and their self-reported neurosensory disturbances were evaluated six months, and one, two, and three years postoperatively. The correlations between the following risk factors and neurosensory disturbances were investigated using univariate analysis and stepwise multivariate analysis: age at operation, sex, type of movement (advancement, setback, or rotation), concurrent genioplasty, type of detachment, iliac crest bone graft, and use of dicalcium phosphate synthetic bone graft. Probabilities of less than 0.05 were accepted as significant. Three years postoperatively, 57 patients (15%) reported altered sensation of the lower lip or chin. Older age correlated significantly with neurosensory disturbances (p<0.0001). Greater mandibular advancement correlated with postoperative "positive" neurosensory phenomena (right side p=0.08; left side p=0.03). Intraoperative surgical manipulation of the left inferior alveolar nerve was significantly associated with postoperative hypoaesthesia (p=0.014). Older age at surgery, extensive mandibular advancement, and surgical manipulation of the left inferior alveolar nerve, were associated with long-term neurosensory disturbances after modified bilateral sagittal split osteotomy. The modified operation seems to safeguard the inferior alveolar nerve from transection, without causing damage to other nerves.

Does Piezosurgery Influence the Severity of Neurosensory Disturbance Following Bilateral Sagittal Split Osteotomy?

The present paper aims to evaluate the long-term incidence and severity of the neurosensory disturbance (NSD) of the inferior alveolar nerve following bilateral sagittal split osteotomy (BSSO) of the mandibular ramus performed with piezosurgery. A retrospective study on patients referred to the Maxillofacial Surgery and Dentistry Clinic of the University of Verona for orthognathic surgery between March 2013 and October 2015 was performed. Inclusion criteria were having undergone BSSO with piezosurgery and follow-up lasting at least 24 months. Exclusion criteria were history of surgical infection, osteosynthesis failure or re-do surgery. The extent of mandibular repositioning movements was retrieved and patients underwent 4 clinical neurosensory tests. Descriptive statistical analysis was performed. 52 patients met the inclusion criteria. Average follow-up was 40 months (range 24-75). 83% of the nerves examined have no or slightly altered sensitivity. Seventy-one percent of patients perceive a moderate to none discomfort and none describes the discomfort as serious (Visual Analogue Scale [VAS] >7). The extent of mandibular repositioning did not have significant influence on the development and severity of the NSD. Resulting data led the Authors to infer that using piezosurgery in BSSO, the severity of the NSD of inferior alveolar nerve is reduced, but the incidence of permanent nerve lesions remains unchanged, compared to historical controls.

Neurosensory Disturbances After Bilateral Sagittal Split Osteotomy Using Piezoelectric Surgery: A Systematic Review

PURPOSE

The objective of the present systematic review was to test the hypothesis of no difference in neurosensory disturbances (NSDs) after bilateral sagittal split osteotomy (BSSO) with piezoelectric surgery compared with conventional techniques.

MATERIALS AND METHODS

A PubMed (Medline), Embase Library, and Cochrane Library search in combination with a manual search of relevant journals was conducted from January 2000 to November 2017. Randomized controlled trials and controlled trials in humans were considered. Primary outcome measures (assessment of neuro-sensitivity by subjective and objective evaluations) and secondary outcome measures (NSD risk factors, patient-reported outcome measures, complications, operating time, and intraoperative bleeding) were considered.

RESULTS

The search provided 241 studies of which 5 eligible studies were included. Meta-analysis was not possible because of considerable heterogeneity. Two studies were characterized by a moderate risk of bias and 3 were characterized by a high risk of bias. Piezoelectric surgery substantially decreased NSDs as evaluated by subjective tests. NSD after BSSO varied from 1.8 to 23.0% with piezoelectric surgery and from 7.3 to 52.0% with conventional techniques after 2 to 12 months. Furthermore, piezoelectric surgery seemed to considerably decrease the frequency of intraoperative bleeding in bimaxillary procedures and decrease the risk of an unfavorable split of the mandible and macroscopic damage of the inferior alveolar nerve.

CONCLUSIONS

The hypothesis of no difference in NSD after BSSO with piezoelectric surgery compared with conventional techniques could be neither confirmed nor rejected owing to insufficient knowledge. However, piezoelectric surgery seems to decrease the risk of NSDs after BSSO compared with conventional techniques. Long-term randomized controlled trials comparing the 2 treatment modalities by standardized subjective and objective electrophysiologic tests are needed before one treatment modality can be considered superior to another.

The variable position of the inferior alveolar nerve (IAN) in the mandibular ramus: a computed tomography (CT) study

INTRODUCTION

This study was designed to quantify the important anatomical landmarks and the path of the inferior alveolar nerve (IAN) within the human mandibular body and ramus, in particular with reference to the bilateral sagittal split osteotomy (BSSO).

MATERIALS AND METHODS

Four hundred and eleven CT scans were studied, 299 of these were involved in determining the position of lingula; and 230 were involved in determining the course of IAN in the mandibular molar region, namely from the mesial of the mandibular first molar to the distal of the mandibular second molar; 118 were involved with both measurements.

RESULTS

On average, the lingula was located 17.0 ± 2.2 mm from the external oblique ridge; 11.6 ± 2.0 mm from the internal oblique ridge; 17.2 ± 2.7 mm from the sigmoid notch; and 15.6 ± 1.9 mm from the posterior border of the mandible. The course of the IAN in the mandibular molar region was found to descend vertically from the distal of the mandibular second molar (7) to reach its lowest point between the first and second molars (6 and 7), and then ascend towards the mesial of the first molar (6). Horizontally, the IAN was found to traverse medially between the distal of the 7 and the middle of the 7, and then changes its path laterally towards the mesial of the 6.

CONCLUSION

Precise knowledge of the individual's position of the IAN will help surgical planning.

Laser Biophotomodulation in Patients with Neurosensory Disturbance of the Inferior Alveolar Nerve After Sagittal Split Ramus Osteotomy: A 2-Year Follow-Up Study

OBJECTIVE

To evaluate the effect of the application of photobiomodulation in a 2-year follow-up period in patients who have been intervened with a sagittal ramus split osteotomy and present neurosensory disturbance of the inferior alveolar nerve.

BACKGROUND

Photobiomodulation is a common clinical tool in dentistry, for its beneficial effects have been shown in surgical and periodontal wound healing, reducing of swelling and pain, neurosensory recovery, and treatment of temporomandibular joint disorders.

METHODS

This is a 2-year follow-up study with an experimental (Laser) group (n = 33) that received photobiomodulation, and a control (Sham) group (n = 9), placebo. All patients from the Laser group received laser applications (continuous wave of 0.353 W/cm², 27 J in 270 sec per session) on days 1, 2, 3, 5, 10, 14, 21, and 28 after surgery. Neurosensory disturbance was evaluated with five tests: Visual Analog Scale (VAS) for pain and sensitivity, sensitivity threshold test, two-point discrimination, and thermal discrimination. All tests were performed before (24 h before surgery) and after surgery (24 h, 28 days, 60 days, 6 months, 1 year, 2 years, more than 2 years). Participants and evaluator were blinded to intervention. Variables were described with absolute frequencies, percentages, and medians. Ordinal and dichotomous variables were compared with Mann-Whitney's and Fisher's tests, respectively.

RESULTS

Clinical improvement was observed during the follow-up period for the Laser group; general VAS for sensitivity was normal in 11 participants from the Laser group at 2 years postsurgery (40.74%), while no participants from the Sham group achieved this (p = 0.0341). Twenty-three participants recovered initial values for two-point discrimination (69.7%) after 2 years of follow-up (p = 0.0025) as well as sensitivity threshold test. General VAS for pain was normal in 31 patients from the Laser group after 2 years of follow-up (93.94%, p = 0.0254).

CONCLUSIONS

Photobiomodulation was effective for neurosensory recovery on sample studied.

CBCT location of the fusion between the buccal and lingual cortical in the mandibular ramus: importance to sagittal split osteotomy

Background

Mandibular Sagittal Split Osteotomy (MSSO) is a popular technique in orthognathic surgery used both to advance and to retreat the mandible. However, MSSO may incur in important complications, such as bad splits and sensorineural injuries. Knowing the location of the fusion between the buccal and lingual cortical (FBLC) in the mandibular ramus and the bone thickness in the region where osteotomies will be performed is determinant in MSSO planning to avoid complications. The aim of this study was to document and evaluate possible differences between sexes regarding the location of the FBLC in relation to the superior cortical of mandibular foramen (MF) and bone thickness in the region of interest for MSSO in a Brazilian population.

Material and Methods

Eighty five cone-beam Computed Tomography (CBCT) scans were used to perform linear measurements to determine the location of the FBLC. Bone thickness from the mandibular canal (MC) to the cortical external surfaces and the diameter of the MC were measured at three different points: mandibular ramus (A), mandibular angle (B) and mesial of the second molar (C).

Results

The FBLC was located at a mean distance of 8.3 mm from the superior cortical of the MF in males and 8.1 mm in females. There was no difference between males and females regarding the mean bone thickness from the MC to the buccal external surface at all the points investigated (p >>0.05). Bone thickness from the lingual external surface to the MC was bigger among females than males in regions B and C (p<0.05). The diameter of the MC was bigger among males in regions B and C.

Conclusions

Sexual dimorphism regarding mandibular bone thickness but not regarding the location of FBLC was present. This fundamental knowledge may assist to the panning of MSSO.

Key words:Cone-Beam Computed Tomography, mandibular nerve, orthognathic surgery, sagittal split ramus osteotomy.

Autofluorescence spectroscopy for nerve-sparing laser surgery of the head and neck-the influence of laser-tissue interaction

The use of remote optical feedback systems represents a promising approach for minimally invasive, nerve-sparing laser surgery. Autofluorescence properties can be exploited for a fast, robust identification of nervous tissue. With regard to the crucial step towards clinical application, the impact of laser ablation on optical properties in the vicinity of structures of the head and neck has not been investigated up to now. We acquired 24,298 autofluorescence spectra from 135 tissue samples (nine ex vivo tissue types from 15 bisected pig heads) both before and after ER:YAG laser ablation. Sensitivities, specificities, and area under curve(AUC) values for each tissue pair as well as the confusion matrix were statistically calculated for pre-ablation and post-ablation autofluorescence spectra using principal component analysis (PCA), quadratic discriminant analysis (QDA), and receiver operating characteristics (ROC). The confusion matrix indicated a highly successful tissue discrimination rate before laser exposure, with an average classification error of 5.2%. The clinically relevant tissue pairs nerve/cancellous bone and nerve/salivary gland yielded an AUC of 100% each. After laser ablation, tissue discrimination was feasible with an average classification accuracy of 92.1% (average classification error 7.9%). The identification of nerve versus cancellous bone and salivary gland performed very well with an AUC of 100 and 99%, respectively. Nerve-sparing laser surgery in the area of the head and neck by means of an autofluorescence-based feedback system is feasible even after ER-YAG laser-tissue interactions. These results represent a crucial step for the development of a clinically applicable feedback tool for laser surgery interventions in the oral and maxillofacial region.

Is Low-Level Laser Therapy Effective for Treatment of Neurosensory Deficits Arising From Sagittal Split Ramus Osteotomy?

PURPOSE

This study investigated the effectiveness of low-level laser therapy (LLLT) for treating neurosensory impairment after bilateral sagittal split osteotomy (BSSO).

MATERIALS AND METHODS

This randomized, double-blinded, split-mouth trial included patients requiring BSSO. After surgery, 1 side of each patient was randomly assigned to laser therapy and the other side served as the control. At 24, 48, and 72 hours after surgery, LLLT was accomplished by intraoral application of a 660-nm laser around the surgical site (200 mW, 10 seconds, 2 J, 1.5 J/cm²) followed by extraoral irradiation by an 810-nm laser (200 mW, 10 seconds, 2 J, 7 J/cm²) along the distribution of the inferior alveolar nerve. Subsequently, extraoral irradiation was repeated 2 times per week for 3 weeks along the path of the inferior alveolar nerve, lower lip, and chin. On the control side, the treatment was similar to the laser side but with laser simulation. The main outcome was assessing nerve damage by a "2-point discrimination test" before and up to 60 days after surgery.

RESULTS

The sample consisted of 16 patients. No significant difference was found between the laser and control sides before and after surgery and on postoperative days 15 and 30 (P > .05). The 2-point discrimination distance was significantly shorter on the laser side than on the control side on postoperative days 45 and 60 (P < .05).

CONCLUSION

LLLT was effective in the treatment of neurosensory disturbances arising from BSSO. Therefore, LLLT can be recommended to accelerate the recovery of sensory aberrations in patients undergoing BSSO.