Facial soft tissue response to anterior segmental osteotomies: A systematic review

Int. J. Oral Maxillofac. Surg. 2010; 39: 1050–1058 doi:10.1016/j.ijom.2010.07.002, available online at http://www.sciencedirect.com

Invited Review Paper Orthognathic Surgery

Facial soft tissue response to anterior segmental osteotomies: A systematic review

Y. S. N. Jayaratne, R. A. Zwahlen, J. Lo, L. K. Cheung Discipline of Oral & Maxillofacial Surgery, Faculty of Dentistry, The University of Hong Kong, Hong Kong

Y. S. N. Jayaratne, R. A. Zwahlen, J. Lo, L. K. Cheung: Facial soft tissue response to anterior segmental osteotomies: A systematic review. Int. J. Oral Maxillofac. Surg. 2010; 39: 1050–1058. # 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. Bimaxillary protrusion is prevalent among Asians and anterior segmental osteotomies are commonly used for its surgical correction. The objective of this study was to evaluate the soft tissue changes resulting from anterior segmental osteotomies. The electronic databases PubMed, Scopus and ISI Web of knowledge were searched for potentially eligible studies using a set of predetermined keywords. Full texts meeting the inclusion criteria were retrieved and their references were manually searched for additional relevant articles. The study details and outcome data of these reports were extracted using spreadsheets for comparison. The methodological quality of each study was assessed. Eleven studies met the inclusion criteria. Lateral cephalometry was used in all studies. A reduction of the labial prominence with an increase in the nasolabial angle was noted subsequent to anterior segmental osteotomies. The magnitude of the reported soft tissue changes and their ratios corresponding to the osseous movements varied among studies. Long-term, prospective, methodologically sound clinical trials with larger samples and threedimensional quantification are required to provide sufficient information for predicting the soft tissue response to anterior segmental osteotomies.

Evidence-based practice has gained popularity among clinicians as it facilitates the integration of best available scientific knowledge in routine clinical practice9. Systematic reviews are an integral part of the evidence-based practice and decision-making process. Apart from summarizing and clarifying the existing data they permit the identification of gaps in current knowledge, allowing recommendations to be made for future research22. Evidencebased data on maxillofacial surgery in 0901-5027/1101050 + 09 $36.00/0

general and orthognathic surgery in particular are scarce18. Segmental osteotomies in the anterior region of the mandible and maxilla were reported in 1849 by HULLIHEN13 and in 1921 by COHN-STOCK5. Subsequently, several modifications to the surgical technique of anterior segmental osteotomy (ASO) have been proposed7,17,32,33. ASOs are indicated primarily for correction of dentoalveloar protrusion. They are also useful for correcting anterior open

Keywords: anterior segmental osteotomy; facial soft tissue; cephalometry; orthognathic surgery; systematic review; evidence-based practice. Accepted for publication 7 July 2010 Available online 11 August 2010

bite, closing dental spaces between segments and can be combined with other osteotomies to achieve optimal correction of dentofacial aesthetics and occlusion. The surgery usually consists of extraction of one premolar on each side. Vertical bone cuts are subsequently made at the extraction site. A horizontal bone cut about 5 mm beneath the tooth apices is carried out to join the vertical osteotomies on either side. Thereafter the axial inclination of the mobilized anterior segment

# 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

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Fig. 1. The surgical technique of anterior segmental osteotomy.

can be altered. Once the desired vertical, anterior or posterior location of the anterior segment has been achieved, it is fixed with plates and screws (Fig. 1). ASOs can lead to major changes in the facial aesthetics, so reliable predictions of these changes are crucial to match the expectation of the patients. Bimaxillary dentoalveolar protrusion is prevalent in the Asian population16,20,23 and ASOs are frequently employed in the surgical correction of this deformity. Clinicians require quantitative information on the facial changes brought about by ASOs to plan the hard tissue (HT) movement required to achieve the desired soft tissue (ST) position. Although there are several reports on the ST changes brought about by ASO, their outcomes have not been systematically analyzed. The aims of this systematic review are to evaluate the ST changes resulting from ASO, to identify the ratios for ST response to HT movement from ASO, and to identify the strength and weakness of studies on ST response to ASO. Materials and methods

Electronic databases PubMed, Scopus and ISI Web of knowledge were searched in January 2009 using the following keywords: (1) (Wassmund) OR (Wunderer) OR (Hofer) OR (Kole) OR (Cupar) OR (subapical) OR (anterior segmental); (2) (soft tissue) OR (profile) OR (morphology); (3) osteotom*; (4) (#1) AND (#2) AND (#3). The search strategy was initially developed for PubMed but revised appropriately

to suit the other two databases. A combination of free text terms with Boolean operators and truncation were used. No restrictions were placed on the year or language of publication. The search strategy was designed in consultation with a senior librarian. The citations retrieved from each database were exported to the EndNote1 (Thomson Reuters; Carlsbad, CA, USA) bibliographic management software. Duplicates were discarded. The titles and abstracts were screened and the hard copies of all relevant articles were retrieved. Their reference lists were manually searched for any related articles. All these articles were independently assessed by 2 authors (YSNJ and RAZ) against the following inclusion criteria: maxillary and/or mandibular ASOs performed alone or in combination with other surgical procedures or orthodontics; clinical studies with human subjects, randomized controlled trials, case controlled studies or case series (before and after studies); and quantifiable changes of the facial appearance assessed using any imaging method. Review articles, case reports, studies using animal models or cadavers and those focusing on cleft, trauma or syndromic patients were excluded. Total mandibular subapical alveolar osteotomies or multisegmental Le Fort I osteotomies were excluded. The study details and outcome data related to ASO were collected using a prefabricated data extraction form. Only the data pertaining to ASO were extracted, if a study compared the effects of several interventions. The methodological quality of each study was checked with a quality

assessment checklist based on published criteria4,10,12,15,25. Some of these criteria were modified to suit the current study. Data extraction and quality appraisal were performed by two authors (YSNJ and JL) independently. Any disagreements were resolved by consensus. All data were entered into Excel spreadsheets for comparison. Results

Eleven studies that met the selection criteria were included for this review2,11,16,19–21,24,26–29. The sequence of selecting studies and the number of articles remaining at each stage is illustrated in Fig. 2. All articles that met the inclusion criteria were retrospective analyses of case series. Apart from a single Chinese article28, the rest were published in English (Table 1). Most publications (82%) originated from the Asian region. 199 patients underwent ASO. 52% of these patients were female and 12% were male, while the data on gender were not reported for the rest. The patients were aged 17–53 years. Bimaxillary dentoalveolar protrusion was the most common diagnosis. Bimaxillary surgery was performed in 7 studies11,16,19,20,24,26,29 while isolated maxillary ASOs were carried out in 3 studies2,27,28 (Table 2). Additional procedures, such as genioplasty and corticotomy, were performed in some patients in two studies16,19. Most of the studies did not present details on the stabilization or fixation methods. Seven studies16,19–21,26– 28 mentioned that all or some of the subjects underwent orthodontic treatment. Some authors compared the effects of

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Table 1. Demographic data from the selected studies.

Authors (year)

Country

Race

Mean age (years)

Age range (years)

Type of deformity

Males

Females

Total

AYOUB et al. (1991) DEWAN & MARJADI (1983) KIM et al. (2002) LEE et al. (2007)

UK India

NR Indian

2 NR

8 NR

10 10

NR NR

17–23 NR

Anterior maxillary excess Bimaxillary protrusion

South Korea South Korea

Korean Korean

2 0

20 36

27 Group 2 – 28y 2 months; Group 3 – 25y

21–33 NR

Bimaxillary protrusion Bimaxillary protrusion – Class I molars

LEW & LOH (1991)

Singapore

Chinese

NR

18 Group 2 – 20; Group 3 – 16 NR

NR

NR

NR

LEW et al. (1989)

Singapore

Chinese

7

12

19

23.4

18–28

NADKARNI (1986) O’ REILLY (1989)

India USA

NR 0

NR 14

25 14

NR 25.5

NR 20–30

OKUDAIRA et al. (2008) PAN et al. (1997) PARK et al. (2008)

Japan China South Korea

Indian Black Americans Japanese Chinese Korean

7 5 1

13 10 29

20 15 30

29.1 NR NR

17.9–53.3 20–30 22–50

Mandibular dentoalveolar protrusion (Class III) Class I bimaxillary dentoalveolar protrusion Class I bimaxillary protrusion Bimaxillary dentoalveolar protrusion NR Anterior maxillary protrusion Bialveolar or bimaxillary proclination

NR, not reported.

ASO with other interventions. LEE et al.19 assessed the effects of orthodontics alone (group 1), corticotomy assisted orthodontics with anterior mandibular subapical osteotomy (group 2) and bimaxillary ASO (group 3). LEW & LOH21 compared intraoral vertical ramus osteotomy and anterior mandibular subapical osteotomy.

Lateral cephalometry was used in all studies for the assessment of ST changes (Table 3). PARK et al.29 used lateral and frontal photographs in addition to cephalometry. The exact timing of presurgical imaging was stated only in a single article26, while postsurgical imaging was done at least 6 months after the operation

in most (8/11) articles. Hand tracing was the commonest analysis method used (5/11), while some authors digitalized the landmarks alone (2/11) or subsequent to hand tracing (4/11). The horizontal and vertical reference planes used for measurements varied widely among the studies. The outcome of the quality appraisal is shown in Table 4. Most studies (9/11) lacked well defined inclusion and exclusion criteria. Selection of the patients was not random or consecutive in any of the studies. Data collection was not performed at consistent time frames in nearly all the studies. An assessment on reliability of cephalometry was performed only in 6 studies2,16,20,21,26,27. Only 2 studies26,28 used stable landmarks such as the anterior wall of the sella turcica or cribriform plate for the superimposition of preoperative and postoperative images. Concurrent procedures such as genioplasties and corticotomies were performed in 2 studies (Table 2). The effect of confounding factors such as age, gender, surgical methods, fixation, orthodontic treatment or relapse were not taken into account during statistical analysis in any of the studies. As the studies were heterogeneous in terms of the participants, methods and quality, a meta-analysis was not feasible to pool their results. Soft tissue changes

Fig. 2. A flow chart of the study selection process.

Only 2 studies reported the mean horizontal and vertical movements of pronasale and subnasale (Table 5). The movements

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Table 2. Summary of the interventions carried out in different studies. Inter maxillary fixation

Pre/postsurgical orthodontics

Authors (year)

Maxillary surgery

Splints

Fixation method

AYOUB et al. (1991)

Anterior maxillary osteotomy Anterior maxillary osteotomy 1. Wunderer – 18 patients 2. Wassmund – 1 patient 3. Cupar – 1 patient

None

NR

NR

NR

NR

NR

Anterior mandibular osteotomy Anterior segmental osteotomy

NR

NR

NR

NR

NR

NR

NR

NR

Yes – 8 patients

LEE et al. (2007)

Wunderer-Group 3 – 16 patients

NR

NR

NR

Yes

LEW & LOH (1991)

NR

Anterior segmental osteotomy – 20 patients in group 2 and 16 patients in group 3 Anterior mandibular subapical osteotomy

1. Augmentation genioplasty – 3 patients 2. Reduction genioplasty – 2 patients Corticotomy assisted maxillary orthodontic treatment – for 20 patients in Group 2 NR

Yes

Yes

Yes

LEW et al. (1989)

Wunderer

NR

Yes

Yes

Intraosseous wiring NR

Yes

NADKARNI (1986)

Anterior maxillary osteotomy 1. Maxillary subapical setback – 7 patients 2. Premaxillary setback – 7 patients Anterior maxillary osteotomy with modified technique based on Wunderer and Wassmund Anterior maxillary osteotomy Modified anterior segmental osteotomy

NR

NR

NR

NR

NR

NR

NR

NR

NR

Yes

None

NR

NR

NR

Plates

Yes

None

None

NR

NR

NR

Yes

Modified anterior segmental osteotomy

NR

NR

NR

NR

NR

DEWAN & MARJADI (1983) KIM et al. (2002)

O’ REILLY (1989)

OKUDAIRA et al. (2008)

PAN et al. (1997) PARK et al. (2008)

Mandibular surgery

Anterior segmental osteotomy Mandibular subapical osteotomy Mandibular subapical setback – all patients

Other special procedures

NR, not reported.

of the pronasale were minimal. A 0.5 mm backward movement of the subnasale was reported by AYOUB et al.2 while OKUDAIRA et al.27 recorded a 1.9 mm shift to the opposite direction. An increase in the nasolabial angle ranging from 8.98 to 188 was noted for maxillary or bimaxillary ASO2,16,19,20,24,29. LEW et al.21 reported a reduction of the nasolabial angle by 2.18 with isolated mandibular ASO. An increase of the nasal width by 3% with a slight widening of the alar base was reported by PARK et al.29 A constant backward movement of the labrale superius (Ls) ranging from 0.9 mm to 7.25 mm was noted. The Ls moved 1.6– 2.4 mm in an inferior direction, indicating a lengthening of the upper lip, but OKU27 reported a superior moveDAIRA et al. ment of this landmark by 1.2 mm. The ratios for horizontal displacement of the upper lip in relation to the maxillary incisor reported in different studies ranged

from 33% to 67% (Table 6). PARK et al.29 assessed transverse changes and reported a reduction of the lip width by 6% and an increase of the philtrum length by 3%. The backward movement of the lower lip ranged from a maximum of 8.36 mm to a minimum of 1.1 mm. An upward movement of the labrale inferius by 0.92–2.6 mm was noted. The ST:HT ratio for the lower lip ranged from 67% to 89% (Table 6). A reduction of the interlabial gap was reported in 5 studies2,19,20,24,28. Discussion

The sample size of the studies included in this systematic review ranged from 10 to 36 subjects. The study samples were heterogeneous and consisted of different ethnicities and age groups. There was a preponderance of Asians and females.

This may be because females tend to seek orthognathic surgery more than males3. Bimaxillary protrusion of the dentoalveolus is more prevalent among Orientals16,20,23 and this may explain why most of the publications originated from Asia. Several flaws in the study design were identified during quality appraisal. All studies were of Level IV evidence. Even though the studies were based on retrospective analysis of patient records, a random or a consecutive selection could have been performed to avoid selection bias. ST movements at all the potential landmarks were not assessed in some studies (Table 5). The nomenclature of the cephalometric landmarks was inconsistent between different studies. Only 5 studies2,20,21,24,29 reported the HT:ST ratios (Table 6). These ratios only focused on the labial landmarks with no corresponding data for the nasal and chin region.

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Table 3. Summary of the imaging methods and techniques used for the analysis.

Authors (year)

Imaging method

Timing of presurgical imaging

Timing of postsurgical imaging

Tracing method

Reference for registration of pre- and postsurgical images

Reference lines for measurements

AYOUB et al. (1991)

Lat.Ceph

NR

After 6 months

H+D

NR

DEWAN AND MARJADI (1983) KIM et al. (2002)

Lat.Ceph

NR

After 4 yrs

H

NR

X – Indiana line; Y – perpendicular to above at S NR

Lat.Ceph

NR

H+D

NR

NR

LEE et al. (2007)

Lat.Ceph

NR

1. Within 1 week 2. At least 1 year NR

H+D

NR

LEW and LOH (1991)

Lat.Ceph

NR

At least 6 months

D

NR

LEW et al. (1989)

Lat.Ceph

NR

H

NADKARNI (1986) O’ REILLY (1989)

Lat.Ceph Lat.Ceph

NR Within 1 month

15–24 months (average = 19.8  3.6) NR 6–12 months

H H

OKUDAIRA et al. (2008)

Lat.Ceph

NR

6.7  3 months

H

SN Plane registered at S NR Anterior cranial base structures NR

X – SN line; Y – True Vertical Line X – 7 degrees to SN line; Y – perpendicular to above at N X – 7 degrees to SN line; Y – perpendicular to above at N NR X – SN line; Y – perpendicular to above at S

PAN et al. (1997) PARK et al. (2008)

Lat.Ceph 1. Lat.Ceph 2. Lateral and frontal photo

NR NR

8–24 months At least 6 months

H+D D

Sella NR

X – parallel to Frankfort plane through S; Y – perpendicular to above at S X – 6.5 degrees to SN ; Y – NR X – Frankfort horizontal; Y – perpendicular to above at N

NR, not reported; Lat.Ceph, lateral cephalogram; H, hand tracing; D, digitalization; S, sella turcica; N, nasion; X, horizontal reference plane; Y, vertical reference plane.

It may take at least 6 months for the postsurgical oedema and haematoma to resolve and the ST to stabilize6,8,31. This criterion was fulfilled in most studies (8/ 11) but some authors did not specify the exact timing of postsurgical imaging (Table 3). The data should have been collected at constant time intervals and their range should have been specified in the articles. This inconsistency in the follow-up cephalography may be an inherent error related to the retrospective study design. The follow-up times of patients were relatively short. Only DEWAN & MAR11 JADI evaluated patients after 4 years. However, the results of this study should be interpreted with caution because of its small sample size (Table 4). There is a lack of information on long-term ST response to ASO in the scientific literature, so future studies should focus on this aspect. The surgical techniques or fixation methods were not described adequately in most studies. It was not possible to analyze the influence of fixation techniques on the ST changes. Several modifications have been proposed to the surgical technique of ASO. The effect of such modifications on postoperative swelling as well as individual surgical skills may further influence the final ST position.

The paired t-test was commonly used for comparison of preoperative and postoperative ST changes. The paired t-test should only be used if data follow a normal distribution. If not, a non-parametric test should be employed. It is recommended that the exact p-value should be quoted rather than stating p > 0.0534. The reported standard deviations for ST landmarks were quite high in most studies, indicating a wide variation among the patient’s ST response to ASO (Table 5). Several factors, such as surgical techniques, fixation methods, orthodontic treatment and relapse should be taken into account when assessing ST changes. The thickness and elasticity of ST may vary with race, gender and age. All these variables may play a role in determining the final ST position. The labial prominence reduced subsequent to ASO. The patients also achieved better lip competence as evident from the reduction of the interlabial gap (Table 5). The nasal landmarks appear quite stable as opposed to those of the lips. The increase in nasolabial angle is mainly attributed to the retraction of the Ls rather than movements of the nasal landmarks. This may increase prominence of the nasal tip so clinicians should consider surgical techniques rather than ASO, when managing patients with obtuse nasolabial angle.

The labiomental fold moved less than the lower lip, which might be due to its firmer attachment to the underlying HT. Even though a direct manipulation of the HT pogonion is not performed during ASO, some studies reported minor movements in its ST counterpart. Such changes of the ST pogonion may result from relaxation of the mentalis muscle and redistribution of ST following reduction of the labiomental fold. The results of this systematic review indicate the need for prospective clinical trials with larger samples to provide sufficient information for predicting the ST changes from ASO. The use of methodologically sound protocols and long-term follow-ups are also advocated. The available information on transverse changes was minimal as most studies evaluated only horizontal and vertical facial changes. Three-dimensional imaging techniques should be used to quantify the HT and ST changes. Blinded assessors, preferably not directly involved in providing treatment, should be employed to prevent bias during the evaluation of facial changes. In this study, the authors have striven to meet the established core principles and methods for performing systematic reviews14. The literature search was not restricted to a single database or language.

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Table 4. The results of the quality assessment.

Criterion

AYOUB et al. (1991)

DEWAN & MARJADI (1983)

KIM et al. (2002)

LEE et al. (2007)

LEW & LOH (1991)

LEW et al. (1989)

NADKARNI (1986)

OKUDAIRA et al. (2008)

O’ REILLY (1989)

PAN et al. (1997)

PARK et al. (2008)

Objective clearly formulated

*

*

*

*

*

*

*

*

*

[TD$INLE]

*

Explicit inclusion and exclusion criteria

*

*

*

*

*

*

*

*

*

*

*

Sample size > 30 subjects

*

*

*

*

*

*

*

*

*

*

*

Sample size estimated before collection of data

*

*

*

*

*

*

*

*

*

*

*

Similar baseline characteristics

[TD$INLE]

*

*

*

*

*

*

*

Consecutive recruitment of patients

*

*

*

*

*

*

*

*

*

*

*

Prospective data collection

*

*

*

*

*

*

*

*

*

*

*

Data collection at constant intervals

*

*

[TD$INLE]

*

*

*

*

*

*

*

*

Consistent absence or presence of orthodontic appliances during imaging

*

*

*

*

*

*

*

*

*

*

*

Follow-up time greater than 2 yrs

*

*

*

*

*

*

*

*

*

*

*

No concurrent procedures or such procedures are taken into account in the study design/data analysis

*

*

*

*

*

*

*

*

*

*

*

Appropriate measurement methods

*

*

*

*

*

*

*

*

*

[TD$INLE]

*

Blinded examiner

*

*

*

*

*

*

*

*

*

*

*

Images registered using structures unaffected by surgery or on a stable reference line

*

*

*

*

*

*

*

*

*

*

*

Evaluation of both profile and full facial soft tissue changes or 3D analysis

*

*

*

*

*

*

*

*

*

*

*

Reliability assessment/error study done

*

*

*

*

*

*

*

*

*

*

*

Adequate level of agreement in the reliability assessment/ error study

*

*

*

*

*

*

*

*

*

*

*

Statistical analysis appropriate

*

*

*

*

*

*

*

[TD$INLE]

*

[TD$INLE]

*

Subgroup analysis performed

*

*

*

*

*

*

*

*

*

*

*

Major confounders (age, gender, surgical methods, fixation, orthodontic treatment, etc.) adjusted in the analysis

*

*

*

*

*

*

*

*

*

*

*

Relapse taken into account during analysis

*

*

*

*

*

*

*

*

*

*

*

P-value stated

*

[TD$INLE]

*

*

Confidence intervals calculated

*

*

*

*

[TD$INLE]

[TD$INLE]

[TD$INLE] *

[TD$INLE] *

[TD$INLE]

[TD$INLE] *

Criterion *, completely fulfilled; *, not fulfilled, [TD$INLE] , partially fulfilled.

*

[TD$INLE]

[TD$INLE]

[TD$INLE] *

* *

*

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Table 5. The mean soft tissue movements at some selected landmarks. Sn – Vertical Mean (SD)

Ls – Horizontal Mean (SD)

Li – Ls – Vertical Vertical Mean Li –Horizontal Mean (SD) (SD) Mean (SD)

Labiomental fold – Horizontal Mean (SD)

Labiomental fold – Vertical Mean (SD)

Pg – Horizontal Mean (SD)

Pg – Vertical Nasolabial Mentolabial angle angle Mean (SD) Mean (SD) Mean (SD)

Other relevant measurements

AYOUB et al. (1991)

+0.4

0

0.5

0

4.7

2.4

1.1

+2.6

1.2

+0.5

0.7

+0.2

+188

NR

DEWAN & MARJADI (1983)

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

KIM et al. (2002) LEE et al. (2007)

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

+138

NR

NR

NR

NR

NR

LLP ! Group NR 2 = 5.96 (2.21); Group 3 = 5.3 (2.89)

B’ ! Group 2 = 3.84 (4.13); Group 3 = 2.53 (2.81)

NR

Group 2 = NR 0.74 (4.02); Group 3 = +1.15 (2.87)

A’(H) ! Group 2 = 0.73 (2.06); Group 3 = 1.18 (2.36); Interlabial gap – Group 2 = 1.2 mm; Group 3 = +0.41 mm

NR

NR

NR

NR

4.4 (4.2)

NR

B’ ! 3.3 (3.9)

NR

NR

NR

Group 2 = +17.59 (8.61); Group 3 = +11.1 (12.07) 2.1 (8.9)

NR

LEW & LOH (1991)

ULP ! NR Group 2 = 4.3 (1.97); Group 3 = 3.43 (2.43) 0.9 (4.8) NR

NR

Upper lip length = +1.5 (1.0); Lower lip length = +1.8 (0.9); Interlabial gap = -5.8 mm

LEW et al. (1989) NADKARNI (1986)

NR

NR

NR

NR

2.6 (2.3)

NR

3.8 (1.4)

NR

NR

NR

NR

NR

NR

NR

NR

NR

+1.21 (0.8)

NR

NR

NR

+2.4 (0.7)

Mentolabial sulcus = 0.5

NR

NR

NR

+12.2 (1.5) +8.9

O’ REILLY (1989)

NR

NR

NR

NR

7.25 (2.09)

1.6 (1.5)

8.36 (2.36)

+0.92 (1.1)

NR

NR

NR

NR

OKUDAIRA et al. (2008) PAN et al. (1997) PARK et al. (2008)

0.2 (0.6) 0 (0.2)

1.9 (1.1)

+0.2 (0.6) 3.6 (1.8)

2.7 (1.5)

NR

NR

NR

NR

NR

NR

+0.1 (0.3) NR

NR

NR

+2.1 (1.8) NR

0.1 (1)

NR

+1.2 (1.2) NR

Inferior-labial Inferiorlabial sulcus = 4.04 (1.79) sulcus = 0.21 (2.9) B = 0.9 (1.8) B’ > +0.9 (1.8) NR NR

+6.6 (5.5)

NR

NR

NR

NR

NR

3.86 (0.92)

NR

5.55 (1.19)

NR

NR

NR

NR

+14.07 (5.22)

8.81 (16.6)

NR

NR

SLS (H) = 1.8; SLS (V) = 1.6; Interlabial gap = 4.7 mm; Facial convexity = 1.38; Holdway angle = 4.88; H angle = 5.48; Upper lip thickness = +1.3 mm Facial contour angle = 5.78; H-angle = 15.68; Upper lip protrusion = 5.68mm; Lower lip protrusion = 9.1 mm; Upper lip thickness = 0.8 mm H angle = 8.58

Upper lip protrusion = 3.1 mm; Lower lip protrusion = -4.6 mm; Upper lip length = +1.0 (0.3); Interlabial gap = 3.4 mm; Facial convexity angle = 38 SLS(H) = 4.5 (0.94); SLS(V) = 0.94 (0.66)

A’(H) = 3.3 (1.3); A’(V) = +0.7 (1.0) Stms – Stmi = 4.7 (3.7); Is – Stms = 2.0 (2.0); Sn – Stms = +1.3 (1.7) Nasal width = +2.91%; Lip width = 5.54%; Lip thickness = 2.96%; Philtrum length = +2.51%

For landmark data, positive values indicate forward or upward movements and negative values indicate backward or downward movements in millimeters. For linear and angular measurements positive values indicate an increase and negative values indicate a reduction. A0 , soft tissue A point; B0 , soft tissue B point; Ls, labrale superius; Li, labrale inferious; Pg, pogonion; Pn, pronasale; NR, not reported; Sn, subnasale; Stms, stomion superious; Stmi, stomion inferious; SLS, superior labial sulcus; H, horizontal; V, vertical.

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Authors (year)

Sn – Pn – Pn – Horizontal Vertical Horizontal Mean Mean Mean (SD) (SD) (SD)

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Table 6. The reported hard and soft tissue movement ratios. Authors (year)

Upper lip

Lower lip

AYOUB et al. (1991) DEWAN & MARJADI (1983) KIM et al. (2002) LEE et al. (2007) LEW & LOH (1991) LEW et al. (1989)

Upper lip:upper incisor = 60% NR NR NR Upper lip: mandibular incisor = 18% Upper lip: maxillary incisor = 43%

NADKARNI (1986) O’ REILLY (1989) OKUDAIRA et al. (2008) PAN et al. (1997)

Upper lip: maxillary incisor = 33% NR NR Is: Ls = 75% A:A0 = 63% Upper lip: maxillary incisor = 67%

NR NR NR NR Li: mandibular incisor = 69% Lower lip: mandibular incisor = 71% B0 :B = 81% Lower lip: mandibular incisor = 67% NR NR NR

PARK et al. (2008)

Lower lip: mandibular incisor = 89%

The ratios quoted in some studies have been converted to percentages. A, hard tissue A point; A0 , soft tissue A point; Is, incision superious; Li, labrale inferious; Ls, labrale superious; B, hard tissue B point ; B0 , soft tissue B point; NR, not reported.

The internal validity of each study was assessed using a quality appraisal checklist (Table 4). This checklist could be used in the future for planning, reporting and evaluating studies related to orthognathic surgery. As the samples and methods used in the 11 studies were heterogeneous, a meta-analysis was not feasible to pool their results so a narrative synthesis30 was performed. A systematic review cannot generate knowledge. The outcome of a systematic review inevitably depends on the quality of the data available in the scientific literature. Such reviews can demonstrate uncertainty in present understanding, thereby stimulating more and better research1. Future researchers can consider our recommendations to avoid the drawbacks in the existing literature identified by this review. In conclusion, ASO leads to a reduction of the labial prominence with a concomitant increase in the nasolabial angle. The ST changes were primarily confined to the oro-labial region with minimal changes in the nasal and genial landmarks. Firm conclusions on the magnitude of ST changes or their ratios corresponding to the underlying HT cannot be drawn from this review due to a lack of good quality evidence. Prospective, methodologically sound clinical trials with larger samples and three-dimensional quantification are required to provide sufficient information for predicting the ST response to ASO. Funding

None. Competing interest

None.

Ethical approval

Not applicable.

Acknowledgements. The authors would like to thank the following. Mrs Ros Wade, Research Fellow, Centre for Reviews and Dissemination, The University of York for her advice on planning the study and reviewing this manuscript. Mr Sam Lee the Dental Librarian, The University of Hong Kong (HKU) for assisting in the literature search. Miss Vicki Yip from the Dental Media Unit, HKU for preparing the illustrations.

References 1. Alderson P, Roberts I. Should journals publish systematic reviews that find no evidence to guide practice? Examples from injury research. Br Med J 2000: 320: 376–377. 2. Ayoub A, Mostafa Y, el-Mofty S. Soft tissue response to anterior maxillary osteotomy. Int J Adult Orthodon Orthognath Surg 1991: 6: 183–190. 3. Bailey L, Haltiwanger L, Blakey G, Proffit W. Who seeks surgical–orthodontic treatment: a current review. Int J Adult Orthodon Orthognath Surg 2001: 16: 280– 292. 4. Betts NJ, Dowd KF. Soft tissue changes associated with orthognathic surgery. Atlas Oral Maxillofac Surg Clin North Am 2000: 8: 13–38. 5. Cohn-Stock G. Die chirurgische immediatregulierung der kiefer, speziell die chirurgische behandlung der prognathie. Vjschr Zahnheilk Berlin 1921: 37: 320. 6. Collins PC, Epker BN. The alar base cinch: a technique for prevention of alar base flaring secondary to maxillary surgery. Oral Surg Oral Med Oral Pathol 1982: 53: 549–553.

7. Cupar I. Surgical treatment of alterations in form and position of the maxilla. Osterr Z Stomatol 1954: 51: 565. 8. Dann IIIrd JJ, Fonseca RJ, Bell WH. Soft tissue changes associated with total maxillary advancement: a preliminary study. J Oral Surg 1976: 34: 19–23. 9. Dawes M. Evidence-based practice: a primer for health care professionals. 2nd ed. Edinburgh: Elsevier 2005. 10. Deeks JJ, Dinnes J, D’Amico R, Sowden AJ, Sakarovitch C, Song F, Petticrew M, Altman DG. Evaluating nonrandomised intervention studies. Health Technol Assess 2003: 7. 11. Dewan S, Marjadi U. Soft tissue changes in surgically treated cases of bimaxillary protrusion. J Oral Maxillofac Surg 1983: 41: 116–118. 12. Flores-Mir C, Major PW. A systematic review of cephalometric facial soft tissue changes with the activator and bionator appliances in class ii division 1 subjects. Eur J Orthod 2006: 28: 586– 593. 13. Hullihen SP. Case of elongation of the under-jaw and distortion of the face and neck caused by burn, successfully treated. Am J Dent Sci 1849: 9: 157–165. 14. Khan KS. Systematic reviews to support evidence-based medicine: how to review and apply findings of healthcare research. London: Royal Society of Medicine Press 2003. 15. Khan KS, Riet G, Glanville J, Sowden AJ, Kleijnen J. Undertaking systematic reviews of research on effectiveness–CRD’s guidance for those carrying out or commissioning reviews– CRD Report Number 4. 2nd ed. York: York Publishing Services Ltd. 2001. 16. Kim JR, Son WS, Lee SG. A retrospective analysis of 20 surgically corrected bimaxillary protrusion patients. Int J Adult Orthodon Orthognath Surg 2002: 17: 23–27. 17. Ko¨le H. Surgical operations on the alveolar ridge to correct occlusal abnormalities. Oral Surg Oral Med Oral Pathol 1959: 12: 515–529.

1058

Jayaratne et al.

18. Kyzas PA. Evidence-based oral and maxillofacial surgery. J Oral Maxillofac Surg 2008: 66: 973–986. 19. Lee JK, Chung KR, Baek SH. Treatment outcomes of orthodontic treatment, corticotomy-assisted orthodontic treatment, and anterior segmental osteotomy for bimaxillary dentoalveolar protrusion. Plast Reconstr Surg 2007: 120: 1027– 1036. 20. Lew KK, Loh FC, Yeo JF, Loh HS. Profile changes following anterior subapical osteotomy in chinese adults with bimaxillary protrusion. Int J Adult Orthodon Orthognath Surg 1989: 4: 189–196. 21. Lew KKK, Loh FC. A comparison of profile changes between ramus and anterior mandibular subapical osteotomies in class iii Chinese patients. J Oral Maxillofac Surg 1991: 49: 831–837. 22. Margaliot Z, Chung KC. Systematic reviews: a primer for plastic surgery research. Plast Reconstr Surg 2007: 120: 1834–1841. 23. Miyajima K, McNamara Jr JA, Kimura T, Murata S, Iizuka T. Craniofacial structure of japanese and european-american adults with normal occlusions and well-balanced faces. Am J Orthod Dentofacial Orthop 1996: 110: 431–438.

24. Nadkarni PG. Soft tissue profile changes associated with orthognathic surgery for bimaxillary protrusion. J Oral Maxillofac Surg 1986: 44: 851–854. 25. Preoperative Tests: The Use of Routine Preoperative Tests for Elective Surgery. National Institute for Clinical Excellence, June 2003. http://www.nice.org.uk/ nicemedia/pdf/PreopTests_Apps.pdf [accessed 05.07.09]. 26. O’Reilly M. Integumental profile changes after surgical orthodontic correction of bimaxillary dentoalveolar protrusion in black patients. Am J Orthod Dentofacial Orthop 1989: 96: 242. 27. Okudaira M, Kawamoto T, Ono T, Moriyama K. Soft-tissue changes in association with anterior maxillary osteotomy: a pilot study. Oral Maxillofac Surg 2008: 12: 131–138. 28. Pan J, Hu J, Wang D. Soft tissue profile changes following surgical correction for chinese adults with maxillary protrusion. Hua Xi Kou Qiang Yi Xue Za Zhi 1997: 15: 126–128 150. 29. Park JU, Hwang YS. Evaluation of the soft and hard tissue changes after anterior segmental osteotomy on the maxilla and mandible. J Oral Maxillofac Surg 2008: 66: 98–103.

30. Popay J, Roberts H, Sowden A, Petticrew M, Britten N, Arai L, Roen K, Rodgers M. Developing guidance on the conduct of narrative synthesis in systematic reviews. J Epidemiol Community Health 2005: 59: A7. 31. Tomlak DJ, Piecuch JF, Weinstein S. Morphologic analysis of upper lip area following maxillary osteotomy via the tunneling approach. Am J Orthod 1984: 85: 488–493. 32. Wassmund J. Lehrbuch der praktischen chirurgie de Mundes und der Keifer 1935: 1: 260–282. 33. Wunderer S. Erfahrungen mit der operativen behandlung hochgradiger prognathien. Dtsch Zahn Mund Kieferheilk 1963: 39: 451. 34. Zeiger M. Essentials of writing biomedical research papers, New York: McGraw-Hill Professional 2000: p. 167. Address: Lim Kwong Cheung Discipline of Oral & Maxillofacial Surgery Faculty of Dentistry The University of Hong Kong Hong Kong Tel.: +852 28590262 fax: +852 25599014/28575570 E-mail: [email protected]