Protocol and Registration

This systematic review was conducted and reported based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.¹⁰ The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42019131116).

Eligibility Criteria

The following eligibility criteria were based on the participants, intervention, comparators, outcomes, and study designs (PICOS) strategy: (1) participants were patients aged older than 16 years who were treated with orthognathic surgery to correct dentofacial deformities; (2) the intervention was a SFA; (3) comparators were that the studies should include patients with COST as a control or investigate the OHRQoL before and after the SFA; (4) the primary outcome was the OHRQoL evaluated by validated instruments, with at least one time point after surgery-first orthognathic surgery, and secondary outcomes were the treatment duration, skeletal stability and relapse rate, complications, and other changes that might affect patients' QoL; and (5) the study designs were randomized clinical trials (RCTs), controlled clinical trials, and cohort studies.

The exclusion criteria were (1) patients with cleft lip or palate, or with syndromes or systemic diseases related to bone metabolism or the maxillofacial region, or with a previous orthodontic or orthognathic treatment history; (2) OHRQoL only assessed before treatment; and (3) cross-sectional studies, case reports, review articles, abstracts, editorials, or opinions.

Information Sources, Search Strategy, and Study Selection

The electronic search was conducted including PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, EMBASE, Web of Science, SCOPUS, ProQuest Dissertation & Theses Database, System for Information on Grey Literature in Europe, ClinicalTrials.gov, and the following two Chinese databases: China National Knowledge Infrastructure and Chinese Biomedical Literature Database. The search strategy in PubMed combined the medical subject headings terms with free-text words and was adjusted for each database (Supplementary Table 1).

A hand search was undertaken in orthodontic journals. In addition, the reference lists of all eligible studies and related review articles were checked. The searches were conducted in April 2019 with no restriction on language, date, or status of publication.

Two authors selected the studies for eligibility independently and in duplicate. Any disagreements where no decision could be made were resolved by a third author.

Data Extraction and Data Items

Studies that fulfilled the eligibility criteria were collected for data extraction. Two piloted data collection forms were used to record the quantitative and qualitative information. Two authors extracted the desired information independently and in duplicate. Disagreements were resolved by discussing with a third author. Finally, the following items were collected: author, year of publication, country of study, study design, demographic characteristics, dentofacial deformities, treatment protocols, assessment instruments, results, additional outcomes, and conclusion.

Risk of Bias in Individual Studies

The Cochrane collaboration risk-of-bias tool was used to assess the risk of bias of RCTs.¹¹ For nonrandomized clinical trials, the Newcastle-Ottawa Scale was adopted.¹² Two authors assessed the risk of bias independently and in duplicate, and disagreements were resolved with a third author.

Summary Measures, Synthesis of Results, and Quality of Evidence

Because of the lack of extensive data with regard to OHRQoL as well as the heterogeneity in methodology and clinical features, quantitative analysis was not feasible. As a result, the primary outcome was qualitatively analyzed and summarized, with comparisons of OHRQoL conducted between the SFA and COST or before and after surgery-first surgery. The secondary outcomes were also summarized qualitatively. The overall quality of evidence was rated according to the Grading of Recommendations, Assessment, Development, and Evaluation approach.

Study Selection and Characteristics

A total of 31 articles were reserved after screening the titles and abstracts of initially retrieved literature. Of these, 24 articles were excluded with reasons (Supplementary Table 2). Seven articles fulfilled the eligibility criteria and were included in this systematic review.^13–19Figure 1 shows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses flowchart diagram of literature selection.

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The characteristics of the included studies are presented in Table 1. Six articles were cohort studies,^{13–16,18,19} and one was an RCT.¹⁷ Six articles compared the different effects on OHRQoL between the SFA and COST.^{13–15,17–19} The other study investigated the change of OHRQoL before and after the SFA treatment.¹⁶ In total, 214 participants were examined, with the sample sizes in individual studies ranging from 9 to 50. Three studies used a generic measure named the 14-item Oral Health Impact Profile (OHIP-14) questionnaire,^13,18,19 2 studies used a condition-specific Orthognathic Quality of Life Questionnaire (OQLQ),^15,16 and two studies employed both.^14,17 The time points of assessment varied from 2 to 3 weeks after surgery to 2 years after treatment initiation.

Table 1.  Characteristics of Included Studies^a

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Table 1.  Extended.

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Risk of Bias Within Studies

The Newcastle-Ottawa Scale scores of six cohort studies differed from five to seven (Table 2). Five studies had moderate risk of bias,^{13,15,16,18,19} and the other one had low risk of bias.¹⁴ The RCT¹⁷ was ranked as high risk of bias (Table 3).

Table 2.  Risk of Bias Assessment of Nonrandomized Clinical Trials by NOS^a

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Table 3. Risk of Bias Assessment of Randomized Controlled Trial by Cochrane Handbook for Systematic Reviews of Interventions

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Results of Individual Studies

The results of the included studies are summarized in Table 4. All studies showed that patients had lower scores of OHRQoL after combined surgical–orthodontic treatment, whether by the SFA or COST.^13–19 In addition, the effects of complete treatments of the SFA and COST seemed similar, as the OHRQoL in both groups either before or after treatment showed no statistically significant difference.^13,15,18 However, differences were detected during treatment. The OHRQoL of patients treated with the SFA displayed an immediate improvement at the beginning of treatment, and this trend continued throughout the evaluation periods.^13–19 However, in the COST group, the OHRQoL showed a deterioration in the preoperative orthodontic phase, which was followed by progressive improvement after orthognathic surgery.^{13–15,17,18}

Table 4. Results of Included Studies^a

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When comparing the OHRQoL of the same time after surgery in the SFA and COST groups, Huang et al.¹³ demonstrated that the changes did not show any significant difference in total scores and each domain of OHIP-14. Park et al.¹⁵ found similar results: the SFA and COST did not produce any significant difference in each domain of OQLQ 3 months after surgery. Pelo et al.,¹⁷ by using the OQLQ and OHIP-14 instruments, noted that these two procedures resulted in no difference in OHRQoL 1 month after surgery.

Huang et al.¹³ and Wang et al.¹⁸ reported that the average treatment duration in the SFA group was 16.6 months, whereas patients in the COST group were treated for an average of 25.3 months. Feu et al.¹⁴ showed that five of eight participants in the SFA group had completed treatment 2 years later, but participants in the COST group were still in the preoperative phase. In another study recruiting SFA patients, treatment lasted for 15.7 ± 3.31 months until postorthodontic bracket removal.¹⁶

In addition, other pertinent results were also retrieved. One study reported the complication in SFA patients of two patients who suffered from postoperative hypesthesia of the lower lip for 4 to 6 weeks.¹⁶ Two studies found a favorable perception of facial changes of SFA patients after surgery.^14,16 Two studies noted improved psychological parameters in the SFA group.^13,16 Brucoli et al.,¹⁹ using a generic questionnaire named the 36-item Short Form Health Survey, found a similar result to that of the OHIP-14. No information about skeletal stability or relapse rate could be extracted from the included studies.

Finally, the evidence for three significant outcomes was rated as very low to moderate quality by the Grading of Recommendations, Assessment, Development, and Evaluation system (Table 5, Supplementary Table 3).

Table 5. GRADE^a Summary of Findings Table for the Effects of Surgery-First Approach on Patients With Dentofacial Deformities^b

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Summary of Evidence

The surgery-first orthognathic approach has been recently accepted as an alternative to COST. However, the actual impact of SFA on patients' OHRQoL remained unclear. This study was an evidence-based review on this topic.

All included studies reported the improvement of OHRQoL in patients treated with combined orthodontic–surgical treatment whether by SFA or COST,^13–19 demonstrating the necessity and effectiveness of this procedure in patients with dentofacial deformities. Patients seek treatment mostly for improvements in esthetics, function, and psychology. Therefore, the improved facial and dental esthetics, oral masticatory function, self-esteem, and interpersonal relationships after combined treatment may account for this change.

The assessment time points of OHRQoL differed in the included studies, making it unsuitable to quantitatively synthesize the data. Three studies successfully evaluated the patients' OHRQoL both before and after treatment in the SFA and COST groups.^13,15,18 They found that scores of OHRQoL in both the SFA and COST groups showed no significant differences before or after treatment, implying the similar effects of complete treatment by the SFA and COST approaches on OHRQoL. In addition, the most affected domains of the two approaches showed the same descending order according to the OQLQ questionnaire: facial esthetics, oral function, social relationship, and awareness of dentofacial deformity.^15,16 Generally, the two approaches were not different in terms of OHRQoL, and patients with dentofacial deformities would gain a similar improvement in OHRQoL after treatment either by the SFA or COST.

However, differences emerged when the OHRQoLs were compared at different stages during the entire treatment. In the SFA group, because of the elimination of preoperative orthodontic treatment, an immediate improvement was observed at the initiation of treatment.^13–19 By contrast, in the COST group, patients experienced a presurgical deterioration, which was followed by an improvement after surgery.^{13–15,17,18} The preoperative deterioration of patients' OHRQoL treated with COST was realized in different studies and could be attributed to the worsening of malocclusion and psychological disadvantages.²⁰ Dental decompensation in the presurgical phase had a negative impact on facial esthetics, and most patients considered it as the most stressful period during treatment.²¹ Therefore, dental professionals should be aware of the harmful changes during presurgical orthodontic treatment and inform their patients what to expect and, if necessary, help them to overcome the negative effects.²¹

Three studies evaluated the OHRQoL of two groups at the same time after surgery and found no significant difference.^13,15,17 Although the presurgical orthodontic treatment in COST worsened the OHRQoL, the orthognathic surgery improved it to the same level as the postoperative OHRQoL in the SFA. This result indicated the critical role of orthognathic surgery in combined orthodontic–surgical therapy. Regarding the effects on OHRQoL, it can be hypothesized that the SFA may be similar to the last two phases of COST: the combination of surgery and postsurgical orthodontics.

Another advantage of the SFA was the reduction of total treatment duration. In the review, three studies recorded this outcome and found a significantly decreased treatment duration in the SFA group.^13,14,18 It was reported that the presurgical orthodontics in COST lasted for an average of 17 months, followed by orthognathic surgery and approximately 6 to 12 months of postsurgical orthodontic treatment.²² The recent study focusing on treatment time revealed that the total duration for the SFA averaged 14.6 months compared with 22.0 months for COST.²³

The SFA seemed to have an advantage for the prevention of presurgical deterioration of OHRQoL and the reduction of treatment time in comparison with COST, but more issues should be considered before choosing this procedure. For example, the skeletal stability of the SFA and its difference from COST remains inconclusive.^1,24 The exact psychological effects of extended postsurgical orthodontics in the SFA need to be further investigated in the future. Emphasis should be placed on the criteria of patient selection for the SFA. The SFA is primarily indicated for patients with (1) well-aligned to mild crowding of anterior teeth, (2) flat to mild curve of Spee, (3) normal to mild proclination/retroclination of incisors, and (4) minimal transverse discrepancy.²⁵

Limitations

Inadequate reporting hindered the accurate assessment of bias and comprehensive data collection. For example, exact treatment details, numerical data of every domain, total treatment time, and complications were often missing. In addition, heterogeneity in methodology, statistics, and clinical features made it unreliable to quantitatively analyze the results. Each study had different assessment time points, and the measurement methods also varied. All cohort studies were evaluated as having low to moderate risk of bias, and the RCT was evaluated as high. Therefore, additional well-designed, standardized, properly reported prospective trials with homogeneous patients and adequate duration are necessary to provide the best evidence.