Mandibular Setback Research Articles

Fate of the Mandible in Class III Patients Subjected to Bimaxillary Surgery with a New 3D Planning Reference

Class III patients have classically been managed through monomaxillary techniques, mainly involving mandibular setback movements. More recently, according to the upper incisor to soft tissue plane (UI-STP) or Barcelona Line (BL) planning protocol, bimaxillary procedures for upper maxilla advancement and reduced mandibular setback have been recommended in order to secure better aesthetic outcomes and avoid upper airway constriction. The present study describes the jaw movements in the sagittal plane performed in class III patients subjected to bimaxillary surgery following the BL protocol. A retrospective evaluation was performed on 124 class III patients subjected to bimaxillary surgery. All subjects underwent upper maxilla advancement. A total of 112 patients received mandible advancement movement (90.3%), nine received mandibular setback (7.25%), and the mandible underwent no movement along the sagittal dimension in the three remaining patients (2.4%). Mandibular advancement was significantly the most frequent treatment option. The presented results suggest that when the BL planning protocol is used as an aesthetic and functional reference, class III occlusion appears mostly related to maxillary sagittal hypoplasia instead of mandible hyperplasia, so bimaxillary advancement surgery should be considered as one of the first-choice procedures for the treatment of these patients.

Upper airway changes after orthognathic surgery in patients with skeletal class III high-angle malocclusion and mandibular deviation.

This study analyzed the differences in the upper airway of patients with skeletal Class III high-angle malocclusion with and without mandibular deviation, and further investigated whether there are differences in the changes in upper airway space after orthognathic surgery between the two groups. 15 patients with skeletal Class III high-angle malocclusion and mandibular deviation, and 15 patients without mandibular deviation were selected to explore the impact of mandibular deviation on the upper airway. Additionally, 16 patients with mandibular deviation undergoing orthodontic-orthognathic combined treatment, and 13 patients without mandibular deviation, were selected to investigate the differences in the changes in upper airway space after orthognathic surgery between the two groups. In patients with skeletal Class III high-angle malocclusion, the deviation group showed significantly smaller sagittal diameter/maximum transverse diameter, cross-sectional area, volumes of oropharynx and hypopharynx, and total volume compared to the normal group, with all differences being statistically significant. After orthognathic surgery, the postoperative sagittal diameter/maximum transverse diameter of the oropharyngeal airway increased in the deviation group, while it decreased in the normal group. The postoperative reductions in cross-sectional area, volumes, and total volume of the oropharynx and hypopharynx were more pronounced in the normal group. In patients with skeletal Class III high-angle malocclusion, mandibular deviation results in narrowing of the lower portion of the upper airway. The orthognathic surgical correction of mandibular deviation compensates to some extent for the reduction in the cross-sectional area and volume of the upper airway caused by the surgery itself. For patients with skeletal Class III high-angle malocclusion with mandibular deviation, a thorough assessment of the upper airway should precede the selection of orthognathic surgery procedures. For patients with normal preoperative upper airway morphology, consideration may prioritize correction of facial aesthetics and occlusion. For patients with pre-existing narrow upper airways, as mandibular setback exacerbates narrowing and the compensatory effect of mandibular deviation correction on the airway is limited, it is suggested that these patients prioritize bimaxillary surgery or reduce the amount of mandibular setback to better promote postoperative respiratory function health.

Does orthognathic surgery affect tooth root length and volume: a retrospective cohort study.

To examine tooth root length and root volume in cone beam computed tomography (CBCT) images in patients with skeletal Class II and III anomalies who have undergone single-jaw (SJ) and double-jaw (DJ) orthognathic surgery, and to compare the changes between jaws with and without osteotomy. This study was conducted on the archive records of a total of 60 adults: 36 women and 24 men with an average age of 21.1 ± 3.1 years, whose CBCT images were recorded just before orthognathic surgery and within 6-12 months after surgery. The sample was divided into four groups with 15 individuals in each: Class II SJ (mandibular advancement only), Class II DJ (maxillary advancement and impaction with mandibular advancement), Class III SJ (maxillary advancement and impaction), and Class III DJ (maxillary advancement and impaction with mandibular setback). Within groups, statistically significant decreases in root length and root volume were found in the period between preorthognatic and postorthognathic surgery (P < .05). No statistically significant differences were found in comparisons between groups (P > .05). Regardless of the type of skeletal anomaly in the sagittal direction and the orthognathic surgery performed, a statistically significant but clinically insignificant decrease was found in tooth root length and root volume during the postorthognathic surgery period, both in jaws with and without osteotomy.

The effects of mandibular setback surgery on the upper airway and sleep quality in skeletal Class III patients and comparison with control subjects: a pilot study.

The aim of this study was to determine the effects of mandibular setback surgery exceeding 5 mm on upper airway and sleep quality in skeletal Class III patients, with comparisons to Class I controls. Sixteen individuals per group were selected based on their ANB angle and surgical need. 2D and 3D airway analyses were conducted. Sleep quality was assessed using the Epworth Sleepiness Scale, the STOP-Bang questionnaire, and a sleep study. Following surgery, all of the skeletal Class III malocclusion patients transitioned to a Class I relationship. This transformation was accompanied by a significant reduction in pharyngeal airway space, minimum cross-sectional area (minCSA), and airway volume. Additionally, the mandibular plane to hyoid distance and airway length increased, and the total apnea-hypopnea index (AHI), obstructive AHI, and snoring levels were elevated. Compared to the control group, significant narrowing of the minCSA and reduction in airway volume, especially in the lower segment, were observed. However, no significant change in sleep quality was noted. In conclusion, the altered upper airway anatomy after mandibular setback surgery exceeding 5 mm in skeletal Class III patients was associated with an increase in AHI, but overall sleep quality was not altered compared to Class I subjects.

An overview of treatment strategies for class II and class III malocclusions

Class II and class III malocclusions represent common yet complex dental conditions that affect both aesthetics and function. Managing these malocclusions requires an approach tailored to the patient's growth stage, with early interventions focusing on growth modification and adult cases often necessitating surgical solutions. In class II malocclusions, growth modification with functional appliances such as the Twin Block and Herbst appliance promotes mandibular advancement and improves facial harmony in younger patients. For older individuals or those with more severe malocclusions, orthodontic camouflage or mandibular advancement surgery, including bilateral sagittal split osteotomy, is recommended to achieve a balanced occlusal relationship and improve facial proportions. Class III malocclusions, often involving a prognathic mandible or maxillary deficiency, are particularly challenging. For young patients, facemask therapy and rapid maxillary expansion can encourage maxillary growth, while chin cup therapy can control mandibular projection, aiming to improve skeletal balance. In severe adult cases, combined orthodontic-surgical treatments, such as maxillary advancement through Le Fort I osteotomy or mandibular setback procedures, provide durable, functionally stable outcomes. Surgical-orthodontic approaches, including bimaxillary surgery, are particularly advantageous for severe class III cases by effectively addressing the underlying skeletal imbalances and enhancing facial aesthetics. Growth modification techniques emphasize the importance of early diagnosis and intervention, aiming to harness natural growth potential and reduce the need for more invasive treatments later in life. For adult patients, surgical interventions present a definitive solution, delivering substantial improvements in function and appearance. Ongoing advances in both orthodontic and surgical techniques are refining the precision and stability of treatment outcomes, underscoring the need for individualized, age-appropriate strategies in managing class II and class III malocclusions.

Occlusal and Cephalometric Outcomes of Cleft Orthognathic Surgery: A Retrospective Cohort Study.

Aberrant facial growth in individuals affected by orofacial clefts can result in maxillary retrusion and class III malocclusion, with a proportion requiring surgical correction at cessation of growth. This study aimed to evaluate occlusal and cephalometric outcomes of combined orthodontic-orthognathic treatment. Retrospective cohort study in a United Kingdom cleft center. Participants included twenty-seven patients (20 males, 7 females) with cleft (n = 16 UCLP :7 BCLP :4 ICP) who consecutively underwent combined surgical treatment for Class III malocclusion between January 2013 and December 2017. Records were collected pre-treatment (T0), pre-surgery (T1) and at debond (T2). Models were scored using the Peer Assessment Rating (PAR) index and cephalometric radiographs were traced and analyzed. Outcomes were assessed by an independent rater. Mean age at surgery was 21.4 years (SD 4.9). Le Fort 1 advancement (mean 6.1 mm, SD 4.0) was performed in all cases. Additional procedures included mandibular setback (n = 2), cortico-cancellous bone grafting (n = 6) and genioplasty (n = 1). Mean T0 PAR score was 44.8 (SD 11.7), reducing to 3.6 (SD 2.0) at T2, indicating a mean % PAR score reduction of 91.6% (SD 4.7). Class III skeletal profiles improved from a mean T0 ANB of -2.1º (SD 2.2), to 2.8º (SD 1.6) at T2. Mean T0 overjet was -3.3 mm (SD 2.3), increasing to 2.6 mm (SD 1.3) at T2. Cleft orthognathic surgery differs in complexity and approach to routine orthognathics, however, these results demonstrate that occlusal outcomes can still be comparable with non-cleft populations. Outcome data can be used for comparison with other centers providing cleft orthognathic treatment.

Effect of transcutaneous electrical nerve stimulation on maximum mouth opening after orthognathic surgery: a randomised controlled trial.

The present study aims to determine the effect of transcutaneous electrical nerve stimulation (TENS) on maximum mouth opening (MMO) after orthognathic surgery. This study is a randomised clinical trial. The samples of this study were class III patients who are candidates for Le Fort I osteotomy surgery for maxillary advancement and bilateral sagittal split osteotomy (BSSO) for mandibular setback surgery due to the lack of maxilla growth and mandibular prognathism using the Dalpont method. On the day following surgery, the intervention group received TENS physiotherapy and instructions to take analgesics. In the control group, patients only received analgesics. MMO was measured in both groups using a digital caliper preoperatively, 1 month, and 6 months postoperatively. A total of 82 patients participated in this study, who were divided into two groups of 41, intervention and control. The difference in the mean MMO in different periods after surgery of the intervention group (F=59733.350, P<0.001) and the control group (F=32.480, P<0.001) was significant. The pattern of MMO increase over time was not the same in the two groups. There was a steeper slope in the increase of MMO in the intervention group than in the control group. It can be concluded from the results of this study, that the use of TENS after orthognathic surgery can be effective along with analgesics in reducing pain intensity and, subsequently, recovery in MMO in the short term.

Differential Relapse of Proximal and Distal Segments after Mandibular Setback Surgery

Differential Relapse of Proximal and Distal Segments after Mandibular Setback Surgery

The Stress Effects of Mandibular Movements on the Temporomandibular Joint With Sagittal Split Ramus Osteotomy.

The aim of this study was to evaluate the stress changes in the temporomandibular joint (TMJ) after sagittal split ramus osteotomy (SSRO) with finite element analysis (FEA). 5 and 10mm mandibular setback and advancement were applied to models by using SSRO and a control model without osteotomy evaluated. The articular disc was modeled as superelastic, and the stresses on the articular fossa, disc, and condyle were evaluated. The stresses on the cartilage were 1.150 MPa on the 5mm advancement model and 1.506 MPa on the 10mm advancement model. The stresses on the disc were 11.56 MPa on the 5mm advancement model, 7.94 MPa on the 10mm advancement model and the amount were significantly higher than other models. The stress, especially in the cartilage, increased with the amount of advancement. In the setback models, the stresses on the condylar cartilage and the disc were higher than in the control model, and the stress in the condylar cartilage increased with the amount of setback. SSRO increases the stresses in the TMJ components and stresses increase depending on the amount of advancement and setback and may cause the development of joint problems.

Efficacy of the Coronoid Notch and Occlusal Plane As Predictable Landmarks for Determining the Medial Cut Height in Bilateral Sagittal Split Osteotomy: A Split-Mouth Observational Study.

This split-mouth observational study was conducted to assess the reliability and safety of using the coronoid notch and occlusal plane as landmarks to aid surgeons during bilateral sagittal split osteotomy(BSSO). Thirteen patients between the ages of 18 and 30 years, with class II and class III mandibular skeletal malocclusion requiring BSSO, were randomly selected and assigned to each of the study and control groups. A split-mouth study was chosen to conduct this research. Cone beam computed tomography (CBCT) imaging was conducted before the surgery to evaluate the anatomical structure, and three predefined points were marked at the superiormost point of the mandibular foramen, the inferiormost point of the mandibular foramen, and the deepest point of the sigmoid notch. A conventional sagittal split osteotomy was carried out in the control group. Preoperative values were obtained in the study group using the CBCT imaging technique by drawing an imaginary line from the inferiormost part of the mandibular foramen to the line corresponding to the occlusal plane that extended beyond the last molar. The lingual flap reflection was restricted to the internal oblique ridge. The posterior border of the mandible was not reflected. The measurements acquired via CBCT imaging were accurately transferred to the intraoperative surgical site using a vernier caliper. This facilitated the precise completion of the horizontal osteotomy, ascending ramus cuts, and vertical osteotomies. BSSO was performed, the mandibular setback or advancement was done with intermaxillary fixation, and the procedure was completed by rigid fixation. Types of lingual splits, types of lateral bone cut ends (LBCEs), any unfavorable split, and the time taken for the surgery (in minutes) were assessed. The surgery time in the control group (20.1538 ± 2.85325 min) was found to be higher than that in the study group (17.6154 ± 3.59487 min), with a p-value of 0.02. No significant differences were observed when assessing the presence of unfavorable splits in both groups (p = 0.500). Buccal LBCEs were the most prevalent, followed by inferior types. Type I lingual split was the most common in the study group (70%). This technique offers a dependable anatomical reference and significantly reduces surgical time for beginners. Additionally, the patterns of the lingual split were correlated with the types of lateral bone cut ends.

Does mandible ramus height asymmetry affect postoperative skeletal stability in orthognathic surgery patients?

BackgroundRelapses following orthognathic surgery have been reported to exceed 2% to 50%, depending on multiple factors. This study aimed to analyze the stability after orthognathic surgery in patients with mandibular ramus height asymmetry through 3D reconstruction using Cone-beam CT.MethodsThis retrospective cohort study investigated patients who underwent mandibular setback surgery using bilateral sagittal split ramus osteotomy. Three-dimensional CT scans were taken at three different time points. Evaluation of the postoperative stability involved measuring changes in the x, y, and z axes as well as roll and yaw rotations of the mandible at specific landmarks (B point, mental foramen) on 3D CT scans obtained immediately after surgery and 6–12 months postoperatively. They were categorized into four groups based on bilateral mandibular height asymmetry through Asymmetry index (AI). The one-way ANOVA was implemented to compare the intergroup differences and Tukey's post hoc test was employed. Additionally, the Pearson correlation coefficient was also calculated.ResultsA total of 24 patients were included in this study. The corresponding AI, representing the degree of asymmetry in both mandibles, were calculated as Group 1 was 1.25 ± 0.64%, Group 2 was 2.89 ± 0.47%, Group 3 was 5.03 ± 0.51%, and Group 4 was 9.40 ± 1.99%. The x-axis change in Group 4 was significantly larger at 1.71 mm compared to Group 1 at 0.64 mm. The mandibular roll, Group 4 showed a statistically significant increase at 1.33° compared to Group 1 at 0.35°. And there was a significant positive correlation observed between x-axis change and AI (p = 0.019), as well as between mandibular roll and AI (p = 0.025).ConclusionAfter orthognathic surgery, stability was influenced by numerous factors, with the findings of this study suggesting that the degree of ramus height asymmetry in the mandible can be considered one contributing factor.

Evaluation of Minimum Axial Airway Area and Airway Volume in Orthognathic Surgery Patients.

The aim of this study was to compare preoperative and postoperative linear, planar, and volumetric measurements in the pharyngeal airway in orthognathic surgery patients. Preoperative and postoperative cone beam computed tomography (CBCT) images of 60 patients, who underwent maxillary advancement with mandibular setback (Group I, n=25) and bimaxillary advancement (Group II, n=35), were compared. The airway was divided into 3 regions as nasopharynx, oropharynx, and hypopharynx. Linear and planar measurements were made on the reference sections of each region. The minimum axial airway area, the volume of 3 regions, and total airway volume were also measured. Regarding the linear, planar, and volumetric measurements, while there was a statistically significant increase in the measurements for all three regions in Group II, in Group I only the measurements in the nasopharyngeal region demonstrated a statistically significant increase postoperatively ( P <0.05). There was an increase in minimum axial airway areas in both groups; however, it was only statistically significant in Group II ( P <0.05). There was a statistically significant increase in total airway volumes in both groups ( P <0.05). A positive and good correlation was found between the percent increase in the minimum axial area and the percent increase in the total volume ( P <0.05). While bimaxillary advancement surgery results in a significant increase in the pharyngeal airway, mandibular setback with maxillary advancement caused an increase in the total airway. Changes that may occur in the airway should be considered while planning orthognathic surgery.

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.

Three-dimensional changes in the soft tissue chin after mandibular setback surgery in adult Japanese patients with skeletal class III malocclusion

ABSTRACT Purpose The purpose of the present study is to improve the quality of prediction of soft tissue morphology by clarifying the relationship between the amount of three-dimensional (3-D) changes of hard tissue and the morphological differences of the soft tissue chin before and after orthognathic surgery in skeletal class III malocclusion. Materials and methods Preoperative and six-month postoperative CT was used to analyze the changes in 26 adult Japanese skeletal class III patients. The mean age was 25.5 years. Lateral cephalograms were analyzed to evaluate the initial antero-posterior jaw relationship and the changes before and after treatment. Three-D masks and bone structures were reconstructed using 3-D modelling software, and the final chin models were defined for further analysis following voxel-based registration. Correlation and linear regression analyses were performed to clarify the relationship between the movement of the soft tissue chin and the underlying bone. Results The soft tissue chin volume and surface area significantly increased after surgery. The thickness of the chin significantly increased only at pogonion and menton after surgery. Furthermore, a statistically significant correlation between the movement of soft tissue chin and underlying bone was found. Consequently, the regression model predicted the changes in soft tissue chin from the movement of the underlying bone. Conclusion Three-D analysis of the soft tissue chin revealed a significant change in response to surgical orthodontic treatment in skeletal class III adult patients, and soft tissue chin movement could be predicted by using 3-D CT data when planning orthognathic treatment.

Effects of orthognathic surgery on respiratory function during sleep: A prospective longitudinal study.

When treating patients with orthognathic surgery, there might be a risk of obstructive sleep apnoea (OSA) due to soft tissue changes in the upper airways, especially in patients treated with isolated mandibular setback or mandibular setback in combination with maxillary advancement. In the present study, we assessed respiratory function during sleep with home cardiorespiratory polygraphy in 62 patients who had not been previously been diagnosed with OSA at three times: prior to orthognathic surgery for aesthetic and functional indications, and then 3 months and 1 year after surgery. We evaluated surgical displacement based on measurements in three dimensions using pre- and post-operative computed tomography. There were only minor changes in the respiratory parameters such as the apnoea-hypopnoea index (AHI), the apnoea-hypopnoea index in the supine position (AHIsup), the oxygen saturation index (ODI) and the snore index. There was no significant correlation between surgical displacement and the AHI, AHIsup and ODI. There was a weak but significant correlation between vertical displacement of the anterior mandible and the snore index. Within the limitations of the present study, the risk for iatrogenic obstruction of the upper airways seems to be low in patients without OSA treated with orthognathic surgery.

Hard to Soft Tissue Profile Changes in Skeletal Class III Dentofacial Deformities After Maxillary Advancement and Mandibular Setback Orthognathic Surgery

Objective To correlate the sagittal hard tissue movement and soft tissue changes among patients with skeletal class III malocclusion following bimaxillary orthognathic surgery. Material and Methods Fifty-nine subjects with skeletal class III malocclusion treated consecutively with maxillary advancement and mandibular setback were assessed for skeletal and soft tissue linear changes using presurgical (T1) and post-treatment (T2) lateral cephalograms. Pearson’s correlation coefficient test was used to correlate hard and soft tissue parameters. Results The sagittal hard tissue movement and soft tissue changes for all the parameters assessed in maxilla and mandible showed statistically significant correlations. The ratios of changes for the maxillary protrusion [N-A (HP)] to horizontal subnasale (Sn), superior labial sulcus (Sls), and labrale superioris (Ls) were 0.574:1, 0.703:1, and 0.721:1 respectively. The ratio of horizontal labrale inferioris (Li), mentolabial fold (Mlf), and soft tissue (Pg′) to mandibular protrusion [N-B (HP)] were 0.992:1, 0.970:1, and 0.590:1 respectively and to chin protrusion [N-Pg (HP)] were 1.293:1, 1.252:1, and 1.001:1, respectively. The ratios were different for males and females in maxilla and mandible. Conclusion Sagittal hard tissue movement and soft tissue changes are significantly correlated. The soft tissue movement in the mandible were more proportionate compared to the maxilla. The sagittal hard tissue to soft tissues movement ratios were greater in maxilla and lesser at pogonion and mentolabial sulcus in females compared to males. The ratios obtained can be used for predicting postsurgical soft tissue changes.

Three-Dimensional Changes of Condylar Position After Bimaxillary Surgery to Correct Skeletal III Malocclusion: Cone Beam Computed Tomography Voxel-Based Superimposition Analysis

BackgroundThe stability of the condylar position within the first three months after orthognathic surgery in patients with skeletal Class III malocclusion is crucial for subsequent orthodontic treatment. PurposeThe purpose was to compare condylar positional changes three months after bimaxillary surgery to correct skeletal Class III deformities, utilizing the conventional two-dimensional (2D) combined with the cone beam computed tomography (CBCT) voxel-based superimposition analysis. Study design, setting, sampleThis retrospective cohort study included skeletal Class III patients undergoing bimaxillary orthognathic surgery at Khon Kaen University, Thailand in 2020. Exclusion criteria were patients with temporomandibular disorder (TMD) symptoms, facial asymmetry prior to the surgery, or surgical complications. Exposure variableThe exposure variable was the timing, both preoperatively and 3 months postoperatively. This 3-month postoperative time point was chosen because complete healing of the bimaxillary surgery is expected by then, without any potential influence of condylar changes resulting from subsequent orthodontic treatment. Main outcome variablesThe outcome variable is condylar position measurement, joint space (mm) and axial condylar angle (degrees). CovariatesDemographics (age, sex), and surgical details (direction and amount of movement) were collected as covariates. AnalysesStatistical analysis of condylar positional changes and correlations was performed using paired t-test and linear correlation (P-value < 0.05), respectively. ResultsThe sample included 11 subjects (22 condyles), with a mean age of 24±5.24 years. Both 2D measurements and voxel-based 3D superimposition showed significant changes in condylar position three months after bimaxillary surgery: inferior (0.45±0.26 mm, P < 0.001), posterior (0.46±0.39 mm, P = 0.003), lateral (0.38±0.42 mm, P = 0.01) displacement, and inward rotation (5.21±2.54°, P < 0.001). No significant correlation was found between jaw movement distance and condylar changes. Conclusions and relevanceTo our knowledge, this is the first study to report measures of condylar changes at 3 months, when complete healing of the osteotomies would be expected, using Le Fort I osteotomy for maxillary advancement combined with bilateral sagittal split ramus osteotomy (BSSRO) for mandibular setback. These changes are small in magnitude and may be of little relevance to patient care.

“The impact of orthognathic surgery on articulation proficiency and speech intelligibility in skeletal Class III malocclusion: 18 months follow up”

IntroductionOrthognathic surgery results in the positional change of the maxilla and mandible that may affect speech. The present study evaluated the effect of combined maxillary advancement and mandibular setback surgery on articulation proficiency and speech intelligibility in patients with non-syndromic skeletal Class III malocclusion. MethodsIn this prospective study, twenty-five patients with skeletal class III malocclusion and consecutively treated with Lefort-1 maxillary advancement and mandibular setback (BSSO) orthognathic surgery were included in this study. The speech sample was recorded with a digital audio tape recorder one day before surgery and at 3, 6, 9, 12 and 18 months after surgery. Three qualified and experienced speech and language pathologists evaluated articulation errors and intelligibility of speech samples. Repeated One-way analysis of variance was used to compare articulation proficiency and speech intelligibility at different time intervals. ResultsThe substitution, omission, distortion and addition errors showed no significant changes at 3 months and 6 months. The total articulation errors decreased to zero at 9 months and no significant increase was observed till 18 months (P < 0.05). Speech intelligibility showed statistically non-significant improvement at any time interval. Cephalometric skeletal parameters SNA and N ḻ A°. were significantly correlated with addition and total articulation errors at 18 months follow up. ConclusionsThe ortho-surgical treatment improves speech (decreases. articulation errors) in most of the patients usually 6–9 months post-surgery. Speech intelligibility is not affected by bimaxillary orthognathic surgery in skeletal class III patients. The articulation errors were correlated to changes in position of maxilla.

Assessment of Masseter Volume and Postoperative Stability After Orthognathic Surgery in Patients With Skeletal Class III Malocclusion With Facial Asymmetry.

This study aimed to evaluate the effect of orthognathic surgery on masseter volume in patients with skeletal Class III malocclusion with facial asymmetry and the effect of masseter volume on stability in orthognathic surgery. This research studied 16 patients with Class III malocclusion with facial asymmetry who received combined orthodontic-orthognathic treatment and underwent craniofacial computed tomography (CT) before (T0), 2 weeks after (T1), and 6 months after (T2) surgery. Three-dimensional (3D) CT images were retrospectively analyzed, using 3D volume reconstruction to obtain the masseter volume and examine the impact of the masseter volume on stability in orthognathic surgery. A statistically significant difference ( P < 0.05) in the volume of the masseter was found up to 6 months after orthognathic surgery compared with the preoperative period, and the reduction in the masticatory muscle volume on the lengthened side is greater than on the shortened side ( P < 0.05). The volume of both masseters differed according to facial asymmetry, and the difference was significantly reduced after orthognathic surgery ( P < 0.05). During the period time (T1-T2), cephalometric maxillary marker points were not significantly different ( P > 0.05), and mandibular marker points were significantly anteriorly shifted ( P < 0.05). There was an association between the masseter volume and anterior shift of point B (R > 0.5, P < 0.05), the upward and anterior shifts of the gonion point differed between the lengthened and shortened sides ( P < 0.05). The size of the masseter becomes smaller 6 months after orthognathic surgery, and orthognathic surgery improves both bone and soft tissue symmetry. A larger sagittal relapse of mandibular setback occurred in patients with greater masseter volume. Considering these alterations may be helpful in planning orthognathic surgery.

Impacts of mandibular setback with or without maxillary advancement for class III skeletal correction on sleep-related respiratory parameters: A systematic review and meta-analysis.

A systematic review and meta-analysis was conducted to evaluate the impacts of mandibular setback with or without maxillary advancement for class III skeletal correction on respiratory parameters measured by polysomnography (PSG) and to compare these respiratory parameters between these procedures for class III skeletal correction. Six electronic databases were searched up to June 2023. Studies comparing PSG parameters before and after orthognathic surgery for skeletal class III patients were selected for further analysis. The outcomes of interest were apnoea-hypopnea index (AHI), respiratory disturbance index (RDI), the lowest oxygen saturation (lowest SpO2), the average oxygen saturation (mean SpO2), and the 3% oxygen desaturation index (3% ODI). Data extraction, methodological quality assessment, risk of bias assessment, meta-analysis, and subgroup analysis were performed. Sixteen studies with a total of 476 patients who underwent orthognathic surgery for class III skeletal correction were included for meta-analysis. The risk of bias level was moderate for most studies. All PSG parameters before and after orthognathic surgery were not significantly different. The different surgical procedures also did not significantly affect post-operative PSG parameters. 5.8% of patients developed post-operative obstructive sleep apnoea (OSA). Most of them underwent a large distance of mandibular setback. There is a moderate level of evidence that mandibular setback with or without maxillary advancement for class III skeletal correction does not pre-dispose young and healthy patients to obstructive sleep apnoea when evaluated in the short term after surgery. However, post-operatively developed OSA was found in several isolated cases that underwent a large amount of mandibular setback with or without maxillary advancement.