[Growth disturbances of the temporomandibular joint: causes, diagnosis and treatment]. / Groeistoornissen van het kaakgewricht: oorzaken, diagnose en behandeling.

Growth disturbances of the temporomandibular Joint are characterized by mandibular asymmetry, sometimes with secondary maxillar disturbances. Although the clinical symptoms are sometimes quite severe, patients usually have no pain. There are several growth disturbances, but in this article we discuss three particular causes of facial asymmetry, namely hemimandibular growth defects; overdevelopment, underdevelopment and neoplasms of the mandibular joint. Hemimandibular overdevelopment (hyperplasia) is a growth disorder characterized by progressive asymmetry of the mandibula. Hemimandibular hypoplasia, on the other hand, is a growth disorder involving underdevelopment of the condyle mandibulae due to impingement of the growth center and ankylosing. A pronounced asymmetrical face can cause aesthetic problems and always requires diagnostics, because in addition to the hyperplasia and hypoplasia mentioned above, other causes can explain the asymmetry such as, for example, an osteoarthritis or even a tumor emanating from the base of the skull, mandibula or soft tissues.

Facial Asymmetry Caused by Mandibular Condylar Hyperplasia: A Two Center Study.

BACKGROUND: Condylar hyperplasia is a non-neoplastic overgrowth of the mandibular condyle. The disorder is progressive and causes gradual jaw deviation, facial asymmetry, and dental malocclusion. The only treatment capable of stopping hyperplastic growth is surgical condylectomy to remove the upper portion of the condyle containing the deranged growth center. When this procedure is conducted in proportion to the length of the healthy side it may also correct the jaw deviation and facial asymmetry. OBJECTIVES: To assess the degree to which condylectomy corrects the asymmetry and to determine the proportion of patients after condylectomy who were satisfied with the esthetic result and did not desire further corrective surgery. METHODS: We conducted a retrospective analysis of medical records of patients who underwent condylectomy that was not followed by corrective orthognathic surgery for at least 1 year to determine the degree of correction of chin deviation and lip cant. Patient satisfaction from treatment or desire and undergo further corrective surgery was reported. RESULTS: Chin deviation decreased after condylectomy from a mean of 4.8° to a mean of 1.8° (P < 0.001). Lip cant decreased after condylectomy from a mean of 3.5° to a mean of 1.5° (P < 0.001). Most patients (72%) were satisfied with the results and did not consider further corrective orthognathic surgery. CONCLUSIONS: Proportional condylectomy could be a viable treatment to both arrest the condylar overgrowth and achieve some correction of the facial asymmetry.

Establishment of the mid-sagittal reference plane for three-dimensional assessment of facial asymmetry: a systematic review : Establishment of the mid-sagittal reference plane: a systematic review.

OBJECTIVE: To systematically review the literature for mid-sagittal plane establishment approaches to identify the most effective method for constructing the mid-sagittal plane for the evaluation of facial asymmetry. MATERIALS AND METHODS: Six electronic databases (PubMed, Medline (via Ovid), EMBASE (via Ovid), Cochrane Library, Web of Science, and Scopus) and grey literature were searched for the studies that computed the mid-sagittal reference plane three-dimensionally, using a combination of MeSH terms and keywords. The methodological quality and the level of evidence for the included studies were analyzed using QUADAS-2 and GRADE, respectively. RESULTS: The preliminary search yielded 6746 records, of which 42 articles that met the predefined inclusion criteria were included in the final analysis. All the included articles reported the construction of the mid-sagittal reference plane (MSP) using varied methods. The risk of bias and concerns regarding the applicability of the included studies were judged to be 'low'. The level of evidence was determined to be 'low' for the effectiveness of the technique and 'moderate' for the ease of clinical applicability. CONCLUSION: Despite methodological heterogeneity, this review substantiates the comparable efficacy of cephalometric and morphometric MSP construction methods. A fully automated morphometric MSP holds promise as a viable option for routine clinical use. Nevertheless, future prospective studies with an emphasis on the impact, accuracy, and clinical applicability of MSP construction techniques in cases of facial asymmetry are required. CLINICAL RELEVANCE: The present review will assist clinicians in selecting the most suitable method for MSP construction, leading to improved treatment planning and ultimately more favorable treatment outcomes.

Mandibular condyle volumes are associated with facial asymmetry in patients with cleft lip and palate: A retrospective cohort study.

This study compares condylar volumetric asymmetry and facial asymmetry in patients with cleft lip and/or palate (CLP) and controls. The mandibular condyle is important to facial growth, but its role in facial asymmetry for those with CLP has not been described. Condylar volumes and mandibular asymmetry were retrospectively calculated using Mimics Version 23.0 (Materialise, Leuven, Belgium) from patients with CLP undergoing computed tomography (CT) imaging and a cohort of controls. A total of 101 participants, 60 with CLP and 41 controls, had mean condylar volumetric asymmetry of 16.4 ± 17.4 % (CLP) and 6.0 ± 4.0 % (controls) (p = 0.0002). Patients with CLP who had clinically significant chin deviation (>4 mm) had more asymmetric condyles than those without significant chin deviation (p = 0.003). The chin deviated toward the smaller condyle in patients with facial asymmetry more often than in patients without facial asymmetry (81 % vs. 62 %, p = 0.033). While controls had some degree of condylar asymmetry, it tended to be milder and not associated with facial asymmetry. There is a greater degree of condylar volumetric asymmetry in patients with CLP compared to individuals in the general population. Clinically significant facial asymmetry in CLP is associated with a higher degree of condylar asymmetry, with the facial midline deviating toward the smaller condyle.

Facial asymmetry of the hard and soft tissues in skeletal Class I, II, and III patients.

To investigate and compare the facial asymmetry (hard and soft tissues) among skeletal Class I, II, and III patients. A total of 221 subjects, including skeletal Class I (n = 80), skeletal Class II (n = 75), and skeletal Class III (n = 66), were included in the study. CBCT, 22 skeletal landmarks, and 10 soft tissue landmarks were used for the measurements and the asymmetry index was calculated to assess the facial asymmetry. Statistical analyses included one-way ANOVA, Kruskal-Wallis test, and Spearman correlation analysis. The skeletal Class III patients presented greater asymmetry than Class II patients for 10 hard tissue landmarks and 3 soft tissue landmarks (p < 0.05). High correlation of asymmetry was found between four soft tissue landmarks and their corresponding skeletal landmarks (rs ≥ 0.71), as well as Me and ANS (r > 0.86). The ANS and Me in 21.3% patients deviated to contralateral sides. The skeletal Class III patients had more facial asymmetry than the Class II patients. Soft tissues showed similar asymmetry as the underlying hard tissues rather than a compensation of the hard tissue asymmetry. The inconsistency in the deviation of Me and ANS may exacerbate facial asymmetry.

Using craniofacial fluctuating asymmetry to examine the effects of sex, socioeconomic status, and early life experiences on adult age at death in industrial England.

OBJECTIVES: Historical evidence from 18th- and 19th-century England suggests that industrialization's impacts on health were largely negative, especially among marginalized groups. However, available documentary evidence is often biased toward adult men and rarely sheds light on the experiences of other members of the population, such as women and children. Craniofacial fluctuating asymmetry (FA) can serve as a proxy measurement of developmental instability and stress during development. This study examines the associations among age, sex, socioeconomic status (SES), and FA in skeletal samples from industrial-era England. MATERIALS AND METHODS: The sample for this study comes from four industrial-era cemeteries from England (A.D. 1711-1857). Geometric morphometric analyses of three-dimensional landmark coordinate data were used to generate a measure of FA for each individual (Mahalanobis distance). A three-way ANOVA was used to evaluate the impacts of sex, SES, and FA scores on adult age at death (n = 168). RESULTS: Significant associations existed between age at death and SES (p = 0.004) and FA scores (p = 0.094). Comparisons of the estimated means indicated that age at death was consistently higher among high SES individuals and individuals with FA scores less than one standard deviation from the mean. CONCLUSIONS: This study supports findings from previous studies that have suggested that the differences in resource access and environmental buffering generated by socioeconomic inequality can impact longevity and patterns of mortality among socioeconomic status groups. Likewise, stress in early life-evinced by craniofacial fluctuating asymmetry-can influence observed patterns of longevity in adults decades later.

[Preliminary evaluation of chin symmetry with three dimentional soft tissue spatial angle wireframe template].

OBJECTIVE: To develop an efficient and robust method based on three dimensional facial landmarks for evaluating chin region asymmetry at the soft tissue level and to compare it with the traditional mirror-overlap analysis method in order to test its availability. METHODS: Standard symmetrical face was used for mental tubercle coordinate transformation so as to filter soft tissue three dimensional spatial angle and construct corresponding three dimensional spatial angle wireframe template. Ten patients aged 12-32 years with clinical chin region asymmetry diagnosis at the Department of Orthodontics of Peking University Hospital of Stomatology from November 2020 to November 2021 were randomly selected. Three dimensional soft tissue face scan data of the patients were collected by three dimensional face scanner and the landmark points were automatically determined by the Meshmonk non-rigid registration algorithm program, and in this way, the asymmetric three dimensional spatial angle wireframe template and corresponding spatial angle parameters were generated. Mirror-overlap analysis of face scan data was also performed in Geomagic Studio 2015 software and deviation color maps were generated. This study took mirror-overlap analysis as the gold standard method, the response rate of chin region asymmetry was eva-luated by the outcomes of the mirror-overlap analysis and three dimensional spatial angle wireframe template analysis. RESULTS: Nine three dimensional spatial angle indicators were selected through coordinate transformation, and the response rate was calculated using mirror-overlap analysis as the gold standard method. Among these ten selected patients, the response rate of the total chin region asymmetry was 90% (9/10). Using the deviation value of mirror-overlap analysis as a reference, the response rate of chin region asymmetry in the X dimension was 86%, the response rate of chin region asymmetry in the Y dimension was 89%, and the response rate of chin region asymmetry in the Z dimension was 100%. CONCLUSION: The three dimensional soft tissue spatial angle wireframe template proposed in this study has some feasibility in evaluating chin region asymmetry at the soft tissue level, and its ability to recognize asymmetry separately in the three dimensional direction is better than the mirror-overlap analysis method, and the indicators recognition rate still needs to be further improved.

Skeletal facial asymmetry: reliability of manual and artificial intelligence-driven analysis.

OBJECTIVES: To compare artificial intelligence (AI)-driven web-based platform and manual measurements for analysing facial asymmetry in craniofacial CT examinations. METHODS: The study included 95 craniofacial CT scans from patients aged 18-30 years. The degree of asymmetry was measured based on AI platform-predefined anatomical landmarks: sella (S), condylion (Co), anterior nasal spine (ANS), and menton (Me). The concordance between the results of automatic asymmetry reports and manual linear 3D measurements was calculated. The asymmetry rate (AR) indicator was determined for both automatic and manual measurements, and the concordance between them was calculated. The repeatability of manual measurements in 20 randomly selected subjects was assessed. The concordance of measurements of quantitative variables was assessed with interclass correlation coefficient (ICC) according to the Shrout and Fleiss classification. RESULTS: Erroneous AI tracings were found in 16.8% of cases, reducing the analysed cases to 79. The agreement between automatic and manual asymmetry measurements was very low (ICC < 0.3). A lack of agreement between AI and manual AR analysis (ICC type 3 = 0) was found. The repeatability of manual measurements and AR calculations showed excellent correlation (ICC type 2 > 0.947). CONCLUSIONS: The results indicate that the rate of tracing errors and lack of agreement with manual AR analysis make it impossible to use the tested AI platform to assess the degree of facial asymmetry.

Children's Visual Perception of Facial Scarring and Cleft Lip Deformity Using Eye Tracking Data.

OBJECTIVE: The purpose of this study is to determine children's perception of secondary cleft lip deformity (SCLD) using objective eye tracking technology and subjective responses on a survey to understand pediatric perceptions of facial scarring. DESIGN: Cross-sectional study of participants aged 5-17 years old. METHODS: Participants viewed images of children's faces with an eye tracking device. Sixteen images were displayed, 12 with unilateral SCLD and four with no facial scarring. Eye tracking data were obtained. Gaze samples were analyzed for areas of interest (AOIs). Immediately after viewing each image, participants answered two survey questions relating to facial asymmetry attitude toward the child pictured. For analysis, participants were divided into age groups. RESULTS: A total of 259 participants were enrolled (42.5% female). Mean age was 10.5 years and 78% identified as White. In all age groups, total fixation time was greater for SCLD compared to control images. Early elementary age children spent significantly less time assessing the nose AOI compared to other groups, and also spent the least total fixation time and had the lowest visit count on all AOIs. Subjective survey questions showed similar trends with elementary age not noticing facial asymmetry compared to older age groups. CONCLUSION: This study demonstrates the successful use of eye tracking technology in children as young as 5 years old. This study suggests that SCLD is perceived as less noticeable in elementary age children and becomes more noticeable to older groups. Understanding peer perception on SCLD from this study may impact decision on revision surgery for SCLD. LEVEL OF EVIDENCE: IV Laryngoscope, 134:2726-2733, 2024.

Three-dimensional analysis of mandibular morphology asymmetry and temporomandibular joint position in patients with unilateral Brodie bite.

OBJECTIVE: Previous studies have shown unilateral posterior crossbite is associated with mandibular asymmetry in morphology and position. However, it remains unclear whether unilateral Brodie bite plays a similar role in mandibular development. Therefore, this study aims to investigate the morphological and positional symmetry of mandibles in patients with unilateral Brodie bite by three-dimensional anaylsis. METHODS: Fourteen patients with unilateral Brodie bite (mean age 18.43 ± 4.24 years) and fourteen sex- and age-matched patients with normal occlusion (mean age 18.07 ± 5.48 years) underwent cone-beam computed tomography (CBCT) scans. 3D surface mesh models of their mandibles were established using Mimics Research 19.0. The surface matching percentage was compared between the original and mirrored mandible by Geomagic Control X software. Furthermore, the dimension and position of the temporomandibular joint (TMJ) were determined for both groups using InVivoDental 5.0. RESULTS: For surface-to-surface deviation analysis, the percentage of mismatch in patients with unilateral Brodie bite was significantly higher than the control group at ±0.50 mm, ±0.75 mm, and ±1.00 mm tolerance (P < .001). In patients with unilateral Brodie syndrome, the condyles on the scissors-bite side showed a significantly more anterior position (P = .03), greater medial inclination (P < .01), and larger posterior TMJ space (P = .01) than the non-scissors-bite side. CONCLUSION: Patients with unilateral Brodie bite exhibit a more asymmetrical mandibular morphology, with a greater anterior condylar position and posterior joint space on the scissors-bite side, indicating that early diagnosis and treatment may be necessary for patients with unilateral Brodie bite.

Photoanthropometric craniofacial parameters in individuals with osteogenesis imperfecta / Parámetros craneofaciales fotoantropométricos en personas con osteogénesis imperfecta

Background: This study aimed to evaluate facial photoanthropometric parameters in patients with OI.Material and Methods: We selected 20 Brazilian patients diagnosed with OI treated at the Extension Service forMinors in Need of Specialized Treatment of the Dentistry Course at the Federal University of Ceará (Fortaleza,Brazil), of both sexes, without age restriction, and able to understand and sign the informed consent form (ICF).As a control group, 38 non-syndromic Brazilian individuals, categorized as ASA I, able to understand and sign theICF, matched by sex, age, and Legan and Burstone facial profile were selected. The exclusion criteria were: previ-ous orthodontic treatment, craniofacial trauma and/or surgery, and the presence of any other systemic diseases.Photoanthropometric analysis of the 18 facial parameters proposed by Stengel-Rutkowski et al. (1984), previouslyestablished in the literature for craniofacial syndromes, were conducted. A single examiner digitally performedall effective and angular measurements with the CorelDRAWX7® software.Results: Horizontally shortened ears (p<0.001) but larger in height in relation to the face (p=0.012) were shownto be alterations belonging to individuals with OI.Conclusions: OI patients present distinct photoanthropometric parameters inherent in this condition.(AU)

A proposed protocol for correlation between bone density in hemimandibular hyperplasia radiography and histopathological findings - A retrospective study.

The role of low-dose computed tomography (LDCT) in surgical planning can be assessed based on the correlation among bone density (BD/HU), radiographic values, and the histopathological appearance of hyperplastic overgrowth in mandibular condyles (hemimandibular hyperplasia/osteochondroma). The aim of this study was to evaluate the correlation between LDCT indices of bone-density measurements in surgical planning and histopathological specimens. The patients incuded in this study underwent detailed radiological evaluation as preparation for further clinical procedures. Excised condyles were evaluated in terms of bone density index using LDCT, and then histopathologically to investigate the accuracy of surgical procedures and set the basis for future surgical planning. An index value between both condyles' bone densities represented the relative difference between the healthy condyle and the side with hemimandibular hyperplasia (HH). Patients with unilateral condylar hyperplasia (UCH) showed a statistical correlation between condyle heads with increased bone density (BD) and scintigraphic (SCI) values (p < 0.001). On the other hand, correlation between BD and histopathological studies alone was significant (p < 0.001). With the increase in BD measured in HU in UCH condyles, the overall value of fibrous cartilage layer thickness decreased (p < 0.001). Furthermore, histopathological evaluation indicated that increased bone density on the UCH side resulted in increased total thickness (p > 0.001). The proposed index measurements in the mandibular condyles based on LDCT/BD can be used to estimate the degree of required surgical resection. Results from LDCT radiographic studies correlate with histopathological specimens more than scintigraphy.

Esthetic Surgery of the Chin in Cis- and Transgender Patients-Application of T-Genioplasty vs. Single-Piece Segment Lateralization.

Background and Objectives: Correction of lower face asymmetry still remains challenging in maxillofacial surgery. This report describes techniques for the lateral transposition of the symphyseal segment to restore lower face symmetry while maintaining gender-related features in cis- and transgender patients. Materials and Methods: A retrospective review of medical records of 31 patients who attended for esthetic corrective surgery after orthodontic camouflage or orthognathic treatment, or during facial feminization of the lower face between June 2021 and June 2023 was performed. Result: All patients underwent lateralization genioplasty (with or without advancement or setback), either with or without narrowing T-osteotomy supplemented with necessary procedures in order to obtain proper facial balance and desired esthetical effects, such as bichectomy, liposuction, and face and neck lift. The mean asymmetry of the chin was 5.15 mm and was surgically corrected either by single segment lateralization or T-shape narrowing genioplasty depending on the gender and esthetical requirements. No complications were reported. Conclusions: Lateral shift genioplasty serves as a powerful tool in primary and secondary corrective surgery for lower face asymmetry that maintains gender-specific facial features. It may serve either as an additive to orthodontic camouflage or a way to correct previous orthognathic surgery pitfalls. The surgeon performing esthetic genioplasty associated with gender-specific expectations must be trained in facelift and facial liposculpting techniques in order to provide the best results and properly choose the right procedures for the right patients.

Three-dimensional Analysis of the Temporal Bone Morphology in Patients with Craniofacial Microsomia.

OBJECTIVE: To characterise the morphology of temporal bone in patients with craniofacial microsomia (CFM). DESIGN: A retrospective study. SETTING: A craniofacial centre. PATIENTS: Ninety-four patients with unilateral craniofacial microsomia. INTERVENTIONS: Mimics 21.0 (Materialise Inc., Belgium) was used to locate temporal bone landmarks on preoperative computed tomography data. The spatial Cartesian coordinate system was established in 3-matic 13.0 (Materialise Inc., Belgium). The coordinates of each landmark and the distances and angles between the landmarks were calculated. A classification system was used to quantify the severity of the zygomatic arch deformity. MAIN OUTCOME MEASURE(S): The bilateral differences in coordinates, linear and angular measurements, and the severity of temporal bone deformity (TTL δ, Psag δ, Paxiδ, and Tsag δ) among the groups were compared using the paired t-test and Kruskal-Wallis test, respectively. RESULTS: Compared to those of the unaffected side, the landmarks of the inner ear and petrous part on the affected side showed a decrease in the Z-coordinate or an increase in the X-coordinate. A superolateral rotation tendency of the temporal bone on the affected side was found. There were no significant differences in the linear and angular measurements between the groups. The degree of zygomatic arch deformation was lower in the mild group; however, no significant difference was found between the moderate and severe groups. CONCLUSIONS: In patients with CFM, asymmetry of the temporal bone and its inner organs (vestibulocochlear organ, facial nerve, and vessels) exists in multiple dimensions; its severity is not completely consistent with the degree of mandibular involvement.

Impaired face symmetry detection under alcohol, but no 'beer goggles' effect.

BACKGROUND: The 'beer goggles' phenomenon describes sexual attraction to individuals when alcohol intoxicated whom we would not desire when sober. One possible explanation of the effect is that alcohol impairs the detection of facial asymmetry, thus lowering the drinker's threshold for physical attraction. AIMS: We therefore tested the hypotheses that higher breath alcohol drinkers would award more generous ratings of attractiveness to asymmetrical faces, and be poorer at discriminating bilateral facial asymmetry than less intoxicated counterparts. METHODS: Ninety-nine male and female bar patrons rated 18 individual faces for attractiveness and symmetry. Each type of rating was given twice, once per face with an enhanced asymmetry and once again for each face in its natural form. Participants then judged which of two same-face versions (one normal, the other perfectly symmetrised) was more attractive and, in the final task, more symmetrical. RESULTS: Alcohol had no influence on attractiveness judgements but higher blood alcohol concentrations were associated with higher symmetry ratings. Furthermore, as predicted, heavily intoxicated individuals were less able to distinguish natural from perfectly symmetrised face versions than more sober drinkers. CONCLUSIONS: Findings therefore suggest alcohol impairs face asymmetry detection, but it seems that this perceptual distortion does not contribute to the 'beer goggles' phenomenon.

The impact of dental midline angulation towards the facial flow curve on the esthetics of an asymmetric face: Perspective of laypeople and orthodontists.

PURPOSE: The objective of the present article was to evaluate the impact of dental midline angulation in asymmetrical faces. MATERIALS AND METHODS: A full-portrait image was used to create a set of digitally modified images with a different degree of facial asymmetry, towards the right and the left side of the face respectively. Half of the images were designed with an equivalent angulation of the dental midline in respect to the curve of the lower third of the face and half of them without. Through a web survey, 250 laypeople and 250 orthodontists were asked to assess the attractiveness of each image separately. RESULTS: As the asymmetry of the face was increased, facial attractiveness was further decreased both for laypersons and orthodontists. For each one of the modified images, when the dental midline was following the curve that was formed from the inclination of the simulated asymmetry of the face, the smile attractiveness scores were significantly higher compared to a straight dental midline. CONCLUSION: Facial asymmetries derived from the inclination of the nose, the chin and the commissural line of the lips can significantly affect the smile attractiveness. An orientation of the dental midline towards the facial asymmetry in order to follow the facial curve, can be beneficial for the smile attractiveness compared to a perpendicular to the face dental midline. During the design of a smile, clinicians have to take into consideration deviations in facial midline, in order their restorations to be in harmony with the rest of the face. CLINICAL SIGNIFICANCE: During the design of a smile, clinicians have to take into consideration deviations in the facial midline, in order their restorations to be in harmony with the rest of the face.

Deep Learning-based Assessment of Facial Asymmetry Using U-Net Deep Convolutional Neural Network Algorithm.

OBJECTIVES: This study aimed to evaluate the diagnostic performance of a deep convolutional neural network (DCNN)-based computer-assisted diagnosis (CAD) system to detect facial asymmetry on posteroanterior (PA) cephalograms and compare the results of the DCNN with those made by the orthodontist. MATERIALS AND METHODS: PA cephalograms of 1020 patients with orthodontics were used to train the DCNN-based CAD systems for autoassessment of facial asymmetry, the degree of menton deviation, and the coordinates of its regarding landmarks. Twenty-five PA cephalograms were used to test the performance of the DCNN in analyzing facial asymmetry. The diagnostic performance of the DCNN-based CAD system was assessed using independent t -tests and Bland-Altman plots. RESULTS: Comparison between the DCNN-based CAD system and conventional analysis confirmed no significant differences. Bland-Altman plots showed good agreement for all the measurements. CONCLUSIONS: The DCNN-based CAD system might offer a clinically acceptable diagnostic evaluation of facial asymmetry on PA cephalograms.

Helical distraction is superior to linear and circular distraction in mandibular distraction osteogenesis: an in silico study.

Helical mandibular distraction is theoretically better than linear or circular distraction. However, it is not known whether this more complex treatment will result in unquestionably better outcomes. Therefore, the best attainable outcomes of mandibular distraction osteogenesis were evaluated in silico, given the constraints of linear, circular, and helical motion. This cross-sectional kinematic study included 30 patients with mandibular hypoplasia who had been treated with distraction, or to whom this treatment had been recommended. Demographic information and the computed tomography (CT) scans showing the baseline deformity were collected. The CT scans of each patient were segmented and three-dimensional models of the face created. Then, the ideal distraction outcomes were simulated. Next, the most favorable helical, circular, and linear distraction movements were calculated. Finally, errors were measured: misalignment of key mandibular landmarks, misalignment of the occlusion, and changes in intercondylar distance. Helical distraction produced trivial errors. In contrast, circular and linear distractions resulted in errors that were statistically and clinically significant. Helical distraction also preserved the planned intercondylar distance, while circular and linear distractions led to unwanted changes in the intercondylar distance. It is now evident that helical distraction offers a new strategy to improve the outcomes of mandibular distraction osteogenesis.