Intraoral Vertical Ramus Osteotomy Research Articles

Factors affecting unusual postoperative vertical downward movement of mandible after surgery-first approach using intraoral vertical ramus osteotomy

BackgroundIn very rare cases, patients who have undergone surgery-first approach with intraoral vertical ramus osteotomy (IVRO) exhibit unusual downward movements of mandible even up to 1-year post surgery, which makes it difficult for orthodontists to stabilize the occlusion during the postoperative orthodontic period. The aim of this study was to identify factors affecting the unusual downward movement of the mandible 1-year after the surgery-first approach using IVRO, while focusing on cephalometric values.MethodsThis retrospective cohort study sample was divided into two groups based on the amount of vertical movement of the B-point 1-year post surgery (Group S, predictable upward movement; Group U, unpredictable downward movement greater than 2 mm). To evaluate cephalometric changes between the two groups, cephalograms were obtained before surgery, 1 day after surgery, 1 month after surgery, and 1 year after surgery. The data were analyzed using the independent t-test, Mann–Whitney U test with Bonferroni correction, Pearson correlation analysis, and multiple regression analysis.ResultsAt the initial examination, Group U showed a shallower anterior overbite. The vertical surgical change in the B-point was statistically different between the two groups (p < 0.001), indicating that group U exhibited more upward movement of the mandible during surgery. Group U showed significant downward movement of the mandible 1 month after surgery, and this finding persisted until 1 year postoperatively. Clockwise rotation of the mandible was also observed. Surgical vertical movement of the B-point showed a strong correlation with postoperative vertical movement of mandible (r = -0.674; p < 0.001) along a linear relationship, indicating that the amount of postoperative vertical downward movement of the mandible increased as the amount of surgical upward movement of the B-point increased (R2 = 0.449; p < 0.001).ConclusionsThis study revealed that unusual downward movement of the mandible after a surgery-first approach using IVRO is correlated with the amount of upward movement during the surgery. When planning surgery, in cases in which a significant upward movement of the mandible is anticipated, orthodontists should prepare for the possibility of subsequent unusual downward movement and a tendency for the anterior overjet to decrease during the postoperative orthodontic period.

Three-dimensional Analysis of Skeletal Stability in Cleft Lip and Palate Patients Undergoing Bimaxillary Surgery With Le Fort I Osteotomy and Intraoral Vertical Ramus Osteotomy.

Orthognathic surgery in patients with lip and palate clefts is challenging owing to scar tissue from primary repairs and severe deformities. In this study, we evaluated the stability of Le Fort I osteotomy with intraoral vertical ramus osteotomy (IVRO) in patients with cleft lip and palate using 3-dimensional (3D) analysis. This retrospective study comprised 14 cleft lip and palate patients (3 females, 11 males; the average age at surgery: 23.8y) who underwent bimaxillary orthognathic surgery involving Lefort I osteotomy and IVRO. Cone-beam computed tomography (CBCT) images were obtained at preoperative (T0), 1-month postoperative (T1), and 1-year follow-up (T2) periods. The 3D analysis assessed the transitions and rotations of the maxilla and mandible using a virtual triangle. The maxilla showed stability in all directions at the 1-year follow-up with minimal relapse. The distal segment of the mandible exhibited clinically acceptable anterior (1.15mm relapse) movements and pitch rotation (2.88° counterclockwise relapse) during the first year postoperatively. The proximal mandibular segment underwent anterior-inferior transition (1.21 and 2.01mm, respectively) and lateral-outward rotation (4.90° and 7.51°, respectively) postsurgery, remaining unchanged 1 year postoperation. Le Fort I osteotomy with IVRO provides skeletal stability in patients with cleft lips and palates. This study demonstrated a minimal maxillary relapse and clinically acceptable movements in the distal mandibular segment during the first postoperative year. The proximal mandibular segment moved anteriorly and inferiorly, rotated laterally and outward after surgery, and remained unchanged at the 1-year follow-up.

Augmentation genioplasty using discarded bone fragments following proximal segment osteotomy of the ramus in intraoral vertical ramus osteotomy (IVRO)

BackgroundBased on a three-dimensional (3D) orthognathic simulation, this technical report introduces a method for augmentation genioplasty using a proximal bone fragment of the mandible, which is typically discarded in intraoral vertical ramus osteotomy (IVRO).ResultsA 43-year-old female patient diagnosed with Class III malocclusion, presenting with a protruding mandible and long facial height, underwent surgical treatment. The surgical plan involved mandibular setback position using IVRO and augmentation genioplasty. The 3D orthognathic surgery including augmentation genioplasty simulation was performed. An excessively elongated proximal segment was sectioned following IVRO. The inferior part of the sectioned proximal bone fragment of the mandible was positioned to align with the requirements of advancement genioplasty. After ensuring that the placement of the fragment matched that of the simulated surgery, each bone fragment was fixed. At 1.5 years post-surgery, the grafted bone on the augmentation genioplasty was well maintained, with slight bone resorption.ConclusionsAugmentation genioplasty using the proximal bone fragment of the mandible, which is typically discarded in IVRO, reduces the surgical complications associated with chin osteotomy. When a secondary genioplasty is required, genioplasty with osteotomy, movement of the cut bone fragments, partial bone-shaving osteotomy, and additional bone grafting are viable options.

Comparison of the skeletal stability after mandibular counter-clockwise rotation in three surgical procedures.

The treatment of mandibular deformities with an anterior open bite is challenging. In this study, skeletal stability after mandibular osteotomies was evaluated to determine the best treatment for mandibular prognathism with an anterior open bite in three procedures: intraoral vertical ramus osteotomy (IVRO), conventional sagittal split ramus osteotomy (conv-SSRO), and SSRO without bone fixation (nonfix-SSRO). Patients who underwent mandibular osteotomy to correct skeletal mandibular protrusion were included. Changes in skeletal and soft tissues were assessed using lateral cephalograms taken before (T1), 3 ± 2days (T2), and 12 ± 3months (T3) after surgery. Thirty-nine patients were included: nine in the IVRO group and 11 and 19 in the conv- and nonfix-SSRO groups, respectively. The mandibular plane angles (MPAs) of the T2-T1 were - 2.7 ± 2.0 (p = 0.0040), - 3.7 ± 1.7 (p < 0.0001), and - 2.3 ± 0.7 (p < 0.0001) in the IVRO, conv-SSRO, and nonfix-SSRO groups, respectively. The skeletal relapse of the MPAs was not related to the MPA at T2-T1, and it was approximately 1.3° in the conv-SSRO group. The skeletal relapse of the MAPs was significantly correlated with the MPA of T2-T1 in the IVRO (p = 0.0402) and non-fix-SSRO (p = 0.0173) groups. When the relapse of the MPAs was less than 1.3°, the MPA of T2-T1 was calculated as 2.5° in the nonfix-SSRO group. When the MPA of T2-T1 is less than 2.5°, non-fix SSRO may produce a reliable outcome, and when it is more than 2.5°, conv-SSRO may produce better outcomes.

Surgical-Orthodontic Treatment of Class III Malocclusion with Anterior Open Bite

A 21-year-old female came with chief complaints of inability to incise food and poor esthetics. The patient presented with a concave facial profile, long face with a steep mandibular angle, incompetent lip closure, and acute nasolabial angle. Intraorally, she had negative 6 mm overjet, 3 mm open bite and dental crowding. She was diagnosed as severe skeletal Class III malocclusion and anterior open bite. The treatment plan included orthodontic treatment with orthognathic surgery and extraction of maxillary second molars, which were supra-erupted and tipped buccally. The pre-operative orthodontic alignment took 11 months. The surgical correction included maxillary Le Fort I osteotomy with 4 mm advancement, mandibular intraoral vertical ramus osteotomy with 6.5 mm setback and genioplasty. The total surgical-orthodontic treatment time was 16 months. The final result presented a straight profile with stable occlusion. The patient’s facial and dental esthetics, masticatory function, and quality of life were all significantly improved after surgical-orthodontic treatment.

Comparison of the quality of life changes of patients receiving sagittal split ramus osteotomy or intraoral vertical subsigmoid osteotomy for mandibular prognathism.

To investigate and compare the effect of two orthognathic procedures for mandibular setback, namely, sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), on oral health, mental- and physical health-related quality of life across time. Patients with mandibular prognathism and planned for orthognathic surgery were recruited in this study. Patients were randomized into two groups (IVRO and SSRO groups). Quality of life (QoL) was assessed with the 14-item Short-Form Oral Health Impact Profile (OHIP-14) and the 36-item Short-Form Health Survey (SF-36) preoperatively (T0), postoperative 2weeks (T1), 6weeks (T2), 3months (T3), 6months (T4), 12months (T5), and 24months (T6). A comparison of OHIP-14 and SF-36 scores between two groups was conducted. Ninety-eight patients (49 SSRO group, 49 IVRO group) participated in this study. There was no significant difference in OHIP-14 scores between SSRO and IVRO throughout the treatment process. SSRO group had significant reduction of OHIP-14 score (i.e., improving oral health-related QoL) since postoperative 2weeks, whereas IVRO group had significant reduction since postoperative 6weeks. Starting from postoperative 3months, the oral health-related QoL of both groups was already significantly better than the baseline level and continued to steadily improve afterwards. For SF-36, both groups had increased physical health summary score starting from postoperative 2weeks, indicating an early and gradual recovery of physical health-related QoL. The mental health summary score of the SSRO group began to increase from postoperative 2weeks, but that of the IVRO group only began to increase from postoperative 6weeks. Patient age at the time of surgery was positively correlated with OHIP scores in the postoperative period. The study concludes that both SSRO and IVRO contributed to the improvement of QoL in the long term, but oral health- and mental health-related QoL of SSRO groups showed earlier improvement. Undergoing orthognathic surgery at early ages is advised, as older age of patients appeared to have worse QoL. Clinical trial registration number: HKUCTR-1985. Date of Registration: 14 Apr 2015.

What are the Effects of Internal Fixation on Trigeminal Neurosensory Function and the Temporomandibular Joints Following Intraoral Vertical Ramus Osteotomy?

Intraoral vertical ramus osteotomy (IVRO) has, traditionally, been accomplished without internal fixation, necessitating a period of maxillomandibular fixation (MMF). With advances in instrumentation, internal fixation of IVRO is feasible, obviating the need for MMF. The purpose is to investigate the effects of transoral internal fixation on the prevalence of third division trigeminal nerve (CNV3) injury, temporomandibular joint (TMJ) arthralgia, and surgical site bleeding following IVRO. A retrospective study was conducted on patients who underwent IVRO at Vanderbilt University Medical Center between January 2017 and December 2020. The primary predictor variable was fixation status-internal fixation versus MMF. The primary outcome variable was postoperative CNV3 neurosensory disturbance. The secondary outcome variables were TMJ arthralgia and surgical site bleeding. Statistical analysis included Fisher's exact test and McNemar's Chi-squared test. Seventy two subjects (59 IVROs without internal fixation and 65 IVROs with internal fixation) were studied. The frequency of CNV3 neurosensory deficit was 0% in the IVRO without internal fixation group and 3.1% in the IVRO with internal fixation group (P=.49). Within group analysis showed a decreased frequency of postoperative TMJ arthralgia compared to preoperative records in both groups (IVRO without internal fixation group, P=.04 and IVRO with internal fixation group, P=.004). The frequency of active surgical site bleeding controlled with local measures was 1.7% in the IVRO without internal fixation group and 3.1% in the IVRO with internal fixation group (P=1). Internal fixation of IVRO is associated with low incidence of neurosensory deficit, TMJ arthralgia, and active surgical site bleeding.

Computed tomography‐based morphological analysis for intraoral vertical ramus osteotomy in patients with mandibular prognathism

AbstractAimIntraoral vertical ramus osteotomy (IVRO) is an orthognathic surgery for patients with jaw deformity. To avoid complications associated with IVRO, understanding the position of the mandibular foramen and shape of the mandibular ramus in patients with mandibular prognathism is important, which only few studies have reported. Most studies have been performed with dry skulls of older people without jaw deformity. This study aimed to examine the position and shape of the mandibular foramen and ramus, respectively, using computed tomography in patients with mandibular prognathism.MethodsThe study was performed on 50 Japanese patients who underwent IVRO. We examined the position of the mandibular foramen against the occlusal plane, distance between the posterior border of the mandible and mandibular foramen, and thickness of the mandibular ramus.ResultsThe mandibular foramen was vertically located above the occlusal plane at a distance of 2.6 ± 5.1 and 1.2 ± 5.1 mm in men and women, respectively. The distances between the mandibular ramus and foramen, measured with the posterior border line of the mandibular ramus as a criterion, were 15.9 ± 2.2 and 14.4 ± 2.1 mm in men and women, respectively. The thickest parts of the mandibular ramus were 6.8 ± 1.6 and 6.9 ± 0.9 mm in men and women, respectively.ConclusionKnowledge of the accurate position of the mandibular foramen is important for a safe IVRO. Mandibular ramus osteotomy line should be within 10 mm from the posterior border of the mandibular ramus, to avoid inferior alveolar nerve damage.

Mandibular condylar displacement and the associated factors following intraoral vertical ramus osteotomy

ObjectiveIn intraoral vertical ramus osteotomy (IVRO), the proximal and distal bony segments are not fixed rigidly and thus mandibular condyles are easily displaced. Since there have been only a few reports which examined any factors relating to the condylar displacement and mobility, we aimed to analyze the change in position over time through IVRO and elucidate the associated clinical factors. MethodsA retrospective study included 100 condyles in 50 patients. The Schüller's radiographs and posteroanterior cephalograms collected at the determined 6 time points were analyzed. The condylar head position was defined using X-Y coordinates. The amount of condylar displacement, the height of articular eminence and the ramus angulation were measured. The clinical information such as patient’s age, sex, operation time, setback quantity, TMJ noise or pain and surgical methods (1 or 2 jaw surgeries) was collected. Statistical analyses concerning the postoperative condylar displacement was performed. ResultsThe most of condyles showed the significant anterior and inferior shift immediately after surgeries which displacement had been restored over time and mostly resolved in one-year after surgery. We found some positive correlations of the amount of operative condylar displacement with setback quantity, the ramus angulation changes and the height of the articular eminence. The significant differences were found in the items of TMJ noise and surgical method. The recovery amount of condyles was significantly different in the surgical methods. ConclusionOur study provides the detail radiographic data of condyles and some associated factors to which attention should be paid when performing IVRO.

The Versatility of Extraoral Vertical Ramus Osteotomy for Mandibular Prognathism: A Prospective Study.

Orthognathicsurgery simply means alignment of thejaws.The aim of orthognathic surgery is to normalize the relationship of thejawsbetweenthemselves andtherestof thecraniofacialcomplex. Mandibularprognathism is a common clinical problem all over the world. Currently, sagittal ramus osteotomy is the primary choice for correcting most cases of mandibular retrognathism and prognathism. The surgical option for extreme cases ofmandibular prognathism is extraoral vertical ramus osteotomy (EVRO) or intraoral vertical ramus osteotomy (IVRO) or inverted L osteotomy. The aim of this study was to evaluate the versatility of EVRO for mandibular prognathism. Ten patients with the chief complaint of mandibular prognathism with no history of keloid tendency were included in the study. EVRO was done for all patients. The parameters based on which the outcome of the surgical procedure was assessed weretime taken for the surgical procedure, facial harmony both in frontal and profile views postoperatively, and intraoperativeand postoperative complications, and assessment of the postoperative results was done through orthopantomogram (OPG) and 3D CT scan. Thetime takenfortheentiresurgicalprocedure, startingfrom incisiontoclosure, variedbetween80 and 94 minutes with the average time taken for the surgery being 90 ± 8.80 minutes. It was found that there was a statistically significant difference between preoperative (M = 53.4, SD = 5.854) and postoperative evaluation (M = 47.5, SD = 5.039) of the posterior nasal spine to nasion 1 (PNS-N 1) horizontal plane (HP)(mm) withp < 0.001. Similarly, there was a statistically significant difference between preoperative (M = 81.4, SD = 2.716) and postoperative evaluation (M = 74.4, SD = 3.627) of mandible body length (mm) withp < 0.001. However, no statistically significant difference exists between the preoperative and postoperative evaluation of anterior nasal spine (ANS) to PNS (mm) and ramus height Ar-Go (mm). EVRO is an acceptable surgical procedure owing to the fact that it is relatively simple to carry out, its lack of complications, and its good results.

Impact and Stability of Mandibular Setback after Intraoral Vertical Ramus Osteotomy

(1) Background: The purpose of this study was to evaluate stability and complications following mandibular setback using intraoral vertical ramus osteotomy (IVRO) and provide an assessment of IMF (Inter-maxillary Fixation) compliance. (2) Methods: This is a retrospective cohort study. It included a total of 39 patients who underwent 78 IVRO for the treatment of mandibular prognathism between 2005 and 2021 at Sheba Medical Center. Radiographic and clinical examinations were performed preoperatively (T0), 3 days post-surgery (T1) and 8 months post-surgery (T2). Measurements of dental and skeletal stability, as well as neurosensory disturbances and TMJ dysfunctions, were statistically analyzed. (3) Results: The mean mandibular setback was 5.6 mm. A relapse of less than 2 mm was observed at T2. A short-term neurological disturbance was reported in 38.46% of the 39 patients, and 17.94% of them showed full recovery by T2. In 21 patients who underwent IVRO without genioplasty, only 14.28% reported long-term sensory disturbance. In addition, when a vertical osteotomy was performed, neurological damage was 174% higher as compared to oblique osteotomy. The IMF compliance rate for the 6 weeks postoperatively was 100%. (4) Conclusions: IVRO is still a relevant and valid technique for the treatment of mandibular prognathism that provides stable results with minimal complications rate.

Changes in Preexisting Temporomandibular Joint Clicking after Orthognathic Surgery in Patients with Mandibular Prognathism.

This study aimed to investigate the changes in preexisting temporomandibular joint (TMJ) clicking and the new incidence of TMJ clicking after orthognathic surgery. A total of 60 patients (30 men and 30 women) with mandibular prognathism underwent intraoral vertical ramus osteotomy (IVRO) for a mandibular setback. The setback amount and TMJ clicking symptoms (preoperative and one year postoperative) were recorded. To assess the risk of new incidence of TMJ clicking in asymptomatic patients, the cutoff value for postoperative mandibular setback was set at 8 mm. The left and right mandibular setbacks were 11.1 and 10.9 mm in men, respectively, and 10.7 and 10.0 mm in women, respectively. Thus, no difference in setback amount on either side was observed between the sexes. The improvement rate in patients with preexisting TMJ clicking was 69.2% (18 of 26 sides); the postoperative improvement rates were 71.4% (setback amount &gt; 8 mm) and 60% (setback amount ≤ 8 mm). IVRO may reduce the severity of preexisting TMJ clicking. A high setback amount (&gt;8 mm) may not be associated with a considerable increase in the risk of postoperative TMJ clicking.

Surgical cutting guide and single plate fixation for intraoral vertical ramus osteotomy

With the advancement of digital technology over the last few decades, the use of virtual surgical planning and fabrication of surgical guides have tremendously improved the outcomes of various maxillofacial surgical procedures. The intraoral vertical ramus osteotomy (IVRO) is an orthognathic surgical procedure largely employed for mandibular setback in correcting dentofacial deformities. This study describes the design and application of a surgical cutting guide for IVRO. The guide can also be used to facilitate the placement of miniplate fixation. The initial experience at the authors’ centre suggests that the guide has allowed the osteotomy to be performed with increased precision and confidence. Furthermore, the use of miniplate fixation decreased the period of maxillomandibular fixation. However, a larger series is required to evaluate the utility of this system more thoroughly.

Vertical Ramus Osteotomy, Is It Still a Valid Tool in Orthognathic Surgery?

The purpose of this study is to evaluate mandibular osteotomy procedures during orthognathic surgery, with an emphasis on the complications of the two leading procedures: intraoral vertical ramus osteotomy (IVRO) and sagittal split osteotomy (SSO). We conducted a retrospective cohort study by extracting the records of patients who underwent either IVRO or SSO procedures during orthognathic surgery in a single center between January 2010 and December 2019. A total of 144 patients were included (median age of 20.5 years, 52 males). The IVRO:SSO ratio was 118:26 procedures. When referring to all surgeries performed, IVRO procedures were associated with shorter hospitalization than the SSO procedures, while the overall durations of surgery and follow-up periods were comparable. In contrast, when referring only to bimaxillary procedures, the duration of the IVRO bimaxillary procedures was significantly shorter than the SSO bimaxillary procedures. There were 53 complications altogether. Postoperative complications consisting of skeletal relapse, temporomandibular joint dysfunction, sensory impairment, and surgical-site infection were significantly fewer in the IVRO group. Both types of osteotomies have acceptable rates of complications. IVRO appears to be a safer, simpler, though less acceptable procedure in terms of patient compliance.

Does the Levasseur-Merrill Retractor Provide Reliable In Vivo Guidance for the Intraoral Vertical Ramus Osteotomy?

Levasseur-Merrill retractor (LMR) utilization during the intraoral vertical ramus osteotomy (IVRO) helps initiate the osteotomy approximately 7mm from the posterior border of the mandible, preventing damage to the inferior alveolar nerve. The purpose of this invivo study is to evaluate the IVRO placement and the risk of neurosensory deficit (NSD) while using the LMR. This prospective case series was conducted at a single tertiary care center. Medical records were reviewed for medical and demographic information. Inclusion criteria were as follows: underwent the IVRO procedure by a single provider from June 2020 to June 2022 and postoperative cone beam computed tomography images. Exclusion criteria were as follows: age less than 16 years, previous mandibular osteotomies, inadequate clinical documentation, or follow-up. The primary outcome variables included the proximal segment width and proximity of the IVRO to the inferior alveolar foramen. The secondary outcome variable was NSD as measured subjectively by 2-point discrimination, sharp versus dull touch, and light touch with von Frey filaments. The 26 subjects (42 operated sides) were 96% female, with an average age of 30.1years (range 17-54years). The mean proximal segment width was 10.3±1.7mm (95% confidence interval: 9.77, 10.83). The mean distance from the posterior border of the inferior alveolar foramen (IAF) to the osteotomy was -0.89±1.7mm (95% confidence interval: -1.43, -0.35), with negative numbers indicating violation of the IAF. IAF and full bony canal violation occurred in 61.9% and 4.8% of operated sides, respectively. NSD at 6months postoperatively occurred in the 2 sides that experienced full bony canal violation. The LMR did not consistently guide the IVRO position within 7mm from the posterior border of the mandible as previously thought and allows for frequent violation of the IAF. Long-term NSD of the inferior alveolar nerve was infrequent and correlated with violation of the full bony canal.

Influence of different treatment procedures on the temporomandibular joint after mandibular setback in skeletal class III - A retrospective study

The aim of this study was to clarify the effects of three different orthognathic surgical procedures on the temporomandibular joint after mandibular setback. Conventional sagittal split ramus osteotomy (SSRO) with segmental fixation (conv-SSRO), intraoral vertical ramus osteotomy (IVRO), or SSRO without fixation followed by the physiological positioning strategy (nonfix-SSRO) was performed for mandibular setback. Temporomandibular joint disorder (TMD) symptoms were clinically assessed, and the condylar head angle was measured. In total, 129 patients participated. Preoperative TMD and treatment procedure were related to postoperative TMD. A menton deviation of 3.43 mm was the cutoff for the risk of postoperative TMD. The incidence rate of postoperative TMD in the conv-SSRO group was higher than that in the IVRO (p = 0.0197) and nonfix-SSRO (p = 0.0001) groups in asymmetric cases. There was no significant postoperative change in the temporomandibular joint space in each group. In symmetric and asymmetric cases, the condylar head was rotated inwards by 5.82 ± 4.75° (p < 0.0001) and 5.44 ± 3.10° (p < 0.0001), respectively, in the conv-SSRO group, and outwards by −7.98 ± 5.05° (p < 0.0001) and −8.32 ± 6.38° (p < 0.0001), respectively, in the IVRO group, but it was almost stable in the nonfix-SSRO group. Within the limitations of the study it seems that nonfix-SSRO should be preferred over conv-SSRO and IVRO whenever appropriate.

Clinical significance of postoperative skeletal relapse in the treatment of mandibular prognathism: Receiver operating characteristic curve analysis

Postoperative skeletal relapse is the most important issue in patients undergoing orthognathic surgery. This study aimed to investigate clinical skeletal relapse (≥2mm) after mandibular setback surgery (intraoral vertical ramus osteotomy: IVRO) using receiver operating characteristic curve (ROC curve) analysis. Serial cephalograms of 40 patients with mandibular prognathism were obtained at different time points: (1) before surgery (T1), (2) immediately after surgery (T2), and (3) at least with a 2-year follow-up postoperatively (T3). The menton (Me) was used as the landmark for measuring the amount of mandibular setback and postoperative skeletal relapse. Postoperative stability (T32) was divided into groups A and B by skeletal relapse ≥2mm and <2mm, respectively. The area under the ROC curve (AUC) was used to determine the cut-off point for mandibular setback. At the immediate surgical setback (T21), the amount of setback in group A (15.55mm) was significantly larger than in group B (10.97mm). Group A (T32) showed a significant relapse (4.07mm), while group B showed a significant posterior drift (1.23mm). The amount of setback had the highest AUC area (0.788). The cut-off point was 14.1mm (T21) that would lead to a clinical relapse of 2mm (T32). In IVRO, the postoperative mandibular positions reveal posterior drift and anterior displacement (relapse). The experience of clinical observation and patient perception of postoperative skeletal relapse was ≥2mm. In the ROC curve analysis, the cut-off point of setback was 14.1mm.

Comparison of the bite force and occlusal contact area of the deviated and non-deviated sides after intraoral vertical ramus osteotomy in skeletal Class III patients with mandibular asymmetry: Two-year follow-up.

The objectives of this study were to compare the time-dependent changes in occlusal contact area (OCA) and bite force (BF) of the deviated and non-deviated sides in mandibular prognathic patients with mandibular asymmetry before and after orthognathic surgery and investigate the factors associated with the changes in OCA and BF on each side. The sample consisted of 67 patients (33 men and 34 women; age range 15-36 years) with facial asymmetry who underwent 2-jaw orthognathic surgery. OCA and BF were taken before presurgical orthodontic treatment, within 1 month before surgery, and 1 month, 3 months, 6 months, 1 year, and 2 years after surgery. OCA and BF were measured using the Dental Prescale System. The OCA and BF decreased gradually before surgery and increased after surgery on both sides. The OCA and BF were significantly greater on the deviated side than on the non-deviated side before surgery, and there was no difference after surgery. According to the linear mixed-effect model, only the changes in the mandibular plane angle had a significant effect on BF (p < 0.05). There was a difference in the amount of the OCA and BF between the deviated and non-deviated sides before surgery. The change in mandibular plane angle affects the change, especially on the non-deviated side, during the observation period.

A Comprehensive Review of Orthognathic Surgery: Fixation, Relapse, and Complications

Background: This study aims to investigate all papers on orthognathic fixation to better understand changes in operative techniques and fixation materials and to better compare relapse and complication rates. Methods: A PubMed search was conducted of “orthognathic” AND “fixation” in the title or abstract between 1989 and 2020. Results: Three reviewers independently screened 439 papers and extracted data from 166 included papers. Of these studies, 118 investigated sagittal split ramus osteotomies (SSRO), 96 LeFort osteotomies, 25 genioplasties, and 21 intraoral vertical ramus osteotomies (IVRO). The most used fixation materials in the maxilla were titanium miniplates with monocortical screws (n = 65), followed by resorbable miniplates (n = 10); in the mandible, the most common were titanium miniplates (n = 67) and titanium bicortical screws (n = 49). Wide variability was demonstrated in relapse rates by operation, fixation type, and relapse time-point studied. Meta-analysis revealed a significantly higher infection rate in SSRO versus LeFort ( P = .003) and, surprisingly, a trend toward higher relapse rate in titanium versus resorbable fixation at 6 months in SSRO setback ( P = .08). Conclusion: This study reports all the available data on relapse rates across techniques, with non-inferiority of bicortical screws versus miniplates.

Comparison of the bite force and occlusal contact area of the deviated and non-deviated sides after intraoral vertical ramus osteotomy in skeletal Class III patients with mandibular asymmetry: Two-year follow-up

ObjectiveThe objectives of this study were to compare the time-dependent changes in occlusal contact area (OCA) and bite force (BF) of the deviated and non-deviated sides in mandibular prognathic patients with mandibular asymmetry before and after orthognathic surgery and investigate the factors associated with the changes in OCA and BF on each side.MethodsThe sample consisted of 67 patients (33 men and 34 women; age range 15–36 years) with facial asymmetry who underwent 2-jaw orthognathic surgery. OCA and BF were taken before presurgical orthodontic treatment, within 1 month before surgery, and 1 month, 3 months, 6 months, 1 year, and 2 years after surgery. OCA and BF were measured using the Dental Prescale System.ResultsThe OCA and BF decreased gradually before surgery and increased after surgery on both sides. The OCA and BF were significantly greater on the deviated side than on the non-deviated side before surgery, and there was no difference after surgery. According to the linear mixed-effect model, only the changes in the mandibular plane angle had a significant effect on BF (p < 0.05).ConclusionsThere was a difference in the amount of the OCA and BF between the deviated and non-deviated sides before surgery. The change in mandibular plane angle affects the change, especially on the non-deviated side, during the observation period.