Introduction
The aims of this study were to evaluate, using 3-dimensional superimposition techniques, the skeletal changes in Class II subjects with different vertical facial patterns treated with the Herbst appliance and to compare these skeletal changes to those of Class II controls treated with elastics.
Methods
Sixteen Herbst patients who met the inclusion criteria were divided into 2 equal groups based on vertical facial pattern as determined by the Frankfort mandibular plane angle (brachyfacial, ≤22°; mesofacial, 23°-29°) and had cone-beam computed tomographs taken before treatment, 8 weeks after Herbst appliance removal, and after subsequent fixed appliance treatment. Eleven Class II control patients treated with fixed appliances and elastics had cone-beam computed tomographs taken before and after treatment. Three-dimensional models were generated from the cone-beam computed tomography images, registered on the anterior cranial bases, and analyzed using color maps and point-to-point measurements.
Results
There were minimal differences in treatment response between the 2 Herbst groups across all skeletal parameters measured. The Herbst subjects showed a greater inferior displacement of anterior nasal spine compared with the Class II controls (Herbst brachyfacial, −1.44 mm; Herbst mesofacial, −1.95 mm) with other maxillary changes being clinically insignificant. The Herbst subjects showed greater inferior displacement of B-point compared with the Class II controls (Herbst brachyfacial, −2.59 mm; Herbst mesofacial, −2.75 mm). There were no statistically significant differences in mean linear mandibular measurements. All groups showed a trend toward posterior displacement of the condyles and glenoid fossae from the start to the end of treatment, with no significant differences across the 3 groups. There were minimal differences in the changes in gonial angle and Frankfort mandibular plane angle across all groups.
Conclusion
Approximately 2 years after Herbst treatment, the Herbst subjects with different vertical facial patterns showed similar patterns of skeletal change compared with the Class II controls treated with elastics.
Highlights
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Three-dimensional data allow accurate evaluation of skeletal changes with the Herbst appliance.
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Differences in vertical facial pattern are proposed to modify treatment response.
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Minimal differences in maxillary change were found in the Herbst groups vs the control.
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Minimal differences in fossa remodeling were found in the Herbst groups vs the control.
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Minimal differences in mandibular change were found in the Herbst groups vs the control.
Management of Class II malocclusion in a growing person is a routine clinical challenge to orthodontists. Mandibular retrognathism is the predominant etiologic factor in the majority of these malocclusions.
Functional appliances have been used to correct Class II malocclusions through a combination of skeletal and dental changes, and the Herbst appliance is one of the most popular fixed functional appliances because it reduces the level of compliance required. However, despite the widespread use of the Herbst appliance, the exact mechanism of action, and its skeletal and dental effects, are unclear. There are claims of restriction of maxillary growth, forward positioning of the glenoid fossa, mandibular gonial angle changes, and stimulation of condylar growth, with variations of the skeletal component of Class II correction ranging from 13% to 85%.
There should be some certainty for any widely used appliance about the effects on the dentition and skeleton. The inconsistencies in reported treatment outcomes with the Herbst appliance may be because of differences in timing of treatment relative to peak growth, anatomic differences of the study subjects, and use of 2-dimensional cephalometric imaging that is subject to various errors, including the superimposition process, magnification differences, geometric distortion, patient positioning, and obstruction of anatomic structures. There can be bias in the superimposition process if the examiners are not blinded. Two-dimensional angular and linear cephalometric measurements do not adequately describe the complex 3-dimensional (3D) process of bone remodeling and skeletal change with growth and treatment. Now that 3D imaging is widely accessible and able to give a more detailed and accurate picture of the skeleton and dentition, it is incumbent on the orthodontic specialty to use the available tools to determine the real effects of treatment. There has been only 1 published pilot study examining 3D outcomes with the Herbst appliance, and few studies have examined the effects of the first phase of Herbst therapy followed by a further phase of fixed orthodontic appliances. A more detailed study with a larger sample is necessary to enable the specialty to learn more about the effects of the appliance in 3 dimensions. Our group gained access to 3D data of a number of Herbst patients, as well as similar data from patients treated with Class II elastics who could be used as matched controls.
Therefore, the aims of this study were to use 3D imaging and superimposition techniques to assess skeletal changes associated with Class II correction in growing children with different vertical facial patterns treated with the Herbst appliance followed by a subsequent phase of fixed appliances. The changes were compared with a matched group of Class II control patients. Maxillary positional changes, differences in mandibular growth, and condylar and glenoid fossa positional changes were evaluated.
Material and methods
Ethics approval for this retrospective study was obtained from the University of Melbourne Human Research Ethics Committee (ID: 1443363). All Herbst subjects were sourced from the office of a specialist orthodontist. The subjects were selected by searching the database for an item code denoting Herbst appliance insertion.
This retrospective cohort study used a convenience sample. The Herbst sample consisted of 16 patients and was divided on the basis of vertical facial pattern, as determined by the Frankfort mandibular plane angle (FMPA). The sample included 8 mesofacial (FMPA, 23°-29°) subjects (7 girls, 1 boy). The brachyfacial group (FMPA, <22°) also consisted of 8 subjects (4 girls, 4 boys). The sample size was limited by the number of available suitable records.
A control group of 11 deidentified, matched Class II control subjects ( Table I ) treated with Class II elastics was obtained from the University of North Carolina at Chapel Hill and the University of Michigan at Ann Arbor.
| Measurement | Herbst brachyfacial mean | SD | Herbst mesofacial mean | SD | Control mean | SD | P value |
|---|---|---|---|---|---|---|---|
| Age (y) | 13.36 | 0.58 | 12.74 | 0.85 | 13.73 | 0.82 | 0.03 ∗ |
| Sex | 4 female, 4 male | – | 7 female, 1 male | 6 female, 5 male | – | – | |
| Phase 1 duration (mo) | 7.21 | 1.41 | 7.93 | 2.23 | – | – | 0.46 |
| Phase 2 duration (mo) | 20.38 | 3.92 | 19.25 | 4.40 | – | – | 0.60 |
| Total treatment time (mo) | 27.59 | 4.31 | 27.18 | 5.78 | 22.81 | 8.69 | 0.25 |
| ANB (°) | 6.0 | 0.9 | 5.4 | 1.4 | 3.9 | 2.2 | 0.03 † |
| Pog-N perp (mm) | −2.4 | 4.4 | −3.8 | 6.1 | −3.8 | 3.6 | 0.83 |
| Gonial angle (Co-Go-Me) (°) | 118.1 | 3.9 | 127.1 | 5.6 | 122.8 | 4.9 | 0.003 ‡ |
| FMPA (°) | 18.3 | 4.1 | 27.9 | 1.4 | 24.5 | 5.0 | 0.0002 ‡ |
| Class II molar relationship (mm) | 6.6 | 1.5 | 6.3 | 1.5 | 4.6 | 1.4 | 0.01 § |
∗ Significant difference at P <0.05 for Herbst mesofacial vs control group only.
† Significant difference at P <0.05 for Herbst brachyfacial vs control group only.
‡ Significant difference at P <0.05 for Herbst brachyfacial group vs Herbst mesofacial and control group.
§ Significant difference at P <0.05 for Herbst brachyfacial group and Herbst mesofacial vs control group.
The Herbst appliance design consisted of stainless steel crowns fitted to the maxillary and mandibular permanent first molars. A cantilevered arm extended forward from the mandibular first molar to the level of the mandibular first premolar. A well-adapted 0.040-in stainless steel lingual arch connected the left and right mandibular molars, also incorporating an occlusal rest on the mandibular first premolar or second primary molar. A hyrax expansion screw was incorporated in all cases to expand the maxillary arch to accommodate the advanced position of the mandibular arch. The mandible was initially advanced by 5 mm and then progressively advanced in 2-mm increments to bring the incisors into an overcorrected edge-to-edge position. The mean Herbst treatment time in both groups was 7.6 months, which matched the Herbst protocols of other authors. When the incisor relationship did not allow the required advancement, as in Class II Division 2 subjects, limited maxillary fixed appliances were placed to procline the maxillary incisors before placement of the Herbst appliance.
No patient was treated with extractions, and extraoral traction was not used in the control sample.
A power calculation was undertaken using the SPSS statistical software package (version 22.0; IBM, Armonk, NY). This showed that 8 subjects in each group would provide 80% statistical power in detecting a 2-mm difference for mandibular length between the control and treatment groups, assuming a standard deviation of 1.99 mm and significance of P <0.05. This 2-mm difference was considered the threshold for clinical relevance. A pilot study found a 0.71 mm difference between comparable treatment and control groups; however, this difference was not clinically relevant.
Cone-beam computed tomography (CBCT) scans were taken before treatment (T1) for both the Herbst and the Class II control patients, and 8 weeks after completion of the Herbst phase (T2). The Herbst patients all had a subsequent period of fixed appliance treatment. A final CBCT scan was taken once the fixed appliances were removed (T3) for both the Herbst and control subjects. The Herbst and Class II control subjects’ scans were taken using an i-Cat machine (Imaging Sciences International, Hatfield, Pa) with a 16 × 22-cm field of view. All patients were instructed to bite in maximum intercuspation during the scan. Scans at all time points were evaluated to ensure that the condyles were seated in the center of the fossa, and subjects were excluded if the condyles were postured.
The original scans were taken at 0.3 to 0.4 mm 3 voxel size, and then the DICOM files were deidentified and downsized to a 0.5-mm 3 voxel size using 3D Slicer ( www.slicer.org ) to decrease the computational power and time for cranial base registration. A study evaluating CBCT accuracy showed no statistically significant difference in error measurements when the voxel size of the scan was changed from 0.2 to 0.3 to 0.4 mm 3 . ITK-SNAP ( www.itksnap.org ) was used to construct virtual 3D surface models. Scans at T1, T2, and T3 were registered on the anterior cranial base using a fully automated voxel-wise ridged registration technique.
The limits of the anterior cranial base registration were defined anteriorly by the inner cortical layer of the frontal bone, posteriorly by the anterior wall of sella, laterally including the lesser wings of the sphenoid bone, and superiorly including the frontal bone. This area included the cribriform plate and the superior aspect of the ethmoid bone. These structures cease growth by the age of 7 years and are therefore considered stable landmarks. Standardized head orientation of the registered 3D models was used to obtain a common coordinate system, allowing proper assessment of anteroposterior and vertical changes. This method has been shown to be accurate and reproducible.
Qualitative and quantitative assessments of treatment response and growth were calculated using 3D color maps and semitransparencies and point-to-point landmark identification.
Landmarks selected for this study are shown in the Supplementary Figure . Additional landmarks included the geometric center of the condyle, a point in the head of the condyle created by plotting the midpoint of a line joining the medial and lateral poles. Cephalometric landmark placement on 3D structures has been shown to be reproducible and accurate.
The point-to-point measurements are reported as either a 3D distance or a distance split into lateral (x), anteroposterior (y), and vertical (z) coordinates. In contrast to a previous pilot study by LeCornu et al, we chose to decompose some of the 3D landmark point-to-point changes into the 3 axes, because the clinical questions of this study required more precise information regarding the location and amount of changes in each direction. For the y-axis, positive values indicated anterior displacement, and negative values indicated posterior displacement. For the z-axis, positive values indicated superior displacement, and negative values indicated inferior displacement. The lateral (x) axis measurements are not reported due to the lack of clinical significance in this study.
The 2 Herbst groups differing in vertical facial pattern were compared 8 weeks after the appliance was removed (T1-T2) and after the next phase of fixed appliances (T2-T3). After fixed appliance therapy, the 2 Herbst groups were also compared with the Class II control group treated in a single phase with Class II elastics (T1-T3).
Qualitative assessments of maxillary, mandibular, and glenoid fossa skeletal changes at T1-T2, T2-T3, and T1-T3 were performed using color maps and semitransparent overlays of the superimpositions.
Subjects were restricted to adolescents treated near the peak of pubertal growth, as determined by cervical vertebral maturation assessment (stages 3 and 4). All subjects had Class II skeletal (ANB, >4°) and dental relationships (bilateral Class II molar relationships, each side >4 mm).
Subjects were excluded if they had early orthodontic treatment, craniofacial syndromes, or incomplete pretreatment and posttreatment records.
Statistical analysis
Parametric testing was used since the data were normally distributed. Data analysis was undertaken using the Minitab statistical software package (version 17; Minitab, State College, Pa). Means, standard deviations, and ranges were calculated for all subjects. Statistical differences were assessed using 1-way analysis of variance. The Fisher exact test was used to assess differences in skeletal changes between the Herbst and Class II control subjects. Repeated measurements of 10 subjects were made 8 weeks after the initial measurements by an examiner (A.A.), and Bland-Altman plots of the 95% limits of agreement were used to evaluate the reliability of the repeated measures ( Table II ).
| Variable | Mean | SD | P | Limits of agreement | |
|---|---|---|---|---|---|
| Low | High | ||||
| A-point anteroposterior axis (mm) | 0.00 | 0.12 | 0.98 | −0.24 | 0.24 |
| A-point superoinferior axis (mm) | −0.01 | 0.29 | 0.92 | −0.58 | 0.56 |
| ANS anteroposteror axis (mm) | 0.07 | 0.30 | 0.48 | −0.52 | 0.66 |
| ANS superoinferior axis (mm) | 0.11 | 0.66 | 0.62 | −1.18 | 1.39 |
| ANS-PNS (°) | 0.57 | 0.69 | 0.03 | −0.78 | 1.91 |
| Pogonion anteroposterior axis (mm) | 0.00 | 0.13 | 0.96 | −0.26 | 0.26 |
| Pogonion superoinferior axis (mm) | −0.22 | 1.12 | 0.55 | −2.41 | 1.97 |
| B-point anteroposterior axis (mm) | 0.04 | 0.14 | 0.43 | −0.24 | 0.31 |
| B-point superoinferior axis (mm) | −0.16 | 1.07 | 0.64 | −2.23 | 1.94 |
| Right mandibular length (mm) | 0.62 | 0.82 | 0.04 | −0.99 | 2.22 |
| Left mandibular length (mm) | −0.17 | 0.78 | 0.50 | −1.70 | 1.35 |
| Right ramus height (mm) | 0.03 | 0.81 | 0.91 | −1.55 | 1.62 |
| Left ramus height (mm) | −0.89 | 0.88 | 0.01 | −2.62 | 0.84 |
| Right corpus length (mm) | −0.43 | 1.48 | 0.39 | −3.32 | 2.47 |
| Left corpus length (mm) | −0.15 | 0.87 | 0.60 | −1.85 | 1.56 |
| Right gonial angle ( o ) | −0.01 | 2.27 | 0.99 | −4.46 | 4.43 |
| Left gonial angle ( o ) | −0.50 | 0.93 | 0.13 | −2.33 | 1.33 |
| Right FMPA ( o ) | 0.52 | 0.73 | 0.05 | −0.92 | 1.96 |
| Left FMPA ( o ) | 0.61 | 0.58 | 0.01 | −0.53 | 1.75 |
| Right condylion anteroposterior axis (mm) | −0.23 | 0.81 | 0.39 | −1.82 | 1.36 |
| Right condylion superoinferior axis (mm) | −0.08 | 0.28 | 0.41 | −0.63 | 0.47 |
| Left condylion anteroposterior axis (mm) | −0.77 | 0.91 | 0.03 | −2.56 | 1.02 |
| Left condylion superoinferior axis (mm) | 0.02 | 0.45 | 0.91 | −0.86 | 0.89 |
| Geometric center of right condyle anteroposterior axis (mm) | −0.14 | 0.34 | 0.24 | −0.81 | 0.54 |
| Geometric center of right condyle superoinferior axis (mm) | −0.04 | 0.66 | 0.86 | −1.32 | 1.25 |
| Geometric center of left condyle anteroposterior axis (mm) | −0.02 | 0.44 | 0.89 | −0.87 | 0.84 |
| Geometric center of left condyle superoinferior axis (mm) | 0.05 | 0.95 | 0.88 | −1.81 | 1.90 |
| Right anterior fossa anteroposterior axis (mm) | 0.14 | 0.32 | 0.21 | −0.49 | 0.77 |
| Right anterior fossa superoinferior axis (mm) | −0.15 | 0.28 | 0.13 | −0.69 | 0.40 |
| Left anterior fossa anteroposterior axis (mm) | 0.19 | 0.35 | 0.11 | −0.49 | 0.88 |
| Left anterior fossa superoinferior axis (mm) | −0.33 | 0.46 | 0.05 | −1.23 | 0.58 |
| Right posterior fossa anteroposterior axis (mm) | −0.01 | 0.35 | 0.90 | −0.70 | 0.67 |
| Right posterior fossa superoinferior axis (mm) | −0.10 | 0.64 | 0.65 | −1.35 | 1.16 |
| Left posterior fossa anteroposterior axis (mm) | 0.02 | 0.16 | 0.71 | −0.29 | 0.33 |
| Left posterior fossa superoinferior axis (mm) | 0.00 | 0.24 | 0.99 | −0.48 | 0.48 |
Results
The descriptive statistics comparing both Herbst groups (brachyfacial and mesofacial) and the Class II control group are summarized in Table I .
The Herbst groups were well matched with regard to age (brachyfacial, 13.36 years; mesofacial, 12.74 years), duration of Herbst treatment (brachyfacial, 7.21 months; mesofacial, 7.93 months), and duration of fixed appliance therapy that followed (brachyfacial, 20.38 months; mesofacial, 19.25 months). There were significant differences ( P = 0.0002) in the FMPA (brachyfacial, 18.3°; mesofacial, 27.9°) and the gonial angle ( P = 0.003) between the 2 Herbst groups (brachyfacial, 118.1°; mesofacial, 127.1°).
The Herbst groups and the Class II control group were well matched in regard to total treatment time (Herbst brachyfacial, 27.59 months; Herbst mesofacial, 27.18 months; control, 22.81 months) and Pog-N perpendicular (Herbst brachyfacial, −2.4 mm; Herbst mesofacial, −3.8 mm; control, −3.8 mm). There was a significant difference ( P = 0.03) in age between the Herbst mesofacial group and the Class II control group (Herbst mesofacial, 12.74 years; control, 13.73 years). There were also statistically significant differences in the severity of the Class II malocclusion as shown by the average molar occlusion ( P = 0.01) between the groups (Herbst brachyfacial, 6.6 mm; Herbst mesofacial, 6.3 mm; control, 4.6 mm) and the ANB angle ( P = 0.03) between the Herbst brachyfacial and Class II control group (Herbst brachyfacial, 6.0°; control 3.9°).
Qualitative evaluations of the maxillary and mandibular skeletal changes at all times were undertaken using semitransparent overlays and color maps of the cranial base superimpositions ( Figs 1 and 2 ).
Quantitative assessments of maxillary changes at the initial (T1) and final (T3) timepoints are reported in Table III . There were no significant differences in the vertical and anteroposterior positions of A-point or ANS between the 2 Herbst groups according to the y- and z-coordinates. There was a significant difference ( P = 0.01) in the change in vertical position of ANS in the Herbst brachyfacial (−1.44 mm) and Herbst mesofacial ( P = 0.001) (−1.95 mm) groups compared with the Class II control group from T1 to T3. There were no significant differences in palatal plane angulation (ANS-PNS) across all 3 groups from T1 to T3.
| Measurement | Herbst brachyfacial (HB) mean | SD | Herbst mesofacial (HM) mean | SD | Control (C) mean | SD | Difference of means (HM vs HB) (95% CI) | P value | Difference of means (C vs HB) (95% CI) | P value | Difference of means (C vs HM) (95% CI) | P value |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Maxillary skeletal | ||||||||||||
| A point AP (mm) | 0.43 | 0.69 | 0.02 | 1.06 | 0.59 | 1.21 | −0.41 (−1.48, 0.66) | 0.43 | 0.16 (−0.83, 1.16) | 0.74 | 0.57 (−0.42, 1.57) | 0.24 |
| A point SI (mm) | −2.03 | 1.77 | −1.85 | 2.07 | −0.98 | 2.08 | 0.18 (−1.88, 2.23) | 0.98 | 1.04 (−1.27, 3.36) | 0.51 | 0.87 (−1.44, 3.18) | 0.62 |
| ANS AP (mm) | 0.61 | 1.45 | 0.88 | 0.97 | 0.65 | 1.61 | 0.27 (−1.18, 1.71) | 0.71 | 0.03 (−1.31, 1.37) | 0.96 | −0.23 (−1.58, 1.11) | 0.72 |
| ANS SI (mm) | −2.28 | 1.05 | −2.80 | 0.43 | −0.85 | 1.49 | −0.52 (−1.69, 0.66) | 0.38 | 1.44 (0.34, 2.53) | 0.01 ∗ | 1.95 (0.85, 3.04) | 0.001 ∗ |
| Palatal plane (ANS-PNS) (°) | −1.18 | 0.94 | −0.85 | 1.96 | −0.59 | 1.62 | 0.33 (−1.30, 1.95) | 0.68 | 0.59 (−0.93, 2.09) | 0.43 | 0.26 (−1.25, 1.77) | 0.72 |
| Mandibular skeletal | ||||||||||||
| Pogonion AP (mm) | 1.25 | 1.81 | 1.35 | 2.73 | 0.73 | 1.12 | 0.10 (−2.29, 2.49) | 0.99 | −0.52 (−2.74, 1.70) | 0.83 | −0.62 (−2.84, 1.60) | 0.77 |
| Pogonion SI (mm) | −4.88 | 2.70 | −5.09 | 2.63 | −3.72 | 2.86 | −0.22 (−3.65, 3.21) | 0.99 | 1.16 (−2.03, 4.35) | 0.64 | 1.37 (−1.82, 4.56) | 0.54 |
| B Point AP (mm) | 0.70 | 1.28 | 1.01 | 2.23 | 0.56 | 1.17 | 0.31 (−1.32, 1.94) | 0.70 | −0.14 (−1.66, 1.37) | 0.84 | −0.45 (−1.97, 1.06) | 0.54 |
| B point SI (mm) | −5.82 | 2.68 | −5.98 | 2.02 | −3.23 | 2.47 | −0.16 (−2.65, 2.33) | 0.89 | 2.59 (0.28, 4.91) | 0.03 ∗ | 2.75 (0.44, 5.07) | 0.02 ∗ |
| Right mandibular length (Co-Gn) (mm) | 5.65 | 2.81 | 5.68 | 2.57 | 3.35 | 2.36 | 0.03 (−2.61, 2.67) | 0.98 | −2.30 (−4.75, 0.16) | 0.07 | −2.32 (−4.78, −0.13) | 0.06 |
| Left mandibular length (Co-Gn) (mm) | 4.93 | 2.26 | 5.14 | 1.33 | 3.24 | 2.54 | 0.21 (−2.03, 2.44) | 0.85 | −1.70 (−3.77, 0.38) | 0.10 | −1.90 (−3.98, 0.17) | 0.07 |
| Right ramus height (Co-Go’) (mm) | 4.19 | 2.14 | 3.44 | 1.66 | 2.87 | 2.46 | −0.75 (−2.98, 1.48) | 0.49 | −1.31 (−3.38, 0.76) | 0.20 | −0.56 (−2.63, 1.51) | 0.58 |
| Left ramus height (Co-Go’) (mm) | 3.75 | 1.71 | 3.81 | 1.56 | 3.07 | 2.60 | 0.05 (−2.11, 2.21) | 0.96 | −0.69 (−2.70, 1.32) | 0.49 | −0.74 (−2.75, 1.27) | 0.45 |
| Right corpus length (Go-Gn) (mm) | 3.18 | 1.77 | 3.74 | 1.54 | 2.28 | 2.56 | 0.56 (−1.60, 2.70) | 0.60 | −0.90 (−2.90, 1.10) | 0.36 | −1.45 (−3.45, 0.54) | 0.15 |
| Left corpus length (Go-Gn) (mm) | 3.15 | 1.61 | 3.26 | 1.39 | 1.86 | 1.70 | 0.11 (−1.53, 1.75) | 0.89 | −1.29 (−2.82, 0.23) | 0.09 | −1.40 (−2.93, 0.12) | 0.07 |
| Right gonial angle (Co-Go-Me) (°) | −0.78 | 1.41 | 0.46 | 1.28 | −1.13 | 1.52 | 1.24 (−0.23, 2.70) | 0.10 | −0.35 (−1.72, 1.00) | 0.60 | −1.59 (−2.95, −0.22) | 0.02 ∗ |
| Left gonial angle (Co-Go-Me) (°) | −0.42 | 0.77 | −0.05 | 1.65 | −0.40 | 0.92 | 0.37 (−0.81, 1.56) | 0.52 | 0.02 (−1.08, 1.12) | 0.97 | −0.35 (−1.45, 0.75) | 0.52 |
| Right FMPA (°) | 0.16 | 1.82 | −0.38 | 2.48 | −0.35 | 1.51 | −0.54 (−2.53, 1.45) | 0.58 | −0.52 (−2.36, 1.33) | 0.57 | 0.02 (−1.83, 1.87) | 0.98 |
| Left FMPA (°) | 0.50 | 1.41 | 0.17 | 1.60 | 0.26 | 1.07 | −0.33 (−1.72, 1.06) | 0.63 | −0.24 (−1.53, 1.05) | 0.70 | 0.09 (−1.20, 1.38) | 0.89 |
| Condyle/glenoid fossa skeletal | ||||||||||||
| Right anterior fossa AP (mm) | −1.55 | 1.50 | −0.75 | 0.90 | −0.30 | 0.46 | 0.79 (−0.23, 1.82) | 0.12 | 1.25 (0.30, 2.20) | 0.01 ∗ | 0.46 (−0.49, 1.41) | 0.33 |
| Right anterior fossa SI (mm) | −0.54 | 0.73 | −0.80 | 0.47 | −0.16 | 0.56 | −0.26 (−0.87, 0.35) | 0.39 | 0.38 (−0.19, 0.94) | 0.18 | 0.64 (0.07, 1.20) | 0.03 ∗ |
| Left anterior fossa AP (mm) | −0.93 | 1.74 | −0.58 | 0.49 | −0.26 | 0.39 | 0.35 (−0.69, 1.39) | 0.50 | 0.67 (−0.30, 1.63) | 0.17 | 0.32 (−0.64, 1.29) | 0.50 |
| Left anterior fossa SI (mm) | −0.55 | 0.44 | −0.61 | 0.41 | −0.25 | 0.68 | −0.07 (−0.63, 0.50) | 0.81 | 0.30 (−0.22, 0.82) | 0.25 | 0.37 (−0.16, 0.89) | 0.16 |
| Right posterior fossa AP (mm) | −0.57 | 0.77 | −0.31 | 0.62 | −0.52 | 0.85 | 0.27 (−0.52, 1.05) | 0.50 | 0.05 (−0.68, 0.79) | 0.88 | −0.21 (−0.94, 0.52) | 0.56 |
| Right posterior fossa SI (mm) | 0.62 | 1.19 | 0.69 | 0.54 | 0.05 | 0.36 | 0.06 (−0.71, 0.83) | 0.87 | −0.57 (−1.29, 0.14) | 0.11 | −0.63 (−1.35, 0.08) | 0.08 |
| Left posterior fossa AP (mm) | −0.80 | 0.81 | −0.42 | 0.53 | −0.43 | 0.73 | 0.38 (−0.35, 1.11) | 0.29 | 0.38 (−0.30, 1.05) | 0.26 | 0.00 (−0.68, 0.67) | 0.99 |
| Left posterior fossa SI (mm) | 0.82 | 0.98 | −0.15 | 0.12 | 0.01 | 0.43 | −0.97 (−1.71, −0.24) | 0.01 ∗ | −0.81 (−1.49, −0.13) | 0.02 ∗ | 0.16 (−0.52, 0.84) | 0.63 |
| Right condylion AP (mm) | −0.61 | 0.87 | −0.32 | 1.64 | −0.22 | 0.58 | 0.30 (−0.81, 1.40) | 0.58 | 0.39 (−0.64, 1.42) | 0.44 | 0.09 (−0.93, 1.12) | 0.85 |
| Right condylion SI (mm) | −0.58 | 0.73 | −0.64 | 1.03 | 0.03 | 0.56 | −0.06 (−0.86, 0.74) | 0.88 | 0.61 (−0.13, 1.35) | 0.10 | 0.67 (−0.07, 1.41) | 0.08 |
| Left condylion AP (mm) | −0.60 | 1.31 | −0.07 | 0.65 | 0.12 | 0.65 | 0.53 (−0.40, 1.45) | 0.25 | 0.71 (−0.14, 1.57) | 0.10 | 0.19 (−0.67, 1.05) | 0.65 |
| Left condylion SI (mm) | −0.53 | 0.81 | −0.49 | 0.65 | 0.28 | 0.81 | 0.04 (−0.75, 0.83) | 0.92 | 0.81 (0.07, 1.54) | 0.03 ∗ | 0.77 (0.03, 1.50) | 0.04 ∗ |
| Right geometric center of condyle AP (mm) | −1.00 | 0.88 | −0.32 | 1.09 | −0.26 | 0.81 | 0.67 (−0.28, 1.62) | 0.16 | 0.73 (−0.15, 1.62) | 0.10 | 0.06 (−0.82, 0.94) | 0.89 |
| Right geometric center of condyle SI (mm) | −0.34 | 0.65 | −0.41 | 1.02 | −0.49 | 0.64 | −0.08 (−0.87, 0.72) | 0.84 | −0.16 (−0.90, 0.58) | 0.67 | −0.08 (−0.82, 0.66) | 0.83 |
| Left geometric center of condyle AP (mm) | −0.60 | 1.81 | −0.68 | 0.71 | −0.22 | 0.57 | −0.08 (−1.22, 1.07) | 0.89 | 0.39 (−0.68, 1.45) | 0.46 | 0.46 (−0.60, 1.53) | 0.38 |
| Left geometric center of condyle SI (mm) | −0.26 | 0.99 | −0.42 | 1.19 | 0.15 | 0.99 | −0.15 (−1.24, 0.93) | 0.77 | 0.41 (−0.59, 1.42) | 0.41 | 0.57 (−0.44, 1.57) | 0.26 |
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