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 three-dimensional 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 practice . 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 research . Evidence-based data on maxillofacial surgery in general and orthognathic surgery in particular are scarce .
Segmental osteotomies in the anterior region of the mandible and maxilla were reported in 1849 by H ullihen and in 1921 by C ohn -S tock . Subsequently, several modifications to the surgical technique of anterior segmental osteotomy (ASO) have been proposed .
ASOs are indicated primarily for correction of dentoalveloar protrusion. They are also useful for correcting anterior open 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 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 population 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:
(Wassmund) OR (Wunderer) OR (Hofer) OR (Kole) OR (Cupar) OR (subapical) OR (anterior segmental);
(soft tissue) OR (profile) OR (morphology);
(#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 EndNote ® (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 multi-segmental 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 criteria . 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.
Eleven studies that met the selection criteria were included for this review . 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 article , 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.
|Authors (year)||Country||Race||Males||Females||Total||Mean age (years)||Age range (years)||Type of deformity|
|A youb et al. (1991)||UK||NR||2||8||10||NR||17–23||Anterior maxillary excess|
|D ewan & M arjadi (1983)||India||Indian||NR||NR||10||NR||NR||Bimaxillary protrusion|
|K im et al. (2002)||South Korea||Korean||2||18||20||27||21–33||Bimaxillary protrusion|
|L ee et al. (2007)||South Korea||Korean||0||Group 2 – 20; Group 3 – 16||36||Group 2 – 28y 2 months; Group 3 – 25y||NR||Bimaxillary protrusion – Class I molars|
|L ew & L oh (1991)||Singapore||Chinese||NR||NR||NR||NR||NR||Mandibular dentoalveolar protrusion (Class III)|
|L ew et al. (1989)||Singapore||Chinese||7||12||19||23.4||18–28||Class I bimaxillary dentoalveolar protrusion|
|N adkarni (1986)||India||Indian||NR||NR||25||NR||NR||Class I bimaxillary protrusion|
|O’ R eilly (1989)||USA||Black Americans||0||14||14||25.5||20–30||Bimaxillary dentoalveolar protrusion|
|O kudaira et al. (2008)||Japan||Japanese||7||13||20||29.1||17.9–53.3||NR|
|P an et al. (1997)||China||Chinese||5||10||15||NR||20–30||Anterior maxillary protrusion|
|P ark et al. (2008)||South Korea||Korean||1||29||30||NR||22–50||Bialveolar or bimaxillary proclination|
Bimaxillary surgery was performed in 7 studies while isolated maxillary ASOs were carried out in 3 studies ( Table 2 ). Additional procedures, such as genioplasty and corticotomy, were performed in some patients in two studies . Most of the studies did not present details on the stabilization or fixation methods. Seven studies mentioned that all or some of the subjects underwent orthodontic treatment. Some authors compared the effects of ASO with other interventions. L ee et al. assessed the effects of orthodontics alone (group 1), corticotomy assisted orthodontics with anterior mandibular subapical osteotomy (group 2) and bimaxillary ASO (group 3). L ew & L oh compared intraoral vertical ramus osteotomy and anterior mandibular subapical osteotomy.
|Authors (year)||Maxillary surgery||Mandibular surgery||Other special procedures||Inter maxillary fixation||Splints||Fixation method||Pre/post-surgical orthodontics|
|A youb et al. (1991)||Anterior maxillary osteotomy||None||NR||NR||NR||NR||NR|
|D ewan & M arjadi (1983)||Anterior maxillary osteotomy||Anterior mandibular osteotomy||NR||NR||NR||NR||NR|
|K im et al. (2002)||1. Wunderer – 18 patients
2. Wassmund – 1 patient
3. Cupar – 1 patient
|Anterior segmental osteotomy||1. Augmentation genioplasty – 3 patients
2. Reduction genioplasty – 2 patients
|NR||NR||NR||Yes – 8 patients|
|L ee et al. (2007)||Wunderer-Group 3 – 16 patients||Anterior segmental osteotomy – 20 patients in group 2 and 16 patients in group 3||Corticotomy assisted maxillary orthodontic treatment – for 20 patients in Group 2||NR||NR||NR||Yes|
|L ew & L oh (1991)||NR||Anterior mandibular subapical osteotomy||NR||Yes||Yes||Intra-osseous wiring||Yes|
|L ew et al. (1989)||Wunderer||Anterior segmental osteotomy||NR||Yes||Yes||NR||Yes|
|N adkarni (1986)||Anterior maxillary osteotomy||Mandibular subapical osteotomy||NR||NR||NR||NR||NR|
|O’ R eilly (1989)||1. Maxillary subapical setback – 7 patients
2. Premaxillary setback – 7 patients
|Mandibular subapical setback – all patients||NR||NR||NR||NR||Yes|
|O kudaira et al. (2008)||Anterior maxillary osteotomy with modified technique based on Wunderer and Wassmund||None||NR||NR||NR||Plates||Yes|
|P an et al. (1997)||Anterior maxillary osteotomy||None||None||NR||NR||NR||Yes|
|P ark et al. (2008)||Modified anterior segmental osteotomy||Modified anterior segmental osteotomy||NR||NR||NR||NR||NR|
Lateral cephalometry was used in all studies for the assessment of ST changes ( Table 3 ). P ark et al . used lateral and frontal photographs in addition to cephalometry. The exact timing of presurgical imaging was stated only in a single article , 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.
|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|
|A youb et al. (1991)||Lat.Ceph||NR||After 6 months||H+D||NR||X – Indiana line; Y – perpendicular to above at S|
|D ewan and Marjadi (1983)||Lat.Ceph||NR||After 4 yrs||H||NR||NR|
|K im et al. (2002)||Lat.Ceph||NR||1. Within 1 week
2. At least 1 year
|L ee et al. (2007)||Lat.Ceph||NR||NR||H+D||NR||X – SN line; Y – True Vertical Line|
|L ew and L oh (1991)||Lat.Ceph||NR||At least 6 months||D||NR||X – 7 degrees to SN line; Y – perpendicular to above at N|
|L ew et al. (1989)||Lat.Ceph||NR||15–24 months (average = 19.8 ± 3.6)||H||SN Plane registered at S||X – 7 degrees to SN line; Y – perpendicular to above at N|
|N adkarni (1986)||Lat.Ceph||NR||NR||H||NR||NR|
|O’ R eilly (1989)||Lat.Ceph||Within 1 month||6–12 months||H||Anterior cranial base structures||X – SN line; Y – perpendicular to above at S|
|O kudaira et al. (2008)||Lat.Ceph||NR||6.7 ± 3 months||H||NR||X – parallel to Frankfort plane through S; Y – perpendicular to above at S|
|P an et al. (1997)||Lat.Ceph||NR||8–24 months||H+D||Sella||X – 6.5 degrees to SN ; Y – NR|
|P ark et al. (2008)||1. Lat.Ceph
2. Lateral and frontal photo
|NR||At least 6 months||D||NR||X – Frankfort horizontal; Y – perpendicular to above at N|
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 studies . Only 2 studies 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
Only 2 studies reported the mean horizontal and vertical movements of pronasale and subnasale ( Table 5 ). The movements of the pronasale were minimal. A 0.5 mm backward movement of the subnasale was reported by A youb et al. while O kudaira et al . recorded a 1.9 mm shift to the opposite direction. An increase in the nasolabial angle ranging from 8.9° to 18° was noted for maxillary or bimaxillary ASO . L ew et al. reported a reduction of the nasolabial angle by 2.1° with isolated mandibular ASO. An increase of the nasal width by 3% with a slight widening of the alar base was reported by P ark et al.
|Authors (year)||Pn – Horizontal
|Pn – Vertical
|Sn – Horizontal
|Sn – Vertical
|Ls – Horizontal
|Ls – Vertical
|Li – Vertical
|Labiomental fold – Horizontal
|Labiomental fold – Vertical
|Pg – Horizontal
|Pg – Vertical
|Other relevant measurements|
|A youb 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||+18°||NR||SLS (H) = −1.8; SLS (V) = −1.6; Interlabial gap = −4.7 mm; Facial convexity = −1.3°; Holdway angle = −4.8°; H angle = −5.4°; Upper lip thickness = +1.3 mm|
|D ewan & M arjadi (1983)||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||Facial contour angle = −5.7°; H-angle = −15.6°; Upper lip protrusion = −5.6°mm; Lower lip protrusion = −9.1 mm; Upper lip thickness = −0.8 mm|
|K im et al. (2002)||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||+13°||NR||H angle = −8.5°|
|L ee et al. (2007)||NR||NR||NR||NR||ULP → Group 2 = −4.3 (1.97);
Group 3 = −3.43 (2.43)
|NR||LLP → Group 2 = −5.96 (2.21);
Group 3 = −5.3 (2.89)
|NR||B’ → Group 2 = −3.84 (4.13);
Group 3 = −2.53 (2.81)
|NR||Group 2 = −0.74 (4.02);
Group 3 = +1.15 (2.87)
|NR||Group 2 = +17.59 (8.61);
Group 3 = +11.1 (12.07)
|NR||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|
|L ew & L oh (1991)||NR||NR||NR||NR||−0.9 (4.8)||NR||−4.4 (4.2)||NR||B’ → −3.3 (3.9)||NR||NR||NR||−2.1 (8.9)||NR||Upper lip length = +1.5 (1.0); Lower lip length = +1.8 (0.9); Interlabial gap = -5.8 mm|
|L ew et al. (1989)||NR||NR||NR||NR||−2.6 (2.3)||NR||−3.8 (1.4)||NR||NR||NR||NR||NR||+12.2 (1.5)||NR|
|N adkarni (1986)||NR||NR||NR||+1.21 (0.8)||NR||NR||NR||+2.4 (0.7)||Mentolabial sulcus = −0.5||NR||NR||NR||+8.9||NR||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 = −3°|
|O’ R eilly (1989)||NR||NR||NR||NR||−7.25 (2.09)||−1.6 (1.5)||−8.36 (2.36)||+0.92 (1.1)||Inferior-labial sulcus = −4.04 (1.79)||Inferior-labial sulcus = −0.21 (2.9)||NR||NR||NR||NR||SLS(H) = −4.5 (0.94); SLS(V) = −0.94 (0.66)|
|O kudaira et al. (2008)||−0.2 (0.6)||0 (0.2)||1.9 (1.1)||+0.2 (0.6)||−3.6 (1.8)||+1.2 (1.2)||−2.7 (1.5)||+2.1 (1.8)||B = 0.9 (1.8)||B’ > +0.9 (1.8)||−0.1 (1)||+0.1 (0.3)||NR||NR||A’(H) = −3.3 (1.3); A’(V) = +0.7 (1.0)|
|P an et al. (1997)||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||NR||+6.6 (5.5)||NR||Stms – Stmi = −4.7 (3.7); Is – Stms = −2.0 (2.0); Sn – Stms = +1.3 (1.7)|
|P ark et al. (2008)||NR||NR||NR||NR||−3.86 (0.92)||NR||−5.55 (1.19)||NR||NR||NR||NR||NR||+14.07 (5.22)||−8.81 (16.6)||Nasal width = +2.91%; Lip width = −5.54%; Lip thickness = −2.96%; Philtrum length = +2.51%|