ORIGINAL ARTICLES

Soft-tissue and dentoskeletal profile changes associated with mandibular setback osteotomy Hans Gjerup, DDS,* and Athanasios E. Athanasiou, DDS, MSD** Herning and Aarhus, Demnark

The aims of the present retrospective cephalometry study were (1) to describe the interrelationships of the soft-tissue and dentoskeletal profiles after total mandibular setback osteotomies and (2) to detect whether there were any cephalometric Variables that could contribute to an accurate prediction of the surgical effect on the soft-tissue profile. The presurgical and postsurgical lateral cephalograms of 50 consecutively treated patients (37 females and 13 males) were used; these patients had received combined orthodontic-surgical management of mandibular prognathism by means of a bilateral vertical ramus osteotomy withan extraoral approach. At the time of surgery, their ages ranged from 17 to 41 years..Lateral cephalograms with the teeth in habitual occlusion taken before and approximately 1 year after surgery were available for all patients. A computerized cephalometric appraisal, named profile analysis, was developed and used, including variables • corresponding to sagittal and vertical relationships of skeletal and soft-tissue profiles, incisal relationships, soft-tissue thickness, and lip morphology. The statistical elaboration of the data was made by means of paired t test, Pearson's product-moment coefficient correl,ation, and multiple regression analyses. The assessment of the results disclosed that considerable facial changes and improvement took place after the surgical procedure. The skeletal and soft-tissue facial profiles were straightened and the posture of the lips was improved. The normal incisal relationship achieved became influential on the soft tissues Overlying both incisors and led to a better lip competence and posture. Posterior movement at points B and Po was accompanied by reductions ranging from 91% to 103% Of the corresponding soft tissues. The presence of both significant correlation coefficients (p < 0.05) and high r square values (>0.70) in the multiple regression analysis for the osseous tissue variables N-B and N-Po, alone or together with the overjet and S-N-B angle, respectively, reflected their high prediction value with regard to the sagittal relationship of the lower lip, its thickness, and the soft-tissue thickness at the chin area. The findings of Pearson's product-moment coefficient correlation also indicated that the operative changes of the thickness of the Upper lip, the lower lip, and the soft tissue at the chin region are influenced by the initial preoperative thickness of the area. (AM J ORTHODDENTOFACORTHOP 1991 ;100:312-23.)

T h e selection of the proper type and site of osteotomies in orthognathic surgery is based on the extent of the dentofacial deformity, the degree of the desirable jaw movement, and the anticipated soft-tissue changes following surgical intervention. Improvement of the stomatognathic function is a major reason for seeking combined orthodontic-surgical therapy, especially in Scandinavia, '.2 but the consequences of surgery on facial appearance are of great importance, even

From the Royal Dental College, Aarhus. Supported by grants from the Danish Dental Association to the first author, and from the Colgate-Palmolive Company, Danish Dental Association (FLIT), and Danish Medical Research Council (Grant No. 7857) to the second author. *Former Resident, Department of Orthodontics; presently in Community Dental Services. **Associate Professor and Coordinator of Postgraduate Education, Department of Orthodontics. 8/1122402

312

for the patient whose chief complaint is not dominated by the cosmetic rationale. 3 Therefore an accurate prediction of the postoperative facial profile comprises an essential and integral part of the diagnostic and treatment planning procedures of the combined surgicalorthodontic therapy. Posterior surgical repositioning of the mandible produces relatively predictable soft-tissue changes in comparison with maxillary or double-jaw operations, 49 as long as it is not combined with chin or anterior subapical osteotomy, which makes the predetermination of soft-tissue changes more complex: ~° During the last 20 years, several cephalometric investigations have reported on the alterations of the soft-tissue profile that accompany mandibular setback, thus enlighting our understanding of the interplay between dentoosseous and soft tissues and providing data for predicting postsurgical soft-tissue response. The results of our search for

rob,me I00

Profile changes after mandibular setback

Number 4

,G

J

Ns

P

/ Pns

~

S~s

:q L, ui

Tgo° ~ IIs

P~s M

Ms

Fig. 1. The dentoskeletal and soft-tissue cephalometric landmarks used in the profile analysis. A, Point A (subspinale): the point at the deepest midline concavity on the maxilla between the anterior nasal spine and prosthion; Ans, anterior nasal spine: the most anterior point of the anterior nasal spine; Asp, anterior stable point: an arbitrarily chosen point in the symphysis of the mandible; B, point B (supramentale): the point at the deepest midline concavity on the mandibular symphysis between infradentale and pogonion; Ba, basion: the median point of the anterior margin of the foramen magnum located by following the image of the slope of the inferior border of the basilar part of the occipital bone to its posterior limit; G, glabella: the most prominent point in the midsagittal plane of the forehead; lia, incision inferior apical: the midpoint on the bisection of the apical root width of the most prominent mandibular incisor; lii, incision inferior incisal: the incisal edge of the mandibular central incisor; Ils, inferior labiaT sulcus: the point of greatest concavity in the midline of the lower lip between labrale inferius and menton; Isa, incision superior apical: the midpoint on the bisection of the apical root width of the most prominent maxillary incisor; Isi, incision superior incisal: the incisal edge of the maxillary central incisor; L1, lower central incisor: the most labial point on the crown of the mandibular central incisor; M, labrale inferius: the median point in the lower margin of the lower membranous lip; Ls, labrale superius: the median point in the upper margin of the upper membranous lip; M, menton: the most inferior midline point on the mandibular symphysis; Ms, menton soft tissue: the constructed point of intersection of a vertical coordinate from menton and the inferior soft-tissue contour of the chin; N, nasion: the most anterior (midline) point of the frontonasal suture; Ns, nasion soft tissue: the point of deepest concavity of the soft-tissue contour of the root of the nose; O, orbitale: the lowest point in the inferior margin of the orbit, midpoint between right and left images; P, porion (anatomic): the superior point of the external auditory meatus; Pn, pronasale: the most prominent point of the nose; Pns, posterior nasal spine: the intersection of a continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose, marking the dorsal limit of the maxilla; Po, pogonion: the point of tangency of a perpendicular from the mandibular plane to the most prominent convexity of the mandibular symphysis; Pos, pogonion soft tissue: the most prominent point on the soft-tissue contour of the chin; Psp, posterior stable point: an arbitrarily chosen point in the posterior part of the mandibular body; S, sella: the point representing the geometric center of the pituitary fossa (sella turcica); Sis, superior labial sulcus: the point of greatest concavity in the midline of the upper lip between subnasale and labrale superius; Sn, subnasale: the point where the lower border of the nose meets the outer contour of the upper lip; St, stomion: the midpoint between stomion superius and stomion infedus; Sti, stomion infedus: the highest point of the lower lip; Sts, stomion superius: the lowest point of the upper lip; Tgo, tangent gonion: the intersection of the ramus plane (a line tangent to the posterior border of ramus through articulare) and the mandibular plane (a line tangent to the inferior contour of ramus through menton); and U1, upper central incisor: the most labial point on the crown of the maxillary central incisor.

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Am. -I. Orthod. Dentofa¢. Orthop. October 1991

Table I. Survey of various investigations s t u d i e d - - I n t e r p l a y and changes between soft and hard tissues after

mandibular setback osteotomies

Study

I [

Surgical procedure

No. of patients

Follow-up time

Fromm and Lundberg, 19726

Setbackramus

52

2 yr

BjGrk et al., 19714

22 (10)

1 yrand II yr

McNeill et al., 1972u

Setback ramus transverse Setback subcondylar vertical Setback

Lines and Steinhauser, 1974g

Setback

Hershey and Smith, 19747 Worms, 1976~2 Kajikawa, 19799

Setback ramus vertical Setback Setback ramus or corpus Setback Setback ramus oblique vertical Setback subcondylar

Robinson et at., 19715

Wilmot, 1981~3 Wisth, 1981~ Bachmann and Wisth, 1983~ Knowless, 1964~6 Weinstein et al., 1982~7

Setback Setback sagittal split

Mandibzdar rotation

Ls-Po

Pos-Po

Posterior

O.16: I

1: l

lls-B

10 l:l 8

Minimum 3 mo

24

Minimum 6 mo

20 ramus, 13 corpus 41 44

6 wk-3 mo 2 and 10 yr

0.2:1

1: 1

Posterior

0.2: l

Anterior

0.15: i

0.9:1 1:1 1.04: l

1.12:1

Posterior

0.1 : l

0.92: I

0.87:1

O.ll:l

50 20

0.9:1

3-6 mo 4-14 mo, 5-7 yr

Posterior Anterior

A , Increase;V, decrease.

up-to-date literature have been summarized in Table I, which provides data regarding the interplay between hard and soft tissues supplemented by information related to the type o f the setback osteotomy, the size o f the sample, and the follow-up postoperative period. From this literature review, we have concluded that there are some main tendencies regarding the interplay o f the cephalometric landmarks o f the hard- and soft-tissue profiles. In general, posterior repositioning o f the mandible by ramus procedures yields a 90% softtissue change at the chin, labiomental fold, and lower lip relative to the anteroposterior bone change and in contrast with the 20% posterior movement of the upper lip. ~ However, soft-tissue response after mandibular setback osteotomies is in many instances subject to individual variation, and the predictability of softtissue changes is not a precise science. The preoperative orthodontic management could be a factor that has not been taken into consideration in the early research 4,~a6 in which the treatment was performed without conjunctive orthodontic therapy. Investigations with large and homogenous samples, which will be discussed in detail, could add to the existing knowledge. Aims o f the present cephalometric study were (1)

to describe the interrelationships o f the soft-tissue and dentoskeletal profiles following total mandibular setback osteotomies and (2) to detect whether there were cephalometric variables that could contribute to an accurate prediction o f the surgical effect on the soft-tissue profile. MATERIAL AND METHOD The material consisted of presurgical and postsurgieal lateral cephalograms of 50 consecutively treated orthognathic surgery patients (37 females and 13 males) who initially had " severe mandibular prognathism; the surgical procedures for these patients were performed by the three surgeons of the Department of Oral and Maxillofacial Surgery at the Royal Dental College, Aarhus, during the period from Jaunary 1984 to June 1987. The age of the patients at the time of surgery ranged from 17 to 39 years. All patients had orthodontic treatment performed at the school or various private clinics. The orthodontic management before surgical correction was directed at creating a stable postoperative occlusion and included leveling of the curve of Spee, expansion of the dental arches, correction of incisal inclinations, alignment of displaced teeth, and extraction of premolars in some cases. The postsurgieal orthodontic management was limited, producing finishing and final adjustment of the occlusion of the patients. All patients had a bilateral vertical ramus osteotomy through

Volume 100

Profile changes after mandibular setback

Number 4

Li-lii

Lip-chbzl throat angle

Lower lip height: Sti-Ms

Gns-Gn or Ms-M

Lower lip Upper lip height

clttq'ature:

lls I Pos-Ls •

lmm

I:1

•

1.5-2.6 mm

•

2.5 mm

Upper lip curvatare : Sls-Ls

Lower lip • when height • Lower lip • ,,,,hen height •

0.9:1

• 2 mm

• 0.8:1

0.72:1

Lip thickness lfacial height

Upper lip thickness •

0.75:1

0.66:1

31 5

•

•

• 0.96:1 1.07 : I

0.9 mm

• •

1.8 mm

•

•

• when height •

an extraoral incision in the retroangular area. Lightly tightened 0.4 mm soft stainless steel wires for fixation (osteosynthesis) of the mandibular bone fragments were used in almost one half of the cases, with the remaining cases left without any intramandibular fixation. In most of the cases, an interocclusal wafer was used and all patients were kept in intermaxillary fixation for 6 weeks. All subjects were nongrowing patients with natural dentitions and radiographs of sufficient quality, thus permitting accurate cephatometric tracing. Patients with craniofacial anomalies, syndromes, and clefting, and edentulous persons or those who had undergone genioplasty or conjunctive maxillary osteotomy procedures were excluded. Lateral cephalograms with the teeth in habitual occlusion taken just before the operation (TI) (with a maximum time span of 1 week) and approximately 1 year after surgical treatment (T2) (mean time, I 1.4 months, range 5 to 22 months) were available for all patients. No fixed orthodontic appliances were in place during phase T2 for any of the patients. In the selection process of the records, no evaluation of the treatment results of the patients was made. All x-ray films used in the present study were taken in the same cephalostat at the Department of Oral Radiology in the natural head position (mirror position) as previously described by Solow and Tallgren~s with the teeth in habitual occlusion, the lips in repose, and with calculated enlargement of the midsagittal plane structures of 5.55%.

For the purpose of this investigation, a computerized cephalometrie appraisal named profile anal)sis was developed, incorporating variables from different well-known cephalometric analyses~27 and introducing some new measurements. Our analysis was based on a reference system consisting of horizontal (HP) and vertical (VP) planes. The Frankfort horizontal plane was used as the best estimate for the HP and a line perpendicular to this plane through basion, represented the VP, as suggested by Coben. ~2-23Both HP and VP planes created a coordinate system into which all cephalometric landmarks could be located as x and y values and linear variables could be expressed as "effective" distances. The term "effective" corresponds to the projection on the plane HP or VP of the distance between two points, which defines a sagittal or vertical dimension, respectively. In cases in which the Frankfort horizontal plane could not be identified accurately, a plane having a 7° angular divergence from the anterior cranial base plane (S-N) was constmcted as previously recommended.:8.29 The profile cephalometric analysis included 32 landmarks (20 dentoskeletal and 12 soft-tissue) (Fig. 1) and 61 linear and angular variables. In the definition of landmarks, the directions used referred to the planes HP and VP (i.e., the most anterior point of the crown of the incisor means the most anterior point in relation to the vertical reference line VP). The stable points in the mandible were used to provide some information regarding the rotation of its free part after surgery.

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Am. J. Orthod.Dentofac. Or?hop. October 1991

Table II. Difference of means between first and second tracings of the 43 cephalograms traced twice and method's error tested by means of paired t test

Variable

Difference (mean)

I

Statistical significance

Sagittal relationship of skeletal profile N-Po/FH N-A/Po-A S-N-A S-N-B A-N-B S-N-Po A-N-Po AtN-Po N-Arts N-A N-B N-Po

0.17 0.19 0.15 0.01 0.13 0.04 0.10 0.12 0.79 0.10 0.34 0.34

NS NS NS NS NS NS NS NS ** NS NS NS

Vertical relationship of skeletal profile Psp-Asp/S-N Tgo-M/S-N Psp-Asp/FH Tgo-M / FH N-M N-Ans M-Ans

? 0.10 ? 0.11 0.14 0.35 0.20

NS NS * *

6.46 0.06 0.00 1.05 0.69 1.09 0.97 0.09 0.21 0.27

NS NS NS ** NS ** * NS NS NS

NS

lncisal relationship Isi-Isa/Iii-Iia Iii/Isi horizontal lii/Isi vertical lsi-lsa/Ans-Pns Isi-Isa/S-N lii-lia/Tgo-M lii-lia/FH lii/A-Po N-lsi N-lii

Sagittal relationship of soft*tissue profile Ns-Pos/FH Ns-Sls/Sls-Pos G-Sls/Sls-Pos Ns-Pos/Pos-Ls Ls/Pn-Pos LilPn-Pos Pn-Ns Ns-Sn Ns-Sls Ns-Ls Ns-St Ns-Li Ns-lls Ns-Pos

0.05 0.05 0.21 0.05 0.06 0.06 0.14 0.03 0.05 0.01 0.77 O. 14 0.11 0.09

NS NS NS NS NS NS NS NS NS NS ** NS NS NS

NS, Not significant. *p < 0.05; **p 0.7). The variable representing the horizontal linear changes of point B (N-B) can be used by itself (re = 0.88 and 0.94) or together with the horizontal incisal change (Iii/Isi horizontal) (re = 0.9) as a predictor for the sagittal response of the soft tissues in the mandibular region (Ns-Li, Ns-Ils). The variable representing the horizontal linear changes of point Po (N-Po) is also an excellent predictor of the sagittal response of the soft tissues at the chin area (NsPos) by itself (re = 0.96) or together with the S-N-B angle (r2 = 0.96). Although the other results of the regression analysis do include some other significant correlationships, the absence of a high re value creates a limitation for using them with high accuracy into the prediction process of the soft-tissue response. DISCUSSION

A serious consideration of the error of the method and the quality of the sample is of great importance in clinical cephalometric investigations. In reports characterized by unreliable cephalometric elaboration of the data and biased clinical samples, the conclusions must be questioned since the validity of the results has been compromised. In the present study, the majority of cephalometric variables showed nonsignificant differences (p > 0.05) between first and second tracings (Table II) and the soft-tissue variables did not present more differences than the dentoskeletal variables as confirmed in previous studies. 32"33However, there were still some variables that exhibited significant differences. Those consisted of cephalometric measurements including the landmark Ans in the horizontal (N-Ans) and vertical planes (N-Ans and M-Ans), the long axes of maxillary and mandibular incisors (Isi-Isa/Iii-Iia, IsiIsa/Ans-Pns, Iii-Iia/Tgo-M, and Iii-Iia/FH), the landmark stomion in the horizontal (Ns-St) and the vertical (Sn-St, Sn-Sts, St-Ms and St-IIs) planes, and variables indicating thickness of the chin and lower lip (Pos-Po and Ils-B, respectively) and protrusion of the lower lip (Li/Pos-Ls). Solow 34 has shown similar patterns of errors with regard to the tracing of incisors whose apices cannot be identified easily. 3s Wisth and Boe 32also have experienced difficulties in reproducing vertical measurements of the soft tissues. The large number of setback subjects and the fact that these patients have had the same type of osteotomy and were operated under almost identical conditions by the three surgeons provided a very uniform and representative sample, especially when compared to the data of other investigations with small numbers of pa-

Profile changes after mandibular setback

321

Table Vl. Linear sagittal changes of soft-tissue landmarks after movements of skeletal landmarks Iii, B, and Po (expressed in percentage)

Variable[lie Ls Li lls Pos

I -93% ---

B 16% 91% 103% 101%

I

Po 15% 82% 93% 91%

tients, 5"s with surgical procedures performed in different clinics, 7 with more than one type of osteotomy5,9"~3 or without any description of the material, t~'~2"~6In the sample of the present study, all patients had been subjected to orthodontic treatment and had fixed appliances during surgery. In a number of the early investigations,4.6'16 there was no conjunctive orthodontic therapy. The presurgical records of our patients were taken just before the surgical procedure; the maximum interval was 1 week. Although the follow-up period in the material was relatively long, (approximately 1 year), a rather great range existed. This range is supposed to be of minor importance since other studies have shown minimum changes to take place during a long-term period 4:3'~4 and because the soft tissues are being redistributed to a new equilibrium fairly soon after the operation. ,7 Assessment of the results demonstrated that considerable facial changes and improvement took place following the mandibular setback operation. The skeletal and soft-tissue facial profiles were straightened and the posture of the lips was improved. However, the face remained slightly prognathic. The normal incisal relationship that was achieved became influential on the soft tissues overlying both incisors and led to better lip competence and posture. The group of patients studied showed not only significant correlationships between changes of the sagittal relationships of skeletal and softtissue profiles, but of the vertical changes of the upper lip also. Although the anterior facial height was not altered at all, stomion moved inferiorly and the upper lip flattened similarly to the findings of previous reports. 4"6"9"12'15However, the height of the lower lip was decreased. This finding was in agreement with the articles of Worms t2 and Kajikawa, 9 but in opposition to the suggestions of Bachmann and Wisth. 15 The true rotation of the mandibular corpus was equal in amount and direction to the rotation of the mandibular plane. Significant morphologic alterations of the lips were associated with the correction of mandibular prognathism, including decrease of the inclination and flat-

322

~i,~rtm a n d A t h a n a s i o u

Am. J. Orthod. Dentofac. Orthop. October 1991

o

A

(

,~ Li " * - 9 1 %

Li -4-82%

I Is ~ 1 0 3 %

IIs ~ 9 3 %

P o s " - 101%

J

PoS ..~-9 1 %

J

Fig. 2. Average soft-tissue changes expressed as percentage of dentoosseous movement of landmarks B (A) and Po (B) after mandibular setback osteotomy.

tening of the upper lip, and conformed to previous reports. 5"7'9"12"1a'16 It is likely that the upper lip, because

of the abnormal incisal relationship before surgery, is kept in a "pseudoposition" as a form of adaptation and compensation. 5.g The increase in the inclination and curvature of the lower lip, which occurred in our sample, has been previously described very often. 57"9"ntna'lr"n7 The relative deepening of the mentolabial fold occurred without being associated with a change of the thickness of the lip (not at this point nor at the incisal level). Only at the chin region was there a slight increase in thickness, which tended to deepen the sulcus. Although it Was anticipated that the decrease in the height of the lower lip could make its freestanding part thicker and more protrusive, the lack of such findings may support the explanation of Weinstein et al. 17 for distribution of the soft tissues on the transverse dimension. The current study showed that in the bilateral vertical ramus osteotomy, posterior movement at points B and Po was accompanied by reductions ranging from 91% to 103% of the corresponding soft tissues (Table VI). The results of this study are about the same as the findings of other reports concerning the direct and predictable effect of skeletal repositioning on the soft-tissue face at chin, labiomental fold, and lower lip for the setback osteotomies. 4"7-9a3 Conclusions by direct comparisons of our data with data from the literature should be carefully drawn, not only because of the differences in the characteristics of the sample and the cephalometric appraisals used but also because of deviations in the time when the postsurgical records were taken.

The presence in our study of significant correlation coefficients and high r 2 values in the multiple regression analysis for the independent osseous tissue variables N-B and N-Po, alone or together with the overjet and S-N-B angle, respectively, reflects their high prediction value with regard to the sagittal relationship of the lower lip. Fig. 2 illustrates the average soft-tissue changes expressed as percentage of dentoosseous movement of the landmarks B and Po of our mandibular setback data, which can be used during treatment planning. It should be emphasized that those numbers are only mean values and some flexibility exists in most of the individual cases. In addition, findings of Pearson's productmoment coefficient correlation indicate that the operative changes of the thickness of the upper lip, the lower lip, and the soft tissue at the chin region are influenced by the initial preoperative thickness of the area (Table IV). Although the correlation analysis does show significant correlationship between the horizontal changes of the dentoskeletal structures and changes of lip morphology and some vertical changes, the regression analysis does not allow us to make any prediction of the vertical changes or the changes of the lip morphology by use of the investigated cephalometric variables as predictors. Application of the suggested prediction values delivered from the present study regarding soft-tissue response in mandibular setback cases must take place after the presurgical orthodontic management has been completed and the patient is ready for the operation. Assessment of the estimated profile characteristics before the initiation of the combined orthodontic-surgical treatment must take into consideration the effect of the presurgicaI orthodontic treatment and can be much more difficult because of the presence of significant occlusal interferences causing mandibular dislocation in many patients who seek orthognathic surgery to correct dentofacial deformities. 36 Prediction cephalometric analysis can provide preliminary consideration of the various treatment options and contributes significantly to the successful management of the case and to the informational and psychologic preparation of the patient. However, it must be remembered that after surgery (I) the facial soft-tissue structures exhibit three-dimensional changes of shape, posture, and position,H' ~7(2) an altered muscular function is established, 37 and (3) continuous osseous and soft-tissue changes take place during the lifetime, as thus forming a more complex and unpredictable pattern. We gratefully acknowledge the contributions of Dr. Jens Eriksen, Director of the Institute of Orthodontic Computer Science, Aarhus; Mr. Erik Gotfredsen, Chief of the Computer

Volume I00 Number 4 Systems Department, Royal Dental College, Aarhus; and Mr. Svend Terp, Associate Professor, Institute of Economics and Statistics, University of Aarhus, for the statistical elaboration of the data of the present study. Iqr:IeEFtl::IqCE$ 1. Wictorin L, Hillerstrom K, Sorensen S. Biological and psychological factors in patients with malformations of the jaws: a study of 95 patients prior to treatment. Seand J Plast Reconstr Surg 1969;3:138-46. 2. Athanasiou AE, Melsen B, Eriksen J. Concerns, motivation, and experience of orthognathic surgery patients: a retrospective study of 152 patients. Int J Adult Orthod Orth~nath Surg 1989;4:4755. 3. Heldt L, Haffke EA0 Davis LF. The psychol~ical and social aspects of orth~nathic treatment. AM J ORmOO 1982;82:31828. 4. Bj/Srk N, Eliasson S, Wictorin L. Changes in facial profile after surgical treatment of mandibular protrusion. Scand J Plast Reconstr Surg 1971;5:41-6. 5. Robinson WW, Speidel TM, Isaacson RJ, ~,VormsT%V. Soft tissue profile change produced by reduction of mandibular prognathism. Angle Orthod 1971;41:227-35. 6. Fromm B, Lundberg M. The soft tissue facial profile before and after surgical correction of mandibular protrusion. Acta Odontol Scand 1972;28:157-77. 7. Hershey HC, Smith LH. Soft-tissue profile change associated with surgical correction of the prognathic mandible. AM J OR"rHoD 1974;65:483-502. 8. Lines PA, Steinhauser EW. Soft tissue changes in relation to movement of hard structures in orthognathic surgery. J Oral Surg 1974;32:89 I-6. 9. Kajikawa Y. Changes in soft tissue profile after surgical correction of skeletal Class 111malocclusion. J Oral Surg 1979;37:16774. 10. Wolford LM, Hilliard FW, Dugan DJ. Surgical treatment objective: a systematic approach to the prediction tracing. St. Louis: CV Mosby, 1985:54-74. 11. McNeill RW, Proffit WR, White RP. Cephalometrie prediction for orthodontic surgery. Angle Orthod 1972;42:154-64. 12. Worms FW. Surgical orthodontic treatment plan: profile analysis and mandibular surgery. Angle Orthod 1976;46:1-25. 13. Wilmot DR. Soft tissue profile changes following correction of Class III malocclusions by mandibular surgery. Br J Orthod 1981;8:175-81. 14. Wistb PJ. What happened to them. Postoperative survey of patients 10 years after surgical correction of mandibular prognathism. AM J ORTIIOD 1981;80:525-35. 15. Bachmann J, Wisth PJ. Comparison of two methods of profile prediction in surgical treatment of mandibular prognathism. J Oral Maxillofac Surg 1983;41:17-23. 16. Knowless CC. Change in profile following surgical reduction of mandibular protrusion. Br J Plast Surg 1964;18:434-55. 17. Weinstein S, 11arris EF, Archer SY. Lip morphology and area changes associated with surgical correction of mandibular prognathism. J Oral Rehabil 1982;9:335-54. 18. Sotow B, Tallgren A. Natural head position in standing subjects. Acta Odontol Scand 1971;29:519-607. 19. Bjrrk A. The face inprofile. Svenska Tandlak Tid 1947;40(suppl 5B).

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20. Downs WB. Variations in facial relations: their significance in treatment and pr~nosis. AM J ORI'HOD 1948;34:812-40. 21. Steiner CC. Cephalometrics as a clinical tool. In: Kraus BS, Riedel RA, eds. Vistas in orthodontics. Philadelphia: Lea & Febiger, 1962:131-61. 22. Coben SE. The integration of facial skeletal variants. AM J OR"ntOD 1955;41:407-34. 23. Coben SE. Basion horizontal: an integrated concept of craniofacial growth and cephalometric analysis. Jenkintown, Pennsylvania: Computer Cephalometrics Associated, 1986:23-8. 24. Burstone CJ. The integumental profile. AM J OR'rHOD 1958;44: 1-25.

25. Ricketts RM, Bench RW, Gugino CF, Hilgers JJ, Schulhof RI. Bioprogressive therapy. Denver, Colorado: Rocky Mountain/Orthodontics, 1979:55-70. 26. Holdaway RA. A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part I. AM J ORTHOD 1983; 84:1-28. 27. Holdaway RA. A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part II. AM J OR'roOD 1984; 85:279-93. 28. Burstone CJ, James RB, Legan H, Murphy GA, Norton L. Cephalometrics for orthognathic surgery. J Oral Surg 1978;36: 269-77. 29. Legan HL, Burstone CJ. Soft tissue analysis for orthognathic surgeD,. J Oral Surg 1980;38:744-51. 30. Nie NH, Hull CH, Jenkins JG, Steinbrenner K, Bent DH. Statistical package for the social sciences. New York: McGrawHill, 1975. 31. Miller SL. Introductory statistics for dentistry and medicine. Reston, Virginia: Reston Publishing, 1981. 32. Wisth PJ, Boe OE. Reliability of cephalometric soft tissue measurements. Arch Oral 13ioi 1975;20:595-9. 33. Hillesund E, Fjeld D, Zachrisson BU. Reliability of soft-tissue profile in cephalometry. AM J ORraOD 1978;74:537-50. 34. Solow B. The pattern of craniofacial associations. Acta Odontol Scand 1966;24(suppl 46). 35. Baunuind S, Frantz R. The reliability of head film measurements. 1. Landmark identification. AM J OR'rlIOD 1971;60:11127. 36. Athanasiou AE, Melsen B, Mavreas D, Kimmel FP. Stomatognathic function of patients who seek orth~nathic surgery to correct dentofacial deformities. Int J Adult Orthod Orthognath Surg 1989;4:239-54. 37. Wickwire NA, White RP, Proffit WR. The effect of mandibular osteotomy on tooth position. J Oral Surg 1972;30:184-90. 38. Behrents RG. A treatise on the continuum of growth in the aging craniofacial skeleton [Doctoral thesis]. Ann Arbor: University of Michigan, 1984. Reprint requests to: Dr. Athanasios E. Athanasiou Department of Orthodontics The Royal Dental College Vennelyst Boulevard DK-8000 Aarhus C Denmark