Accuracy of a digital workflow for bimaxillary orthognathic surgery: comparison of planned and actual outcomes.

AIM: The aim of the present prospective proof-of-concept study was to evaluate the accuracy of 3D orthognathic surgical planning and CAD/CAM splints by comparing planned with actual postoperative outcomes. MATERIALS AND METHODS: Ten patients scheduled for bimaxillary orthognathic surgery to correct a skeletal Class III dentofacial deformity were recruited. All subjects had CBCT scans taken not more than 2 months preoperatively and within the 1-week postoperative period. The distance between six dental landmarks (midpoint of the maxillary and mandibular incisors, mesiobuccal cusps of the maxillary and mandibular first molars) and three intersecting symmetry planes (Frankfort horizontal plane [FHP], midsagittal plane [MSP], and coronal plane [CP]) were measured, and the differences between the virtually simulated and actual postoperative models were computed. The threshold for accuracy was set at 2 mm. RESULTS: Differences between the planned and actual outcomes were analyzed via chi-square tests and two-tailed paired student t tests. The overall mean linear difference for all six landmarks was 0.98 mm. The overall mean linear differences for both maxillary and mandibular landmarks relative to the FHP, MSP, and CP were 1.3, 0.7, and 0.9 mm, respectively. Four cases showed all linear differences of the six landmarks to be < 2.0 mm, while the other six cases had at least one linear difference of > 2.0 mm, the majority of which were in the superior-inferior direction. There were statistically significantly greater inaccuracies in the FHP compared with the MSP and CP (P < 0.05). CONCLUSION: Most of the linear differences between the simulated and actual outcomes were clinically acceptable. However, greater linear differences were seen in the superior-inferior direction, indicating a greater surgical error in achieving the desired vertical position of the maxillomandibular complex. (Int J Comput Dent 2022;25(4):397-0; doi: 10.3290/j.ijcd.b2599749).

Accuracy and clinical fit of milled versus rapid prototyped orthognathic surgical splints.

Three-dimensional (3D) printing has become an integral part of orthognathic surgery. However, there is a lack of studies evaluating accuracy of orthognathic surgical splints fabricated from subtractive milling versus additive 3D printing. The primary aim of this in-vitro study was to compare the differences in trueness between milled and 3D-printed splints, while the secondary aim was to compare the differences in clinical fit of these splints. A sample of eight patients was selected, and STL files of the final orthognathic surgical splint were used to fabricate three splints for each of the eight cases. The first splint was fabricated by subtractive milling (SM), whereas the second and third splints were 3D printed with Digital Light Processing (DLP) and Laser Stereolithography (SLA), respectively. Paired superimposition of scans was performed using a reference model. The clinical fit of the splints to the printed models was also assessed. The mean root mean square (RMS) deviations for the SM, SLA, and DLP were 0.11 ± 0.02, 0.16 ± 0.02 and 0.14 ± 0.02 respectively. The post-hoc analysis showed that the SM splints had the highest accuracy (p < 0.01). However, DLP splints showed the best clinical fit, followed by SM and SLA. In conclusion, splints fabricated by SM were more accurate than those fabricated by 3D printing, although this difference may not be clinically significant. The site, rather than the magnitude of the errors, may have a greater effect on the clinical usability of splints. In general, SM and DLP splints demonstrated a good clinical fit and were suitable for the fabrication of surgical splints.

Virtual surgical planning in orthognathic surgery: a dental hospital's 10-year experience.

PURPOSE: The primary objective of this study was to evaluate how the utilization of virtual surgical planning (VSP) and the epidemiological profile of patients undergoing orthognathic surgery (OGS) have changed in the past decade. METHODS: The records of patients who had undergone orthognathic surgery at a national dental hospital were reviewed. Trends in VSP, epidemiological data, presentation of dentofacial deformity, and management details were recorded. RESULTS: A total of 1184 patients were included in this study. The majority of the patients seeking treatment in this dental hospital were young Chinese adults with dentofacial deformities requiring bimaxillary surgeries. Most patients presented with a skeletal Class III pattern (79.0%), and asymmetry was diagnosed in 80.8% of all cases. CONCLUSION: There was an initial slow pick-up rate for VSP, but this rapidly increased to a high adoption rate of 98.7-100% between 2019 and 2021. Together with an increasing body of evidence suggesting greater accuracy in VSP, utilization in this technology can be enhanced with greater familiarity with the technology and improvements in the VSP services.

Evaluation of the accuracy of cone beam computed tomography (CBCT) generated tooth replicas with application in autotransplantation.

OBJECTIVES: The primary aim of this study was to assess the linear and geometric accuracy of 3-dimensional (3D) printed tooth replicas when compared to the actual tooth. The secondary aims were to compare the accuracy of three different 3D printers and to evaluate dimensional changes of tooth replicas after sterilization. METHODS: A sample of 16 teeth were selected from recruited patients. Segmentation was carried out to generate files from the patient's cone beam computed tomography (CBCT) data, Tooth replicas were then printed using three printers making use of Polyjet, laser stereolithography (SLA) and digital light processing (DLP) technology respectively. These replicas, along with the actual tooth, were scanned by an optical scanner. Replicas were sent for sterilization and scanned again. Paired superimposition of the scans was performed. RESULTS: A mean length difference of 0.36 mm and mean geometric (root mean square [RMS]) difference of 0.56 mm was found. Qualitative analysis showed that the replicas were generally larger in size. Repeated ANOVA tests showed that the Polyjet printer had the highest accuracy (p<0.0001). After sterilization, there was an overall mean length difference of 0.10 mm and RMS deviation of 0.02 mm. CONCLUSION: This study found that there was a significant difference in linear and geometric measurements of the tooth replicas when compared to the actual tooth. This study also provides evidence that the printer which made use of Polyjet technology was able to produce more accurate models than SLA or DLP printers. Printed tooth models demonstrated clinically insignificant changes after heat sterilization. CLINICAL SIGNIFICANCE: 3D printed tooth replicas derived from the patient's CBCT data may be used in autotransplantation to increase predictability of the procedure. In order for this novel digital approach to realize its potential, it is critical to address questions as to how accurate the various printing technologies are in fabricating replicas.

Accuracy of 3-dimensional soft tissue prediction for orthognathic surgery in a Chinese population.

OBJECTIVES: This study aims to determine the validity of a 3D planning software in predicting the soft tissue outcome of Chinese patients undergoing orthognathic surgery for correction of Skeletal III dentofacial deformity. METHODS: Pre- and post-operative 3D facial stereophotogrammetric scans and cone beam computed tomography were taken for 10 Chinese patients who had underwent orthognathic surgery. The pre-operative 3D facial scan was integrated with the pre-operative CBCT using the ProPlan CMF software. The simulated soft tissue 3D face was then compared with the actual 3D facial scan obtained at least 6 months postoperatively. Two outcome measures were computed as follows (i) mean absolute difference between meshes (ii) percentage of points where the distance between the two meshes is 2mm or less. RESULTS: The mean absolute difference between the predicted and actual soft tissue surface meshes for the full face and the 6 anatomic regions ranged from 0.72mm to 1.42 mm. The mean absolute distance between the meshes for all the anatomic regions were within 2 mm (p<0.05). The percentage of mesh points with less than 2mm error ranged from 72.5% to 92.5%. The accuracy of soft tissue prediction, assessed using mean absolute distance for the full face, was significantly correlated to the amount of sagittal surgical movement (r=0.707, p=0.022). The lower lip was also found to be the least accurate. CONCLUSIONS: Using ProPlan CMF, the accuracy of 3D soft tissue predictions for bimaxillary orthognathic surgery in Chinese Skeletal III patients were clinically satisfactory.

Subjective evaluation of the accuracy of video imaging prediction following orthognathic surgery in Chinese patients.

PURPOSE: The aims of this retrospective study were to assess the subjective accuracy of predictions generated by a computer imaging software in Chinese patients who had undergone orthognathic surgery and to determine the influence of initial dysgnathia and complexity of the surgical procedure on prediction accuracy. PATIENTS AND METHODS: The sample consisted of 40 Chinese patients who had completed treatment involving orthodontics and orthognathic surgery. All the patients had lateral cephalometric radiographs and profile photographs taken within 3 months before surgery and at least 6 months after surgery. The computer-generated predicted images and the actual post-treatment images were displayed simultaneously to a panel of orthodontists, oral maxillofacial surgeons and laypersons to allow side-by-side comparison. The panel was asked to determine which image was more esthetic and to rate the likeness between the actual and predicted images using a 10 cm visual analog scale. RESULTS: The results showed that the actual image was judged to be more esthetic in 82% of the cases, with the orthodontists more likely to select the actual profile compared to laypersons (P = .005). Orthodontists and surgeons rated the likeness of the images similarly while laypersons rated the likeness significantly lower than the clinicians (P = .012 and P = .015, respectively). Skeletal III cases were judged to be less accurately predicted than skeletal II cases by laypersons (P = .006) and orthodontists (P = .036). Cases treated by single-jaw osteotomy were given better ratings compared to cases with bimaxillary osteotomy by all panel groups but the differences did not reach significant level. CONCLUSIONS: Skeletal III cases managed by bimaxillary osteotomy were least accurately predicted by the computer program. As there exists a possibility that the predicted image may be judged to be more esthetic than the actual image, clinicians must make extra effort to manage patient expectations when using computer simulations for patient education.

Evaluation of the linearity of soft- to hard-tissue movement after orthognathic surgery.

INTRODUCTION: Our aim in this study was to investigate whether a linear relationship exists between soft- to hard-tissue changes for both maxillary and mandibular landmarks over a wide range of skeletal changes. METHODS: The sample consisted of 30 Chinese patients with Class III malocclusion treated with bilateral sagittal split osteotomy and LeFort I advancement. Lateral cephalograms were taken within 2 months before surgery and at least 6 months after surgery. Soft- and hard-tissue changes were recorded by computer-supported measurements of presurgical and postsurgical lateral cephalograms. To evaluate the linear association between soft- and hard-tissue movement, a quadratic function of hard-tissue movement adjusted for sex was initially fitted to the data. The residual plots were used to examine the appropriateness of the fitted quadratic function, and the lack of fit was examined by the F test. A linear function was fitted to the data when the quadratic term was not significant. RESULTS: Visual inspection of the scatter plots of the 5 pairs of corresponding soft- and hard-tissue landmarks showed that relationships between the soft and hard tissues were reasonably linear for both male and female subjects, except for the Sn-ANS pair that showed a curvilinear relationship. Statistical tests confirmed that the association for the Sn-ANS pair was quadratic. CONCLUSIONS: The results of this study provide evidence of a linear relationship between soft- to hard-tissue changes for mandibular landmarks over a wide range of skeletal changes. The nonlinear response of maxillary soft tissues to underlying hard-tissue change in the Sn-ANS pair supports the use of nonlinear ratios for selected maxillary soft- to hard-tissue movements in simulation software.

Orthodontic-surgical management of an unusual dilacerated maxillary incisor.

Orthodontic traction of an impacted dilacerated maxillary central incisor is clinically challenging and often results in a long treatment duration. A case of an unusual dilacerated central incisor with a 90° crown-root angulation and palatally displaced crown is presented herein. Using a single stage open window exposure of the crown on the palatal aspect with light orthodontic traction force, the impacted dilacerated central incisor crown was successfully positioned in alignment with the contralateral incisor.

An Asian community's perspective on facial profile attractiveness.

AIM: To assess the facial profile preferences of laypersons in an Asian community and the influence of age, ethnic and gender on profile selection. METHODS: A sample of 149 laypersons (65.1% Chinese, 21.5% Malays and 13.4% Indians), comprising of 112 females (75.2%) participated in the study. The mean age was 24.6 years (SD 4.4). A facial profile photograph and a lateral cephalometric radiograph of a Chinese male and female adult with a normal profile and a class I incisor and skeletal relationship were digitized to create a baseline template. Computerized digital photographic image modification was carried out on the template to obtain seven facial profiles [bimaxillary protrusion, protrusive mandible, retrusive mandible, normal profile (incisor and skeletal class I pattern), retrusive maxilla, protrusive maxilla and bimaxillary retrusion] for each gender. The laypersons were asked to rank the profiles of each gender on a scale of 1 (very attractive) to 7 (least attractive). RESULTS: Orthognathic Chinese male and female profiles were perceived to be the most attractive. A male orthognathic profile with normative Chinese cephalometric values was perceived to be more attractive than a 'flatter' bimaxillary retrusive profile. Bimaxillary retrusion and normal Chinese female profiles were perceived to be the most attractive. A male or female profile with a protrusive mandible was judged to be the least attractive. Age, gender and ethnicity were nonsignificant predictors for the most attractive female profile. CONCLUSIONS: Orthognathic Chinese male and female profiles were judged to be the most attractive by Asian adult laypersons. Male and female profiles with mandibular protrusion were judged to be the least attractive.

Outcome of orthognathic surgery in Chinese patients. A subjective and objective evaluation.

OBJECTIVE: To evaluate the outcome of orthognathic surgery by objective cephalometric measurement of posttreatment soft-tissue profile and by subjective evaluation of profile esthetics by laypersons and clinicians. MATERIALS AND METHODS: The sample consisted of 30 Chinese patients who had completed combined orthodontic and orthognathic surgical treatment. The posttreatment cephalograms of these patients were analyzed with respect to profile convexity, facial height, and lip contours and these were compared to the previously established esthetic norms. Line drawings of the soft-tissue profile were displayed to a panel comprising six laypersons and six clinicians who scored the esthetics of each profile using a 7-point scale. RESULTS: Complete normalization of cephalometric soft-tissue variables was not achieved with orthognathic surgery in most patients, with four of the six soft-tissue cephalometric measurements showing significant differences compared to the esthetic norms. There were good correlations in the esthetic scores between laypersons and clinicians, even though clinicians tend to rate the profiles more favorably. Facial convexity and facial height did not significantly influence the subjective scores of both the laypersons and clinicians. Lower lip protrusion was the only cephalometric variable that significantly influenced clinicians' assessment of profile esthetics (P<.01). CONCLUSIONS: Profile convexity and lower facial height proportion had little influence on both lay and professional perception of profile esthetics. Lower lip position is the only cephalometric variable that significantly influenced clinicians' assessment of profile esthetics.

Perceptions of dental esthetics of Asian orthodontists and laypersons.

INTRODUCTION: The aim of the study was to determine the impact of anterior dental crowding, overjet, overbite, dental spacing, and type of malocclusion on dental esthetic perceptions of Asian orthodontists. METHODS: Twenty-one Asian orthodontists (10 men, 11 women) and 158 adult laypersons (38 men, 120 women) rated the attractiveness of 50 pairs of black-and-white intraoral photographic prints of various types of malocclusions. Each pair included a frontal and a right buccal view of the dentition at maximum intercuspation. Raters used a visual analogue scale (VAS), with "least attractive" (0 mm) and "most attractive" (100 mm) as the 2 extremes, to score the dental esthetics of the photographs. A principal investigator objectively measured the dental traits from study models. Linear regression analysis was performed with VAS scores as the dependent variable and anterior dental crowding, overjet, and overbite measurements as the independent variables. Independent sample t tests were used to determine the effect of dental spacing on the VAS scores. The Kruskal-Wallis test was used to determine the effect of type of malocclusion (Class I, Class II Division 1, Class II Division 2, Class III) on VAS scores. RESULTS: Increased overjet (>6 mm) and severe maxillary dental crowding (>8 mm) were found to be significantly correlated with laypersons' VAS scores (P <.05). Reverse overjet was found to be significantly correlated with orthodontists' VAS scores (P <.05). No significant correlation was found between overbite, dental spacing, and VAS scores. Class III malocclusions were significantly perceived to be the most unesthetic by orthodontists. CONCLUSIONS: Overjet was the major occlusal trait that influenced the perceptions of dental esthetics of both laypersons and orthodontists.

Spectrum and management of dentofacial deformities in a multiethnic Asian population.

OBJECTIVE: The aim of this retrospective study is to investigate the spectrum and management of dentofacial deformities in a multiethnic Asian community. MATERIALS AND METHODS: Over a period of 3 years (2001 to 2003), 212 patients with dentofacial deformities who had undergone orthognathic surgery in a national tertiary specialist center in Singapore were reviewed. Patients with cleft lip and palate or syndromes were excluded. RESULTS: The mean age (range: 16 to 58 years) of the patients was 24.0 years (SD 6.4) and the ratio of female to male was 1.3:1. The predominant ethnic group was Chinese (91.5%). The majority of the patients had skeletal Class III pattern (68%). Asymmetry was diagnosed in 36% of all cases and in 48% of skeletal Class III cases. Vertical maxillary excess was diagnosed in 21% of all cases and in 47% of skeletal Class II cases. Bimaxillary surgery involving LeFort and bilateral sagittal split osteotomies was performed in 84% of skeletal Class III cases and in 73% of all cases. Segmental osteotomy and genioplasty were performed in 41% of the cases. CONCLUSIONS: The findings suggest that the majority of the patients were young Chinese adults with two-jaw deformities requiring bimaxillary surgeries with genioplasty or segmental osteotomy. This finding may reflect the greater severity of dentofacial deformities in patients in the Asian community.

Corrigendum to "A Study of Success Rate of Miniscrew Implants as Temporary Anchorage Devices in Singapore".

[This corrects the article DOI: 10.1155/2015/294670.].

Soft and hard tissue changes after bimaxillary surgery in Chinese Class III patients.

Cephalometric studies have shown that the Chinese race tends to have a greater preponderance of skeletal Class III malocclusion. It has also been reported that the soft tissue response to hard tissue movement varies among racial types. The aims of this retrospective cephalometric study were to assess the results of bimaxillary surgery on Chinese subjects presenting with Class III malocclusions and to evaluate the correlation between soft and hard tissue change. The sample consisted of 34 Chinese patients treated with bilateral sagittal split osteotomy and Le Fort I advancement. Lateral cephalograms were taken immediately before surgery and at least six months after surgery. Soft and hard tissue changes were recorded by computer-supported measurements of presurgical and postsurgical lateral cephalograms. Linear regression procedures were used to assess the degree of correlation in terms of soft to hard tissue changes between the two cephalograms. The results showed that there was normalization of the cephalometric variables after surgery. Mandibular soft and hard tissue movements showed a strong correlation in the horizontal direction and a moderate correlation in the vertical direction. Maxillary soft and hard tissue movement showed a moderate to weak correlation in both the horizontal and vertical directions. The ratios of soft to hard tissue movements derived from this study would contribute to the database for planning prediction.

Appropriateness of orthodontic referrals: self-perceived and normative treatment needs of patients referred for orthodontic consultation.

OBJECTIVES: The aims of this prospective study were to evaluate the self-perceived and normative orthodontic treatment needs of children referred for orthodontic consultation and to determine the proportion of children who were inappropriately referred. METHODS: The sample consisted of 257 children with a mean age of 12.0 years (SD = 2.4). An orthodontist assessed the children's normative treatment need using the dental health component (DHC) of the index of orthodontic treatment need (IOTN), and for patients in the mixed dentition the need for interceptive treatment was assessed. Questionnaires were answered by both the child and the parent to assess satisfaction with dental appearance and desire for treatment. RESULTS: The distribution of the IOTN grades showed that 73% of the children had definite need while 27% had borderline/no need for orthodontic treatment. Twenty-six per cent of children and 17% of parents did not express orthodontic concern, even though more than half of these children were in definite need of treatment as assessed by IOTN. The children's orthodontic concern was significantly related to the DHC scores. Out of the 103 children who were in the mixed dentition, only about 16% required interceptive treatment. CONCLUSIONS: The results indicated that a significant number of children were inappropriately referred for orthodontic treatment. Referring dentists need to assess the normative treatment needs of the children as well as the children's and parents' commitment and desire for orthodontic treatment before deciding on the need for referral.

Use of the apically repositioned flap in the management of labially impacted maxillary central incisors.

Management of labially impacted maxillary central incisors often requires a coordinated surgical and orthodontic approach. In such cases, the treatment objective is surgical exposure of the unerupted incisor, preferably with a functional width of keratinized gingiva on the labial surface. Tooth exposure is then followed by orthodontic intervention to move the tooth to the line of occlusion. This paper describes three cases where the apically repositioned flap technique was used to manage labially impacted maxillary central incisors.

Orthodontic-surgical management of an impacted dilacerated maxillary central incisor: a clinical case report.

Dilaceration is one of the causes of maxillary central incisor eruption failure. Surgical excision is frequently the first choice of treatment for a severely dilacerated incisor. In this article, the case of a horizontally impacted and dilacerated maxillary central incisor was diagnosed and treated by surgical exposure using the apically repositioned flap technique combined with orthodontic traction. The dilacerated incisor was successfully moved into alignment, with pulpal vitality and periodontal health present 2 years following treatment.

Professional assessment of facial profile attractiveness.

INTRODUCTION: The aim of this study was to compare the assessments of Chinese facial profile attractiveness by orthodontists and oral surgeons. METHODS: The sample comprised 31 dental professionals (20 orthodontists, 11 oral surgeons) in an Asian community. Facial profile photographs and lateral cephalometric radiographs of 2 Chinese adults (1 man, 1 woman) with normal profiles, Class I incisor relationships, and Class I skeletal patterns were digitized. The digital images were modified by altering cephalometric skeletal and dental hard tissue Chinese normative values in increments of 2 standard deviations in the anteroposterior plane to obtain 7 facial profiles for each sex. The images were bimaxillary protrusion, protrusive mandible, retrusive mandible, normal profile (Class I incisor with Class I skeletal pattern), retrusive maxilla, protrusive maxilla, and bimaxillary retrusion. The Mann-Whitney U test was used to determine professional differences in assessment. Multiple regression analysis was performed with age, professional status, sex, and number of years in practice as independent variables. RESULTS AND CONCLUSIONS: A strong correlation was found in the profile assessment between orthodontists and oral surgeons. Normal and bimaxillary retrusive Chinese male and female profiles were judged to be highly attractive by orthodontists and oral surgeons. Chinese male and female profiles with protrusive mandibles were judged the least attractive. There was a difference in professional opinion about the most attractive male profile (P < .05), with orthodontists preferring a flatter profile and oral surgeons preferring a fuller normal Chinese profile. Sex of dental professionals and number of years in clinical practice were found to affect profile rankings.

A comparative assessment of the perception of Chinese facial profile esthetics.

INTRODUCTION: The aim of this study was to compare the perception of male and female Chinese facial profile esthetics between dental professionals, dental students, and laypersons. MATERIAL: The sample comprised 31 dental professionals (20 orthodontists, 11 oral surgeons), 92 dental students, and 152 laypersons in an Asian community. The facial profile photographs and lateral cephalometric radiographs of a Chinese man and a woman, each with a normal profile, a Class I incisor relationship, and a Class I skeletal pattern, were digitized. The digital images were modified to obtain 7 facial profiles for each sex. The images were constructed by altering cephalometric skeletal and dental hard tissue Chinese normative values by 2 standard deviations in the anteroposterior plane only. The 7 profiles were (1) bimaxillary protrusion, (2) protrusive mandible, (3) retrusive mandible, (4) normal profile (Class I incisor with Class I skeletal pattern), (5) retrusive maxilla, (6) protrusive maxilla, and (7) bimaxillary retrusion. RESULTS: Normal and bimaxillary retrusion Chinese male and female profiles were perceived to be highly attractive by all 3 groups. Profiles with a protrusive mandible were perceived to be the least attractive. Dental professionals, dental students, and laypersons were highly correlated for the perception of male (r > 0.67) and female (r > 0.93) profile esthetics. All correlation coefficients were found to be significant for the perception of female profiles, but, for male profiles, only the correlation coefficient between dental students and laypersons was significant. CONCLUSIONS: Chinese male and female profiles that were normal or had bimaxillary retrusion were perceived to be highly attractive by dental professionals, dental students, and laypersons, and profiles with a protrusive mandible were perceived to be the least attractive. Dental students and laypersons were more tolerant of a male profile with a retrusive mandible than were dental professionals, and all groups were more tolerant of bimaxillary protrusion in women than in men. Dental professionals, dental students, and laypersons had a similar trend in male and female esthetic preferences. The perception of female profiles by all 3 groups was highly and significantly correlated. Only the perception of male esthetics by dental students and laypersons was not significantly correlated with dental professionals.

Predictability of soft tissue profile changes following bimaxillary surgery in skeletal class III Chinese patients.

PURPOSE: The aim of this study was to evaluate the accuracy of soft tissue profile predictions generated by a recently developed computer program (Computer-Assisted Simulation System for Orthognathic Surgery [CASSOS] 2001, SoftEnable Technology, Ltd, Hong Kong) in Chinese skeletal Class III patients treated with bimaxillary surgery. MATERIALS AND METHODS: Presurgical and posttreatment lateral cephalograms of 35 Chinese patients who had combined 1-piece Le Fort I and bilateral sagittal split osteotomies were digitized using the CASSOS 2001 program, and a cranial base superimposition was performed. The hard tissue movements were simulated on the presurgical cephalogram until good superimposition of the hard tissues on the presurgical and posttreatment cephalograms was achieved. A customized cephalometric analysis consisting of 32 linear measurements was used to analyze the differences in the soft tissue profile between the actual posttreatment results and the computer-generated predictions. RESULTS: Comparison of the predicted and actual changes found that 16 of the 32 soft tissue measurements were significantly different ( P <.05). Most of the significant prediction errors were observed in the upper and lower lip region. The software tended to underestimate the vertical position of both the upper and lower lip and overestimate the horizontal position of the lower lip. However, the mean differences were relatively small, with the greatest mean difference being 2 mm in the vertical position of stomium inferius. The CASSOS 2001 program produced a clinically useful prediction of soft tissue profile changes following bimaxillary surgery in skeletal Class III Chinese patients.