Sagittal Split Research Articles

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

BackgroundNeurosensory 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. PurposeThe purpose of this study was to evaluate the influence of IAN exposure and manipulation during SSRO on functional sensory recovery (FSR). Study designThis 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 variableDegree 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) ; 3) Nerve partially encased in proximal segment and fully dissected free (PS). Outcome variablesThe 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. CovariatesThe covariates were sex, age, skeletal diagnosis, degree of movement, and concomitant genioplasty/subapical procedure. AnalysesKaplan-Meier survival analysis, Cox proportional hazards regression, and Mcnemar test were utilized. P-value < 0.05 was significant. ResultsIn 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= 0.001, <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 RelevanceAfter 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.

Long-term Skeletal Stability of Mandibular Surgery with Bilateral Sagittal Split Ramus Osteotomy—Advancement Versus Setback: A Systematic Review and Meta-analysis

Objectives The aim of this study was to evaluate and compare the long-term skeletal stability of mandibular advancement and mandibular setback achieved with bilateral sagittal split ramus osteotomy (BSSRO) procedure in adult patients with a minimum follow-up of at least 1 year. Methods A literature search was systematically performed according to PRISMA guidelines from four databases without limitation till 15 June 2021. Available literature was assessed for long-term skeletal stability as horizontal/vertical changes at cephalometric point B following conventional mandibular surgery (BSSRO) with rigid internal fixation. The quality of selected articles was assessed using Newcastle–Ottawa scale and the meta-analysis was carried out with Q statistic method, I-squared statistics, and fixed-effect model to estimate the pooled mean and Begg–Mazumdar bias indicator. Results A total of five studies (three pertaining to mandibular advancement and two setback groups) were included for comparative evaluation of relapse. The mean horizontal relapse was 7.85% pertaining to mandibular advancement (4.2–7.06 mm) as compared to 27% pertaining to mandibular setback (7.18–10.26 mm). The meta-analysis of four included studies (two in each group) revealed significant differences in long-term skeletal stability of mandibular advancement and setback (pooled proportion = 20.10; 95% confidence interval = 2.48–39.57). Conclusion Mandibular setback can be expected to relapse by 21.7–32.3% (mean 27%) as compared to mandibular advancement accounting for a relapse of 2.1–15.4% (mean 7.85%) in adult patients. Hence, mandibular advancement is a relatively stable procedure in the long term. PROSPERO registration number: CRD42021261466

Does the Low and Short Medial Cut Affect Lingual Nerve Recovery after Sagittal Split Osteotomy?

The purpose of this study was to evaluate the recovery of lingual nerve (LN) neurosensory function in patients undergoing sagittal split osteotomy (SSO) with a low and short medial horizontal cut. This was a prospective study of patients with mandibular deformities undergoing SSO with a low and short medial horizontal cut over a 4-year period. The outcomes of interest were neurosensory recovery of the LN, as assessed objectively using functional sensory recovery (FSR) and subjectively by patient report. The sample included 123 SSOs in 62 subjects with a mean age of 19.3 ± 3.1 years. Thirty-seven subjects (61.7%) were female. Mandibular advancements were performed in 52 SSOs (42.3%); mandibular setbacks were performed in 71 SSOs (57.7%). One subject underwent revision BSSO. FSR was achieved at 122 LNs (99.1%) within 6 weeks postoperatively, with 120 sites (97.5%) having S4 sensation at 6 weeks. Decreased LN sensation was reported at 10 (8.3%) sites at 1 week postoperatively. At 6 weeks postoperatively, 118 sites (97.5%) had reported normal sensation. By 12 weeks postoperatively, all LN sites had S4 sensation and there were no subjective complaints. Revision sagittal split osteotomy was associated with prolonged (≥6 weeks) time to S4 sensation ( P = 0.02) and subjective complaint of decreased sensation ( P = 0.02). LN sensory recovery occurs rapidly following the low and short SSO, with 99% of sites achieving FSR and subjectively normal sensation within 6 weeks of surgery and all patients achieving FSR with S4 sensation by 12 weeks postoperatively. LN sensory recovery may be prolonged in patients undergoing revision SSO. Therapeutic, IV.

Does Removal of Third Molars at the Time of Sagittal Split Osteotomy Impact Intraoperative Complications? A Retrospective Review from a Single Institution and Single Surgeon from 2015 - 2021

Does Removal of Third Molars at the Time of Sagittal Split Osteotomy Impact Intraoperative Complications? A Retrospective Review from a Single Institution and Single Surgeon from 2015 - 2021

Impact of Different Osteotomy Techniques on Bone Reserve in the Osteotomy Line in Sagittal Split Osteotomy: Experimental In Vitro Study in Caprine Mandible Model.

The objective of this study was to investigate of the effect of piezzo and conventional osteotomy techniques on bone reserve in the osteotomy line and comminuted fracture ratios that is able to compromise bone to bone contact negatively. Bilateral sagittal split ramus osteotomy was performed on 12 fresh male Thracian curly caprine mandible. In the first group (n: 12) osteotomies were performed with piezzo device. In the second group (n: 12) osteotomies were performed with micromotor and manual osteotomes. Operative time was measured. The number of comminuted fractures, length and width of the osteotomy, and the space between the osteotomy lines was evaluated from 3-dimensional computed tomography scans. The mean value of procedure duration was 320.4±10.76 seconds for piezo osteotomy and 238.8±8.29 seconds for conventional micromotor ( P <0.0001). Number of comminuted fractures was 1.41±1.3 in piezoelectric group, 1.5±1.3 in conventional group and the difference was not statistically significant (p: 0,88). Osteotomy lengths and widths were 35.58±5.2, 2.196±1.9 and 36.23±5.05, 2.27±1.85 in the piezzo and conventional groups, respectively. (p lengths :0,75; p widths :0,92) The volume of the bony interface between the distal and proximal segments of the mandible after osteotomy was 166.3±184.2mm 3 in the piezzo group and 163.5±129.3mm 3 in the conventional group (p: 0,96). The piezo surgery and the conventional osteotomy were found to be similar in terms of the gap between the distal and proximal mandible and the number of comminuted fractures. The duration to perform the conventional osteotomy was found to be shorter than the piezo surgery.

Changes of Temporomandibular Joint Morphology and Symptoms in Class II Malocclusion Patients With Bilateral Sagittal Split Ramous Osteotomy.

This study included 46 patients with class II malocclusion ranging in age from 19 to 39 years old treated with bilateral sagittal split ramous osteotomy (BSSRO). Left and right temporomandibular joints (TMJs) of each subject were evaluated independently with cone-beam computed tomography (CBCT) before operation (T1), 1 week after operation (T2), and 1 year after operation (T3) and assessed the effects of orthognathic surgery (OGS) on the temporomandibular joint disease (TMD) symptoms. Temporomandibular joint morphology evaluation included condylar volume, condylar area, cortical bone thickness, depth of the mandibular fossa, fossa thickness, joint nodule angle, joint space, and condyle-fossa relationship, which were calculated by using the Mimics software and 3-matic software. Data were statistically analyzed with SPSS software (P <0.05 means statistically significant). In our study, bilateral TMJs have no difference in T3. Bilateral sagittal split ramous osteotomy had no significant effect on the articular fossa. The condyle volume and surface area decreased from T1 to T3, but the cortical thickness of the bone did not change significantly. More anterior condyle positions in T1 and more posterior in T3.21 patients had at least 1 sign or symptom of TMD in T1 and 27 patients in T3. Four patients who were asymptomatic in T1 developed pain after surgery, 10 developed noises, 12 showed limited mouth opening, and 8 had abnormal opening patterns. It is concluded that more condylar posterior position after BSSRO and the reduction of condyle may be related to the enlargement of anterior space. The number of patients with joint symptoms increased postoperative, and the impact of BSSRO on TMD may be negative.

Clinical Stability of Bespoke Snowman Plates for Fixation following Sagittal Split Ramus Osteotomy of the Mandible.

Maxillofacial skeletal surgery often involves the use of patient-specific implants. However, errors in obtaining patient data and designing and manufacturing patient-specific plates and guides can occur even with accurate virtual surgery. To address these errors, bespoke Snowman plates were designed to allow movement of the mandible. This study aimed to compare the stability of bespoke four-hole miniplates with that of a bespoke Snowman plate for bilateral sagittal split ramus osteotomy (SSRO), and to present a method to investigate joint cavity changes, as well as superimpose virtual and actual surgical images of the mandible. This retrospective study included 22 patients who met the inclusion criteria and underwent orthognathic surgery at a university hospital between 2015 and 2018. Two groups were formed on the basis of the plates used: a control group with four-hole bespoke plates and a study group with bespoke Snowman plates. Stability was assessed by measuring the condyle-fossa space and superimposing three-dimensional virtual surgery images on postoperative cone-beam computed tomography (CBCT) scans. No significant differences were observed in the condyle-fossa space preoperatively and 1 year postoperatively between the control and study groups. Superimposing virtual surgery and CBCT scans revealed minimal differences in the landmark points, with no variation between groups or timepoints. The use of bespoke Snowman plates for stabilizing the mandible following SSRO exhibited clinical stability and reliability similar to those with bespoke four-hole plates. Additionally, a novel method was introduced to evaluate skeletal stability by separately analyzing the condyle-fossa gap changes and assessing the mandibular position.

Secondary Treatment of Mandibular Bone Fracture Using Sagittal Split Osteotomy and Segmentation of the Mandible: A Case Report

The secondary treatment of mandibular bone fractures poses a great challenge due to the complexity of several factors, such as incorrect primary fracture repositioning, inadequate internal fixation, nonunion, necrosis, local inflammation and infection, tooth loss, and malocclusion, serving as obstacles encountered by surgical teams. The aim of this case report is to detail the planning process, surgical technique, and outcome of the secondary treatment of the post-traumatic deformation, bone exposure, and partial necrosis of the mandible. The new approach described herein incorporated 3D planning and printing procedures, employing surgical techniques such as the segmentation of the mandible with unilateral sagittal split osteotomy and the vertical osteotomy of the mandibular body. New, stable occlusion; appropriate spatial relations; and proper osteosynthesis of the mandible were achieved. The encouraging results obtained demonstrate that the described method can be incorporated in similar cases of the secondary treatment of mandibular fractures and possibly lead to shorter hospitalization and convalescence and lower the associated costs.

Extensive Tophaceous Pseudogout of the Temporomandibular Joint, Reconstructed with Custom Alloplastic Temporomandibular Joint and Mandibular Sagittal Split Osteotomy

Extensive Tophaceous Pseudogout of the Temporomandibular Joint, Reconstructed with Custom Alloplastic Temporomandibular Joint and Mandibular Sagittal Split Osteotomy

Modification of Sagittal Split Osteotomy in Class II Asymmetry: Optimizing Bone Contact between Proximal and Distal Segments.

Computer-assisted surgical simulation (CASS) allows more precise orthognathic surgery. However, few studies have evaluated associations between CASS-designed bilateral sagittal split osteotomy (SSO) and bone contact surface in class II mandibular asymmetry. This study aims to evaluate the effects of using computer-assisted simulation and design modification of SSO to improve bony contact in skeletal class II asymmetry. This retrospective analysis reviewed 28 patients with class II asymmetry who underwent orthognathic surgery, including 15 with modified SSO (group CS) and 13 with conventional SSO (group C). Modified SSO was designed under CASS. Operative characteristics, postoperative outcomes, and complications were collected and compared between the two groups. Bony contact was found at the distal end of the proximal segment in all group CS patients, while bone gap was noted in all group C patients ( P < 0.05). Moreover, bone graft was used in four group C patients but was not used in all cases in group CS patients ( P < 0.05). A trend toward lower operative time or perioperative bleeding was noted in group CS, but without statistical significance. After 1-year follow-up, inferior alveolar nerve disturbances were noted in two group CS patients and one group C patient. Palpable bone gap with uneven jaw line was noted in two group C patients 1 year after surgery and one patient received fat graft treatment. The simulation-based SSO modification provides appropriate contact surface and eliminates the bone gap between proximal and distal segments in class II asymmetry. Therapeutic, III.

Risk factors for postoperative facial swelling at 1 week after bimaxillary orthognathic surgery in Class III patients

ObjectiveTo quantify facial swelling at 1 week after Le Fort I osteotomy and bilateral sagittal splitting ramus osteotomy in Class III patients and to identify factors contributing to the swelling based on clinical, morphologic, and surgical variables. Study DesignData from 63 patients were examined in this single-center, retrospective study. Facial swelling was quantitatively measured by superimposing computed tomography data taken in the supine position at 1 week and 1 year postoperatively and extracting the area of maximum intersurface distance. Age, sex, body mass index, thickness of subcutaneous tissue, and of masseter muscle, maxillary length (A-VRP), mandibular length (B-VRP), and posterior maxillary height (U6-HRP), surgical movement (ΔA-VRP, ΔB-VRP, ΔU6-HRP), drainage method, and usage of facial bandages were examined. Multiple regression analysis was performed using the above factors. ResultsThe median swelling at 1 week postoperatively was 8.35 IQR (5.99–11.47) mm. Multiple regression analysis revealed three factors that were significantly associated with facial swelling: Use of postoperative facial bandages (P=0.03), masseter muscle thickness (P=0.03), and ΔB-VRP (P=0.04). ConclusionAbsence of a facial bandage, thin masseter muscle, and large horizontal mandibular movement are risk factors for facial swelling at 1 week postoperatively.

Evaluation of the lower face enlargement following mandibular osteotomy: Bilateral sagittal split osteotomy (BSSO) vs supra basilar sagittal Split Osteotomy (SBSSO)

IntroductionThe current most common technique for mandibular split is the sagittal split osteotomy described by Obwegeser and modified by Dalpont and Epker. Several studies have shown a lower face enlargement while employing these techniques. The supra-basilar sagittal split osteotomy described in 2017 seems to be an interesting alternative as mandibular angles remain in continuity with the internal valve. The aim of this study was to evaluate lower face enlargement by comparing two techniques: sagittal split osteotomy and supra-basilar sagittal split. Materials and MethodsCephalograms were analyzed before and after surgery. Bigonial distances (BGD) were measured in frontal cephalograms, ramus length and distances between upper and lower incisors on lateral cephalogram. Control of those measures was also performed by measuring the Nasion-Anterior Clinoid distance and intercanthal distance to assess the comparability and error rate. Finally, a comparison of cephalograms before and after surgery to assess bigonial enlargement, ramus elongation and advancement was performed. ResultsOut of the 69 patients, 18 had a Bilateral Sagittal Split (BSSO) and 52 had a Supra-Basilar Sagittal Split (SBSSO). The error rate and patients’ characteristics were the same in the two groups. A statistically significant widening of the bigonial distance with the BSSO in comparison with the SBSSO was found (BGD difference: 5.82 mm (BSSO) vs - 1.47 mm (SBSSO), p < 0,001). A greater ramus elongation with the SBSSO was found (ramus elongation: 1.12 mm (BSSO) vs 5.1 mm (SBSSO)). This study has shown that the supra-basilar sagittal split is an interesting way to avoid the widening of the mandibular angles.

Evaluation and Comparison of Cervical Spine Posture in Class II Division I Patients Treated with Twin Block Appliances, Forsus Appliances, and Bilateral Sagittal Split Osteotomy: A Cephalometric Study.

It has been speculated that a change in cervical spine posture occurs due to forward repositioning of the mandible. Therefore, this study aimed to evaluate and compare the cervical spine posture in Class II division one patient treated with three different treatment modalities. A retrospective cohort study was conducted using pre and post-treatment lateral cephalograms of Class II Division one patients who have undergone orthodontic therapy using twin block appliance, Forsus, and bilateral sagittal split osteotomy (BSSO). This study included a total of 57 subjects comprising 19 subjects in each group. Seven cervical, three sagittal, and one vertical parameters were compared within and between each group. The data were tested using the Dependent t-test, One-way analysis of variance, and Tukey's post hoc test. A significant difference existed between the pre- and post-treatment angular measurements within the three groups showing a change in the cervical spine posture with forward positioning of the mandible. A comparison of mean changes in angular measurements between the three groups showed a significant difference in SNA, SNB, ANB, and odontoid process tangent-cervical vertebral tangent (OPT-CVT), indicating a change in the cervical posture. OPT-CVT angle predicts a change in cervical spine posture after treatment with a significant difference in the Twin Block group (P = 0.029) compared to Forsus and BSSO groups. Thus, the twin block group results in a more upright craniocervical posture than the other two treatment groups.

Does the Posterior Bending Osteotomy in Bilateral Sagittal Split Osteotomy Affect the Condyle Position in Asymmetric Patients?

To measure and compare changes in postoperative condylar position following bilateral sagittal split osteotomy in patients with asymmetry treated using a posterior bending osteotomy (PBO) and conventional methods (shaving of premature contacts). Participants were randomized to either the PBO or conventional group. The inclusion criteria were the need for bilateral sagittal split osteotomy or bimaxillary asymmetric surgery (menton deviation >4mm). The primary outcome variable was changes in the condylar position in the axial, coronal, and sagittal planes 6months after surgery, whereas the secondary outcome variable was changes in temporomandibular joint symptoms. Covariates included surgery type, deformity type, age, and sex. Categorical and numerical variables were analyzed using Fisher exact χ2 test and 2-way analysis of covariance. The study sample comprised 42 patients with a mean age of 23.3years; 57.5% were women. The alteration in the coronal condyle angle was 0.8⁰ ± 0.86⁰ in the PBO and 2.72⁰ ± 0.81⁰ in the conventional group. The differences in the condylar position in the coronal plane were not statistically significant (P=.129). The alteration in the axial condyle angle was 2.31⁰ ± 1.74⁰ in the PBO group and 5.65⁰±1.65⁰ in the conventional group. The alteration in the sagittal plane was 0.44⁰ ± 1.52⁰ in PBO and 0.47⁰ ± 1.44⁰ in the conventional group. Alterations in axial (P=.194) and sagittal (P=.976) condylar positions were insignificant. In the conventional group, statistically significant differences were found in the axial (P=.002) and coronal (P=.002) planes, and the condyle turned inward in both planes. There were no statistically significant differences between the groups or within the groups in the sagittal plane (P>0,5). In PBO and conventional groups, joint noise examination revealed positive results in 11 and 6 patients preoperatively and 1 and 2 patients postoperatively, respectively. A statistically significant decrease in joint noise was detected in the PBO group (P=0,04). The maximum mouth opening without pain was 5.95±1.47 in the PBO group and 7.91±1.39 in the conventional group, respectively. The alteration was not statistically significant between the groups but was significant within the groups (P<.001). PBO effectively prevents premature contact between mandibular segments in facial asymmetry.

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

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

Delayed Presentation of Actinomycosis Following Orthognathic Surgery: An Old Nemesis and a Difficult Diagnosis: Case Presentation and Review of the Literature.

Review of the literature with report of Case. To review the presentation of Actinomycosis specifically as it occurs with mandibular osteotomies. A review of the literature and report of an additional case. While minor infections secondary to local factors are usually seen 2-3weeks after surgery, late infections are rare. Host factors may play a role. When actinomycosis is diagnosed, long-term antibiotics are necessary. Actinomycosis is very rare following orthognathic surgery. It usually occurs in the mandible and following a sagittal split. Time of presentation for actinomycosis can vary from 6weeks to 4 months as in our case. Infections occurring this late after surgery should be treated with suspicion of actinomycosis obtaining both cultures and tissue biopsies. Treatment involves an incision and drainage and long-term antibiotics.

Three Different Fixation Modalities following Mandibular Setback Surgery with Sagittal Split Ramus Osteotomy: A Comparative Study using Three-dimensional Finite Elements Analysis.

The provision of sufficient stability after maxillofacial surgery is essential for the reduction of complications and disease recurrence. The stabilization of osteotomized pieces results in rapid restoration of normal masticatory function, reduction of skeletal relapse, and uneventful healing at the osteotomy site. We aimed to compare qualitatively stress distribution patterns over a virtual mandible model after bilateral sagittal split osteotomy (BSSO) bridged with three different intraoral fixation techniques. This study was conducted in the Oral and Maxillofacial Surgery Department of Mashhad School of Dentistry, Mashhad, Iran, from March 2021-March 2022. The mandible computed tomography scan of a healthy adult was used to generate a 3D model; thereafter, BSSO with a 3mm setback was simulated. The three following fixation techniques were applied to the model: 1) two bicortical screws, 2) three bicortical screws, and 3) a miniplate. The bilateral second premolars and first molars were placed under mechanical loads of 75, 135, and 600N in order to simulate symmetric occlusal forces. Finite element analysis (FEA) was carried out in Ansys software, and the mechanical strain, stress, and displacement calculations were recorded. The FEA contours revealed that stress was mainly concentrated in the fixation units. Although bicortical screws presented better rigidity than miniplates, they were associated with higher stress and displacement readings. Miniplate fixation demonstrated the most favorable biomechanical performance, followed by fixation with two and three bicortical screws, respectively. Intraoral fixation with miniplates in combination with monocortical screws can serve as an appropriate fixation arrangement and treatment option for skeletal stabilization after BSSO setback surgery.

Are There Differences in Fracture Patterns in Mandibular Ramus Sagittal Osteotomies Between Hunsuck/Epker, Wolford, and Posnick Modifications?

Despite decades of study, the best technique for mandibular ramus sagittal osteotomy has not been definitively determined. The purpose of the present study was to compare fracture patterns, inferior alveolar nerve (IAN) visualization, and torque required for mandibular sagittal splitting using the Hunsuck/Epker, Wolford, and Posnick techniques. This was a laboratory (exvivo), randomized, a single-blind study performed to evaluate sagittal split osteotomies in porcine mandibles using a specifically designed test system. The study's predictor variable was the osteotomy technique, which was divided into 3 groups: Group Hunsuck/Epker (GHE), group Wolford (GW), and group Posnick (GP). The outcome variables were lingual fracture pattern, torque in newtons (N) required to separate the mandible, and IAN visualization. The covariates were mandibular radiodensity and time between dejection and the experiment. The Kolmogorov-Smirnov normality statistics and analysis of variance with Tukey post test statistics were performed. Pvalue <.05 was considered statistically significant. The sample was composed of 120 equally divided porcine hemimandibles in each group. The torque forces were significantly lower (P<.001) when using the Posnick technique (2.07±0.22N) than when using the Hunsuck/Epker technique (4.45±0.32N) and Wolford (3.00±0.21N). GW (93.3%) and GHE (56.7%) showed a higher prevalence of lingual fracture in the posterior region of the mandibular canal (P<.001), while the GP (90%) had a higher frequency of lingual fracture pattern on the mylohyoid sulcus (P<.001). In more than 90% (P<.001) of the mandibles in GW and GHE, the IAN visualization was higher than 50%. In the GP, 90% (P<.001) of patients had IAN visualization of less than 50%. The Posnick technique required less torque to perform the sagittal osteotomy in a pig mandible and had good predictability (90%) for the less preferred lingual fracture pattern and minimal visualization of the nerve. The Wolford technique provided the best predictability (93%) for the preferred lingual fracture pattern and the best nerve visualization. Caution must be exercised when extrapolating the results from animal models to human applications.

Association between Bilateral Sagittal Split Osteotomy Setback and Autorotation of the Mandible

Introduction: The study aimed to evaluate the autorotation for Class III malocclusions after the bilateral sagittal split osteotomy (BSSO) setback procedure . Methodology: This retrospective study includes lateral cephalograms of eight males and three females total of 11 patients who had undergone BSSO, without any other additional surgeries. The Frankfurt-Horizontal (F-H) plane was used as a reference and manual superimposition was done. Considering stable mandibular landmarks, reference line perpendicular (RLp) and reference line (RL) were drawn as x and y coordinates, respectively. Pre- and postsurgical statistics were used to compare using paired t-test where P &lt; 0.05 was set for statistical significance. Results: Superimposed tracings showed no significant difference in pre- and postsurgical treatments. There was no statistically significant amount of autorotation after the BSSO setback procedure (P = 0.714). Conclusion: Hence, BSSO setback surgery will not cause any significant amount of autorotation of the mandible. If autorotation is required it must be incorporated into treatment planning.

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.

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. 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. 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). 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.