The threshold of acceptability of excessive gingival display by laypersons: a systematic review

Excessive gingival display ('gummy smile') is often an esthetic concern for the patient. There is a difference in perception of smile esthetics between dentists and laypersons. Understanding what is acceptable to laypersons is critical to achieve patient satisfaction in terms of smile esthetics. The present study aimed to identify the ideal and acceptable range of excessive gingival display as defined by laypersons.

A systematic English language literature search was carried out in the following electronic bibliographic databases: PubMed, Scopus, CENTRAL (Cochrane Central Register of Controlled Trials), Web of Science, and EMBASE, according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The quality of the articles was assessed using the AXIS tool as well as 11 additional criteria that were specifically designed for the study.

Out of the 1263 potentially eligible articles selected in the initial search, 34 were included in the final review. A total of 16 articles identified both the ideal values and the range of acceptance of excessive gingival display, 10 only the range of acceptance, and 8 only the ideal values. From the pooled sample, the mean threshold of acceptance was -0.84 ± 1.43 mm, the range of acceptance was +3 to -2.7 mm, and the median was 0.0 mm.

The present study concluded that laypersons considered minimal gingival exposure (GE) or minimal tooth coverage (TC) to be the most esthetic. However, a smile falling in the range of 3 mm of GE to 2.7 mm of TC was considered acceptable. Knowledge of laypersons' threshold of acceptance of excessive gingival display can guide clinicians in evidence-based dental esthetic treatments.