Original Article
Three-dimensional evaluation of the relationship between jaw divergence and facial soft tissue dimensions Roberto Rongoa; Joseph Saswat Antounb; Yi Xin Limc; George Diasd; Rosa Vallettae; Mauro Farellaf ABSTRACT Objective: To evaluate the relationship between mandibular divergence and vertical and transverse dimensions of the face. Materials and Methods: A sample was recruited from the orthodontic clinic of the University of Otago, New Zealand. The recruited participants (N 5 60) were assigned to three different groups based on the mandibular plane angle (hyperdivergent, n 5 20; normodivergent, n 5 20; and hypodivergent, n 5 20). The sample consisted of 31 females and 29 males, with a mean age of 21.1 years (SD 6 5.0). Facial scans were recorded for each participant using a three-dimensional (3D) white-light scanner and then merged to form a single 3D image of the face. Vertical and transverse measurements of the face were assessed from the 3D facial image. Results: The hyperdivergent sample had a significantly larger total and lower anterior facial height than the other two groups (P , .05), although no difference was found for the middle facial height (P . .05). Similarly, there were no significant differences in the transverse measurements of the three study groups (P . .05). Both gender and body mass index (BMI) had a greater influence on the transverse dimension. Conclusions: Hyperdivergent facial types are associated with a long face but not necessarily a narrow face. Variations in facial soft tissue vertical and transversal dimensions are more likely to be due to gender. Body mass index has a role in mandibular width (GoGo) assessment. (Angle Orthod. 2014;84:788–794.) KEY WORDS: Craniofacial morphology; Jaw divergence; White-light scanner; Soft tissue analysis
INTRODUCTION PhD Student, Department of Neuroscience, Reproductive Science and Oral Science, University of Naples ‘‘Federico II,’’, Naples, Italy. b Senior Lecturer, Discipline of Orthodontics, Department of Oral Sciences, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Otago, New Zealand. c Resident, Discipline of Orthodontics, Department of Oral Sciences, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Otago, New Zealand. d Senior Lecturer, Department of Anatomy, University of Otago, Otago, New Zealand. e Associate Professor, Department of Neuroscience, Reproductive Science and Oral Science, University of Naples ‘‘Federico II,’’, Naples, Italy. f Professor and Chair, Discipline of Orthodontics, Department of Oral Sciences, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Otago, New Zealand. Corresponding author: Dr Mauro Farella, Discipline of Orthodontics, Department of Oral Sciences, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, PO Box 647, Dunedin 9054, New Zealand (e-mail: [email protected]) a
Craniofacial growth anomalies are often accompanied by different patterns of mandibular growth that are generally described as hyperdivergent, normodivergent, and hypodivergent.1–3 The hyperdivergent pattern, or long face, is typically associated with a decreased posterior to anterior facial height ratio, an increased lower facial height, and a steep mandibular plane.4 The hypodivergent pattern, or short face, exhibits opposite features to the hyperdivergent pattern.5 The clinical features of these growth patterns are well described in the literature and often manifest as either a skeletal open or deep bite.6–9 It has been suggested that head form is closely associated with both vertical and transverse growth patterns.10,11 Dolichocephalic head forms have been described as having a narrow face and hyperdivergent mandible, while brachycephalic skulls exhibit a broader face and hypodivergent mandible.12 These stereotypic descriptions of head form suggest a close association between skeletal divergence and vertical and transverse facial growth. It is noteworthy, however, that
Accepted: December 2013. Submitted: September 2013. Published Online: February 21, 2014 G 2014 by The EH Angle Education and Research Foundation, Inc. Angle Orthodontist, Vol 84, No 5, 2014
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DOI: 10.2319/092313-699.1
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3D EVALUATION OF JAW DIVERGENCE Table 1. Descriptive Statistics of the Sample Hyperdivergent (n 5 20)
Normodivergent (n 5 20)
Hypodivergent (n 5 20)
Total (N 5 60)
P Value
Sex Male, % Female, % Mean age 6 SD, y Body mass index 6 SD, kg/m2
9 11 20.1 22.4
(45) (55) 6 3.5 6 2.8
10 10 21.8 23.5
these classical descriptions are mainly based on the two-dimensional analysis of lateral cephalograms.10,11 These techniques have some important drawbacks such as a high incidence of artifacts and errors and the lack of a third dimension.13 Moreover, the type and severity of different skeletal patterns are often masked by the facial soft tissues. Until the end of the 1950s, a common perception was that the integumental profile followed passively the underlying hard tissue, although later studies demonstrated that the soft tissues have an independent growth potential.14,15 Recent advances in biomedical imaging have made it possible to assess the facial hard and soft tissues in three dimensions (3D). Cone-beam computed tomography is a useful method for the simultaneous evaluation of both the soft and hard tissues but is often not suitable for retrospective samples because of the unnecessary dose of radiation.16 An alternative method to capture this information involves the combined use of pretreatment head films to evaluate the hard tissues and 3D scanners to assess the soft tissues. The latter method has the advantages of being noninvasive, free of radiation, and able to be used on large numbers of healthy people.17 The aim of this study was therefore to evaluate the relationship between mandibular divergence and vertical and transverse dimensions of the face through the combined use of lateral cephalograms and a whitelight structured 3D scanner. MATERIALS AND METHODS The study was designed to detect a large effect size, as only major differences in craniofacial width between different jaw divergence groups were considered to be clinically relevant. To detect an effect size $0.8, with a 5 .05 and b 5 .80 (one-tail test), it was found that at least 20 participants per group were needed. Sixty participants were therefore recruited from the orthodontic clinic of the University of Otago. The sample consisted of 31 females and 29 males of New Zealand European origin, with a mean age of 21.1 6 5.0 years (Table 1). Participants were included in the study if they were willing to participate, had a good-quality cephalogram, and provided informed consent. Exclusion criteria included having greater than four missing
(50) (50) 6 7.1 6 3.3
10 10 21.4 25.1
(50) (50) 6 3.8 6 6.9
29 31 21.1 23.7
(48.3) (51.7) 6 5.0 6 4.8
— — .545 .186
permanent teeth (excluding third molars), inflammatory or degenerative diseases of the temporomandibular joint, cleft lip and/or palate, craniofacial syndromes, facial asymmetry, ongoing orthodontic treatment, or a history of facial fractures or orthognathic surgery. The study was approved by the University of Otago Ethics Committee (12/054). Cephalometric Analysis The Sella-Nasion mandibular plane angle (SNMP)18 was used to allocate selected participants from the entire radiography archive of the Otago University’s orthodontic clinic (n . 2500) to three groups: hyperdivergent (M 5 9, F 5 11; SNMP $42u), normodivergent (M 5 10, F 5 10; 27u # SNMP # 37u), and hypodivergent (M 5 10, F 5 10; SNMP #22u). A single calibrated investigator (Dr Rongo) carried out this assessment for all 60 pretreatment cephalograms. Soft Tissue Analysis A 3D white-light scanner (HDI Advance, BDB Solution, Burnaby, Canada) was used to capture facial scans of the study participants after initial calibration according to the manufacturer’s instructions. To ensure consistency, facial scans were carried out in a standard setting that included similar lighting conditions and a fixed scanner position. Prior to scanning, removable round markers were attached to the face to localize several anthropometric points that required palpation (Tragion, Gonion, Nasion, and Menton). The remaining landmarks were identified by visually inspecting the scans. The scanner system consisted of a projector and two cameras (U-Eye SE UI-1480SE, 5MP, CMOS; IDS Imaging Development Systems GMBH, Obersulm, Germany) with attached lenses (Fujinon TV Lens HF 12.5SA-1 1:1.4/12.5 mm; Fujifilm Holdings Corporation, Tokyo, Japan). The projector and the two cameras were mounted on an aluminum bar that was attached to a tripod (Manfrotto, Bassano del Grappa, Italy). Specialized software was used to capture the data from the light scanner (FlexScan3D, 3D3 Solutions, Burnaby, Canada). The two cameras were attached on either side of the projector with the lenses slightly convergent toward the Angle Orthodontist, Vol 84, No 5, 2014
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Statistical Analysis The facial measurements used in the present study consisted of three vertical and four transverse variables (Figure 1). Descriptive statistics were computed using the Statistical Package for Social Sciences (SPSS version 20.0, Chicago, Ill). Univariate and multivariate analysis of variance were used to test for differences between groups after adjusting for age, gender, and BMI. Similar models unadjusted for BMI and height (data not shown) were also produced. Bonferroni correction was carried out for post hoc tests. Figure 1. Facial landmarks used in the study: Ex exocanthion is the soft tissue point located at the outer commissure of each eye fissure; Or soft tissue orbitale is the soft tissue point located at the most inferior level of each infraorbital rim, located at the level of the 3D hard tissue cephalometric orbitale landmark; Na soft tissue nasion is the midpoint on the soft tissue contour of the base of the nasal root at the level of the frontonasal suture; Sn subnasale is the midpoint on the nasolabial soft tissue contour between the columella crest and the upper lip; Me soft tissue menton is the most inferior midpoint on the soft tissue contour of the chin located at the level of the 3D cephalometric hard tissue Menton landmark; Tr tragion is the point located at the upper margin of each tragus; Go soft tissue gonion is the most lateral point on the soft tissue contour of each mandibular angle, located at the same level as the 3D hard tissue cephalometric point.19
participant’s position. The scanner was positioned approximately 110 cm away from the participant. Study participants were seated and instructed to look straight ahead at the projector, with the head held in the natural head position (NHP). Black velvet was placed behind the participants to avoid any distortion and reflection of the light. Six scans were recorded to form a complete 3D image of each participant’s face. The facial scans consisted of (1) two frontal scans with the head in NHP and (2) two lateral scans obtained at 60u and 90u to the long axis of the light scanner. The second step was repeated for the opposite side of the face. During the scans, participants were asked to stay as still as possible in NHP, with their teeth together and eyes closed. The scans were used to produce six successive 3D meshes, which were then aligned, superimposed, and merged to create a single 3D image of each participant’s face (FlexScan3D, 3D3 Solutions). Facial measurements were made using a 3D inspection and mesh processing software, which was specifically developed for the dimensional analysis of 3D point clouds (GOM Inspect, GOM mbH, Braunschweig, Germany). Each participant’s height and weight were also recorded at the time of the scans to calculate body mass index (BMI). Angle Orthodontist, Vol 84, No 5, 2014
Method Error The technical errors of measurement were calculated from 12 randomly selected participants. A set of seven measurements was reassessed by one examiner after a memory washout period of at least 8 weeks. The method error for the seven measurements was calculated using Dahlberg’s formula.20 Systematic differences between duplicated measurements were tested using a paired Student’s t-test with the type I error set at .01.21 The method errors (%) were very low for linear measurements, ranging from 0.1% to 0.4%. There was no systematic error for any of the seven measurements (Student’s t-test; P . .01). To assess reliability, 13 participants (8 males and 5 females) were randomly selected and rescanned under the same conditions. The method errors (%) were very low for linear measurements, ranging from 0.7% to 1.2%. There was no systematic error for any of the seven measurements (Student’s t-test; P . .01). To assess the validity of the measurement tool, three dry skulls with clearly defined landmarks were scanned similarly to the experimental protocol. Although these hard tissue landmarks do not pertain directly to the validity of the soft tissue points, they provided a useful proxy for assessing the validity of the technique in measuring the intended markers. Five linear variables (Na-Ans, G-Ans, Ex-Ex, Po-Po, G-Op) were used to compare the measurements obtained directly from the skulls and those from the digital scans. The method errors (%) were again very low, ranging from 0.2% to 1.4%. There was no systematic error for any of the five measurements (Student’s t-test; P . .01). RESULTS A descriptive summary of the study sample is presented in Table 1. There were no significant differences in BMI for either the jaw divergence group (P 5 .178) or gender (P 5 .768). In the 3D soft tissue analysis (Table 2), the total facial height (NaMe) was significantly larger in the
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3D EVALUATION OF JAW DIVERGENCE
Figure 2. Frontal (A, B) and lateral (C, D) views of two participants with a hyperdivergent (A, C) and a hypodivergent (B, D) facial type.
P 5 .007). On the other hand, middle facial height (NaSn) was very similar in all three groups (P . .05). With respect to the transverse dimension, there were no significant differences among the three groups except for mandibular width (GoGo), which was slightly larger in hyperdivergent (114.3 6 8.2 mm) than hypodivergent individuals (112.8 6 9.9 mm; P 5 .032).
hyperdivergent group (124.6 6 7.6 mm) than in the hypodivergent (115.6 6 8.5 mm; P , .001) and normodivergent groups (120.4 6 6.4 mm; P 5 .019). The hyperdivergent group also had an increased lower anterior facial height (SnMe 5 76.5 6 5.4 mm) in comparison with both hypodivergent (68.6 6 6.9 mm; P , .001) and normodivergent groups (72.0 6 6.0 mm;
Table 2. Soft Tissue Dimensions in the Vertical and Transversal Planes by Mandibular Divergence (Mean 6 Standard Deviation) in Millimeters Hyperdivergent Mean NaMe NaSn SnMe ExEx OrOr TrTr GoGo
124.6 52.6 76.5 94.7 71.0 139.8 114.3
SD 6 6 6 6 6 6 6
a,b
7.6 5.0 5.4a,b 5.0 4.3 7.3 8.2a
Normodivergent Mean 120.4 6 6.4 52.1 6 3.2 72.0 6 6.0 94.9 6 4.9 70.7 6 8.9 142.9 6 8.4 112.2 6 11.0
SD
Hypodivergent Mean 115.6 50.7 68.6 96.6 73.7 142.8 112.8
SD 6 6 6 6 6 6 6
8.5 4.0 6.9 4.7 4.7 5.9 9.9
P Valued (Unadjusted for BMI)
P Valuee
.000 .189 .000 .345 .259 .189 .462
.000 .172 .000 .442 .292 .343 .027
a
Bonferroni post hoc test statistically significantly different between hyperdivergent and hypodivergent. Bonferroni post hoc test statistically significantly different between hyperdivergent and normodivergent. c Bonferroni post hoc test statistically significantly different between normodivergent and hypodivergent. d Adjusted for sex and age. e Adjusted for sex, gender, age, and body mass index (BMI). Bold font: Statistically significant. b
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Table 3. Soft Tissue Dimensions in the Vertical and Transversal Planes by Sex (Mean 6 SD) in Millimeters Male Mean NaMe NaSn SnMe ExEx OrOr TrTr GoGo
124.9 6 53.4 6 75.7 6 98.0 6 73.7 6 147.1 6 119.9 6
Female SD
7.5 4.3 6.5 4.5 5.3 5.8 8.6
Mean 115.8 6 50.3 6 69.3 6 93.0 6 70.0 6 137.0 6 106.7 6
SD 6.4 3.4 5.7 3.9 6.9 4.7 5.1
P Valuea (Unadjusted for BMI)
P Valueb
.000 .002 .000 .000 .024 .000 .000
.000 .002 .000 .000 .029 .000 .000
a
Adjusted for age. Adjusted for age and body mass index (BMI). Bold font: Statistically significant. b
As expected, males had significantly larger vertical and transverse measurements than females (Table 3). All of the facial measurements were significantly associated with gender, even after adjusting for BMI (P , .05). Examples of hyperdivergent and hypodivergent facial types are given in Figure 2. DISCUSSION Several important findings were identified from the comparison between mandibular divergence and facial soft tissue dimensions. In particular, the three study groups differed significantly with respect to the vertical dimension but not for any of the four transverse measurements investigated. Mandibular width, however, was slightly increased in the hyperdivergent group after adjusting for BMI, although this was not considered to be clinically significant (>1.5 mm). Nonetheless, this finding was somewhat surprising since hypodivergent facial types are generally considered as having broader faces.12 One plausible explanation for this misconception is that a significant increase in BMI can sometimes obscure the underlying vertical morphology. In other words, hyperdivergent individuals may appear to have a flat mandibular plane that resembles a hypodivergent head form because of the overlying fat tissue. Indeed, overweight/obese people accumulate fat in the cheek areas22 but not around soft tissue menton, subnasion, and nasion.23,24 Increased cheek thickness may affect the correct localization of soft tissue gonion,19 thus resulting in an overall appearance of a square face (ie, hypodivergent). In general, the findings of the present study did not support the notion that the transverse dimension of the face is associated with vertical facial features. Although hyperdivergent individuals have previously been reported to have a low width to height ratio of the underlying skeletal structures of the head,11 the data collected on soft tissue dimensions suggested that this is mainly because of an increase in facial height rather than width. A recent study on facial dimensions also Angle Orthodontist, Vol 84, No 5, 2014
reported a similar transverse dimension in individuals with different cephalic indices.25 In contrast to the current findings, vertical measurements in that study were also similar between the various cephalic groups. It is noteworthy, however, that the age group of the two study samples differed, and this may have accounted for the differences in vertical dimension. Since transverse growth ceases relatively early in life,26,27 it is not surprising that both studies identified a difference in this dimension irrespective of the sample’s age. Vertical facial development, on the other hand, is often the last dimension to cease growth27,28 and is therefore more likely to exhibit greater variation in older samples such as the present one. Sexual dimorphism was also evident for all of the vertical and transverse measurements in the present sample. In general, females had a narrower face than males, especially in the lower third of the face (ie, GoGo). Males, however, exhibited larger vertical measurements than females. These findings are consistent with a previous anthropometric study.29 The current findings provide data describing the vertical and transverse features of the face in individuals with different jaw divergence. This information could be helpful in the treatment planning of orthognathic surgery cases presenting with either hyperdivergent or hypodivergent jaw patterns. Indeed, both mandibular advancement and setback procedures have a direct effect on the transverse dimension of the face, especially the intergonial distance.30,31 The present study has a number of limitations that should be noted. Some of the landmarks were difficult to localize on the facial scans through visual inspection alone (eg, Gonion, Menton, Tragion, and Nasion). In general, landmarks located on smooth surfaces are often difficult to identify on 3D images without the use of reference markers.32,33 To improve landmark identification, some of the more difficult landmarks were directly labeled with round markers.33,34 Nonetheless, it is possible that some of the unmarked landmarks were associated with a higher degree of measurement error. Second, patients were instructed to look straight ahead
3D EVALUATION OF JAW DIVERGENCE
while recording the scans, and this was assumed to replicate the NHP. A consistent head posture is particularly important in this type of study, since stretching of the soft tissues can occur as a result of postural changes.35 Although no specific aids (eg, mirrors) were used to position the head, it would be expected that most participants would have exhibited a NHP since this is a highly reproducible head posture.36,37 Finally, the findings are restricted to the soft tissues of the face and may not necessarily be valid for making assumptions about the underlying skeletal pattern. On the other hand, stereophotogrammetric techniques have a number of important advantages, especially in these types of studies. The low cost, lack of radiation, and quick exposure time permit it to be used in large clinical and nonclinical samples. Moreover, these new imaging techniques allow researchers to evaluate multiple planes, both cross-sectionally and longitudinally. Finally, the present study demonstrated that this 3D imaging technique is both valid and reliable for evaluating facial form. Future research in the field of craniofacial growth and development may therefore greatly benefit from this simple and noninvasive imaging technique. CONCLUSIONS N The soft tissue facial form of hyperdivergent individuals is associated with a long face pattern but not necessarily a narrow one. Variation in the transverse dimension is more likely to be due to gender and BMI. N The relatively simple and noninvasive 3D imaging technique used in this study has been shown to be reliable. Findings from this study support its use for investigating facial form in larger samples. REFERENCES 1. Schudy FF. Vertical growth versus anteroposterior growth as related to function and treatment. Angle Orthod. 1964;34: 75–93. 2. Bjo¨rk A. Prediction of mandibular growth rotation. Am J Orthod. 1969;55:585–599. 3. Karlsen AT. Association between facial height development and mandibular growth rotation in low and high MP-SN angle faces: a longitudinal study. Angle Orthod. 1997;67: 103–110. 4. Schendel SA, Eisenfeld J, Bell WH, Epker BN, Mishelevich DJ. The long face syndrome: vertical maxillary excess. Am J Orthod. 1976;70:398–408. 5. Opdebeeck H. The short face syndrome. Am J Orthod. 1978;73:499–511. 6. Nanda SK. Patterns of vertical growth in the face. Am J Orthod Dentofacial Orthop. 1988;93:103–116. 7. Sassouni V. A classification of skeletal types. Am J Orthod. 1969;55:109–123.
793 8. Cangialosi TJ. Skeletal morphologic features of anterior open bite. Am J Orthod. 1984;85:28–36. 9. Baccetti T, Franchi L, McNamara JA Jr. Longitudinal growth changes in subjects with deep bite. Am J Orthod Dentofacial Orthop. 2011;140:202–209. 10. Enlow DH, Kuroda T, Lewis AB. The morphological and morphogenetic basis for craniofacial form and pattern. Angle Orthod. 1971;41:161–188. 11. Bhat M, Enlow DH. Facial variations related to headform type. Angle Orthod. 1985;55:269–280. 12. Enlow DH. Handbook of Facial Growth. London, UK: Saunders (W.B.) Co Ltd; 1982. 13. Hoefert CS, Bacher M, Herberts T, et al. Implementing a superimposition and measurement model for 3D sagittal analysis of therapy-induced changes in facial soft tissue: a pilot study. J Orofac Orthop. 2010;71:221–234. 14. Burstone CJ. Integumental contour and extension patterns. Angle Orthod. 1959;29:93–103. 15. Subtelny JD. A longitudinal study of soft tissue facial structures and their profile characteristics, defined in relation to underlying skeletal structures. Am J Orthod. 1959;45: 481–507. 16. van Vlijmen OJ, Kuijpers MA, Berge´ SJ, et al. Evidence supporting the use of cone-beam computed tomography in orthodontics. J Am Dent Assoc. 2012;143:241–252. 17. Baik HS, Jeon JM, Lee HJ. Facial soft-tissue analysis of Korean adults with normal occlusion using a 3-dimensional laser scanner. Am J Orthod Dentofacial Orthop. 2007;131: 759–766. 18. Steiner CC. Cephalometrics for you and me. Am J Orthod. 1953;39:729–755. 19. Swennen GRJ, Schutyser F, Hausamen JE. Three-Dimensional Cephalometry: A Color Atlas and Manual. Berlin, Germany: Springer; 2005. 20. Dahlberg G. Statistical Methods for Medical and Biological Students. New York, NY: Interscience Publications; 1940. 21. Houston WJ. The analysis of errors in orthodontic measurements. Am J Orthod. 1983;83:382–390. 22. Mortimore IL, Marshall I, Wraith PK, Sellar RJ, Douglas NJ. Neck and total body fat deposition in nonobese and obese patients with sleep apnea compared with that in control subjects. Am J Respir Crit Care Med. 1998;157:280–283. 23. Donofrio LM. Fat distribution: a morphologic study of the aging face. Dermatol Surg. 2000;26:1107–1112. 24. Pilsl U, Anderhuber F. The chin and adjacent fat compartments. Dermatol Surg. 2010;36:214–218. 25. Ferrario VF, Sforza C, Poggio CE, Schmitz JH, Colombo A. Soft tissue facial morphology related to headform: a threedimensional quantitative analysis in childhood. J Craniofac Genet Dev Biol. 1997;17:86–95. 26. Hesby RM, Marshall SD, Dawson DV, et al. Transverse skeletal and dentoalveolar changes during growth. Am J Orthod Dentofacial Orthop. 2006;130:721–731. 27. Snodell SF, Nanda RS, Currier GF. A longitudinal cephalometric study of transverse and vertical craniofacial growth. Am J Orthod Dentofacial Orthop. 1993;104:471–483. 28. Pecora NG, Baccetti T, McNamara JA Jr. The aging craniofacial complex: a longitudinal cephalometric study from late adolescence to late adulthood. Am J Orthod Dentofacial Orthop. 2008;134:496–505. 29. Budai M, Farkas LG, Tompson B, Katic M, Forrest CR. Relation between anthropometric and cephalometric measurements and proportions of the face of healthy young white adult men and women. J Craniofac Surg. 2003;14: 154–161. Angle Orthodontist, Vol 84, No 5, 2014
794 30. Joss CU, Joss-Vassalli IM, Kiliaridis S, Kuijpers-Jagtman AM. Soft tissue profile changes after bilateral sagittal split osteotomy for mandibular advancement: a systematic review. J Oral Maxillofac Surg. 2010;68:1260–1269. 31. Joss CU, Joss-Vassalli IM, Berge´ SJ, Kuijpers-Jagtman AM. Soft tissue profile changes after bilateral sagittal split osteotomy for mandibular setback: a systematic review. J Oral Maxillofac Surg. 2010;68:2792–2801. 32. Aldridge K, Boyadjiev SA, Capone GT, DeLeon VB, Richtsmeier JT. Precision and error of three-dimensional phenotypic measures acquired from 3dMD photogrammetric images. Am J Med Genet A. 2005;138A:247–253. 33. Aynechi N, Larson BE, Leon-Salazar V, Beiraghi S. Accuracy and precision of a 3D anthropometric facial
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analysis with and without landmark labeling before image acquisition. Angle Orthod. 2011;81:245–252. Wong JY, Oh AK, Ohta E, et al. Validity and reliability of craniofacial anthropometric measurement of 3D digital photogrammetric images. Cleft Palate Craniofac J. 2008;45:232–239. Hoogeveen RC, Sanderink GC, Berkhout WE. Effect of head position on cephalometric evaluation of the soft-tissue facial profile. Dentomaxillofac Radiol. 2013;42(6):20120423. Peng L, Cooke MS. Fifteen-year reproducibility of natural head posture: a longitudinal study. Am J Orthod Dentofacial Orthop. 1999;116:82–85. Cooke MS, Wei SH. A summary five-factor cephalometric analysis based on natural head posture and the true horizontal. Am J Orthod Dentofacial Orthop. 1988;93:213–223.
Three-dimensional evaluation of the relationship between jaw divergence and facial soft tissue dimensions Roberto Rongoa; Joseph Saswat Antounb; Yi Xin Limc; George Diasd; Rosa Vallettae; Mauro Farellaf ABSTRACT Objective: To evaluate the relationship between mandibular divergence and vertical and transverse dimensions of the face. Materials and Methods: A sample was recruited from the orthodontic clinic of the University of Otago, New Zealand. The recruited participants (N 5 60) were assigned to three different groups based on the mandibular plane angle (hyperdivergent, n 5 20; normodivergent, n 5 20; and hypodivergent, n 5 20). The sample consisted of 31 females and 29 males, with a mean age of 21.1 years (SD 6 5.0). Facial scans were recorded for each participant using a three-dimensional (3D) white-light scanner and then merged to form a single 3D image of the face. Vertical and transverse measurements of the face were assessed from the 3D facial image. Results: The hyperdivergent sample had a significantly larger total and lower anterior facial height than the other two groups (P , .05), although no difference was found for the middle facial height (P . .05). Similarly, there were no significant differences in the transverse measurements of the three study groups (P . .05). Both gender and body mass index (BMI) had a greater influence on the transverse dimension. Conclusions: Hyperdivergent facial types are associated with a long face but not necessarily a narrow face. Variations in facial soft tissue vertical and transversal dimensions are more likely to be due to gender. Body mass index has a role in mandibular width (GoGo) assessment. (Angle Orthod. 2014;84:788–794.) KEY WORDS: Craniofacial morphology; Jaw divergence; White-light scanner; Soft tissue analysis
INTRODUCTION PhD Student, Department of Neuroscience, Reproductive Science and Oral Science, University of Naples ‘‘Federico II,’’, Naples, Italy. b Senior Lecturer, Discipline of Orthodontics, Department of Oral Sciences, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Otago, New Zealand. c Resident, Discipline of Orthodontics, Department of Oral Sciences, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Otago, New Zealand. d Senior Lecturer, Department of Anatomy, University of Otago, Otago, New Zealand. e Associate Professor, Department of Neuroscience, Reproductive Science and Oral Science, University of Naples ‘‘Federico II,’’, Naples, Italy. f Professor and Chair, Discipline of Orthodontics, Department of Oral Sciences, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Otago, New Zealand. Corresponding author: Dr Mauro Farella, Discipline of Orthodontics, Department of Oral Sciences, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, PO Box 647, Dunedin 9054, New Zealand (e-mail: [email protected]) a
Craniofacial growth anomalies are often accompanied by different patterns of mandibular growth that are generally described as hyperdivergent, normodivergent, and hypodivergent.1–3 The hyperdivergent pattern, or long face, is typically associated with a decreased posterior to anterior facial height ratio, an increased lower facial height, and a steep mandibular plane.4 The hypodivergent pattern, or short face, exhibits opposite features to the hyperdivergent pattern.5 The clinical features of these growth patterns are well described in the literature and often manifest as either a skeletal open or deep bite.6–9 It has been suggested that head form is closely associated with both vertical and transverse growth patterns.10,11 Dolichocephalic head forms have been described as having a narrow face and hyperdivergent mandible, while brachycephalic skulls exhibit a broader face and hypodivergent mandible.12 These stereotypic descriptions of head form suggest a close association between skeletal divergence and vertical and transverse facial growth. It is noteworthy, however, that
Accepted: December 2013. Submitted: September 2013. Published Online: February 21, 2014 G 2014 by The EH Angle Education and Research Foundation, Inc. Angle Orthodontist, Vol 84, No 5, 2014
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DOI: 10.2319/092313-699.1
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3D EVALUATION OF JAW DIVERGENCE Table 1. Descriptive Statistics of the Sample Hyperdivergent (n 5 20)
Normodivergent (n 5 20)
Hypodivergent (n 5 20)
Total (N 5 60)
P Value
Sex Male, % Female, % Mean age 6 SD, y Body mass index 6 SD, kg/m2
9 11 20.1 22.4
(45) (55) 6 3.5 6 2.8
10 10 21.8 23.5
these classical descriptions are mainly based on the two-dimensional analysis of lateral cephalograms.10,11 These techniques have some important drawbacks such as a high incidence of artifacts and errors and the lack of a third dimension.13 Moreover, the type and severity of different skeletal patterns are often masked by the facial soft tissues. Until the end of the 1950s, a common perception was that the integumental profile followed passively the underlying hard tissue, although later studies demonstrated that the soft tissues have an independent growth potential.14,15 Recent advances in biomedical imaging have made it possible to assess the facial hard and soft tissues in three dimensions (3D). Cone-beam computed tomography is a useful method for the simultaneous evaluation of both the soft and hard tissues but is often not suitable for retrospective samples because of the unnecessary dose of radiation.16 An alternative method to capture this information involves the combined use of pretreatment head films to evaluate the hard tissues and 3D scanners to assess the soft tissues. The latter method has the advantages of being noninvasive, free of radiation, and able to be used on large numbers of healthy people.17 The aim of this study was therefore to evaluate the relationship between mandibular divergence and vertical and transverse dimensions of the face through the combined use of lateral cephalograms and a whitelight structured 3D scanner. MATERIALS AND METHODS The study was designed to detect a large effect size, as only major differences in craniofacial width between different jaw divergence groups were considered to be clinically relevant. To detect an effect size $0.8, with a 5 .05 and b 5 .80 (one-tail test), it was found that at least 20 participants per group were needed. Sixty participants were therefore recruited from the orthodontic clinic of the University of Otago. The sample consisted of 31 females and 29 males of New Zealand European origin, with a mean age of 21.1 6 5.0 years (Table 1). Participants were included in the study if they were willing to participate, had a good-quality cephalogram, and provided informed consent. Exclusion criteria included having greater than four missing
(50) (50) 6 7.1 6 3.3
10 10 21.4 25.1
(50) (50) 6 3.8 6 6.9
29 31 21.1 23.7
(48.3) (51.7) 6 5.0 6 4.8
— — .545 .186
permanent teeth (excluding third molars), inflammatory or degenerative diseases of the temporomandibular joint, cleft lip and/or palate, craniofacial syndromes, facial asymmetry, ongoing orthodontic treatment, or a history of facial fractures or orthognathic surgery. The study was approved by the University of Otago Ethics Committee (12/054). Cephalometric Analysis The Sella-Nasion mandibular plane angle (SNMP)18 was used to allocate selected participants from the entire radiography archive of the Otago University’s orthodontic clinic (n . 2500) to three groups: hyperdivergent (M 5 9, F 5 11; SNMP $42u), normodivergent (M 5 10, F 5 10; 27u # SNMP # 37u), and hypodivergent (M 5 10, F 5 10; SNMP #22u). A single calibrated investigator (Dr Rongo) carried out this assessment for all 60 pretreatment cephalograms. Soft Tissue Analysis A 3D white-light scanner (HDI Advance, BDB Solution, Burnaby, Canada) was used to capture facial scans of the study participants after initial calibration according to the manufacturer’s instructions. To ensure consistency, facial scans were carried out in a standard setting that included similar lighting conditions and a fixed scanner position. Prior to scanning, removable round markers were attached to the face to localize several anthropometric points that required palpation (Tragion, Gonion, Nasion, and Menton). The remaining landmarks were identified by visually inspecting the scans. The scanner system consisted of a projector and two cameras (U-Eye SE UI-1480SE, 5MP, CMOS; IDS Imaging Development Systems GMBH, Obersulm, Germany) with attached lenses (Fujinon TV Lens HF 12.5SA-1 1:1.4/12.5 mm; Fujifilm Holdings Corporation, Tokyo, Japan). The projector and the two cameras were mounted on an aluminum bar that was attached to a tripod (Manfrotto, Bassano del Grappa, Italy). Specialized software was used to capture the data from the light scanner (FlexScan3D, 3D3 Solutions, Burnaby, Canada). The two cameras were attached on either side of the projector with the lenses slightly convergent toward the Angle Orthodontist, Vol 84, No 5, 2014
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Statistical Analysis The facial measurements used in the present study consisted of three vertical and four transverse variables (Figure 1). Descriptive statistics were computed using the Statistical Package for Social Sciences (SPSS version 20.0, Chicago, Ill). Univariate and multivariate analysis of variance were used to test for differences between groups after adjusting for age, gender, and BMI. Similar models unadjusted for BMI and height (data not shown) were also produced. Bonferroni correction was carried out for post hoc tests. Figure 1. Facial landmarks used in the study: Ex exocanthion is the soft tissue point located at the outer commissure of each eye fissure; Or soft tissue orbitale is the soft tissue point located at the most inferior level of each infraorbital rim, located at the level of the 3D hard tissue cephalometric orbitale landmark; Na soft tissue nasion is the midpoint on the soft tissue contour of the base of the nasal root at the level of the frontonasal suture; Sn subnasale is the midpoint on the nasolabial soft tissue contour between the columella crest and the upper lip; Me soft tissue menton is the most inferior midpoint on the soft tissue contour of the chin located at the level of the 3D cephalometric hard tissue Menton landmark; Tr tragion is the point located at the upper margin of each tragus; Go soft tissue gonion is the most lateral point on the soft tissue contour of each mandibular angle, located at the same level as the 3D hard tissue cephalometric point.19
participant’s position. The scanner was positioned approximately 110 cm away from the participant. Study participants were seated and instructed to look straight ahead at the projector, with the head held in the natural head position (NHP). Black velvet was placed behind the participants to avoid any distortion and reflection of the light. Six scans were recorded to form a complete 3D image of each participant’s face. The facial scans consisted of (1) two frontal scans with the head in NHP and (2) two lateral scans obtained at 60u and 90u to the long axis of the light scanner. The second step was repeated for the opposite side of the face. During the scans, participants were asked to stay as still as possible in NHP, with their teeth together and eyes closed. The scans were used to produce six successive 3D meshes, which were then aligned, superimposed, and merged to create a single 3D image of each participant’s face (FlexScan3D, 3D3 Solutions). Facial measurements were made using a 3D inspection and mesh processing software, which was specifically developed for the dimensional analysis of 3D point clouds (GOM Inspect, GOM mbH, Braunschweig, Germany). Each participant’s height and weight were also recorded at the time of the scans to calculate body mass index (BMI). Angle Orthodontist, Vol 84, No 5, 2014
Method Error The technical errors of measurement were calculated from 12 randomly selected participants. A set of seven measurements was reassessed by one examiner after a memory washout period of at least 8 weeks. The method error for the seven measurements was calculated using Dahlberg’s formula.20 Systematic differences between duplicated measurements were tested using a paired Student’s t-test with the type I error set at .01.21 The method errors (%) were very low for linear measurements, ranging from 0.1% to 0.4%. There was no systematic error for any of the seven measurements (Student’s t-test; P . .01). To assess reliability, 13 participants (8 males and 5 females) were randomly selected and rescanned under the same conditions. The method errors (%) were very low for linear measurements, ranging from 0.7% to 1.2%. There was no systematic error for any of the seven measurements (Student’s t-test; P . .01). To assess the validity of the measurement tool, three dry skulls with clearly defined landmarks were scanned similarly to the experimental protocol. Although these hard tissue landmarks do not pertain directly to the validity of the soft tissue points, they provided a useful proxy for assessing the validity of the technique in measuring the intended markers. Five linear variables (Na-Ans, G-Ans, Ex-Ex, Po-Po, G-Op) were used to compare the measurements obtained directly from the skulls and those from the digital scans. The method errors (%) were again very low, ranging from 0.2% to 1.4%. There was no systematic error for any of the five measurements (Student’s t-test; P . .01). RESULTS A descriptive summary of the study sample is presented in Table 1. There were no significant differences in BMI for either the jaw divergence group (P 5 .178) or gender (P 5 .768). In the 3D soft tissue analysis (Table 2), the total facial height (NaMe) was significantly larger in the
791
3D EVALUATION OF JAW DIVERGENCE
Figure 2. Frontal (A, B) and lateral (C, D) views of two participants with a hyperdivergent (A, C) and a hypodivergent (B, D) facial type.
P 5 .007). On the other hand, middle facial height (NaSn) was very similar in all three groups (P . .05). With respect to the transverse dimension, there were no significant differences among the three groups except for mandibular width (GoGo), which was slightly larger in hyperdivergent (114.3 6 8.2 mm) than hypodivergent individuals (112.8 6 9.9 mm; P 5 .032).
hyperdivergent group (124.6 6 7.6 mm) than in the hypodivergent (115.6 6 8.5 mm; P , .001) and normodivergent groups (120.4 6 6.4 mm; P 5 .019). The hyperdivergent group also had an increased lower anterior facial height (SnMe 5 76.5 6 5.4 mm) in comparison with both hypodivergent (68.6 6 6.9 mm; P , .001) and normodivergent groups (72.0 6 6.0 mm;
Table 2. Soft Tissue Dimensions in the Vertical and Transversal Planes by Mandibular Divergence (Mean 6 Standard Deviation) in Millimeters Hyperdivergent Mean NaMe NaSn SnMe ExEx OrOr TrTr GoGo
124.6 52.6 76.5 94.7 71.0 139.8 114.3
SD 6 6 6 6 6 6 6
a,b
7.6 5.0 5.4a,b 5.0 4.3 7.3 8.2a
Normodivergent Mean 120.4 6 6.4 52.1 6 3.2 72.0 6 6.0 94.9 6 4.9 70.7 6 8.9 142.9 6 8.4 112.2 6 11.0
SD
Hypodivergent Mean 115.6 50.7 68.6 96.6 73.7 142.8 112.8
SD 6 6 6 6 6 6 6
8.5 4.0 6.9 4.7 4.7 5.9 9.9
P Valued (Unadjusted for BMI)
P Valuee
.000 .189 .000 .345 .259 .189 .462
.000 .172 .000 .442 .292 .343 .027
a
Bonferroni post hoc test statistically significantly different between hyperdivergent and hypodivergent. Bonferroni post hoc test statistically significantly different between hyperdivergent and normodivergent. c Bonferroni post hoc test statistically significantly different between normodivergent and hypodivergent. d Adjusted for sex and age. e Adjusted for sex, gender, age, and body mass index (BMI). Bold font: Statistically significant. b
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Table 3. Soft Tissue Dimensions in the Vertical and Transversal Planes by Sex (Mean 6 SD) in Millimeters Male Mean NaMe NaSn SnMe ExEx OrOr TrTr GoGo
124.9 6 53.4 6 75.7 6 98.0 6 73.7 6 147.1 6 119.9 6
Female SD
7.5 4.3 6.5 4.5 5.3 5.8 8.6
Mean 115.8 6 50.3 6 69.3 6 93.0 6 70.0 6 137.0 6 106.7 6
SD 6.4 3.4 5.7 3.9 6.9 4.7 5.1
P Valuea (Unadjusted for BMI)
P Valueb
.000 .002 .000 .000 .024 .000 .000
.000 .002 .000 .000 .029 .000 .000
a
Adjusted for age. Adjusted for age and body mass index (BMI). Bold font: Statistically significant. b
As expected, males had significantly larger vertical and transverse measurements than females (Table 3). All of the facial measurements were significantly associated with gender, even after adjusting for BMI (P , .05). Examples of hyperdivergent and hypodivergent facial types are given in Figure 2. DISCUSSION Several important findings were identified from the comparison between mandibular divergence and facial soft tissue dimensions. In particular, the three study groups differed significantly with respect to the vertical dimension but not for any of the four transverse measurements investigated. Mandibular width, however, was slightly increased in the hyperdivergent group after adjusting for BMI, although this was not considered to be clinically significant (>1.5 mm). Nonetheless, this finding was somewhat surprising since hypodivergent facial types are generally considered as having broader faces.12 One plausible explanation for this misconception is that a significant increase in BMI can sometimes obscure the underlying vertical morphology. In other words, hyperdivergent individuals may appear to have a flat mandibular plane that resembles a hypodivergent head form because of the overlying fat tissue. Indeed, overweight/obese people accumulate fat in the cheek areas22 but not around soft tissue menton, subnasion, and nasion.23,24 Increased cheek thickness may affect the correct localization of soft tissue gonion,19 thus resulting in an overall appearance of a square face (ie, hypodivergent). In general, the findings of the present study did not support the notion that the transverse dimension of the face is associated with vertical facial features. Although hyperdivergent individuals have previously been reported to have a low width to height ratio of the underlying skeletal structures of the head,11 the data collected on soft tissue dimensions suggested that this is mainly because of an increase in facial height rather than width. A recent study on facial dimensions also Angle Orthodontist, Vol 84, No 5, 2014
reported a similar transverse dimension in individuals with different cephalic indices.25 In contrast to the current findings, vertical measurements in that study were also similar between the various cephalic groups. It is noteworthy, however, that the age group of the two study samples differed, and this may have accounted for the differences in vertical dimension. Since transverse growth ceases relatively early in life,26,27 it is not surprising that both studies identified a difference in this dimension irrespective of the sample’s age. Vertical facial development, on the other hand, is often the last dimension to cease growth27,28 and is therefore more likely to exhibit greater variation in older samples such as the present one. Sexual dimorphism was also evident for all of the vertical and transverse measurements in the present sample. In general, females had a narrower face than males, especially in the lower third of the face (ie, GoGo). Males, however, exhibited larger vertical measurements than females. These findings are consistent with a previous anthropometric study.29 The current findings provide data describing the vertical and transverse features of the face in individuals with different jaw divergence. This information could be helpful in the treatment planning of orthognathic surgery cases presenting with either hyperdivergent or hypodivergent jaw patterns. Indeed, both mandibular advancement and setback procedures have a direct effect on the transverse dimension of the face, especially the intergonial distance.30,31 The present study has a number of limitations that should be noted. Some of the landmarks were difficult to localize on the facial scans through visual inspection alone (eg, Gonion, Menton, Tragion, and Nasion). In general, landmarks located on smooth surfaces are often difficult to identify on 3D images without the use of reference markers.32,33 To improve landmark identification, some of the more difficult landmarks were directly labeled with round markers.33,34 Nonetheless, it is possible that some of the unmarked landmarks were associated with a higher degree of measurement error. Second, patients were instructed to look straight ahead
3D EVALUATION OF JAW DIVERGENCE
while recording the scans, and this was assumed to replicate the NHP. A consistent head posture is particularly important in this type of study, since stretching of the soft tissues can occur as a result of postural changes.35 Although no specific aids (eg, mirrors) were used to position the head, it would be expected that most participants would have exhibited a NHP since this is a highly reproducible head posture.36,37 Finally, the findings are restricted to the soft tissues of the face and may not necessarily be valid for making assumptions about the underlying skeletal pattern. On the other hand, stereophotogrammetric techniques have a number of important advantages, especially in these types of studies. The low cost, lack of radiation, and quick exposure time permit it to be used in large clinical and nonclinical samples. Moreover, these new imaging techniques allow researchers to evaluate multiple planes, both cross-sectionally and longitudinally. Finally, the present study demonstrated that this 3D imaging technique is both valid and reliable for evaluating facial form. Future research in the field of craniofacial growth and development may therefore greatly benefit from this simple and noninvasive imaging technique. CONCLUSIONS N The soft tissue facial form of hyperdivergent individuals is associated with a long face pattern but not necessarily a narrow one. Variation in the transverse dimension is more likely to be due to gender and BMI. N The relatively simple and noninvasive 3D imaging technique used in this study has been shown to be reliable. Findings from this study support its use for investigating facial form in larger samples. REFERENCES 1. Schudy FF. Vertical growth versus anteroposterior growth as related to function and treatment. Angle Orthod. 1964;34: 75–93. 2. Bjo¨rk A. Prediction of mandibular growth rotation. Am J Orthod. 1969;55:585–599. 3. Karlsen AT. Association between facial height development and mandibular growth rotation in low and high MP-SN angle faces: a longitudinal study. Angle Orthod. 1997;67: 103–110. 4. Schendel SA, Eisenfeld J, Bell WH, Epker BN, Mishelevich DJ. The long face syndrome: vertical maxillary excess. Am J Orthod. 1976;70:398–408. 5. Opdebeeck H. The short face syndrome. Am J Orthod. 1978;73:499–511. 6. Nanda SK. Patterns of vertical growth in the face. Am J Orthod Dentofacial Orthop. 1988;93:103–116. 7. Sassouni V. A classification of skeletal types. Am J Orthod. 1969;55:109–123.
793 8. Cangialosi TJ. Skeletal morphologic features of anterior open bite. Am J Orthod. 1984;85:28–36. 9. Baccetti T, Franchi L, McNamara JA Jr. Longitudinal growth changes in subjects with deep bite. Am J Orthod Dentofacial Orthop. 2011;140:202–209. 10. Enlow DH, Kuroda T, Lewis AB. The morphological and morphogenetic basis for craniofacial form and pattern. Angle Orthod. 1971;41:161–188. 11. Bhat M, Enlow DH. Facial variations related to headform type. Angle Orthod. 1985;55:269–280. 12. Enlow DH. Handbook of Facial Growth. London, UK: Saunders (W.B.) Co Ltd; 1982. 13. Hoefert CS, Bacher M, Herberts T, et al. Implementing a superimposition and measurement model for 3D sagittal analysis of therapy-induced changes in facial soft tissue: a pilot study. J Orofac Orthop. 2010;71:221–234. 14. Burstone CJ. Integumental contour and extension patterns. Angle Orthod. 1959;29:93–103. 15. Subtelny JD. A longitudinal study of soft tissue facial structures and their profile characteristics, defined in relation to underlying skeletal structures. Am J Orthod. 1959;45: 481–507. 16. van Vlijmen OJ, Kuijpers MA, Berge´ SJ, et al. Evidence supporting the use of cone-beam computed tomography in orthodontics. J Am Dent Assoc. 2012;143:241–252. 17. Baik HS, Jeon JM, Lee HJ. Facial soft-tissue analysis of Korean adults with normal occlusion using a 3-dimensional laser scanner. Am J Orthod Dentofacial Orthop. 2007;131: 759–766. 18. Steiner CC. Cephalometrics for you and me. Am J Orthod. 1953;39:729–755. 19. Swennen GRJ, Schutyser F, Hausamen JE. Three-Dimensional Cephalometry: A Color Atlas and Manual. Berlin, Germany: Springer; 2005. 20. Dahlberg G. Statistical Methods for Medical and Biological Students. New York, NY: Interscience Publications; 1940. 21. Houston WJ. The analysis of errors in orthodontic measurements. Am J Orthod. 1983;83:382–390. 22. Mortimore IL, Marshall I, Wraith PK, Sellar RJ, Douglas NJ. Neck and total body fat deposition in nonobese and obese patients with sleep apnea compared with that in control subjects. Am J Respir Crit Care Med. 1998;157:280–283. 23. Donofrio LM. Fat distribution: a morphologic study of the aging face. Dermatol Surg. 2000;26:1107–1112. 24. Pilsl U, Anderhuber F. The chin and adjacent fat compartments. Dermatol Surg. 2010;36:214–218. 25. Ferrario VF, Sforza C, Poggio CE, Schmitz JH, Colombo A. Soft tissue facial morphology related to headform: a threedimensional quantitative analysis in childhood. J Craniofac Genet Dev Biol. 1997;17:86–95. 26. Hesby RM, Marshall SD, Dawson DV, et al. Transverse skeletal and dentoalveolar changes during growth. Am J Orthod Dentofacial Orthop. 2006;130:721–731. 27. Snodell SF, Nanda RS, Currier GF. A longitudinal cephalometric study of transverse and vertical craniofacial growth. Am J Orthod Dentofacial Orthop. 1993;104:471–483. 28. Pecora NG, Baccetti T, McNamara JA Jr. The aging craniofacial complex: a longitudinal cephalometric study from late adolescence to late adulthood. Am J Orthod Dentofacial Orthop. 2008;134:496–505. 29. Budai M, Farkas LG, Tompson B, Katic M, Forrest CR. Relation between anthropometric and cephalometric measurements and proportions of the face of healthy young white adult men and women. J Craniofac Surg. 2003;14: 154–161. Angle Orthodontist, Vol 84, No 5, 2014
794 30. Joss CU, Joss-Vassalli IM, Kiliaridis S, Kuijpers-Jagtman AM. Soft tissue profile changes after bilateral sagittal split osteotomy for mandibular advancement: a systematic review. J Oral Maxillofac Surg. 2010;68:1260–1269. 31. Joss CU, Joss-Vassalli IM, Berge´ SJ, Kuijpers-Jagtman AM. Soft tissue profile changes after bilateral sagittal split osteotomy for mandibular setback: a systematic review. J Oral Maxillofac Surg. 2010;68:2792–2801. 32. Aldridge K, Boyadjiev SA, Capone GT, DeLeon VB, Richtsmeier JT. Precision and error of three-dimensional phenotypic measures acquired from 3dMD photogrammetric images. Am J Med Genet A. 2005;138A:247–253. 33. Aynechi N, Larson BE, Leon-Salazar V, Beiraghi S. Accuracy and precision of a 3D anthropometric facial
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