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 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.

Results

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 .

A flow chart of the study selection process.

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.

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.

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.

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.