Systematic review
Laypeople's perceptions of frontal smile esthetics: A systematic review

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Highlights

  • Thresholds for the main features of smile and dental esthetics could be identified.

  • Overall risk of bias was low to moderate.

  • This review is the first attempt to quantify laypeople's smile esthetic perceptions.

Introduction

The emphasis on dental esthetics has increased in recent years. There are, however, differences in esthetic perceptions among professional and lay groups. The aim of this comprehensive review was to update previous reviews and answer the following research question: Can lay thresholds for acceptance of smile esthetic anomalies be defined?

Methods

A systematic search in the medical literature (PubMed, PMC, NLM, Embase, Cochrane Central Register of Controlled Clinical trials, Web of Knowledge, Scopus, Google Scholar, and LILACs) was performed to identify all peer-reviewed articles reporting data regarding evaluations of laypeople's perceptions of dental esthetic factors.

Results

Of the 6032 analyzed articles, 66 studies were selected for the final review process. Among the selected articles investigated perceptions of diastema, 15 analyzed modifications in tooth size and shape, 8 considered incisor positions, 15 evaluated midline discrepancies, 16 investigated buccal corridors, 26 analyzed gingival display and design, 3 considered lip height, and 20 investigated miscellaneous factors. Threshold values were identified for the following features: diastema (0-2 mm), tooth size and shape of incisor position, midline discrepancy (0-3 mm), buccal corridors (5-16 mm), gingival exposure (1.5-4 mm), occlusal canting (0°-4°), and overbite (2-5 mm). Furthermore, few other smile characteristics were found to be significantly associated with perception of smile aesthetics, even though any threshold could be detected.

Conclusions

On the basis of the obtained results, threshold values for the main features of smile and dental esthetics could be identified. Limitations of the present study were the heterogeneity of data which made it impossible to perform a meta-analysis, and the lack of information about sample selection and selective outcome reporting.

Section snippets

Protocol and registration

This comprehensive review protocol was registered in the International Prospective Register of Systematic Review (http://www.crd.york.ac.uk/PROSPERO/; protocol number CRD42015017781) and modified in January 2016.

Eligibility criteria

The inclusion and exclusion criteria are presented in Table I. The reference lists of included articles were perused, and references related to the articles were followed up.

Information sources, search strategy, and study selection

On April 1, 2016, a systematic search in the medical literature was performed to identify all peer-reviewed

Study selection and characteristics

Among the 6032 analyzed articles, 66 were selected for the final review process.1, 3, 4, 8, 9, 10, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84 The article selection procedure have been described in the PRISMA flow chart (Fig). Among the selected articles, 10 investigated perceptions of diastema, 15

Summary of evidence

Lay perceptions of smile esthetics are important to better understand the treatment goals from a patient's viewpoint. The results of this review permitted the identification of several smile features that should be well addressed during the definition of an orthodontic treatment plan. As stated by Proffit et al,85 the most important aspect of facial animation is the smile, which is a critically important part of social interactions. Various characteristics may contribute to smile esthetics

Conclusions

Thresholds of acceptance of smile esthetic characteristics were attempted in this review. However, in view of the lack of overlapping studies, the subjective nature of the assessment, and the difficulty in inferring clinical relevance from nonclinical studies, the clinical applicability of these results should be considered with caution.

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    All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported.

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