Aim/Objective: This study aimed to assess the real influence of four criteria on smile attractiveness: diastema, smile line, gingival display and midline. Material and Method: A search on MEDLINE (PubMed), chochrane, embase and EBD review was conducted using 7 key words via Boolean equations. Papers published between 2005 and 2016 and meeting the eligibility criteria were identified after reading their titles and abstracts. During the reading of the full text, a critical analysis of the methodology followed was conducted on the basis of the reading grid and the literature analysis. Results: Among the 1376 references initially found, 37 articles met the inclusion criteria. 31 articles were classified as high quality, 5 as average and one article as lower. Articles concluded that the diastema decreases the attractiveness such as the gingival display, but a limit of 2 mm is admitted for gingival exposure and a value of 1mm of diastema remain acceptable. A smile line parallel to the lower lip is the ideal form but the flat smile can be acceptable even preferred for the Men models. For the midline a small deviation of 3 mm can be considered acceptable. Compared to the professionals, patients are less sensitive only for the midline and the diastema in its minimal variations Conclusion: The results of this study reveal that the four criteria influence the smile attractiveness. This approach that we followed can be applied to other aesthetic criteria as well as to other parameters influencing such as gender, ethnic differences etc.
