This retrospective study was carried out in accordance with the ethical standards set forth in the 1964 Declaration of Helsinki. Informed written consent was obtained from each patient and a parent or guardian. Ethical approval with the number of 95A11181 was obtained from the Craniomaxillofacial Research Center before patient recruitment.
Lateral cephalograms of all of class III patients who had attended the private practice orthodontic office from 2011 to 2016 and met the inclusion criteria were selected for the study.
The inclusion criteria were as follows:
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1.
Dental class III malocclusion
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2.
ANB of 0° to − 4.5°; − 8.5 < Wits appraisal < − 1 mm
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3.
No syndromic or medically compromised patients
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4.
No previous surgical intervention
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5.
No obvious transversal discrepancy
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6.
No mandibular functional shift (lack of pseudo-class III)
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7.
Normal overjet and overbite after completion of treatment
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8.
Skeletally mature patients
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9.
Patients who have achieved adequate functional and esthetic results at the end of their treatment
By placing the significance level at 0.05 and the power at 90%, a sample size of 58 patients would be needed [16].
Out of a total number of 430 class III patients, 65 met the inclusion criteria and were selected to participate in this study. The camouflage group comprised of 36 patients (15 males and 21 females) with the mean age of 23.5 (SD 4.8) years old and confidence interval 25.6–21.2, and the surgery group comprised of 29 patients (12 males and 17 females) with the mean age of 24.8 (SD 3.1) and confidence interval 26–22.3. There was no spastically significant difference in age between groups P < 0.9.
Treatment of the camouflage patients included treatment with fixed orthodontic appliances in both jaws. While the majority of camouflage group patients were treated without teeth extractions, 6 of them underwent the extraction of the lower first premolars and the upper second premolars. The treatment of all of these patients was focused on flaring of the upper incisors and retraction of the lower incisors throughout class III mechanics, specially by application of class III elastics.
The patients of the surgery group also received fixed orthodontic treatment in both jaws. Nine patients had also undergone extractions of the upper first premolar and the lower second premolar teeth, while the rest were treated without extractions. Their surgical treatments were performed in the forms of either bimaxillary surgery (5 patients), maxillary advancement (16 patients), or mandibular setback (8 patients).
The pretreatment records (containing panoramic and lateral cephalograms, intra- and extra-oral photographs, and plaster models) were presented to three board-certified orthodontists. They were asked to divide the patients into the camouflage and surgery groups solely based on these records. Based on their judgment, the camouflage and surgery group consisted of 34 and 31 patients, respectively.
Cephalometric analysis
The following cephalometric parameters were measured:
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PoOr-NBa: cranial deflexion angle
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NSAr: sella turcica angle
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BaSN: cranial base angle
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SNA: sagittal position of the maxilla relative to the anterior part of the cranial base
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SNB: sagittal position of the mandible relative to the anterior part of the cranial base
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ANB: sagittal maxillo-mandibular disparity
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Wits appraisal: sagittal disparity between Ao and Bo, orthogonal projections of A and B on the occlusal plane
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NAPog: angle showing the position of point A relative to the N-Pog facial plane
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PP-SN: inclination of the palatal plane relative to the anterior cranial base
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ML-SN: divergence of the mandibular plane relative to the anterior part of the cranial base
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Npog-SN: angle formed by the facial plane and the anterior part of the cranial base
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GoMe-SN: angle of facial divergence
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Occ/ML: inclination of the functional occlusal plane relative to the lower mandibular margin
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Occ/F: inclination of the functional occlusal plane relative to the Frankfurt plane
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PP-ML: inclination of the palatal plane relative to the lower mandibular margin
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ArGoMe: goniac angle
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Go upper or NGoAr: upper gonial angle;
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Go lower or NGoMe: lower gonial angle;
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Y-Axis: SN to S-gnathion
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U1-SN: inclination of the upper incisors relative to the anterior cranial base;
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L1-ML: inclination of the lower incisors relative to the lower mandibular margin;
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U1-L1: internal interincisal angle;
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Holdaway H angle: angle formed by soft tissue nasion–soft tissue pogonion–tangent to the upper lip
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Z angle: angle formed by the soft tissue pogonion–the more protrusive lip with the Frankfurt plane
All of the measurements were done separately by two skilled orthodontists. In case of any significant difference in any of the measurements, the variable would be remeasured by both of them and also a third party. The interexaminer reliability (i.e., level of agreement) between the two investigators was estimated by calculating the intraclass correlation coefficient (ICC). ICCs extended from 0.68 to 1, indicating acceptable to perfect reliability of the measurements. The magnification factor of each cephalogram was standardized at 8%.
Patient satisfaction was evaluated using the visual analog scale (VAS) [17, 18]. The subjects were asked to record their satisfaction with their facial and dental characteristics on a 10 cm VAS having phrases “very dissatisfied” (score 0) on the left end and “very satisfied” (score 10) on the right end.
Statistical analysis
Mann-Whitney U test was used to compare the variables between the two groups. Stepwise discriminant analysis was applied to identify the dentoskeletal variables that best separate the groups. The discriminant function coefficients were calculated for each of the selected variables along with a constant. An equation was developed for calculating the individual scores of the patients. Discriminant analysis was also used to calculate a mean score or centroid for all patients in each group.