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Changes in soft tissue profile after orthodontic treatment with and without extractions
ORIGINAL ARTICLE
Changes in soft tissue profile after orthodontic treatment with and without extractions I˙lken Kocadereli, DDS, PhD Ankara, Turkey The effects of orthodontic treatment on the facial profile, with or without the extraction of teeth, have greatly concerned orthodontists. A study was made of 80 patients with Angle Class I malocclusion. Forty patients (24 girls, 16 boys) did not undergo extraction of teeth, and 40 patients (23 girls, 17 boys) underwent extraction of maxillary and mandibular first premolars. Data were obtained from the corresponding lateral radiographs of the head taken before and after orthodontic treatment. The purpose of this study was to compare the response of the soft tissue of the facial profile in Class I malocclusions treated with and without the extraction of the 4 first premolars. The main soft tissue differences between the groups at the end of treatment were more retruded upper and lower lips in the extraction patients. (Am J Orthod Dentofacial Orthop 2002;122: 67-72)
E
valuating facial profiles and facial balance is a continuous learning process for orthodontists. The debate concerning the extraction of teeth and its effect on the facial profile began more than 100 years ago. Many studies concerned with the effects of orthodontic treatment on the facial profile have focused on predictive aspects of the relationship between the incisors and the lips; the goal was to relate changes in incisor position to changes in lip protrusion.1-8 Proffit,9 analyzing data from the orthodontic clinic at the University of North Carolina, indicated that changes in extraction frequencies over the past 40 years are almost entirely due to an increase and then a decrease in the extraction of the 4 first premolars. The initial increase (1953-1963) occurred primarily in a search for greater long-term stability; the more recent decline (1983-1993) seems to be due to several factors, including greater concern about the impact of extraction on facial esthetics, data suggesting that extraction does not guarantee stability, concern about temporomandibular dysfunction, and changes in technique. Orthodontists have long recognized that the extraction of premolars often is accompanied by changes in the soft tissue profile. At times, these changes result in substantial improvements in the profile and frequently justify the extraction of teeth in patients without other Associate professor, Department of Orthodontics, Faculty of Dentistry, Hacettepe University, Ankara,ខ Turkey Reprint requests to: Dr Ilken Kocadereli, Su¨slu¨ Sokak No: 4/6, MebusevleriTandog˘an, 06580 Ankara, Turkey; e-mail, [email protected]. Submitted, April 2001; revised and accepted, November 2001. Copyright © 2002 by the American Association of Orthodontists. 0889-5406/2002/$35.00 ⫹ 0 8/1/125235 doi:10.1067/mod.2002.125235
indications. At other times, however, premolar extraction can lead to a flatter profile.10 The purpose of this study was to compare the soft tissue profile changes in patients with Class I malocclusions who were treated with 4 first premolar extractions with a group of patients treated with similar appliances but without extractions. MATERIAL AND METHODS
A study included 80 white patients presenting with Angle Class I malocclusions. None of them had a severe craniofacial anomaly, and all were to be treated with edgewise appliances. No teeth were extracted in 40 patients (24 girls, 16 boys); 4 first premolars were extracted in 40 (23 girls, 17 boys). The mean ages of the patients at the beginning of treatment were similar in both groups: 12.82 ⫾ 2.37 years for the extraction group and 12.31 ⫾ 2.19 years for the nonextraction group. The average treatment times were 26.35 ⫾ 13.25 months for the nonextraction group and 31.53 ⫾ 14.10 months for the extraction group. At the end of treatment, all patients were considered to be well treated, displayed Class I canine and molar relationships, and had overbites between 10% and 25%; both dental arches were well aligned, with teeth interdigitated. In the nonextraction group, crowding was 3.18 ⫾ 2.18 mm in the maxilla and 3.15 ⫾ 1.86 mm in the mandible. In the extraction group, crowding was 7.20 ⫾ 2.44 mm in the maxilla and 5.35 ⫾ 2.50 mm in the mandible. The decision of whether to extract was based on an evaluation of the need for space to align the teeth (crowding shown by arch length–tooth size anal67
68 Kocadereli
Table I.
American Journal of Orthodontics and Dentofacial Orthopedics July 2002
Cephalometric points, lines, and angles used to evaluate changes in soft tissue profile
Points Nt, nose tip Sn, subnasale Ss, sulcus superior Ls, labrale superior Li, labrale inferior Si, sulcus inferior Pog⬘, soft-tissue pogonion A, Point A B, Point B Na, nasion Or, orbitale Po, porion Pog, pogonion Lines E-line Subnasale-pogonion plane H-line Profile line Frankfort horizontal plane NA line NB line APog line Axial inclination of maxillary incisor Axial inclination of mandibular incisor Angles Z-angle (°) Nasolabial angle (°) Labiomental angle (°) H-angle (°) Maxillary incisor-NA (°) Maxillary incisor-APog (°) Mandibular incisor-NB (°) Mandibular incisor-APog line (°) Interincisal angle (°)
Most anterior point on sagittal contour of nose Point at junction of columella and upper lip Point of greatest concavity between labrale superior and subnasale Most anterior point on convexity of upper lip Most anterior point on convexity of lower lip Point of greatest concavity between labrale inferior and soft-tissue pogonion Most anterior point on soft-tissue chin Point at deepest midline concavity on maxilla between anterior nasal spine and prosthion Point at deepest midline concavity on mandibular symphysis between infradentale and pogonion Most anterior point of frontonasal suture in median plane Lowest point in inferior margin of orbit, midpoint between right and left images Superior point of external auditory meatus Most anterior point of bony chin in median plane Esthetic line proposed by Ricketts, extending between Nt and Pog⬘ Line proposed by Burstone to measure labial protrusion, extending between Sn and Pog⬘ Harmony line proposed by Holdaway, tangential to Pog⬘ and Ls Line tangent to soft tissue chin and most prominent lip Horizontal plane running through porion and orbitale Line extending between nasion and Point A Line extending between nasion and Point B Line extending between Point A and pogonion
Inner inferior angle formed by intersection of Frankfort horizontal plane and profile line Formed by intersection of line originating in Sn, tangent to lower margin of nose, and line traced between Sn and Ls Formed by intersection of line traced between Li and Si, and line traced between Si and Pog⬘ Formed by intersection of NB line and harmony (H) line Formed by intersection of maxillary incisor axial inclination and nasion-Point A line Formed by intersection of maxillary incisor axial inclination and Point A-pogonion line Formed by intersection of mandibular incisor axial inclination and nasion-Point B line Formed by intersection of mandibular incisor axial inclination and Point A-pogonion line Formed by intersection of maxillary and mandibular incisor axial inclinations
ysis) and the cephalometric position of the mandibular incisors. Data were obtained from lateral cephalometric radiographs taken before and after orthodontic treatment, with the patient in a standing position, the teeth in occlusion, and the lips relaxed. The patients were asked to close on the molars and not to stress the lips. All cephalograms were obtained on the same cephalometric unit. All landmarks were identified by 1 investigator (I.K.) and checked for accuracy of location. All radiographs were traced by the same person (I.K.) and digitized with an RMO JOE (Rocky Mountain Orthodontics, Denver, Colo). The landmarks were digitized twice on separate occasions by the same investigator. Allowable intrainvestigator discrepancies were predetermined at 0.5 mm and 0.5°.
The cephalograms were oriented with the facial profile to the right. The cephalometric points, lines, and measurements used in this study to evaluate the changes in the soft tissue facial profile are defined in Table I. The linear and angular measurements are shown in Figures 1 and 2. Values reported in this study were calculated by subtracting the pretreatment value from the posttreatment value. Thus, a nasolabial angle that becomes more obtuse during treatment would have a positive value. Retraction of the lips relative to the E-line and Sn-Pog⬘ line would have a negative value because a measurement to the left of the reference line was recorded as negative. For example, a typical change for upper lip to E-line would be recorded as (⫺5) – (⫺1) ⫽ ⫺4. A typical change for upper lip to Sn-Pog⬘ would be from ⫹4 mm pretreat-
American Journal of Orthodontics and Dentofacial Orthopedics Volume 122, Number 1
Fig 1. Linear cephalometric measurements (mm): 1, sulcus superior–E line; 2, subnasale-pogonion plane– labrale superior; 3, labrale superior–E-line; 4, subnasale-pogonion plane–labrale inferior; 5, labrale inferior– E-line; 6, sulcus inferior–E-line; 7, lower incisor–nasion _ Point B line; 8, lower incisor–Point A_Pogonion line; 9, upper incisor–nasion_Point A line; 10, upper incisor– Point A_ pogonion line.
ment to ⫹2 mm posttreatment, recorded as (⫹4) – (⫹2)⫽ ⫺2. The groups were compared with t tests. RESULTS
Table II lists descriptive statistics for changes in facial profile after orthodontic treatment with extraction of 4 first premolars and nonextraction. The changes in maxillary and mandibular incisors to APog line (angular and linear) were statistically significant (P ⬍ .05). The changes in mandibular incisor-NB (°), maxillary incisor-NA (°), maxillary incisor-NA (mm), mandibular lip–E-line (mm), and subnasale-Pog⬘–labiale inferior (mm) were statistically significant (P ⬍ .05). The changes in H-angle, labiomental angle, sulcus superior– E-line, and sulcus inferior–E-line were not statistically significant (P ⬎ .05). For the extraction group, the maxillary and mandibular incisors showed a retroclination during treatment. In the nonextraction group, a forward tipping of the incisors was noted. The changes in incisor inclination proved to be significant. DISCUSSION
The study of beauty and harmony of the facial profile has been central to the practice of orthodontics
Kocadereli 69
Fig 2. Angular cephalometric measurements (°): 1, Zangle; 2, nasolabial angle; 3, labiomental angle; 4, H-angle; 5, upper incisor–NA; 6, upper incisor–APog; 7, lower incisor–NB; 8, lower incisor–APog line; 9, interincisal angle.
from its earliest days. The main purpose of the present study was to compare the effects of first premolar extraction on the facial profile between a sample of patients when 4 first premolar extractions were considered necessary and a similar sample when a conservative treatment was adopted. Lip structure seems to have an influence on lip response to incisor retraction. In an attempt to determine the effects of incisor retraction on the profile, several studies have been conducted to quantify and predict the relationship between incisor retraction and lip retraction.11-16 Measurement of the lips relative to Ricketts’16 E-line and Burstone’s17,18 subnasale–soft tissue pogonion (Sn-Pog⬘) line focuses attention on the relationship of nose, lips, and chin. In both groups, the upper and the lower lips were less protrusive after treatment. In the extraction group, the upper and the lower lips moved back relative to the E-line and Sn-Pog⬘ line. For the nonextraction group, the backward change of the lip region was less pronounced. At the end of treatment in this study, the mean values for upper and lower lips were slightly more protrusive than Ricketts’ esthetic ideal.16 Taking into account the flexible and mobile lip texture, a rather large variability in lip position can be
70 Kocadereli
Table II.
American Journal of Orthodontics and Dentofacial Orthopedics July 2002
Changes in facial profile Initial Extraction
Sulcus superior E-line (mm) Sn-Pog⬘ ⫽ labrale superior (mm) Labrale superior - E-line (mm) Sn-Pog⬘ - labrale inferior (mm) Labrale inferior E-line (mm) Sulcus inferior E-line (mm) Mand1 - NB line (mm) Mand1 - APog line (mm) Max1 ⫽ NA line (mm) Max1 - APog line (mm) Z-angle (°) Nasolabial angle (°) Labiomental angle (°) H-angle (°) Max1 - NA (°) Max1 - APog (°) Mand1 - NB (°) Mand1 - APog (°) Interincisal angle (°)
Nonextraction
Final P
Extraction
Nonextraction
Difference P
Extraction
Nonextraction
P
⫺10.2 ⫾ 2.3
⫺9.4 ⫾ 2.4
⫺10.7 ⫾ 2.3
⫺10.4 ⫾ 2.1
⫺0.47 ⫾ 1.6
⫺0.95 ⫾ 1.9
4.2 ⫾ 2.1
3.6 ⫾ 2.0
3.2 ⫾ 1.7
3.6 ⫾ 2.0
⫺0.9 ⫾ 1.5
0.05 ⫾ 1.6
⫺3.0 ⫾ 3.4
⫺3.0 ⫾ 2.9
⫺4.1 ⫾ 2.7
⫺3.5 ⫾ 2.9
⫺1 ⫾ 1.9
⫺0.4 ⫾ 2.2
4.3 ⫾ 2.6
3.1 ⫾ 2.3
3.2 ⫾ 2.2
3.5 ⫾ 2.3
⫺1.1 ⫾ 1.4
0.5 ⫾ 1.9
**
⫺0.6 ⫾ 3.7
⫺1 ⫾ 3.1
⫺1.4 ⫾ 3.2
⫺1 ⫾ 2.9
⫺1.1 ⫾ 2.0
⫺0.08 ⫾ 2.4
**
⫺5.0 ⫾ 2.8
⫺5.2 ⫾ 2.4
⫺5.7 ⫾ 2.4
⫺5.2 ⫾ 2.8
⫺0.76 ⫾ 1.6
⫺0.26 ⫾ 1.7
5.4 ⫾ 2.2
4.1 ⫾ 1.5
*
4.8 ⫾ 1.5
5.4 ⫾ 1.8
⫺0.4 ⫾ 1.6
1.3 ⫾ 1.5
**
3.2 ⫾ 2.4
2.0 ⫾ 2.5
*
2.5 ⫾ 2.1
3.9 ⫾ 2.5
*
⫺0.7 ⫾ 1.8
1.9 ⫾ 2.2
**
4.8 ⫾ 2.2
4.5 ⫾ 1.5
4.2 ⫾ 1.8
5.5 ⫾ 2.0
*
⫺0.6 ⫾ 2.4
1.0 ⫾ 2.0
**
6.9 ⫾ 3.0
5.6 ⫾ 2.8
*
5.5 ⫾ 1.8
6.8 ⫾ 2.5
*
⫺1.1 ⫾ 2.2
1.1 ⫾ 2.0
**
67.5 ⫾ 8.9 121.7 ⫾ 18.9
71.5 ⫾ 7.4 131.8 ⫾ 21
* **
69.1 ⫾ 8.2 126.5 ⫾ 16.3
71.7 ⫾ 6.4 128.5 ⫾ 18.7
1.8 ⫾ 4.7 4.8 ⫾ 23
⫺0.09 ⫾ 4.7 0.47 ⫾ 24.7
139.4 ⫾ 10.5
137.5 ⫾ 12.4
139.7 ⫾ 10.3
137.1 ⫾ 9.5
0.36 ⫾ 10.6
⫺0.05 ⫾ 11.38
4.8 ⫾ 4 21.9 ⫾ 5.4 28.8 ⫾ 7.2 25.8 ⫾ 6.5 22.5 ⫾ 4.0
5.2 ⫾ 3.7 20.8 ⫾ 6.1 26.1 ⫾ 6.2 22.9 ⫾ 7.3 20.9 ⫾ 5.6
5.9 ⫾ 3.6 20.3 ⫾ 7.0 25.9 ⫾ 5.1 23.1 ⫾ 6.5 20.9 ⫾ 5.0
5.2 ⫾ 3.6 25.5 ⫾ 6.3 29.1 ⫾ 5.8 27.3 ⫾ 7.5 26.1 ⫾ 5.7
** * * **
1.1 ⫾ 2.6 ⫺1.5 ⫾ 6.6 ⫺2.4 ⫾ 6.3 1.9 ⫾ 6.6 ⫺1.0 ⫾ 6.1
0.1 ⫾ 2.9 4.5 ⫾ 6.0 2.5 ⫾ 6.6 3.8 ⫾ 6.4 4.5 ⫾ 6.4
** ** ** **
125.8 ⫾ 18.3
132.7 ⫾ 9.5
133.1 ⫾ 8.5
121.7 ⫾ 20.4
**
4.3 ⫾ 9.4
⫺8.2 ⫾ 9.8
**
*
*
*
Extraction, n ⫽ 40; nonextraction, n ⫽ 40. *P ⬍ .05; **P ⬍ .005. Mand, mandibular; Max, maxillary.
expected on lateral cephalograms even when patients are instructed to keep their lips relaxed and their teeth in occlusion.19 The lip extension can easily adapt to incisor displacements and become wider or narrower, due to extensive mobility.20 When lip position is evaluated in the framework of the growing nose and chin, the lips drop slightly backward as the nose and the chin grow forward to a greater extent than the lip regions. This relatively backward evolution of the lips remains within conventional esthetic prescriptions. The lip movement in the nonextraction group proved to be less important than the effect of nose and chin growth because, even in this group, the lip regions moved backward with respect to the nose-chin line. Lip structure seems to have an influence on lip response to
incisor retraction. Oliver4 found that patients with thin lips or a high lip strain displayed a significant correlation between incisor retraction and lip retraction, but patients with thick lips or low lip strain displayed no such correlation. In addition, Wisth15 found that lip response, as a proportion of incisor retraction, decreased as the amount of incisor retraction increased. This seems to indicate that the lips have some inherent support. In this study, for the extraction group, the maxillary and mandibular incisors showed greater retroclination after treatment than before. In the nonextraction group, a forward tipping of the incisors after treatment was noted. The changes in incisor inclination proved to be significant. When compared with the normative value
Kocadereli 71
American Journal of Orthodontics and Dentofacial Orthopedics Volume 122, Number 1
according to Steiner,21 the posttreatment mean in the nonextraction group was excessive for the maxillary and mandibular incisors. In the extraction group, the mean posttreatment value was close to the normative value for both the maxillary and mandibular incisors. For occlusal stability, Downs22 preferred an interincisal angle of 135.4°. The analysis of Steiner21 indicates an interincisal angle of 131°. In this study, in the extraction group, the inclination of the incisors was reduced, and the distal movement of the incisal edges was accompanied by a mean increase of the interincisal angle of about 4.5°, normalizing the interincisal angle. In the nonextraction group, the proclination of the incisors was more evident in the mandibular incisor region. The increased inclination of the incisors was combined with a forward movement of the incisal edges and created a mean decrease of the interincisal angle of about 8° compared with a posttreatment value of 121°. The ideal range for the nasolabial angles is defined as between 90° and 120°. In a study by De Smit and Dermaut,23 the mean nasolabial angle for a mixed study group was found to be 110°. The mean value of the nasolabial angle in the present study was at a relatively high level, which increased with active treatment. The nasolabial angle was increased in the extraction group (4.8°). The difference between the 2 groups was not significant. These findings agreed with the results of Finnoy et al,24 who found that their extraction group had a significantly greater increase of the nasolabial angle than the nonextraction group. The depth of the plica labiomentalis plays an important role in the esthetic evaluation of the facial profile. In a study concerning soft tissue profile preference, De Smit and Dermaut23 reported that a flattening of the mental fold led to a more drastic loss of esthetic preference than a deepening. Considering the large standard deviations, the changes during treatment found in the present study have limited clinical importance. Merrifield’s25 study of facial profiles in a sample of 120 treated and untreated patients with pleasing facial esthetics led to the development of the Z-angle to quantify balance, or lack thereof, of the lower facial profile. He found the normal Z-angle range in his sample to be 72° to 83°. In this study, the pretreatment Z-angle of the extraction group was 67.5° compared with 71.5° for the nonextraction group. In the extraction group, the posttreatment Z-angle became 69°, an increase of 1.5°. In the nonextraction group, the Zangle remained the same (71.5°). The mean finished profile assessment for the extrac-
tion patients fell within the pleasing normal range, as measured by the Holdaway26,27 H-line. Soft tissue profiles were examined in 160 orthodontic patients treated by removing the 4 first premolars by Drobocky and Smith.10 The mean changes for the total sample included an increase of 5.2° in the nasolabial angle and retraction of the upper and lower lips of 3.4 and 3.6 mm to the E-line, respectively. When they compared the profile changes to values representing normal (or ideal) facial esthetics, it was evident that extracting the 4 first premolars generally did not result in a “dished-in” profile.10 The findings of the present study indicate that, when a decrease of lip procumbency is desirable, extracting premolars and retracting incisors is a viable option to achieve these objectives. However, individual variation in response is large. Incisor retraction in one patient might lead to a large amount of lip retraction, whereas, in another patient, a similar amount of retraction might lead to only minimal improvement in lip procumbency. It would therefore be prudent to tell the patient about the expected average change, but also that it could be different in his or her particular instance. In addition, when a 13- or 14-year-old patient presents for treatment, and the main objective is to reduce the prominence of the lips, the patient’s sex should be considered. In an adolescent boy, the nose and chin will continue to grow much more than in a girl. This will have the effect of decreasing lip procumbency relative to the SnPog⬘ line and especially to a line drawn from the tip of the nose to the tip of the chin. CONCLUSIONS
Measuring esthetics is very complex; in general, after orthodontic treatment with 4 premolar extractions, facial profile esthetics are improved, even if some standards were not reached (nasal and chin changes) because of remaining growth. Finally, the overall esthetic results of these relatively big changes on the facial soft tissue profile are very difficult to measure with numbers alone, and, to a certain degree, it is a matter of subjective opinion, variable in nonextreme cases from person to person, and even according to modes, races, and social groups.
REFERENCES 1. Hershey HG. Incisor tooth retraction and subsequent profile change in post-adolescent female patients. Am J Orthod 1972; 61:45-54. 2. Jacobs JD. Vertical lip changes from maxillary incisor retraction. Am J Orthod 1978;74:396-404. 3. Lo FD, Hunter WS. Changes in nasolabial angle related to maxillary incisor retraction. Am J Orthod 1982;82:348-91.
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American Journal of Orthodontics and Dentofacial Orthopedics July 2002
4. Oliver BM. The influence of lip thickness and strain on upper lip response to incisor retraction. Am J Orthod 1982;82:141-9. 5. Rains MD, Nanda R. Soft-tissue changes associated with maxillary incisor retraction. Am J Orthod 1982;81:481-8. 6. Talass MF, Talass L, Baker RC. Soft-tissue profile changes resulting from retraction of maxillary incisors. Am J Orthod Dentofacial Orthop 1987;91:385-94. 7. Yogosawa F. Predicting soft tissue profile changes concurrent with orthodontic treatment. Angle Orthod 1990;60:199-206. 8. Battagel JM. The relationship between hard and soft tissue changes following treatment of Class II Division 1 malocclusions using edgewise and Fra¨ nkel appliance techniques. Eur J Orthod 1990;12:154-65. 9. Proffit WR. Forty-year review of extraction frequencies at a university orthodontic clinic. Angle Orthod 1994;64:407-14. 10. Drobocky OB, Smith RJ. Changes in facial profile during orthodontic treatment with extraction of four first premolars. Am J Orthod Dentofacial Orthop 1989;95:220-30. 11. Bloom LA. Perioral profile changes in orthodontic treatment. Am J Orthod 1961;47:371. 12. Rudee DA. Proportional profile changes concurrent with orthodontic therapy. Am J Orthod 1964;50:421-34. 13. Garner LD. Soft tissue changes concurrent with orthodontic tooth movement Am J Orthod 1974;66:357-77. 14. Roos N. Soft tissue changes in Class II treatment. Am J Orthod 1977;72:165-75. 15. Wisth PJ. Soft tissue response to upper incisor retraction in boys. Br J Orthod 1974;1:199-204.
16. Ricketts RM. Esthetics, environment and the law of lip relation. Am J Orthod 1968;54:272-89. 17. Burstone CJ. The integumental profile. Am J Orthod 1958;44:125. 18. Burstone CJ. Lip posture and its significance in treatment planning. Am J Orthod 1967;53:262-84. 19. Hillesund E, Fjeld D, Zachrisson BU. Reliability of soft-tissue profile in cephalometrics. Am J Orthod 1978;74:537-50. 20. Saelens NA, De Smit A. Therapeutic changes in extraction versus non-extraction orthodontic treatment. Eur J Orthod 1998; 20:225-36. 21. Steiner CC. Cephalometrics in clinical practice. Am J Orthod 1959;29:8-29. 22. Downs WB. Analysis of the dentofacial profile. Angle Orthod 1956;26:191-7. 23. De Smit A, Dermaut L. Soft tissue profile preference. Am J Orthod 1984;86:67-73. 24. Finnoy JP, Wisth PJ, Boe OE. Changes in soft tissue profile during and after orthodontic treatment. Eur J Orthod 1987;9:6878. 25. Merrifield LL. The profile line as an aid in critically evaluating facial esthetics. Am J Orthod 1966;52:804-22. 26. Holdaway RA. A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part I. Am J Orthod 1983;84:128. 27. Holdaway RA. A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part II. Am J Orthod 1984; 85:279-93.
Editors of the American Journal of Orthodontics and Dentofacial Orthopedics 1915 to 1931 Martin Dewey 1931 to 1968 H. C. Pollock 1968 to 1978 B. F. Dewel 1978 to 1985 Wayne G. Watson 1985 to 2000 Thomas M. Graber 2000 to present David L. Turpin
Changes in soft tissue profile after orthodontic treatment with and without extractions I˙lken Kocadereli, DDS, PhD Ankara, Turkey The effects of orthodontic treatment on the facial profile, with or without the extraction of teeth, have greatly concerned orthodontists. A study was made of 80 patients with Angle Class I malocclusion. Forty patients (24 girls, 16 boys) did not undergo extraction of teeth, and 40 patients (23 girls, 17 boys) underwent extraction of maxillary and mandibular first premolars. Data were obtained from the corresponding lateral radiographs of the head taken before and after orthodontic treatment. The purpose of this study was to compare the response of the soft tissue of the facial profile in Class I malocclusions treated with and without the extraction of the 4 first premolars. The main soft tissue differences between the groups at the end of treatment were more retruded upper and lower lips in the extraction patients. (Am J Orthod Dentofacial Orthop 2002;122: 67-72)
E
valuating facial profiles and facial balance is a continuous learning process for orthodontists. The debate concerning the extraction of teeth and its effect on the facial profile began more than 100 years ago. Many studies concerned with the effects of orthodontic treatment on the facial profile have focused on predictive aspects of the relationship between the incisors and the lips; the goal was to relate changes in incisor position to changes in lip protrusion.1-8 Proffit,9 analyzing data from the orthodontic clinic at the University of North Carolina, indicated that changes in extraction frequencies over the past 40 years are almost entirely due to an increase and then a decrease in the extraction of the 4 first premolars. The initial increase (1953-1963) occurred primarily in a search for greater long-term stability; the more recent decline (1983-1993) seems to be due to several factors, including greater concern about the impact of extraction on facial esthetics, data suggesting that extraction does not guarantee stability, concern about temporomandibular dysfunction, and changes in technique. Orthodontists have long recognized that the extraction of premolars often is accompanied by changes in the soft tissue profile. At times, these changes result in substantial improvements in the profile and frequently justify the extraction of teeth in patients without other Associate professor, Department of Orthodontics, Faculty of Dentistry, Hacettepe University, Ankara,ខ Turkey Reprint requests to: Dr Ilken Kocadereli, Su¨slu¨ Sokak No: 4/6, MebusevleriTandog˘an, 06580 Ankara, Turkey; e-mail, [email protected]. Submitted, April 2001; revised and accepted, November 2001. Copyright © 2002 by the American Association of Orthodontists. 0889-5406/2002/$35.00 ⫹ 0 8/1/125235 doi:10.1067/mod.2002.125235
indications. At other times, however, premolar extraction can lead to a flatter profile.10 The purpose of this study was to compare the soft tissue profile changes in patients with Class I malocclusions who were treated with 4 first premolar extractions with a group of patients treated with similar appliances but without extractions. MATERIAL AND METHODS
A study included 80 white patients presenting with Angle Class I malocclusions. None of them had a severe craniofacial anomaly, and all were to be treated with edgewise appliances. No teeth were extracted in 40 patients (24 girls, 16 boys); 4 first premolars were extracted in 40 (23 girls, 17 boys). The mean ages of the patients at the beginning of treatment were similar in both groups: 12.82 ⫾ 2.37 years for the extraction group and 12.31 ⫾ 2.19 years for the nonextraction group. The average treatment times were 26.35 ⫾ 13.25 months for the nonextraction group and 31.53 ⫾ 14.10 months for the extraction group. At the end of treatment, all patients were considered to be well treated, displayed Class I canine and molar relationships, and had overbites between 10% and 25%; both dental arches were well aligned, with teeth interdigitated. In the nonextraction group, crowding was 3.18 ⫾ 2.18 mm in the maxilla and 3.15 ⫾ 1.86 mm in the mandible. In the extraction group, crowding was 7.20 ⫾ 2.44 mm in the maxilla and 5.35 ⫾ 2.50 mm in the mandible. The decision of whether to extract was based on an evaluation of the need for space to align the teeth (crowding shown by arch length–tooth size anal67
68 Kocadereli
Table I.
American Journal of Orthodontics and Dentofacial Orthopedics July 2002
Cephalometric points, lines, and angles used to evaluate changes in soft tissue profile
Points Nt, nose tip Sn, subnasale Ss, sulcus superior Ls, labrale superior Li, labrale inferior Si, sulcus inferior Pog⬘, soft-tissue pogonion A, Point A B, Point B Na, nasion Or, orbitale Po, porion Pog, pogonion Lines E-line Subnasale-pogonion plane H-line Profile line Frankfort horizontal plane NA line NB line APog line Axial inclination of maxillary incisor Axial inclination of mandibular incisor Angles Z-angle (°) Nasolabial angle (°) Labiomental angle (°) H-angle (°) Maxillary incisor-NA (°) Maxillary incisor-APog (°) Mandibular incisor-NB (°) Mandibular incisor-APog line (°) Interincisal angle (°)
Most anterior point on sagittal contour of nose Point at junction of columella and upper lip Point of greatest concavity between labrale superior and subnasale Most anterior point on convexity of upper lip Most anterior point on convexity of lower lip Point of greatest concavity between labrale inferior and soft-tissue pogonion Most anterior point on soft-tissue chin Point at deepest midline concavity on maxilla between anterior nasal spine and prosthion Point at deepest midline concavity on mandibular symphysis between infradentale and pogonion Most anterior point of frontonasal suture in median plane Lowest point in inferior margin of orbit, midpoint between right and left images Superior point of external auditory meatus Most anterior point of bony chin in median plane Esthetic line proposed by Ricketts, extending between Nt and Pog⬘ Line proposed by Burstone to measure labial protrusion, extending between Sn and Pog⬘ Harmony line proposed by Holdaway, tangential to Pog⬘ and Ls Line tangent to soft tissue chin and most prominent lip Horizontal plane running through porion and orbitale Line extending between nasion and Point A Line extending between nasion and Point B Line extending between Point A and pogonion
Inner inferior angle formed by intersection of Frankfort horizontal plane and profile line Formed by intersection of line originating in Sn, tangent to lower margin of nose, and line traced between Sn and Ls Formed by intersection of line traced between Li and Si, and line traced between Si and Pog⬘ Formed by intersection of NB line and harmony (H) line Formed by intersection of maxillary incisor axial inclination and nasion-Point A line Formed by intersection of maxillary incisor axial inclination and Point A-pogonion line Formed by intersection of mandibular incisor axial inclination and nasion-Point B line Formed by intersection of mandibular incisor axial inclination and Point A-pogonion line Formed by intersection of maxillary and mandibular incisor axial inclinations
ysis) and the cephalometric position of the mandibular incisors. Data were obtained from lateral cephalometric radiographs taken before and after orthodontic treatment, with the patient in a standing position, the teeth in occlusion, and the lips relaxed. The patients were asked to close on the molars and not to stress the lips. All cephalograms were obtained on the same cephalometric unit. All landmarks were identified by 1 investigator (I.K.) and checked for accuracy of location. All radiographs were traced by the same person (I.K.) and digitized with an RMO JOE (Rocky Mountain Orthodontics, Denver, Colo). The landmarks were digitized twice on separate occasions by the same investigator. Allowable intrainvestigator discrepancies were predetermined at 0.5 mm and 0.5°.
The cephalograms were oriented with the facial profile to the right. The cephalometric points, lines, and measurements used in this study to evaluate the changes in the soft tissue facial profile are defined in Table I. The linear and angular measurements are shown in Figures 1 and 2. Values reported in this study were calculated by subtracting the pretreatment value from the posttreatment value. Thus, a nasolabial angle that becomes more obtuse during treatment would have a positive value. Retraction of the lips relative to the E-line and Sn-Pog⬘ line would have a negative value because a measurement to the left of the reference line was recorded as negative. For example, a typical change for upper lip to E-line would be recorded as (⫺5) – (⫺1) ⫽ ⫺4. A typical change for upper lip to Sn-Pog⬘ would be from ⫹4 mm pretreat-
American Journal of Orthodontics and Dentofacial Orthopedics Volume 122, Number 1
Fig 1. Linear cephalometric measurements (mm): 1, sulcus superior–E line; 2, subnasale-pogonion plane– labrale superior; 3, labrale superior–E-line; 4, subnasale-pogonion plane–labrale inferior; 5, labrale inferior– E-line; 6, sulcus inferior–E-line; 7, lower incisor–nasion _ Point B line; 8, lower incisor–Point A_Pogonion line; 9, upper incisor–nasion_Point A line; 10, upper incisor– Point A_ pogonion line.
ment to ⫹2 mm posttreatment, recorded as (⫹4) – (⫹2)⫽ ⫺2. The groups were compared with t tests. RESULTS
Table II lists descriptive statistics for changes in facial profile after orthodontic treatment with extraction of 4 first premolars and nonextraction. The changes in maxillary and mandibular incisors to APog line (angular and linear) were statistically significant (P ⬍ .05). The changes in mandibular incisor-NB (°), maxillary incisor-NA (°), maxillary incisor-NA (mm), mandibular lip–E-line (mm), and subnasale-Pog⬘–labiale inferior (mm) were statistically significant (P ⬍ .05). The changes in H-angle, labiomental angle, sulcus superior– E-line, and sulcus inferior–E-line were not statistically significant (P ⬎ .05). For the extraction group, the maxillary and mandibular incisors showed a retroclination during treatment. In the nonextraction group, a forward tipping of the incisors was noted. The changes in incisor inclination proved to be significant. DISCUSSION
The study of beauty and harmony of the facial profile has been central to the practice of orthodontics
Kocadereli 69
Fig 2. Angular cephalometric measurements (°): 1, Zangle; 2, nasolabial angle; 3, labiomental angle; 4, H-angle; 5, upper incisor–NA; 6, upper incisor–APog; 7, lower incisor–NB; 8, lower incisor–APog line; 9, interincisal angle.
from its earliest days. The main purpose of the present study was to compare the effects of first premolar extraction on the facial profile between a sample of patients when 4 first premolar extractions were considered necessary and a similar sample when a conservative treatment was adopted. Lip structure seems to have an influence on lip response to incisor retraction. In an attempt to determine the effects of incisor retraction on the profile, several studies have been conducted to quantify and predict the relationship between incisor retraction and lip retraction.11-16 Measurement of the lips relative to Ricketts’16 E-line and Burstone’s17,18 subnasale–soft tissue pogonion (Sn-Pog⬘) line focuses attention on the relationship of nose, lips, and chin. In both groups, the upper and the lower lips were less protrusive after treatment. In the extraction group, the upper and the lower lips moved back relative to the E-line and Sn-Pog⬘ line. For the nonextraction group, the backward change of the lip region was less pronounced. At the end of treatment in this study, the mean values for upper and lower lips were slightly more protrusive than Ricketts’ esthetic ideal.16 Taking into account the flexible and mobile lip texture, a rather large variability in lip position can be
70 Kocadereli
Table II.
American Journal of Orthodontics and Dentofacial Orthopedics July 2002
Changes in facial profile Initial Extraction
Sulcus superior E-line (mm) Sn-Pog⬘ ⫽ labrale superior (mm) Labrale superior - E-line (mm) Sn-Pog⬘ - labrale inferior (mm) Labrale inferior E-line (mm) Sulcus inferior E-line (mm) Mand1 - NB line (mm) Mand1 - APog line (mm) Max1 ⫽ NA line (mm) Max1 - APog line (mm) Z-angle (°) Nasolabial angle (°) Labiomental angle (°) H-angle (°) Max1 - NA (°) Max1 - APog (°) Mand1 - NB (°) Mand1 - APog (°) Interincisal angle (°)
Nonextraction
Final P
Extraction
Nonextraction
Difference P
Extraction
Nonextraction
P
⫺10.2 ⫾ 2.3
⫺9.4 ⫾ 2.4
⫺10.7 ⫾ 2.3
⫺10.4 ⫾ 2.1
⫺0.47 ⫾ 1.6
⫺0.95 ⫾ 1.9
4.2 ⫾ 2.1
3.6 ⫾ 2.0
3.2 ⫾ 1.7
3.6 ⫾ 2.0
⫺0.9 ⫾ 1.5
0.05 ⫾ 1.6
⫺3.0 ⫾ 3.4
⫺3.0 ⫾ 2.9
⫺4.1 ⫾ 2.7
⫺3.5 ⫾ 2.9
⫺1 ⫾ 1.9
⫺0.4 ⫾ 2.2
4.3 ⫾ 2.6
3.1 ⫾ 2.3
3.2 ⫾ 2.2
3.5 ⫾ 2.3
⫺1.1 ⫾ 1.4
0.5 ⫾ 1.9
**
⫺0.6 ⫾ 3.7
⫺1 ⫾ 3.1
⫺1.4 ⫾ 3.2
⫺1 ⫾ 2.9
⫺1.1 ⫾ 2.0
⫺0.08 ⫾ 2.4
**
⫺5.0 ⫾ 2.8
⫺5.2 ⫾ 2.4
⫺5.7 ⫾ 2.4
⫺5.2 ⫾ 2.8
⫺0.76 ⫾ 1.6
⫺0.26 ⫾ 1.7
5.4 ⫾ 2.2
4.1 ⫾ 1.5
*
4.8 ⫾ 1.5
5.4 ⫾ 1.8
⫺0.4 ⫾ 1.6
1.3 ⫾ 1.5
**
3.2 ⫾ 2.4
2.0 ⫾ 2.5
*
2.5 ⫾ 2.1
3.9 ⫾ 2.5
*
⫺0.7 ⫾ 1.8
1.9 ⫾ 2.2
**
4.8 ⫾ 2.2
4.5 ⫾ 1.5
4.2 ⫾ 1.8
5.5 ⫾ 2.0
*
⫺0.6 ⫾ 2.4
1.0 ⫾ 2.0
**
6.9 ⫾ 3.0
5.6 ⫾ 2.8
*
5.5 ⫾ 1.8
6.8 ⫾ 2.5
*
⫺1.1 ⫾ 2.2
1.1 ⫾ 2.0
**
67.5 ⫾ 8.9 121.7 ⫾ 18.9
71.5 ⫾ 7.4 131.8 ⫾ 21
* **
69.1 ⫾ 8.2 126.5 ⫾ 16.3
71.7 ⫾ 6.4 128.5 ⫾ 18.7
1.8 ⫾ 4.7 4.8 ⫾ 23
⫺0.09 ⫾ 4.7 0.47 ⫾ 24.7
139.4 ⫾ 10.5
137.5 ⫾ 12.4
139.7 ⫾ 10.3
137.1 ⫾ 9.5
0.36 ⫾ 10.6
⫺0.05 ⫾ 11.38
4.8 ⫾ 4 21.9 ⫾ 5.4 28.8 ⫾ 7.2 25.8 ⫾ 6.5 22.5 ⫾ 4.0
5.2 ⫾ 3.7 20.8 ⫾ 6.1 26.1 ⫾ 6.2 22.9 ⫾ 7.3 20.9 ⫾ 5.6
5.9 ⫾ 3.6 20.3 ⫾ 7.0 25.9 ⫾ 5.1 23.1 ⫾ 6.5 20.9 ⫾ 5.0
5.2 ⫾ 3.6 25.5 ⫾ 6.3 29.1 ⫾ 5.8 27.3 ⫾ 7.5 26.1 ⫾ 5.7
** * * **
1.1 ⫾ 2.6 ⫺1.5 ⫾ 6.6 ⫺2.4 ⫾ 6.3 1.9 ⫾ 6.6 ⫺1.0 ⫾ 6.1
0.1 ⫾ 2.9 4.5 ⫾ 6.0 2.5 ⫾ 6.6 3.8 ⫾ 6.4 4.5 ⫾ 6.4
** ** ** **
125.8 ⫾ 18.3
132.7 ⫾ 9.5
133.1 ⫾ 8.5
121.7 ⫾ 20.4
**
4.3 ⫾ 9.4
⫺8.2 ⫾ 9.8
**
*
*
*
Extraction, n ⫽ 40; nonextraction, n ⫽ 40. *P ⬍ .05; **P ⬍ .005. Mand, mandibular; Max, maxillary.
expected on lateral cephalograms even when patients are instructed to keep their lips relaxed and their teeth in occlusion.19 The lip extension can easily adapt to incisor displacements and become wider or narrower, due to extensive mobility.20 When lip position is evaluated in the framework of the growing nose and chin, the lips drop slightly backward as the nose and the chin grow forward to a greater extent than the lip regions. This relatively backward evolution of the lips remains within conventional esthetic prescriptions. The lip movement in the nonextraction group proved to be less important than the effect of nose and chin growth because, even in this group, the lip regions moved backward with respect to the nose-chin line. Lip structure seems to have an influence on lip response to
incisor retraction. Oliver4 found that patients with thin lips or a high lip strain displayed a significant correlation between incisor retraction and lip retraction, but patients with thick lips or low lip strain displayed no such correlation. In addition, Wisth15 found that lip response, as a proportion of incisor retraction, decreased as the amount of incisor retraction increased. This seems to indicate that the lips have some inherent support. In this study, for the extraction group, the maxillary and mandibular incisors showed greater retroclination after treatment than before. In the nonextraction group, a forward tipping of the incisors after treatment was noted. The changes in incisor inclination proved to be significant. When compared with the normative value
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American Journal of Orthodontics and Dentofacial Orthopedics Volume 122, Number 1
according to Steiner,21 the posttreatment mean in the nonextraction group was excessive for the maxillary and mandibular incisors. In the extraction group, the mean posttreatment value was close to the normative value for both the maxillary and mandibular incisors. For occlusal stability, Downs22 preferred an interincisal angle of 135.4°. The analysis of Steiner21 indicates an interincisal angle of 131°. In this study, in the extraction group, the inclination of the incisors was reduced, and the distal movement of the incisal edges was accompanied by a mean increase of the interincisal angle of about 4.5°, normalizing the interincisal angle. In the nonextraction group, the proclination of the incisors was more evident in the mandibular incisor region. The increased inclination of the incisors was combined with a forward movement of the incisal edges and created a mean decrease of the interincisal angle of about 8° compared with a posttreatment value of 121°. The ideal range for the nasolabial angles is defined as between 90° and 120°. In a study by De Smit and Dermaut,23 the mean nasolabial angle for a mixed study group was found to be 110°. The mean value of the nasolabial angle in the present study was at a relatively high level, which increased with active treatment. The nasolabial angle was increased in the extraction group (4.8°). The difference between the 2 groups was not significant. These findings agreed with the results of Finnoy et al,24 who found that their extraction group had a significantly greater increase of the nasolabial angle than the nonextraction group. The depth of the plica labiomentalis plays an important role in the esthetic evaluation of the facial profile. In a study concerning soft tissue profile preference, De Smit and Dermaut23 reported that a flattening of the mental fold led to a more drastic loss of esthetic preference than a deepening. Considering the large standard deviations, the changes during treatment found in the present study have limited clinical importance. Merrifield’s25 study of facial profiles in a sample of 120 treated and untreated patients with pleasing facial esthetics led to the development of the Z-angle to quantify balance, or lack thereof, of the lower facial profile. He found the normal Z-angle range in his sample to be 72° to 83°. In this study, the pretreatment Z-angle of the extraction group was 67.5° compared with 71.5° for the nonextraction group. In the extraction group, the posttreatment Z-angle became 69°, an increase of 1.5°. In the nonextraction group, the Zangle remained the same (71.5°). The mean finished profile assessment for the extrac-
tion patients fell within the pleasing normal range, as measured by the Holdaway26,27 H-line. Soft tissue profiles were examined in 160 orthodontic patients treated by removing the 4 first premolars by Drobocky and Smith.10 The mean changes for the total sample included an increase of 5.2° in the nasolabial angle and retraction of the upper and lower lips of 3.4 and 3.6 mm to the E-line, respectively. When they compared the profile changes to values representing normal (or ideal) facial esthetics, it was evident that extracting the 4 first premolars generally did not result in a “dished-in” profile.10 The findings of the present study indicate that, when a decrease of lip procumbency is desirable, extracting premolars and retracting incisors is a viable option to achieve these objectives. However, individual variation in response is large. Incisor retraction in one patient might lead to a large amount of lip retraction, whereas, in another patient, a similar amount of retraction might lead to only minimal improvement in lip procumbency. It would therefore be prudent to tell the patient about the expected average change, but also that it could be different in his or her particular instance. In addition, when a 13- or 14-year-old patient presents for treatment, and the main objective is to reduce the prominence of the lips, the patient’s sex should be considered. In an adolescent boy, the nose and chin will continue to grow much more than in a girl. This will have the effect of decreasing lip procumbency relative to the SnPog⬘ line and especially to a line drawn from the tip of the nose to the tip of the chin. CONCLUSIONS
Measuring esthetics is very complex; in general, after orthodontic treatment with 4 premolar extractions, facial profile esthetics are improved, even if some standards were not reached (nasal and chin changes) because of remaining growth. Finally, the overall esthetic results of these relatively big changes on the facial soft tissue profile are very difficult to measure with numbers alone, and, to a certain degree, it is a matter of subjective opinion, variable in nonextreme cases from person to person, and even according to modes, races, and social groups.
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American Journal of Orthodontics and Dentofacial Orthopedics July 2002
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Editors of the American Journal of Orthodontics and Dentofacial Orthopedics 1915 to 1931 Martin Dewey 1931 to 1968 H. C. Pollock 1968 to 1978 B. F. Dewel 1978 to 1985 Wayne G. Watson 1985 to 2000 Thomas M. Graber 2000 to present David L. Turpin