Modification of the mandibular split based on a physical model

Context: Using a reliable fixation method after ramus sagittal split osteotomy in order to reduce the chances of treatment relapse and condyle changes is still one of the most noteworthy issues discussed among maxillofacial surgeons. In this study, the results of the up-to-date papers were collected, which identify the eects of the fixation method on the post-operative results, to give the reader a comprehensive view of the new concepts. Evidence Acquisition: The most frequent mandibular surgeries, setbacks, and advancements via the bilateral sagittal split os- teotomy technique were used for a literature search due to the abundance of related articles. Consequently, the following keywords were applied: sagittal split ramus osteotomy, orthognathic surgery, rigid fixation, non-rigid fixation, postoperative relapse, and postoperative stability. Results: The articles were classified according to the surgery procedure: mandibular advancement surgery or mandibular setback surgery. The relapse pattern can be divided into two categories: an early relapse, which is strongly related to the surgery proce- dure, and a late relapse, which can be attributed to the physiologic changes, such as a growth map. The contributing factors can be considered to be the following: a change in ramus in inclination, the mandibular plane, and the fixation type. Conclusions: Using rigid fixation techniques after bilateral sagittal split ramus osteotomy will optimize the stability, but this sta- bility is not influenced by the method of this rigid fixation; although the most commonly suggested technique, bicortical screws, is in the inverted-L position

Influence of Osteotomy Design on Bilateral Mandibular Ramus Sagittal Split Osteotomy

Sagittal split osteotomy has been used to address skeletal deformities involving the mandible. The versatility of the procedure has already been established in the past. This modality has rarely been used as access osteotomy. This article reviews the usage of sagittal split osteotomy for access to various benign pathologies which mainly involves the posterior mandible. The article also discusses various modalities which are used in order to address deeply seated pathologies. The various indications and anatomic consideration for using sagittal split osteotomy along with the advantages of this procedure over other procedures have been discussed. Keywords: Sagittal split osteotomy, Access osteotomy, Bilateral Sagittal Split Osteotomy.

Skeletal and dento-alveolar stability of Le Fort I intrusion osteotomies and bimaxillary osteotomies in anterior open bite deformities: A retrospective three-centre study

Influence of inferior border cut on lingual fracture pattern during bilateral sagittal split osteotomy with splitter and separators: Aprospective observational study.

Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients’ records

Three-dimensional evaluation of positional change of the condyle after mandibular setback by means of bilateral sagittal split ramus osteotomy.

The stability of mandibular advancement is critical for successful treatment. This study aimed to assess the stability of the mandible following bilateral sagittal split osteotomy (BSSO) with two modifications, namely, the Epker and Dal Point techniques. This pre-protocol prospective cohort study evaluated patients with retrognathia. Two BSSO modifications were studied: the Epker modification (group 1) and the Dal Pont modification (group 2). The primary outcome of this study was mandibular stability following advancement. The Epker and Dal Pont BSSO techniques were predictive variables. All measurements were performed before, immediately after, and 24months after surgery. Sixty-seven of 92 patients who underwent BSSO for the correction of retrognathia met the inclusion criteria to participate in the study. There were 33 patients in Group 1 and 34 in Group 2. The mean relapse in the sagittal plane at the B point was 0.51 ± 1.12mm in group 1 and 0.68 ± 0.81mm in group 2. The two groups had no significant difference in the mean amount of sagittal relapse (p = 0.21). The mean vertical relapse at B point was 0.49 ± 0.57mm in group 1 and 0.56 ± 0.10mm in group 2. The results showed no significant differences between the two groups (p = 0.56). The stability of mandibular advancement using the Epker and Dal Pont techniques was the same. The amount of relapse was closely correlated with the magnitude of advancement in both techniques.

Residents' journal review

Neurosensory Alteration in the Lower Lip and Chin Area After Orthognathic Surgery: Bilateral Sagittal Split Osteotomy Versus Inverted L Ramus Osteotomy

In this retrospective analysis, we examined temporomandibular joint space volume and condyle position in 10 patients undergoing bilateral sagittal split mandibular ramus osteotomy plus Le Fort I osteotomy to correct mandibular asymmetry. Cone beam computed tomography was used to map temporomandibular joint prior to (T0), immediately after (T1), and at 1 year after surgery (T2). In the deviated side, we detected significant lateral shift of the condyle in 5 patients at T1, and the shift disappeared at T2. In the non-deviated side, we detected significant medial shift of the condyle in all 10 patients at T1; the shift continued in 9 patients at T2. Temporomandibular joint space volume increased significantly at T1 and returned to presurgical volume at T2. In conclusion, there is significant shift in position of condyle in majority of the patients after bilateral sagittal split mandibular ramus osteotomy. The most consistent and persisting change was medial shift on the nondeviated side.

To determine whether the condylar rotation is affected by asymmetric setback in patients undergoing sagittal split ramus osteotomy. Thirty patients who underwent bilateral sagittal split ramus osteotomy setback surgery were divided into the two groups, symmetric setback and asymmetric setback, according to the right/left difference of setback amount (<2.0, ≥2.0 mm). Condylar long axis changes were evaluated using the three-dimensional superimposition of before and immediately after surgery cone-beam computed tomography volume images. Evaluations were performed separately in lesser setback and greater setback side in patients undergoing asymmetric setback, whereas both side condyles were evaluated together in patients undergoing symmetric setback. Condylar axis changes on axial view were correlated with setback amount or right/left setback difference using Pearson correlation analysis. In general, the condylar axis change occurred in a pattern of inward rotation. The condyles in patients undergoing symmetric setback showed 3.4° rotation in average. In case of asymmetric setback, the lesser setback side showed larger value (4.3°) than the greater setback side (2.3°) with a statistical significance. In the correlation analysis, setback amount showed no significant correlation with the condylar axis changes in both groups. However, correlation with right/left setback difference showed a positive correlation in lesser setback side of patients undergoing asymmetric setback. The findings of this study indicate that large amount of setback alone does not contribute to the change in condylar long axis, but asymmetric setback might cause a change in condylar long axis, particularly on the lesser setback side.

Risk factors of nerve injury during mandibular sagittal split osteotomy

The aim was to conduct a long-term follow-up study on the function and sensitivity of the mandible in advancement and setback patients after bilateral sagittal split osteotomy (BSSO) with rigid internal fixation. The advancement and setback groups consisted of 16 (12 females and 4 males, mean age: 21.4 and 21.3 years, respectively) and 17 (11 females and 6 males, mean age: 27.1 and 27.7 years, respectively). The final follow-up was a mean of 12.7 years (T4) post-operatively. The other follow-up examinations were before surgery (T1) and 7.3/6.6 (T2) and 13.9/14.4 (T3) months after surgery. To evaluate craniomandibular function, mouth-opening capacity, laterotrusion, protrusion, deviations during opening, pain and clicking of the temporomandibular joint (TMJ), muscular pain, and the retruded contact position-intercuspal position (RC-IP) distance were examined. A questionnaire was used to record subjective reports. The neurosensory status was determined with two-point discrimination (2-pd), the pointed, blunt, and light-touch tests. Statistical analysis included the following tests: Wilcoxon signed ranked matched pairs, Mann-Whitney U, paired t, and Fisher's exact test. Bonferroni's adjustments were made for evaluation of the questionnaire and Spearman's rank correlation coefficients to determine the interdependence of selected variables. Craniomandibular function showed restitution at T4 after 12.7 years. The 2-pd at the lip and chin had largely normalized in the two groups at T3. At T4, there was a significant increase of 2-pd at the lip and chin in both groups. The discrimination between sharp and blunt was limited in both groups in 25 per cent of patients at T4. Dysfunctions such as TMJ clicking, bruxism, and pain in the TMJ and muscles were neither increased nor decreased after BSSO. The initial post-surgical neurosensory impairment was barely detectable 1 year post-surgery. The new neurosensory impairment manifested at T4 was probably due to the normal human process of ageing. Neither age, gender, surgical advancement, nor setback showed any significant correlations.

Trigeminal nerve hypesthesia after sagittal split osteotomy in setback cases: correlation of postoperative computed tomography and long-term trigeminal somatosensory evoked potentials