Modern trends in Class III orthognathic treatment: A time series analysis

Objective:To examine the current trends in surgical-orthodontic treatment for patients with Class III malocclusion using time-series analysis.Materials and Methods:The records of 2994 consecutive patients who underwent orthognathic surgery from January 1, 2004, through December 31, 2015, at Seoul National University Dental Hospital, Seoul, Korea, were reviewed. Clinical data from each surgical and orthodontic treatment record included patient''s sex, age at the time of surgery, malocclusion classification, type of orthognathic surgical procedure, place where the orthodontic treatment was performed, orthodontic treatment modality, and time elapsed for pre- and postoperative orthodontic treatment.Results:Out of the orthognathic surgery patients, 86% had Class III malocclusion. Among them, two-jaw surgeries have become by far the most common orthognathic surgical treatment these days. The age at the time of surgery and the number of new patients had seasonal variations, which demonstrated opposing patterns. There was neither positive nor negative correlation between pre- and postoperative orthodontic treatment time. Elapsed orthodontic treatment time for both before and after Class III orthognathic surgeries has been decreasing over the years.Conclusion:Results of the time series analysis might provide clinicians with some insights into current surgical and orthodontic management.     

Lip line changes in Class III facial asymmetry patients after orthodontic camouflage treatment,one-jaw surgery,and two-jaw surgery: A preliminary study

Objective:To evaluate the effects of orthodontic camouflage treatment (OCT), one-jaw surgery, and two-jaw surgery on the correction of lip line cant (LLC) and to examine factors affecting the correction of LLC in Class III craniofacial asymmetry patients.Materials and Methods:A sample of 30 Class III craniofacial asymmetry patients was divided into OCT (n = 10), one-jaw surgery (n = 10), and two-jaw surgery (n = 10) groups such that the pretreatment LLC was similar in each group. Pretreatment and posttreatment cone-beam computed tomography scans were used to measure dental and skeletal parameters and LLC. Pretreatment and posttreatment measurements were compared within groups and between groups. Pearson''s correlation tests and multiple regression analyses were performed to investigate factors affecting the amount and rate of LLC correction.Results:The average LLC correction was 1.00° in the one-jaw surgery group, and in the two-jaw surgery group, it was 1.71°. In the OCT group it was −0.04°, which differed statistically significantly from the LLC correction in the other two groups. The amount and rate of LLC correction could be explained by settling of skeletal discrepancies or LLC at pretreatment with goodness of fit percentages of approximately 82% and 41%, respectively.Conclusions:Orthognathic surgery resulted in significant correction of LLC in Class III craniofacial asymmetry patients, while OCT did not.     

Evaluation of facial soft tissue asymmetric changes in Class III patients after orthognathic surgery using three-dimensional stereophotogrammetry

The aim of this study was to investigate changes in facial soft tissue asymmetry over time after orthognathic surgery in Class III patients using three-dimensional stereophotogrammetry. The study included 101 patients with a skeletal Class III malocclusion (72 female, 29 male; age range 19–53 years, mean age 28.6 years) who underwent orthognathic surgery. The minimum follow-up was 12 months. Three-dimensional photographs were acquired using the 3dMDtrio stereophotogrammetry system, and 21 anthropometric landmark positions were evaluated at three time points: before surgery (T0), 6 months (T1) and 12 months (T2) after surgery. Facial asymmetry was assessed and classified as follows: 0–2 mm, mild; 2–5 mm, moderate;> 5 mm, severe. The average distance for whole face asymmetry differed between T0 (median 0.76 mm) and T1 (median 0.70 mm); however, there was no statistically significant difference at any time point. The chin volume asymmetry score differed significantly between T0 (median 1.11 mm) and T1 and T2 (median 1.08 mm for both; P < 0.001 and P = 0.001, respectively), but not between T1 and T2 (P = 0.061). The study findings indicate that the asymmetry of the facial soft tissues has the potential to return after 6 months, without reaching the baseline.     

骨性III类错畸形患者正颌手术前后力变化的初步研究

目的:应用计算机咬合分析系统,评价正颌手术前后骨性III类错牙合患者牙合力的变化。方法:收集15例骨性III类错牙合需正颌手术病例,利用T-ScanII牙合诊断分析系统在术前1周内、术后3个月和术后6个月时对患者的牙合力进行测定,分析患者的总牙合力(TOF)、MIP/MAX指数、牙合力不对称指数(AOF)、牙合力中心点位置(COF)及咀嚼时最大位移距离(MCOF),应用配对t检验进行比较研究。结果:术后3个月时TOF有所上升,6个月时与术前水平相比已有显著差异(P<0.05),说明患者牙合力水平已有提高。MIP/MAX指数略有下降,但6个月时增大并超过术前水平。AOF术后呈下降趋势,在3个月和6个月时均比术前显著减小(P<0.01,P<0.001)。术后COF逐渐接近正常,MCOF减小,术后6个月时均较术前明显改善,说明患者牙合力水平已有提高。结论:正颌正畸联合治疗能够改善骨性III类错牙合患者的牙合力水平及力平衡性。     

Dimensional changes of maxillary sinuses and pharyngeal airway in Class III patients undergoing bimaxillary orthognathic surgery

Objective:To evaluate the pharyngeal airway and maxillary sinus volume changes after mandibular setback surgery combined with maxillary advancement and/or impaction surgery.Materials and Methods:Seventeen Class III skeletal patients (11 females, 6 males) who required bimaxillary orthognathic surgery were selected. Volumetric measurements were performed using cone beam computed tomography (CBCT) scans preoperatively and 3.9 ± 0.87 months postoperatively. All the CBCT scans were assessed and analyzed using MIMICS 14.0 software. Preoperative and postoperative volumes of pharyngeal airway and maxillary sinuses and the relationship between the amounts of surgical movement of the jaws and the above volumes were statistically evaluated.Results:The pharyngeal airway area presented no significant change except for the lower and total pharyngeal airway volumes in males, in whom a significant decrease was observed (4196.27 ± 2061.11 mm³ and 3375.53 ± 3624.67 mm³, respectively). No significant change was observed in the minimal cross-sectional area of the pharyngeal airway. There was a significant decrease in the volume of the maxillary sinuses after the surgery by 3448.09 ± 3315.56 mm³. No correlation was found between the amount of skeletal movement and the change in the volume of pharyngeal airway or maxillary sinuses.Conclusion:There was a significant decrease only for lower and total pharyngeal airway volumes in males and a significant decrease in the volume of the maxillary sinuses.     

Relapse patterns of two-jaw surgical correction in patients with skeletal Class III malocclusion and different vertical facial types

The aim of this study was to evaluate postoperative relapse after the surgical correction of skeletal Class III deformities of various facial patterns as a guide to surgical planning. A retrospective cohort study of 90 consecutive patients with skeletal Class III malocclusion who underwent bimaxillary surgery was performed. The surgical outcomes and postoperative stability were compared. The primary predictor variable was vertical facial type, which was classified into three groups according to the Frankfort mandibular plane angle (FMA). The primary outcome of angular and linear measurements was obtained using serial cone beam computed tomography scans obtained at time points of preoperative, 1 week after surgery, and orthodontic debonding. No significant difference in skeletal relapse was observed in patients with the different vertical facial types. The mandible displayed a forward and upward relapse in all three groups postoperatively. The patients with a low FMA exhibited a more consistent mandibular relapse pattern than those with a normal or high FMA. These findings suggest that bimaxillary surgery is clinically stable for mandibular prognathism regardless of the vertical facial pattern. However, 1–1.5 mm of overcorrection in the mandible setback should be considered in patients with a low FMA, because of the greater facial depth and consistent forward and upward mandibular relapse pattern.     

Preoperative incisor inclination in patients with Class III dentofacial deformities treated with orthognathic surgery

Our aim was to evaluate cephalometrically the preoperative inclination of the incisors in a group of 50 patients with Class III dentofacial deformities whose immediate preoperative lateral cephalometric radiographs were analysed after they had been treated by maxillary advancement. The radiographs were hand-traced by the same operator who made the cephalometric analysis. Mean values for each measurement were compared with the normal values using Student's t-test (p<0.05). Results showed significantly increased inclination of the upper incisors, with a mean U1-NA angle of 27.58° and a mean U1-PP angle of 116°. The lower incisors were also inclined lingually, with a mean L1-NB angle of 22.53° and a mean IMPA of 83.13°. Thirty-five of the patients had labial inclination of the upper, and 28 lingual inclination of the lower, incisors. Mean inclinations of upper and lower incisors differed from the normal values, and the inclination of the lower incisors was more likely to be decompensated than that of the upper incisors.     

The time-course change in the lip closing force in Class III malocclusion after orthognathic surgery

ObjectivesThe purpose of this study was to examine the changes with time in lip pressure after orthognathic surgery for skeletal Class III patients.Study designThe subjects consisted of 63 patients (32 female and 31 male) diagnosed with mandibular prognathism who underwent sagittal split ramus osteotomy with and without Le Fort I osteotomy. Maximum and minimum lip closing forces were measured with Lip De Cum^®. The changes with time were compared statistically.ResultsThe maximum and minimum lip closing force increased time-dependently in men and women after surgery and there were significant differences between men and women with changes with time in the maximum lip closing force (p = 0.0086) and the minimum lip closing force (p = 0.0302). After 1 year, the Class III group maximum lip closing force was significantly smaller than the control group in both men (p < 0.0001) and women (p < 0.0001).ConclusionsThis study suggests that there was significant difference in over time in the lip closing force between men and women in Class III patients. Although the maximum lip closing force increased with time, it did not reach the level of the control group after 1 year.     

Occlusal plane canting reduction accompanies mandibular counterclockwise rotation in camouflaging treatment of hyperdivergent skeletal Class II malocclusion

ObjectiveTo investigate the occlusal configurations of the hyperdivergent skeletal Class II malocclusion and their alterations during the camouflaging treatment in an attempt to identify occlusal changes that might be related to mandibular counterclockwise rotation.Materials and MethodsCephalograms of 126 subjects with hyperdivergent skeletal Class II malocclusion and 126 subjects with a clinically normal skeletal pattern were chosen. Several measurements were calculated and compared between the groups. To examine the effects of treatment, two groups were established according to mandibular rotation: counterclockwise rotation (CCR) and the opposite clockwise rotation (CR). After 40 subjects were excluded, the other 86 Class II subjects were assigned to CCR (n  =  22) and CR (n  =  64). Their pretreatment (T1), posttreatment (T2), and postretention (T3) cephalograms were obtained. Measurement changes (T3-T1) were analyzed in each group and compared between groups.ResultsCompared with the normal skeletal pattern, the cant of the occlusal plane (OP) of the study subjects was significantly steeper and the vertical heights of the incisors were significantly larger for the malocclusion. Compared with the changes in CR, there was a prominent reduction of the OP canting with remarkable intrusion of the maxillary incisor in CCR.ConclusionIncreased OP canting with overerupted incisors is evident in the hyperdivergent skeletal Class II malocclusion. During the camouflaging treatment, reduction of OP canting could occur. It was accompanied by mandibular counterclockwise rotation and intrusion of the maxillary incisor.     

Long-term stability of maxillary protraction therapy in Class III patients with complete unilateral cleft lip and palate

Objectives:This study evaluated the long-term stability of maxillary protraction (MP) in patients with complete unilateral cleft lip and palate (UCLP) and identified factors influencing relapse and long-term outcomes.Materials and Methods:Twenty-three adolescents with UCLP who underwent MP therapy were recalled when craniofacial growth was close to completion. Subjects exhibiting reverse/positive overjets were assigned to unstable/stable groups. Lateral cephalometric measurements were made before treatment (T0), after active treatment (T1), and at the end of the growth spurt (T2).Results:About 63% of the subjects exhibited positive overjets during follow-up. The unstable group demonstrated higher B–x and Co–Gn distances than the stable group (both P < .05) at T0. More short-term (T0–T1) sagittal advancement of point A (A–y) was evident in the unstable group than in the stable group (P < .05), but no long-term difference was apparent between the two groups (P = .481). During the posttreatment period (T1–T2), the SNA angle and maxillary incisor protrusion (U1–SN angle) were considerably lower in the unstable group than in the stable group (both P < .05). Overall, the unstable group exhibited a lower increase in the vertical extent of point A (A–x) than the stable group from T0 to T2 (P < .05).Conclusions:In the long term, MP affords favorable maxillary advancement in patients with UCLP. A mandibular excess at T0 and vertical maxillary hypoplasia may contribute to the long-term relapse of a reverse overjet.     

Evaluation of long-term soft tissue changes after bimaxillary orthognathic surgery in Class III patients

Objective:To assess soft tissues in the short and long term after bimaxillary surgery in Class III patients by comparing the hard tissue changes and results between time periods.Materials and Methods:Twenty-six Class III adult patients treated with bimaxillary surgery were included in the study. Cephalometric records were taken before surgery (T1) and 5 months (T2), 1.4 years (T3), 3 years (T4), and 5 years (T5) after surgery.Results:There was no significant relapse in skeletal parameters. Overjet was significantly reduced between T4-T3 time intervals (P < .01). There were significant increases in Sn-HR, ULA-HR, LLA-HR, B-B^∧ (P < .01), and B^∧-HR (P < .05) between T4-T3 time intervals. There was no significant change in the soft tissue parameters between T5-T4 time intervals.Conclusion:Soft tissue vertical relapse occurs in skeletally stabile Class III bimaxillary surgery patients in the first 3 years after surgery.     

骨性III类错牙合畸形患者正颌手术前后咀嚼肌功能变化的初步研究

目的:应用肌电图仪评价骨性III类错牙合畸形患者正颌手术前后咀嚼肌功能的变化。方法:收集16例骨性III类错牙合畸形需正颌手术病例和20例正常牙合对照组,应用MedelecSynergy肌电图仪分别在静息放松、正中紧咬、前伸、开口、侧方和咀嚼运动时,测定双侧颞肌前束、咬肌和二腹肌前腹的表面募集电位,并计算其肌不对称指数运动。病例组在术后3个月和6个月时重复测定,采用t检验进行统计学分析,并与对照组进行比较。结果:手术前病例组咀嚼肌电位小于对照组,尤以紧咬和咀嚼时差异显著(P<0.05),肌不对称指数与对照组无差异。术后3个月时,部分肌功能恢复,但紧咬和咀嚼时募集电位下降显著(P<0.001),肌不对称指数也增大,提示此时肌功能尚未完全恢复。术后6个月各种功能运动时的募集电位均大于术前水平,肌不对称指数则基本小于术前水平,说明肌功能有所改善。结论:骨性III类错牙合畸形患者手术前咀嚼肌功能弱于对照组,正颌手术矫正了颌骨位置和咬合关系,改善了患者的咀嚼肌功能。     

Comparison of oropharyngeal airway dimensional changes in patients with skeletal Class II and Class III malocclusions after orthognathic surgery and functional appliance treatment: A systematic review

ObjectiveTo compare the dimensional changes in the oropharyngeal airway in patients with skeletal Class II and Class III malocclusion before and after orthognathic surgery and treatment with a functional appliance.MethodsThe protocol was developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) and was registered to the International Prospective Register of Systematic Reviews (PROSPERO) under the registration number CRD42020170901. Furthermore, the reporting of the present SR was performed based on the PRISMA checklist.ResultsThe use of removable functional appliances increased the volume of the oropharyngeal airway in patients with skeletal Class II malocclusion. Furthermore, the increase in the volume of the oropharyngeal airway following the removable functional appliance treatment was more than that observed after fixed functional appliance treatment in growing patients. For patients with skeletal Class III malocclusion, who underwent the bimaxillary orthognathic surgery, resulted in no change in the dimensions of the oropharyngeal airway.ConclusionGrowing patients who receive removable functional appliance treatment have a more favorable long-term prognosis with regard to the oropharyngeal airway when compared with those who receive fixed functional appliance. Alternatively, in patients aged from (18–22) years with skeletal class III malocclusion Bimaxillary orthognathic surgery was found to be the recomended and superior method of treatment.     

Maxillary incisor inclination of skeletal Class III patients treated with extraction of the upper first premolars and two-jaw surgery: Conventional orthognathic surgery vs surgery-first approach

Objective:To investigate the differences in the amount and pattern of the maxillary incisor (MXI) inclination change in skeletal Class III patients treated with extraction of the maxillary first premolars (MXP1) and two-jaw surgery (TJS) between conventional orthognathic surgery (COS) and surgery-first approach (SFA).Materials and Methods:The study included 60 skeletal Class III patients who had normal maxillary position, prognathic mandible, and mild crowding in the maxillary arch (≤4 mm). The patients were divided into group 1 (COS, n  =  36) and group 2 (SFA, n  =  24). Lateral cephalograms were taken before treatment (T0), 1 month before surgery (T1), within 1 month after surgery (T2), and after debonding (T3) for COS patients and at T0, T2, and T3 for SFA patients. After measurement of the skeletodental variables, statistical analyses were performed.Results:During T0–T2, the amount of MXI inclination change (ΔU1-SN) in group 1 was significantly larger than that in group 2 (−12.8° vs −4.4°; P < .001). During T2–T3, ΔU1-SN in groups 1 and 2 occurred in opposite directions (3.8° vs −5.9°; P < .001). However, the total amount of ΔU1-SN during T0–T3 was not different between groups 1 and 2 (−9.0° vs −10.3°). At T3 the U1-SN values for groups 1 and 2, respectively, moved closer to normal according to the values of the normal range rate (all 83%), relative percentage ratio (102.4% and 100.1%), and achievement ratio (77.7% and 97.8%).Conclusions:The results of this study might provide basic data for predicting the amount and pattern of MXI inclination change in SFA for skeletal Class III TJS patients.     

骨性III类错畸形患者正颌手术前后下颌运动轨迹变化的初步研究

目的:应用下颌运动轨迹仪评价骨性III类错牙合畸形患者正颌手术前后下颌运动的变化。方法:对15例骨性III类错牙合畸形需正颌手术病例和20例正常牙合对照组,采用ARCUSDigma下颌运动轨迹仪测定受试者最大开口运动,前伸及左右侧边缘运动距离,记录由计算机通过切牙运动模拟的双侧髁突的运动轨迹间的最大差数(MRC)。通过自身比较以及与对照组比较,评价患者在术前、术后3个月及6个月时下颌运动的变化以及髁突运动的对称性。采用团体t检验和配对t检验进行统计学处理。结果:术前患者除开口度外,其他运动距离均小于对照组,前伸运动差异显著(P<0.05);开口时MRC值大于对照组(P<0.05)。术后3个月时,开口度及左侧运动距离下降,前伸和右侧运动略有增加;MRC呈上升趋势。术后6个月时,下颌运动距离均有所增加,除开口度外其余均超过术前水平,与对照组无统计学差异;MRC小于术前水平且与对照组差异无显著性。结论:骨性III类错牙合畸形患者下颌运动水平与正常牙合存在差异,髁突运动对称性较差。正颌手术能够有效地改善患者的下颌运动功能。     

Three-dimensional evaluation of soft tissue change gradients after mandibular setback surgery in skeletal Class III malocclusion

Objective:To evaluate whether mandibular setback surgery (MSS) for Class III patients would produce gradients of three-dimensional (3D) soft tissue changes in the vertical and transverse aspects.Materials and Methods:The samples consisted of 26 Class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalograms and 3D facial scan images were taken before and 6 months after MSS, and changes in landmarks and variables were measured using a Rapidform 2006. Paired and independent t-tests were performed for statistical analysis.Results:Landmarks in the upper lip and mouth corner (cheilion, Ch) moved backward and downward (respectively, cupid bow point, 1.0 mm and 0.3 mm, P < .001 and P < .01; alar curvature-Ch midpoint, 0.6 mm and 0.3 mm, both P < .001; Ch, 3.4 mm and 0.8 mm, both P < .001). However, landmarks in stomion (Stm), lower lip, and chin moved backward (Stm, 1.6 mm; labrale inferius [Li], 6.9 mm; LLBP, 6.9 mm; B′, 6.7 mm; Pog′, 6.7 mm; Me′, 6.6 mm; P < .001, respectively). Width and height of upper and lower lip were not altered significantly except for a decrease of lower vermilion height (Stm-Li, 1.7 mm, P < .001). Chin height (B′-Me′) was decreased because of backward and upward movement of Me′ (3.1 mm, P < .001). Although upper lip projection angle and Stm-transverse projection angle became acute (Ch_Rt-Ls-Ch_Lt, 5.7°; Ch_Rt-Stm-Ch_Lt, 6.4°, both P < .001) because of the greater backward movement of Ch than Stm, lower lip projection angle and Stm-vertical projection angle became obtuse (Ch_Rt-Li-Ch_Lt, 10.8°; Ls-Stm-Li, 23.5°, both P < .001) because of the larger backward movement of Li than labrale superius (Ls).Conclusions:Three-dimensional soft tissue changes in Class III patients after MSS exhibited increased gradients from upper lip and lower lip to chin as well as from Stm to Ch.     

Relapse of skeletal class III with anterior open bite after bimaxillary orthognathic surgery depending on maxillary posterior impaction and mandibular counterclockwise rotation

The goal of this study is to evaluate relapse after orthognathic surgery of skeletal class III with anterior open bite depending on the posterior impaction and mandibular counterclockwise rotation. Patients (n = 29) were divided into two groups according to the change of mandibular occlusal plane angle (MnOP): Group A had a clockwise change of MnOP > 0° (n = 11) and Group B had a counterclockwise change of MnOP < −2° (n = 18). Lateral cephalograms were analyzed preoperatively, and at immediate stage, six weeks, six months, and one year after surgery. One year after surgery, the stability of the maxilla was good in both groups. Upward movement of the mandible was observed six weeks after surgery due to mandibular autorotation. The amount of mean relapse was small, although a significant difference was observed horizontally between groups. Group B demonstrated more forward movement of B point, pogonion, and menton than Group A (p < 0.05). SNB angle increased in both groups (p < 0.05). At one year follow up, good occlusal stability was observed in both groups with positive overbite. Our study suggested that bimaxillary procedures with clockwise and counterclockwise rotation of mandibular occlusal planes for correction of mandibular prognathism with anterior open bite appeared to be relatively stable procedures.     

Soft tissue response after Class III bimaxillary surgery: Impact of surgical change in face height and long-term skeletal relapse

Objective:To analyze the impact of surgical change in anterior face height and skeletal relapse on the long-term soft tissue profile.Materials and Methods:Cephalometric radiographs of 81 patients taken before surgery and at five time points during a 3-year follow-up period were analyzed. All patients had Le Fort I and bilateral sagittal split osteotomies. The patients were divided into three subgroups according to the change in anterior face height during surgery. Calculations of soft to hard tissue ratios were based on the long-term soft tissue response relative to the surgical repositioning.Results:The horizontal surgical repositioning varied considerably, depending on whether anterior face height was increased or decreased. For upper lip prominence, the pattern of long-term change was the same irrespective of change in face height. In all groups, upper lip thickness decreased in both the short term and the long term, particularly in patients with surgical increase in face height. Lower lip thickness increased in the short term but decreased during the follow-up period. There were significant associations between horizontal soft tissue and corresponding hard tissue changes, except for soft tissue A-point and upper lip, when face height was increased. The ratios were higher for mandibular variables than for maxillary variables, particularly for B-point and pogonion when anterior face height had decreased.Conclusion:A change in facial height influences the soft tissue response. The mandibular soft tissues closely follow skeletal relapse beyond 2 months postsurgery. The findings have clinical implications for the relative maxillary and mandibular repositioning when planning surgery.     

平面与错畸形的关系

平面是颅面部错畸形矫治的基础,平面倾斜度将影响颌骨的生长发育、口腔功能、上下颌骨关系、牙齿咬合以及面部美观。各类错均存在不同程度的平面偏斜,本文就平面与错畸形检查、诊断、治疗计划设计关系的研究进展作一综述。