Modified Mandibular Inferior Border Sagittal Split Osteotomy Reduces Postoperative Risk for Developing Inferior Border Defects

Is it necessary to use bone grafts to prevent defects at the lower border of the mandible after mandibular advancement?-a systematic review

INTRODUCTION

Defects in the lower border of the mandible may represent an aesthetic problem after mandibular advancement in orthognathic surgery. The use of bone grafts has been reported in the literature as a possibility to reduce these defects in the postoperative period.

OBJECTIVE

The objective of this systematic review is to answer the following research question: Is it necessary to use bone grafts to prevent defects at the lower border of the mandible after mandibular advancement?

METHODS

The literature search was conducted on MEDLINE via PubMed, Scopus, Central Cochrane, Embase, LILACS, and Sigle via Open Gray up until December 2020. Five studies were eligible for this systematic review, considering the previously established inclusion and exclusion criteria.

RESULTS

1340 mandibular osteotomies were evaluated, with a mean advance of 8 mm, being 510 with bone graft (42 defects), 528 without graft (329 defects), and 302 with an alternative technique (32 defects). Regarding the type of bone graft used, three articles used xenogenous or biomaterial grafts and two allogenous bone grafts. The results of the meta-analysis showed a reduction in the presence of defects in the bone graft group: OR 0.04, 95% CI = 0.01, 0.19; p = 0.0005, (I2 = 87%; p < 0.0001).

CONCLUSION

The use of bone grafts seems promising in reducing defects in the lower border of the mandible after mandibular advancement. New controlled prospective studies with a larger number of participants are needed to ensure the effectiveness of this procedure.

Risk factors for lower border notching after bilateral mandibular sagittal ramus advancement: three-dimensional evaluation

Bilateral sagittal split osteotomy (BSSO) mandibular advancement can cause mandibular lower border notching (MLBN). The objective of this study was to calculate the incidence of MLBN and identify risk factors. This single-centre, retrospective study was performed between January 2018 and November 2020, in the Maxillofacial Surgery Department, Centre Hospitalier Universitaire, Caen. Patients who underwent BSSO advancement and had cone beam computed tomography (CBCT) scans obtained preoperatively, immediately postoperative (within 1 week), and late postoperative (≥1 year) were included. Measurements were made on the CBCT images. A total of 113 patients (226 operated sides) were enrolled. Mean age at the time of surgery was 17 years; 66.4% of patients were female and 33.6% were male. MLBN was observed on 35 operated sides (15.5% of sides). Advanced age (P = 0.002) and the degree of mandibular advancement (P = 0.008) were determined to be risk factors for developing MLBN. Sex, the operated side, third molar removal, and genioplasty were not associated with an increased occurrence of MLBN. Older patient age at the time of surgery and the requirement for a large advancement should be taken into consideration by the surgeon in order to reduce the risk of MLBN by using a modified BSSO procedure or bone grafting.

Influence of lingual plate fracture pattern on remodelling site during the healing process of sagittal split ramus osteotomy

The purpose of this study was to investigate whether differences in the pattern of the lingual plate split in sagittal split ramus osteotomy (SSRO) affect the remodelling of the split site. Sixty-one patients with mandibular prognathism (122 sides) underwent SSRO. Computed tomography (CT) was performed at 1 week and 1 year after SSRO. Bone splits were classified according to the lingual split scale (LSS) and the lateral bone cut end (LBCE) by evaluating CT images at 1 week. The remodelling at the split sites was evaluated by superimposing the CT images obtained at 1 week and 1 year. Regarding the LSS pattern, significant differences were observed in the distance between anteroposterior ramus points (P = 0.033) and the ramus area in the axial image (P = 0.011). The LBCE pattern also showed a significant difference in the distance between anteroposterior ramus points (P = 0.043). In conclusion, the differences in the lingual plate split and ramus cut end of the SSRO influence the postoperative remodelling in the anteroposterior region of the split site.

Modified Intraoral C-Osteotomy

ABSTRACT

Repeated sagittal split osteotomy might impose an increased risk for damage of the inferior alveolar nerve. Another contemporary orthognathic issue is surgical management of malocclusion following condylar resorption. Here we describe a modified C-osteotomy technique as a proposed solution for these difficulties in orthognathic surgery. The modified C-osteotomy might induce less stress on the condyles reducing the risk for relapse subsequent to condylar resorption, as well as reduce the risk of inferior alveolar nerve damage.

Modified vertical osteotomy cut in bilateral sagittal split osteotomy

Bilateral sagittal split osteotomy (BSSO) is the most common orthognathic surgical procedure for the correction of facial deformities. Like any other surgical procedure, it is also associated with a risk of complications. One of these is described in the literature as notching at the lower inferior border of the mandible. Such discontinuity in the contour of the lower border is often a concern for patients. To overcome this complication, we recommend a modified vertical osteotomy cut while performing BSSO.

Biomechanical validation of a modified genioplasty distractor

PURPOSE

Genioplasty is a surgical procedure that is used to enhance the shape and appearance of the chin. It can be performed alone or in combination with other jaw-related surgeries either for medical or cosmetic purposes. Recently many studies have been reported for mandibular reconstruction with distraction osteogenesis. However, these distractors can cause some complications such as incorrect prolongation of hard tissues due to the lack of guiding section. The purpose of this study is to manufacture a novel genioplasty distractor and measure its biomechanical stability and reliability for different activation lengths in mandibular bone.

METHODS

The modified genioplasty distractor was manufactured from grade 2 and grade 5 (Ti6AI4V) titanium alpha + beta alloy which was biocompatible and adequately rigid for possible in situ application in the future and a sample holder was manufactured for compressive strength testing.

RESULTS

Test results showed that our modified genioplasty distractors withstood 300 N compression force for activation lengths from 0 to 11 mm. Recorded stress values were in the range of 0.110 MPa to 0.389 MPa.

CONCLUSION

The modified genioplasty distractor developed and tested here is a promising surgical tool that has the potential to reduce genioplasty related complications especially in demanding cases.

Computed tomography assessment of mandibular morphologic changes and the inferior mandibular border defect after sagittal split ramus osteotomy

OBJECTIVE

This study aimed to assess mandibular morphologic changes to the condyle, ramus, mandibular body, and inferior mandibular border defect after sagittal split ramus osteotomy in class II and III patients.

STUDY DESIGN

The relationships among the condyle, ramus, and mandibular body measured by computed tomography preoperatively and postoperatively were assessed and factors related to the reduction of the condylar square and mandibular inferior border defect were examined.

RESULTS

Patients included 72 female patients with jaw deformity (36 skeletal class II cases, 36 skeletal class III cases). Postoperative reduction of the condylar square was significantly correlated with preoperative condylar height in patients with class II (P = .0297) vs preoperative condylar height and preoperative mandibular height in patients with class III (P < .0001). A mandibular inferior border defect was found in 18 of 72 class II sides (25.0%) and was significantly related to the position of the osteotomy line and attachment side of the inferior border cortex (P < .0001).

CONCLUSIONS

This study's findings suggest that the postoperative reduction of the condyle could be associated with preoperative condylar height. However, the mandibular inferior border defect in class II advancement surgery could be independently associated with technical factors in sagittal split ramus osteotomy.

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.

How to Prevent Mandibular Lower Border Notching After Bilateral Sagittal Split Osteotomies for Major Advancements: Analysis of 168 Osteotomies

PURPOSE

Mandibular ramus bilateral sagittal split osteotomy (BSSO) has been the most commonly used technique in orthognathic surgery for mandibular advancement. However, a common complication of BSSO has been the occurrence of visible and palpable osseous defects at the inferior border of the mandible. The aim of the present study was to determine whether bone grafting of the osseous defect at surgery would reduce the defect at 1 year postoperatively compared with no bone grafting.

MATERIALS AND METHODS

The present retrospective cohort study evaluated patients who had undergone mandibular ramus BSSO for 10 mm or more of advancement. The primary predictor variable was BSSO surgery with bone grafting of the defect (graft group [GG]) versus no bone graft (no graft group [NGG]). The size of the mandibular ramus inferior border defect was the outcome variable considered within the framework of a 1-year postoperative cone beam computed tomography (CBCT) analysis. Gender, age, and the amount of advancement were also considered in the multilevel regression analyses.

RESULTS

From January 2012 to November 2016, 84 patients (168 osteotomies) had undergone BSSO surgery with 10 mm or more of mandibular advancement at the Facesurgery Center (Parma, Italy). Their mean age was 27.4 years (range, 17 to 44 years). Of the 84 patients, 40 had undergone BSSO with bilateral bone grafts (GG). The monocortical block of the iliac crest bone was used as the bone homograft. The final residual defect was measured at 1 year postoperatively on CBCT scans. The GG and NGG had presented with a mean final defect of 0.7 mm (range, 0 to 4.5 mm) and 3.0 mm (range, 0 to 5.5 mm), respectively. Complete absence of the defect was achieved in 72% of the osteotomies in the GG and 9% of the osteotomies in the NGG.

CONCLUSIONS

The use of an iliac crest bone allograft block in the gap between 2 segments during mandibular advancement of 10 mm or more substantially reduced the size and incidence of inferior border defects.

The use of xenografts to prevent inferior border defects following bilateral sagittal split osteotomies: three-dimensional skeletal analysis using cone beam computed tomography

The aim of this retrospective study was to investigate grafting in the osteotomy gap during bilateral sagittal split osteotomy (BSSO), using a xenograft and fibrin glue. Hard tissue defects in the inferior mandibular border were assessed using cone beam computed tomography scans taken 1 week and 1year postoperatively. The study group of 20 patients underwent bone grafting during BSSO (mean age 26.1years; mean horizontal displacement 8.5mm) and the control group of 20 patients did not (mean age 30.2 years; mean horizontal displacement 7.6mm). The mean height of the mandibular defects was significantly lower in the study group, but there was no significant difference in volume measurements between the groups. Grafting had a negligible effect on large displacements (9.0-15.0mm), which might have been due to an inadequate amount and/or positioning of the graft, or to poor dimensional stability. This may be resolved by improved graft positioning or by using a different kind of (xeno)graft.

Modified Mandibular Sagittal Split Osteotomy

INTRODUCTION

Mandibular osteotomies aim to displace the dental arch to the necessary position, ideally without limitation, while preserving inferior alveolar nerve (IAN) function. Supraforaminal osteotomies offer nerve safety but limit the extent of advancement, whereas Epker and Obwegeser-Dal Pont osteotomies enable unchallenged mandibular advancement but are associated with an inferior border notch. Here, we describe a new technique to avoid such disadvantages.

TECHNICAL NOTE

The beginning of the procedure was similar to Epker's technique, with sectioning of the lingual cortex up to the level of the lingula. Sectioning of the buccal cortex was stopped 3 to 4 mm above the inferior border and then performed horizontally up to the gonial angle in total thickness. The inferior border periosteum and muscles attachments were conserved and hence, appropriately vascularized.

DISCUSSION

This technique offers 4 advantages: absence of the inferior border notch, lower risk of damage to the IAN than with Epker's technique, sufficiently large bony surface to obtain bone healing as in Epker's technique, and no limitation to setback movement in contrast to Obwegeser-Dal Pont's or the supraforaminal osteotomy techniques.

Early Complications From the Use of Calcium Phosphate Paste in Mandibular Lengthening Surgery. A Retrospective Study

PURPOSE

Calcium phosphate paste is used in mandibular lengthening surgery to avoid unesthetic notching at the lower border and to help stabilize the segments when osteosynthesis slippage is a concern. The aim of this study was to investigate whether the hardened paste increases the incidence of infections.

MATERIALS AND METHODS

This was a retrospective cohort study of medical charts of all patients who underwent a bilateral sagittal split osteotomy from February 2012 through July 2015. The outcome and predictor variables were postoperative infection and calcium phosphate paste use, respectively. Other study variables included age, gender, tobacco use, type of fixation, type of surgery, antibiotic prophylaxis regimen, third molar extraction, and medical comorbidities. Variables were analyzed using the Fisher exact test and logistic regression.

RESULTS

The sample included 196 patients (115 female and 81 male) 9 to 57 years old. The overall infection rate was 12.2%. Of the 102 patients who received calcium phosphate paste, 18.6% developed an infection compared with 5.3% in the control group. The difference in infection rate was statistically significant (odds ratio = 0.14; 95% confidence interval [CI], 0.04-0.48; P = .002) after adjusting for the other variables. Of the 392 surgical sites, 204 had received calcium phosphate paste, of which 10.3% became infected. Of the 188 sites without defect reconstruction, 6 (3.2%) became infected (P = .008 by bivariate analysis). There was a statistically significant association between third molar removal and infections (odds ratio = 8.01; 95% CI, 1.28-50.1; P = .026) and between the use of amoxicillin plus clavulanate and the use of cefazolin (odds ratio = 3.92; 95% CI, 0.87-17.63; P = .07).

CONCLUSION

There was a relevant trend of increased infection with calcium phosphate paste use. Third molar removal also was identified as a risk factor. Prospective studies after procedural modifications are recommended to determine whether the benefits of using calcium phosphate paste outweigh the risks.

Are there risk factors for osseous mandibular inferior border defects after bilateral sagittal split osteotomy?

PURPOSE

Bone defects of the inferior mandibular border (osseous inferior border defects) can cause unesthetic postoperative outcomes after bilateral sagittal split osteotomy (BSSO). The aim of this study was to estimate the frequency of osseous inferior border defects after BSSO and to identify risk factors for this complication.

MATERIALS AND METHODS

This retrospective study included consecutive patients who underwent BSSO for mandibular retrognathia. The primary outcome was the presence/absence of osseous inferior border defects. Predictors included the mandibular movement, rotation of the occlusal plane, postoperative proximal segment position, pattern of lingual fracture, occurrence of bad split, and presence of third molars.

RESULTS

The study sample consisted of 200 patients and had a mean follow-up of 13 months. The mean mandibular advancement and rotation was respectively 5.8 mm and 5.4° clockwise. Osseous inferior border defects were present in 7.0% of splits and in 12.5% of patients. Significant risk factors for inferior border defects included increased advancement, increased clockwise rotation, cranial rotation of the proximal segment, and a split originating in the lingual cortex.

CONCLUSION

In conclusion, osseous inferior border defects occur significantly more often in cases with large mandibular advancement, increased clockwise rotation of the occlusal plane, malpositioning of the proximal segment, and a split originating in the lingual cortex.