# Effects of Surgically Assisted Rapid Palatal Expansion on Facial Soft Tissues: A Systematic Review
## 4 Discussion
Statistically significant differences were obtained: a decrease of 0.9 mm and an increase of 0.7 mm. The explanation for these contradictory results may be the fact that these studies evaluated different surgical techniques: [PERSON] et al. [23] used an alar cinch and V-Y suture whereas [PERSON] et al. did not [25]. Nevertheless, the changes were small and clinically insignificant. Nasolabial angle is another important parameter in determining the attractiveness of facial profile. This angle is formed by labiale superius, collumela peak, and subnasale. [PERSON] et al. found a non-significant median decrease of 2.0 degrees [23]. [PERSON] et al. found a median decrease of 0.04 degrees in the group that had conventional suturing of the upper lip, practically reporting no change. However, the group that had a simple V-Y suture of the upper lip exhibited a decrease of 2.6 degrees [20]. The strengths of the present review include a methodology following clear-cut guidelines. The search strategies employed were exhaustive, covering electronic, manual, and gray literature material up to November 2020. Their character was comprehensive, including every available study in English, irrespective of date and status of publication. Every effort to decrease bias in the methodology employed was made. As a result, screening, verification of eligibility, abstraction of information, and assessment of risk of bias and of the quality of evidence were all performed in duplicate, and any disagreement was resolved by discussion or consultation until a final agreement was achieved. The gold standard of study design is the RCT. The comparator in an RCT evaluating SARPE would include either non-surgical approaches, e.g., orthodontics only, or another intervention group, i.e., different techniques still within the context of SARPE, such as using different expanders. The two types of comparators would provide insight into different effects and answer different research questions; the first would estimate the effect of SARPE on the facial soft tissues, whereas the second would compare these effects between two or more different approaches to SARPE. However, studies of inferior study design (non-randomized studies (NRS) and uncontrolled studies) were additionally included in the present systematic review for various reasons. First and foremost, RCTs cannot answer the first question, as it is unethical to randomly assign a patient presenting skelatelly narrow maxilla to the orthodontics-only control group. Consequently, we resort to NRSs and uncontrolled studies as the only means of assessing the effect of SARPE on facial soft tissues. In contrast, RCTs are the ideal design to answer the second question, i.e., which SARPE-related treatment benefits the patients more, since it is ethically acceptable to randomize a patient in need of SARPE to either of the SARPE-related treatment groups. The second reason to include NRSs is the general lack of RCTs available in the literature on this subject. Finally, future research will benefit from the evaluation of the weaknesses of the available studies. Another potential source of bias in the present review could be the exclusion of articles in non-English language. Further limitations in this study arise from the nature and the characteristics of the data retrieved during the review process. Most of the included studies were nonrandomized trials except for one [17], with different surgical/expansion protocols. In some of the studies, these protocols were vaguely described. Additionally, the control groups differed between the eligible studies. It is evident that more high-quality prospective studies with respect to the clinical outcomes of SARPE on facial soft tissues need to be carried out in the future. A standardized methodology, including control samples, would be valuable in obtaining comparative results.