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

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.

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.

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.

The Temporary Mental Nerve Paresthesia as an Outcome of Dentigerous Cyst Removal during Preparation for Dental Implant Placement: A Case Report

The usage of xenograft material is widely used in almost all oral cavity bone defects for regenerative and reconstructive purposes. The presented xenograft usage in the following care report enabled good bone defect healing and enabled the preservation of affected premolars. It is quite common to use any possible variations of bone materials to ensure bone defect improved healing. In some cases, the scope of surgeries requires the removal of each cyst within close proximity to various nerves and vessels. The inferior alveolar, infraorbital, lingual, and mental nerves are those most commonly adjacent to most operating sites in jaw bones. The usage of some additional materials such as collagen sponges, bone substitutes, resorbable membranes, or other additional materials are useful in each bone defect reconstruction but should be handled with care, as described in the following case. Before planning their usage, it is important to perform each surgery with close cone beam computed tomography imaging, which is very helpful to establish the scope of each lesion and the proximity of vital structures. There are a lot of factors that might influence any possible nerve damage, especially the different nerve anatomical variations. Even factors including the subperiosteal preparation and compression of adjacent tissues might influence later nerve function. When the lesion is expanding through the buccal cortical plate and when soft tissue fluctuation is present, some special care is needed. Similar to the presented case, a limitation in crushing, blowing, or any irritation of nerve fibers improves later postoperative outcomes. When the wound and surrounding tissues are handled with care, a limited possibility of any damage or paresthesia can occur. When the nerve itself is damaged or cut, loss of function can be permanent. Immediately after or even prophylactic prescription 1–2 days before the surgery of Vitamin B with NSAIDs (Non-steroidal anti-inflammatory drugs) (or other additional supplementary medicaments can improve nerve function in time. Possible nerve damage can be divided into many etiological factors. A quite different situation arises when the nerve is pulled in by the cyst growth into the cyst wall. The presented case report describes the outcomes of a cyst removal from the mandibular basis and treatment modalities.

National Trends in Orthognathic Surgery: A Multi-Institutional Analysis of 6640 Patients

BACKGROUND

LeFort I osteotomy (LF1) and bilateral sagittal split osteotomy (BSSO) have unique operative challenges and inherent anatomic considerations that predispose to certain adverse outcomes, yet their respective complication profiles continue to be debated given conflicting results from single-center investigations. The purpose of this study is to perform a multi-institutional analysis of complications, socioeconomic trends, and financial charges associated with orthognathic surgery.

METHODS

A retrospective cohort study was conducted of orthognathic procedures performed in the United States from 2010 through 2020 using the Pediatric Health Information System. Patients younger than 12 years of age were excluded. Medical complications, surgical complications, and admission costs were compared across procedures. Socioeconomic determinants and trends across regions of the country were also analyzed.

RESULTS

During the study interval, 6640 patients underwent orthognathic surgery, including LF1 (59.2%, n=3928), BSSO (14.4%, n=959), and double-jaw surgery (26.4%, n=1753). Patients undergoing LF1 were more likely to experience overall complications (P<0.001), infections (P<0.001), and blood transfusions (P<0.001) than those undergoing BSSO. High-volume hospitals were more likely to perform double-jaw procedures than other hospitals (P<0.001), yet high-volume hospitals were less likely to have surgical complications (P=0.014). Patient admission charges related to orthognathic operations at high-volume hospitals were less than other hospitals (P<0.001). Household income was higher for orthognathic procedures performed at high-volume hospitals (P<0.001). White patients were 1.5 times more likely to choose a farther, higher volume hospital for orthognathic surgery than the one locally available (P=0.041).

CONCLUSIONS

LeFort I osteotomy procedures had higher infection and transfusion rates than BSSO procedures. High-volume hospitals were more likely to perform double-jaw procedures, yet high-volume hospitals had fewer complications and decreased admission charges. Future study will be needed to further elucidate case-mix index details and socioeconomic determinants of health contributing to these disparities.

Evaluation of the Anatomic Position of the Mandibular Canal Regarding to the Segments of the Mandibular Sagittal Split Ramus Osteotomy to Diminish the Possibility of Injuries: a Pilot Study

Objectives

This pilot study evaluated the relationship between inferior alveolar nerve location through computed tomography scan and intraoperative inferior alveolar nerve entrapment after bilateral sagittal split osteotomy.

Material and Methods

Overall, 20 helicoidal computed tomography scans were evaluated in patients with facial deformities who underwent to bilateral sagittal split osteotomy (BSSO). The distance from the mandibular canal to the internal surface of the buccal and lingual cortical bone, mandibular thickness, bone density and proportion of medullary and cortical bone in 3 regions were evaluated. During the intraoperative period, the segment to which the nerve remained adhered after performing BSSO was analysed, and the data correlated.

Results

The distance from the mandibular canal to the buccal cortical bone showed a mean of 2.6 mm when the inferior alveolar nerve was adhered to the distal segment and mean of 0.7 mm when the nerve was adhered to the proximal segment. The thickness was 11.2 mm and 9.8 mm when the nerve was adhered the distal the proximal segments respectively. Mandibular thickness, distance from the mandibular canal to the buccal and lingual cortical were statistically related to intraoperative nerve entrapment (P < 0.05).

Conclusions

Narrow jaws and the distance from the mandibular canal to buccal cortical bone less than 2 mm increases the risk of the inferior alveolar nerve entrapment in bilateral sagittal split osteotomy.

Starting a Swedish national quality registry for orthognathic surgery: a tool for auditing fundamentals of care

BACKGROUND

National quality registries (NQRs) provide open data for user-directed acquisition. National Quality Registry (NQR) data are often used to analyze the rates of treatment success and adverse events for studies that aim to improve treatment quality and patient satisfaction. Thus, NQRs promote the goal of achieving evidence-based therapies. However, the scientific literature seldom focuses on the complex process of initiating, designing, and implementing an NQR. Starting an NQR may be particularly challenging in a setting where specialized care is decentralized, such as orthognathic surgery in Sweden. The present study describes the initiation and early phases of a new NQR for orthognathic surgery in Sweden.

METHODS

The initial inventory phase included gaining knowledge on regulations, creating economic plans, and identifying pitfalls in existing NQRs. Next, a crude framework for the registry was achieved. Outcome measures were selected with a nation-wide questionnaire, followed by a Delphi-like process for selecting parameters to include in the NQR. Our inclusive process comprised a stepwise introduction, feedback-based modifications, and preparatory educational efforts. Descriptive data were collected, based on the first 2 years (2018-2019) of registry operation.

RESULTS

Two years after implementation, 862 patients that underwent 1320 procedures were registered. This number corresponded to a 91% coverage rate. Bimaxillary treatments predominated, and the most common were a Le Fort I osteotomy combined with a bilateral sagittal split osteotomy (n = 275). Reoperations were conducted in 32 patients (3.6%), and the rate of patient satisfaction was 95%.

CONCLUSIONS

A National Quality Registry should preferentially be started and maintained by an appointed task force of active clinicians. A collaborative, transparent, inclusive process may be an important factor for achieving credibility and high coverage, particularly in a decentralized setting.

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).

Pediatric Orthognathic Surgery: National Analysis of Perioperative Complications

BACKGROUND

Orthognathic surgery has traditionally been performed after skeletal maturity. Although these procedures are also being performed in children, the implications of earlier intervention and specific risk factors in this younger population remain unknown.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program Pediatric dataset was queried for orthognathic procedures performed in 2018. Complications, readmissions, and reoperations were analyzed with appropriate statistics.

RESULTS

Overall adverse event rate after orthognathic surgery in pediatric patients was 7.8% (n = 22 of 281), which were associated with having any comorbidity (P < 0.001), overall respiratory comorbidities (P = 0.004), structural pulmonary abnormality (P < 0.001), developmental delay (P = 0.035), structural central nervous system abnormality (P < 0.001), and neuromuscular disorder (P = 0.035). Most common complications were excessive bleeding (2.5%), surgical site infection (1.1%), and pneumonia (0.7%). Orthognathic surgery in children below 6 years of age is associated with significantly increased adverse events (P < 0.001), including surgical site infection (P < 0.001), pneumonia (P = 0.022), readmission (P < 0.001), and reoperation (P < 0.001). Le Fort I osteotomies (P < 0.001) and bilateral sagittal split osteotomies (P = 0.009) took significantly longer for older patients in the years of permanent dentition than younger patients in the years of deciduous dentition. Single- and double-jaw procedures in pediatric patients have similarly low adverse events (P all ≥0.130). Interestingly, bilateral sagittal split osteotomies performed before 13.5 years of age were associated with a higher risk of adverse events (P = 0.012), such that these younger patients were 7.1 times more likely to experience adverse events if their procedure was performed earlier.

CONCLUSIONS

Orthognathic surgery is relatively safe, but children in the years of deciduous dentition under 6 years of age have significantly increased risk of adverse events.

Effects of Platelet-Rich Fibrin/Collagen Membrane on Sciatic Nerve Regeneration

ABSTRACT

Alternative treatment approaches to improve the regeneration ability of damaged peripheral nerves are currently under investigation. The aim of the current study was to evaluate the effects of leucocyte/platelet-rich fibrin (L-PRF) with or without a collagen membrane as a supporter on crushed sciatic nerve healing in a rat model. Recovery of motor function and electrophysiologic measurements were evaluated at 4 weeks postoperatively. The whole number of myelinated axons, peripheral nerve axon density, average nerve fiber diameter (μm), and G-ratio were analyzed and compered among the groups. Functional, electrophysiological, and histological evaluations showed no significant difference among the groups with the exception of the L-PRF with collagen membrane groups that showed relatively positive effects on the functional and histological nerve recovery. In addition, the collagen membrane with L-PRF can be effect in nerve regeneration.

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.

Comparison of the piezoelectric cutter with a conventional cutting technique in orthognathic surgery

The use of a piezoelectric cutter has been reported to improve outcomes in orthognathic surgery, particularly with regards to neurosensory disturbance of the inferior alveolar nerve. The aims of this retrospective longitudinal cohort study were to compare outcomes regarding neurosensory disturbance, and operating time. During two 15-month periods a single surgeon treated 24 consecutive patients with a conventional cutting technique and a further 24 consecutive patients with a piezoelectric cutter. In both groups the duration of operation was noted, and neurosensory disturbance graded at 12-month follow up. Neurosensory recovery was better in the piezoelectric group than in the conventional group (p=0.01), and the duration of operation nearly identical. We conclude that the piezoelectric cutter offers advantages with regards to neurosensory deficit over a more conventional technique without the previously-reported disadvantage of a longer operating time.

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.

Evaluation of the lingual fracture patterns after bilateral sagittal split osteotomy according to Hunsuck/Epker modified by an additional inferior border osteotomy using a burr or ultrasonic device

This study was conducted to compare fracture patterns and operation times after sagittal split osteotomy (SSO) by Hunsuck/Epker approach, performed using a burr or ultrasonic device, with and without osteotomy modification. A total of 80 SSOs were performed in fresh human cadavers using a burr or ultrasonic device to investigate the influence of surgical instruments as well as an additional bone cut on the inferior border of the mandible in terms of lingual fracture patterns. The times required for osteotomy and sagittal split were measured, and postoperative cone beam computed tomography images of all splits were analyzed. Without an additional inferior osteotomy, preferred splits according to Hunsuck/Epker were achieved in 35% of cases (7/20) with the burr and 45% (9/20) with the ultrasonic instrument. The inferior modification resulted in a greater number of unwanted fracture patterns in both groups. There was no relationship between the split technique and the fracture pattern (P=0.7854). Statistically significant differences in osteotomy time were observed between burr osteotomy and modified burr osteotomy (P=0.006), as well as modified ultrasonic osteotomy (P<0.001), but not between burr and ultrasonic surgery both without the inferior cut (P=0.36). The bone cut on the inferior border did not improve split control, but rather increased the risk of unwanted fractures and extended the operation time.

Major Complications and 30-Day Morbidity for Single Jaw Versus Bimaxillary Orthognathic Surgery as Reported by NSQIP

OBJECTIVE

Acute complications in orthognathic surgery are reported in single-institution studies with small sample sizes. We aimed to analyze risk factors for acute complications using a national data set to better inform surgical decision-making.

METHODS

2005-2015 National Surgical Quality Improvement Program (NSQIP) data sets were analyzed for patients undergoing Le Fort 1 and/or bilateral sagittal split osteotomies (BSSO) for nontraumatic indications. Demographics, comorbidities, medical, and surgical 30-day complications were tabulated. A logistic regression model was used to determine predictors of complications.

RESULTS

Five hundred eight patients met the inclusion criteria: 228 underwent Le Fort I osteotomies, 152 BSSO, and 128 patients underwent both during a single surgical encounter. Overall complication rate was 4.5% (23/508). Superficial infection was the most common complication (11 in BSSO and 2 in Le Fort I cohorts). Increasing age and undergoing BSSO alone were associated with higher overall complication rates (P < .05) and surgical complications specifically (P < .05). Patients undergoing the combined procedure had shorter operative time (208 minutes) than the times for Le Fort I osteotomies alone (177 minutes) and BSSO alone (155 minutes) added together and did not have a longer hospital stay (P = .608) or increased need for transfusion (P = 1.0) compared to the surgeries being done separately.

CONCLUSION

This is the first complication risk factor analysis for Le Fort I osteotomy and BSSO using the multi-institutional NSQIP data set. Combining BSSO and Le Fort I osteotomy leads to a shorter overall operative time and does not increase hospital stay duration or 30-day complication rate when compared to the 2 procedures being done separately.

Bimaxillary orthognathic surgery with a conventional saw compared with the piezoelectric technique: a longitudinal clinical study

The only cutting technique used for osteotomies in orthognathic surgery for many years has been a saw, but recently piezoelectric surgery has been introduced as a possible alternative. The aim of this study was to find out if piezoelectric surgery can be more comfortable for patients having orthognathic surgery. A total of 25 patients with dentofacial deformities (seven male and 18 female), were treated from January 2016 to September 2017. In 11 patients, osteotomies were made using a conventional saw, while in 14 a piezoelectric device was used. The variables assessed were: operating time, postoperative swelling, postoperative pain, and cutaneous sensitivity of the upper and lower lips. The duration of operation for the piezosurgery group was significantly longer than that for controls, but the patients had less swelling at all follow-up visits, and the difference was significant at the 30-day follow-up (p=0.045). Those who had piezosurgery had significantly less pain at the three-day follow up (p=0.035). There was a significant difference in cutaneous sensitivity only for the right side of the upper lip and only at the one-day follow-up. We conclude that piezoelectric surgery offers some advantages in lessening swelling and the perception of pain after orthognathic surgery, but further investigations are required.

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.