Temporomandibular joint function 10-15 years after mandibular setback surgery and six weeks of intermaxillary fixation

Abstract Intermaxillary fixation (IMF) is a classic method for immobilization of the mandible after mandibular fractures and corrective surgery. However, it has been suggested that IMF may be a risk for developing temporomandibular joint (TMJ)-related symptoms, especially when applied for longer periods. Objective: To evaluate the clinical function of TMJs and masticatory muscles 10-15 years after mandibular setback surgery and subsequent six weeks of IMF. The patients' self-reported TMJ and masticatory muscle symptoms were also addressed. Methodology: Thirty-six patients (24 women and 12 men) treated with intraoral vertical ramus osteotomies and subsequent six weeks of IMF, underwent a clinical examination of TMJs and masticatory muscles 10-15 years after surgery and completed a five-item structured questionnaire reporting subjective TMJ-related symptoms. Mean age by the time of clinical examination was 34.1 years (range 27.2-59.8 years). The clinical outcome was registered according to the Helkimo clinical dysfunction index. Descriptive and bivariate statistics were performed and level of significance was set to 5%. Results: Mean maximum unassisted mouth opening 10-15 years after surgery was 50.1 mm, (range 38-70 mm, SE 1.2), statistically significantly greater in men compared to women (p=0.004). Mean Helkimo dysfunction group was 1.5 (range 1-3, SE 0.10). Eighty-one percent experienced pain on palpation in either the masseter muscle, temporal muscle or both, and 31% experienced pain when moving the mandible in one or more directions. Thirty-one percent reported pain from palpating the TMJs. In the questionnaire, none reported to have pain during chewing or mouth opening on a weekly or daily basis, but 22% reported difficulties with maximum opening of the mouth. Conclusion: Ten to fifteen years after mandibular setback surgery the patient's mandibular range of movement is good. Despite clinically recognizable symptoms, few patients reported having TMJ- or masticatory muscle-related symptoms in their daily life.

Three-dimensional analysis of changes in airway space after bimaxillary orthognathic surgery with maxillomandibular setback and their association with obstructive sleep apnea / 대한악안면성형재건외과학회지

BACKGROUND: Bimaxillary orthognathic surgery with maxillomandibular setback is often accompanied by changes in airway space. We analyzed the changes in airway space before and after surgery and assessed their association with obstructive sleep apnea. METHODS: This study is based on the cohort of 13 adult patients (9 males, 4 females, average age 23.85 years) who underwent bimaxillary orthognathic surgery with maxillomandibular setback. We performed computed tomography and portable polysomnography before and after the surgery to assess changes in airway space and Apnea-Hypopnea Index (AHI) values (total, supine, non-supine). RESULTS: The oropharyngeal airway volume decreased by 29% after the surgery, which was statistically significant (p < .05). The upper airway volume and hypopharyngeal airway volume were decreased, but not significantly (4 and 19%, respectively). The changes in airway surface area were statistically significant at all levels examined (p < .05). Changes in the maximum anteroposterior width of the airway were also significant at all levels (p < .05). However, the changes in maximum lateral width were only statistically significant at C2 level (p < .05). AHI values were increased after the surgery but not significantly at any position. CONCLUSIONS: Although bimaxillary surgery with maxillomandibular setback significantly reduces the airway space, it does not affect AHI values or induce obstructive sleep apnea.

Effects of bodily retraction of mandibular incisors versus mandibular setback surgery on pharyngeal airway space: A comparative study / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare the changes induced in the pharyngeal airway space by orthodontic treatment with bodily retraction of the mandibular incisors and mandibular setback surgery without extraction. METHODS: This retrospective study included 63 adult patients (32 men and 31 women). Thirty-three patients who had been treated via four-bicuspid extraction and bodily retraction of the mandibular incisors (incisor retraction, IR group) were compared with 30 patients who had been treated via mandibular setback surgery (MS group) without extraction. Lateral cephalograms were acquired and analyzed before (T1) and after treatment (T2). RESULTS: The superior pharyngeal airway space did not change significantly in either group during treatment. The middle pharyngeal airway space decreased by 1.15 ± 1.17 mm and 1.25 ± 1.35 mm after treatment in the IR and MS groups, respectively, and the decrease was comparable between the two groups. In the MS group, the inferior pharyngeal airway space (E-IPW) decreased by 0.88 ± 1.67 mm after treatment (p < 0.01). The E-IPW was larger in the MS group than in IR group at T1, but it did not differ significantly between the two groups at T2. No significant correlation was observed between changes in the pharyngeal airway space and the skeletal and dental variables in each group. CONCLUSIONS: The middle pharyngeal airway space decreased because of the posterior displacement of the mandibular incisors and/or the mandibular body. The E-IPW decreased only in the MS group because of the posterior displacement of only the mandibular body.

Tonsillectomy as prevention and treatment of sleep-disordered breathing: a report of 23 cases / 대한악안면성형재건외과학회지

BACKGROUND: The paradigm of tonsillectomy has shifted from a treatment of recurrent throat infection to one of multi-discipline management modalities of sleep-disordered breathing (SDB). While tonsillectomy as a treatment for throat problems has been performed almost exclusively by otorhinolaryngologists, tonsillectomy as a part of the armamentarium for the multifactorial, multidisciplinary therapy of sleep-disordered breathing needs a new introduction to those involved in treating SDB patients. This study has its purpose in sharing a series of tonsillectomies performed at the Seoul National University Dental Hospital for the treatment and prevention of SDB in adult patients. METHODS: Total of 78 patients underwent tonsillectomy at the Seoul National University Dental Hospital from 1996 to 2015, and 23 of them who were operated by a single surgeon (Prof. Jin-Young Choi) were included in the study. Through retrospective chart review, the purpose of tonsillectomy, concomitant procedures, grade of tonsillar hypertrophy, surgical outcome, and complications were evaluated. RESULTS: Twenty-one patients diagnosed with SDB received multiple surgical procedures (uvulopalatal flap, uvulopalatopharyngoplasty, genioglossus advancement genioplasty, tongue base reduction, etc.) along with tonsillectomy. Two patients received mandibular setback orthognathic surgery with concomitant tonsillectomy in anticipation of postoperative airway compromise. All patients showed improvement in symptoms such as snoring and apneic events during sleep. CONCLUSIONS: When only throat infections were considered, tonsillectomy was a procedure rather unfamiliar to oral and maxillofacial surgeons. With a shift of primary indication from recurrent throat infections to SDB and emerging technological and procedural breakthroughs, simpler and safer tonsillectomy has become a major tool in the multidisciplinary treatment modality for SDB.

Changes of lip morphology following mandibular setback surgery using 3D cone-beam computed tomography images / 대한악안면성형재건외과학회지

BACKGROUND: The aims of this study are to evaluate the lip morphology and change of lip commissure after mandibular setback surgery (MSS) for class III patients and analyze association between the amount of mandibular setback and change of lip morphology. METHODS: The samples consisted of 14 class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalogram and cone-beam CT were taken before and about 6 months after MSS. Changes in landmarks and variables were measured with 3D software program Ondemand™. Paired and independent t tests were performed for statistical analysis. RESULTS: Landmarks in the mouth corner (cheilion, Ch) moved backward and downward (p .05, p < .005). On lateral view, upper lip prominent point (UP) moved downward and stomion moved backward and upward and the angle of Ls-UP-Stm (°) was decreased. Lower lip prominent point (LP) moved backward and downward, and the angle of Stm-LP-Li (°) was increased. Li moved backward. Finally, landmarks in the lower incisor tip (L1) moved backward and upward, but stomion moved downward. After surgery, lower incisor tip (L1) was positioned more superiorly than stomion (p < .05). There were significant associations between horizontal soft tissue and corresponding hard tissue. The posterior movement of L1 was related to statistically significantly about backward and downward movement of cheilion. CONCLUSIONS: The lip morphology of patients with dento-skeletal class III malocclusion shows a significant improvement after orthognathic surgery. Three-dimensional lip morphology changes in class III patients after MSS exhibited that cheilion moved backward and downward, upper lip projection angle became acute, lower lip projection angle became obtuse, change of upper lip area on lateral view was increased, change of lower lip area decreased, and morphology of lower lip was protruding. L1 was concerned with the lip tissue change in statistically significant way.

Retrospective study of changes in pharyngeal airway space and position of hyoid bone after mandibular setback surgery by cephalometric analysis / 대한악안면성형재건외과학회지

BACKGROUND: The posterior movement of mandible was known as the main cause of the changes in the pharyngeal airway space (PAS) and the postoperative obstructive sleep apnea (OSA). The purpose of this study was to know the changes of PAS and position of hyoid bone. METHODS: Lateral cephalographies of 13 patients who had undergone sagittal split ramus osteotomy (SSRO) setback surgery were taken preoperatively (T1), postoperatively within 2 months (T2), and follow-up after 6 months or more (T3). On the basis of F-H plane, diameters of nasopharynx, oropharynx, and hypopharynx were measured. The movements of the soft palate, tongue, and hyoid bone were also measured. RESULTS: The amount of mandible setback was 7.5 +/- 3.8 mm. In the measurements of PAS, there was a statistically significant decrease of 2.8 +/- 2.5 mm in nasopharynx (P < 0.01), and 1.7 +/- 2.4 mm in oropharynx (P < 0.01) were observed after surgery. The hypopharynx decreased 1.0 +/- 2.1 mm after surgery and continuously decreased 1.0 +/- 2.8 mm at follow-up. The changes in hyoid bone position showed the posterior movement only after surgery and posteroinferior movement at follow-up. CONCLUSIONS: The PAS such as nasopharynx, oropharynx, and hypopharynx showed relatively high correlation with the amount of mandibular setback. The change of resistance in upper airway may be important for the prevention of OSA after mandibular setback surgery.

Retrospective study on change in pharyngeal airway space and hyoid bone position after mandibular setback surgery

OBJECTIVES: The purpose of this study was to evaluate changes in the pharyngeal airway space and hyoid bone position after mandibular setback surgery with bilateral sagittal split ramus osteotomy (BSSRO) and to analyze the correlation between the amount of mandibular setback and the amount of change in pharyngeal airway space or hyoid bone position. MATERIALS AND METHODS: From January 2010 to February 2013, a total of 30 patients who were diagnosed with skeletal class III malocclusion and underwent the same surgery (BSSRO) and fixation method in the Division of Oral and Maxillofacial Surgery, Department of Dentistry at the Ajou University School of Medicine (Suwon, Korea) were included in this study. Lateral cephalograms of the 30 patients were assessed preoperatively (T1), immediately postoperatively (T2), and 6 months postoperatively (T3) to investigate the significance of changes by time and the correlation between the amount of mandibular setback and the amount of change in the airway space and hyoid bone position. RESULTS: Three regions of the nasopharynx, oropharynx, and hypopharynx were measured and only the oropharynx showed a statistically significant decrease (P<0.01). A significant posterior and inferior displacement of the hyoid bone was found 6 months after surgery (P<0.01). Analysis of the correlation between the amount of mandibular setback and the amount of final change in the airway space and hyoid bone position with Pearson's correlation showed no significant correlation. CONCLUSION: In this study, the oropharynx significantly decreased after mandibular setback surgery, and changes in the surrounding structures were identified through posteroinferior movement of the hyoid bone during long-term follow-up. Therefore, postoperative obstructive sleep apnea should be considered in patients who plan to undergo mandibular setback surgery, and necessary modifications to the treatment plan should also be considered.

Use of mini-implants to avoid maxillary surgery for Class III mandibular prognathic patient: a long-term post-retention case / 대한치과교정학회지

Because of the potential morbidity and complications associated with surgical procedures, limiting the extent of orthognathic surgery is a desire for many orthodontic patients. An eighteen-year-old woman had a severe Class III malocclusion and required bi-maxillary surgery. By changing the patient's maxillary occlusal plane using orthodontic mini-implants, she was able to avoid the maxillary surgery; requiring only a mandibular setback surgery. To accurately predict the post-surgery outcome, we applied a new soft tissue prediction method. We were able to follow and report the long-term result of her combined orthodontic and orthognathic treatment. The changes to her occlusal plane continue to appear stable over 6 years later.

Análise cefalométrica das vias aéreas superiores de pacientes Classe III submetidos a tratamento ortocirúrgico / Cephalometric analysis of the upper airways of Class III patients subjected to orthosurgical treatment

OBJETIVO: o objetivo deste estudo foi avaliar as alterações causadas por cirurgia ortognática de recuo mandibular associada ou não à cirurgia maxilar combinada nas vias aéreas superiores (VAS). MÉTODOS: foram avaliadas radiografias cefalométricas de perfil pré-cirúrgicas e pós-cirúrgicas imediatas de 17 pacientes com Classe III. Foram realizadas medições do diâmetro do espaço aéreo (EA) no plano sagital, nas regiões correspondentes à hipofaringe e à orofaringe; também foram registradas as alterações na posição do osso hioide. Utilizou-se o teste t pareado e o coeficiente Pearson, buscando possíveis associações entre as alterações esqueléticas e as ocorridas no EA. RESULTADOS: observou-se redução significativa do EA na região da hipofaringe (média de 3,10mm, p=0,024). O osso hioide sofreu deslocamento inferior e posterior, além de diminuição da distância entre o mesmo e a região anterior da mandíbula. Não foi possível correlacionar, quantitativamente, a redução anteroposterior do EA com o recuo mandibular. Entretanto, observou-se correlação forte entre o diâmetro inicial do EA e a quantidade de redução observada ao nível da hipofaringe, e moderada em relação à orofaringe. CONCLUSÕES: o recuo mandibular pode causar estreitamento significativo das VAS, principalmente na porção mais inferior (hipofaringe). Portanto, deve-se atentar para sua avaliação durante o plano de tratamento ortocirúrgico, já que não foram descartados possíveis efeitos deletérios dessas alterações nas funções do indivíduo.

OBJECTIVE: The aim of this study was to evaluate the effects of orthognathic surgery for mandibular setback - with and without combined maxillary surgery - on the upper airways (UA).METHODS: Immediate lateral preoperative and postoperative cephalometric radiographs of 17 Class III patients were evaluated. Measurements of airway space (AS) diameter were taken in the sagittal plane in the hypopharyngeal and oropharyngeal regions, and changes in hyoid bone position were also recorded. Paired t-test and Pearson's coefficient were applied seeking for potential associations between skeletal and AS changes.RESULTS: Significant AS reduction was noted in the hypopharyngeal region (mean= 3.10 mm, p= 0.024). The hyoid bone was displaced inferiorly and posteriorly, thereby reducing its distance to the anterior mandibular region. No quantitative correlation could be established between anteroposterior AS reduction and mandibular setback. However, there was a strong correlation between initial AS diameter and the amount of reduction observed in the hypopharynx, but only moderate correlation with the oropharynx.CONCLUSIONS: Mandibular setback can cause significant UA narrowing, especially in the inferior-most portion (hypopharynx). Therefore, special attention should be given to UA evaluation when formulating an orthosurgical treatment plan since the potential deleterious effects of these changes on functions of the patients should not be overlooked.

Changes of Pharyngeal Airway Space after Mandibular Setback Surgery in Computed Tomography Images

Clinical analysis of early reoperation cases after orthognathic surgery

The factors influencing the relapse and recurrence of skeletal deformity after the orthognathic surgery include various factors such as condylar deviation, the amount of mandibular set-back, stretching force by the soft tissues and muscles around the facial skeleton. The purpose of this report is to recognize and analyze the possible factors of reoperation after orthognathic surgery, due to early relapses. Six patients underwent reoperation after the orthognathic surgeries out of 110 patients from 2006 to 2009 were included in this study. In most cases, clincal signs of the insufficient occlusal stability, anterior open bite, and unilateral shifting of the mandible were founded within 2 weeks postoperatively. Although elastic traction was initiated in every case, inadequate correction made reoperation for these cases inevitable. The chief complaints of five cases were the protruded mandible combined with some degree of asymmetric face and in the other one case, it was asymmetric face only. Various factors were considered as a major cause of post-operative instability such as condylar sagging, counter-clockwise rotation of the mandibular segment, soft tissue tension related with asymmetrical mandibular set-back, preoperatively existing temporomandibular disorder (TMD), poor fabrication of the final wafer, and dual bite tendency of the patients.

Analysis of masseter muscle in facial asymmetry before and after orthognathic surgery using 3-dimensional computed tomography / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to understand the differences in masseter muscle (MM) between the shifted and non-shifted sides in facial asymmetry patients, and the changes shown by MM after mandibular surgery. METHODS: Pre- and post-operative CT scans were performed on 12 Class III patients with facial asymmetry who were treated by intraoral vertical ramus osteotomy and 10 subjects with normal occlusion. Using the V-works 4.0 program (Cybermed, Seoul, Korea), 3-dimensional images of the mandible, and MM were reconstructed, and evaluated. RESULTS: In the asymmetry group, the MM angle between the shifted and non-shifted sides was only significantly different (p < 0.05). Compared with normal occlusion, the asymmetry group showed a significantly smaller volume and maximum cross-sectional area in both sides of MM (p < 0.05). After mandibular surgery, the angle of MM (p < 0.01) and differences in angle between the shifted and non-shifted sides of MM (p < 0.05) were significantly decreased. The thickness in the maximum cross-sectional area was significantly increased (p < 0.01). After surgery, MM in facial asymmetry patients was similarly changed to those in the normal occlusion group except for widths. CONCLUSIONS: MM in facial asymmetry was definitely different from those in normal occlusion. However, this study suggests that MM changed symmetrically in conjunction with the mandible after proper mandibular surgery.

Changes in hyoid bone and tongue positions, and oral cavity volume after mandibular setback by sagittal split ramus osteotomy

Changes of transverse mandibular width after intraoral vertical ramus osteotomy

PURPOSE: In order to clarify the correlation of mandibular setback using bilateral intraoral vertical ramus osteotomy (BIVRO) and post-surgical transverse mandibular width (TMW), this study examined the pre- and postsurgical changes in hard and soft tissues of TMW and the relationship of TMW and the amount of mandibular setback. PATIENTS AND METHODS: One-hundred seven patients who had undergone BIVRO were evaluated radiographically and clinically. A comparison study of the changes in hard and soft tissue after surgery in all 107 patients was performed with preoperative, 1 month, 3 month, 6 month and 1 year postoperative posteroanterio cephalograms and clinical photographs by tracing. And this changes were evaluated in parts to amounts of mandibular setback. RESULTS: Statistically significant increases of TMW in hard and soft tissue from preoperative to postoperative 1 month were seen. TMW in hard tissue from 1 month to 1 year postopertive were gradually decreased. TMW in soft tissue was not changed uniformly but almost equal to pre-operative width. And there was no significant correlation between TMW and amount of mandibular setback. CONCLUSIONS: The results show that mandibular setback using BIVRO did not significantly influence increasing of TMW in soft tissue.

A study of bone resorption at the posterior border of distal segment after bilateral sagittal split ramus osteotomy of manibular prognathic patients

PURPOSE: This study is to predict the changes of the distal segment by investing the resorption of the excessive distal segment regarding the amount of setback after BSSRO. MATERIAL AND METHODS: 20 patients with Mandible prognathism treated by Obwegeser-Dal Pont method during the years 2000 to 2002 were selected for this study. Group A consisted of 5 males and 5 females with a setback amount of 10mm and above(Mean 10.80mm+/-1.03, n=20) and Group B consisted of 2 males and 8 females with a setback amount of below 10mm.(Mean 6.10mm+/-1.10, n=20) Panorama X-ray was taken at day 1, 1month, 3months, 6months, and 12months after the surgery. Resorption areas of excessive distal segment were measured on these panorama X-rays and compared. RESULTS: There was bone resorption in both groups. Group A showed more bone resorption than Group B. Group B showed slightly higher resorption rate than Group A. However, there was no statistically significant difference between the resorption rates of Group A and Group B. (P>0.05) CONCLUSION: More bone resorption occurred with a larger amount of setback and about one third of the excessive distal segment underwent resorption, irrespective of the amount of setback.

Accuracy of soft tissue profile change prediction in mandibular set-back surgery patients: a comparison of Quick Ceph Image Pro(TM) (ver 3.0) and V-Ceph(TM) (ver 3.5) / 대한치과교정학회지

The purpose of this study was to test and compare the accuracy and reliability of soft tissue profile predictions generated from two computer software programs (Quick Ceph Image Pro(TM) (ver 3.0) and V-Ceph(TM) (ver 3.5)) for mandibular set-back surgery. The presurgical and postsurgical lateral cephalograms of 40 patients (20 males and 20 females) were traced on the same acetate paper with the reference taken as the cranial base outline. The presurgical skeletal outlines were digitized onto each computer program and the mandible was moved to mimic the expected surgical procedure with reference to the mandibular anterior border and lower incisor position of the actual postsurgical skeletal outline. The soft tissue profile was generated and the amount and direction of skeletal movement was calculated with each software. The predicted soft tissue profile was compared to the actual postsurgical soft tissue profile. There were differences between the actual and the predicted surgical soft tissue profile changes in the magnitude and direction, especially the upper lip, lower lip and the soft tissue chin (p < 0.05). Quick Ceph had more horizontal measurement errors and thickness errors for the upper lip and lower lip, but V-Ceph had more vertical measurement errors of the lower lip (p < 0.05). There was a positive correlation between the prediction errors and the amount of mandibular movements in the vertical position of Sn, the horizontal position of Ls and the upper lip thickness for V-Ceph, and there was a negative correlation in the horizontal position and the thickness of the lower lip for Quick Ceph (p < 0.05). However, all of the prediction errors of both imaging softwares were ranged within 3 mm, and this was considered to be allowable clinically.

A clinical study on the effects of bilateral sagittal split ramus osteotomy on the postoperative condylar positional changes in the mandibular prognathism

A Study On The Change Of Airway Space And Cranial, Cervical Angulation After Mandibular Setback Operation

In the study of craniofacial deformity, it is very important that identifying the factor which can affect the morphology and which is closely related to the morphology, because it can not only improve the comprehension of growth and developmental process but also be applied in growth prediction and treatment modality. Several investigators have already mentioned the characterstics of head posture and airway space in relations to morphologic difference. But it is very meaningful work in clarifying the correlation between morphology, head posture and airway space that observing the change of head posture after morplologic change caused by operation and the change of airway space after same procedure. To investigate above correlation, I selected normal group which is consisted of 43 adults and mandibular prognathism group which is consisted of 47 adults who had been operated by sagittal split ramus osteotomy and were followed up more than 1 year. With their lateral skull radiograghs, reference lines which can evaluate each measuring points and areas without effect of postural change were first determined. And using above reference lines, change of airway space, positional change of tongue and hyoid, change of cranial and cervical angulations were measured. The results obtained from the study were as follows 1. In the change of head posture, the position of tongue and hyoid neighboring to pharynx is more closely related to the reference line of cervical column than to reference line of cranium. 2. After mandibular setback operation, the airway dimension was decreased to 81.6% of preoperative state at 1 month postoperatively and was slightly increased to 89.7% at 1 year postoperatively. 3. Posterior movement of tongue plays important role in decrease of airway dimension and inferior movement of hyoid was closely correlated with posterior movement of tongue. 4. Postoperative anterior movement of mandible, namely, morphologic relapse had correlation with relapse phenomenon of airway dimension. 5. Craniocervical angulation increased postoperatively. Especially in the postoperative early state, there was increased foreward inclination of cervical angulation rather than increase of cranial angulation. But at postoperative 1 year it was observed that cervical inclination was returned to preoperative state and cranial angulation was increased gradually. 6. Increase rate of airway dimension was correlated with the increase of cranial angulation from postoperative 1 month to 1 year. In conclusion, relapse tendency of airway dimension following increase of cranial angulation was found after mandibular setback operation and it is considered that increase of cranial angulation is one of compensatory mechanism in airway maintenance.

A Study on the mandibular setback osteotomy and reduction genioplasty in mandibular prognathism with long anterior facial height / 대한치과교정학회지

The purpose of this study was to evaluate the amount and interrelationship of hard and soft tissue changes after mandibular setback osteotomy and reduction genioplasty in mandibular prognathism with long anterior facial height. The control group (Group A) consisted of 20 patients who had severe horizontal discrepancy. They experienced presurgical orthodontic treatment and orthognathic surgery via mandibular setback. The experimental group (Group B) consisted of 20 patients who had severe horizontal and vertical discrepancy. They experienced presurgical orthodontic treatment and orthognathic surgery via mandibular setback and reduction genioplasty. The presurgical and postsurgical lateral cephalograms were valuated. The computerized statistical analysis was carried on with EXCEL 97 program. The results were as follows : 1. The correlation of hard and soft tissue horizontal changes in lower 2/3 of lower anterior facial height were high for both groups. The correlation coefficients of hard tissue changes and Ls, Stm, Li changes in group B were moderately higher than Group A. 2. The correlation of hard and soft tissue vertical changes in Group B were lower than Group A. (except for pointB-Ils, Me-Me') 3. The ratio for soft tissue to Pog in Group B was lower than Group A. The ratios of hard and soft tissue vertical changes were 32% at Ils, 54% at Pog', and 60% at Me'. 4. The ratio of lower anterior facial height to total anterior facial height was reduced for both group. But ratio of upper 1/3 of lower anterior facial height to total anterior facial height did not changed significantly in Group B. 5. Reduction genioplasty combined with mandibular setback procedure showed no change in upper one third(Sn-Stm) and significant decrease(Stm-Me') in the lower two thirds of the soft-tissue anterior lower facial height.

A cephalometric study on changes of facial morphology in the frontal view following mandible setback surgery(bssro) in patients with skeletal class iii dentofacial deformities

0.05) postoperatively. 3. In the facial index, hard tissue decreased(0.23+/-2.21%), but soft tissue increased(2.41+/-3.46%) with statistical significance. CONCLUSION: One of the main purpose of orthognathic surgery is to achieve facial esthetics and harmony. In order to fullfill this purpose, it is important to carry out a precise presurgical treatment planning by estimating the changes of frontal profile after surgery.