Evaluation of the golden proportion in the natural dentition: A systematic review and meta-analysis

Statement of problem: Different proportions of tooth width ratios have been evaluated, and the golden proportion is the best known. Although the prevalence of the golden proportion has been evaluated in different ethnic groups and populations, a meta-analysis of these studies is lacking. Purpose: The purpose of this systematic review and meta-analysis was to investigate the existence and suitability of the golden proportion for tooth width ratios and to assess the prevalence of the golden proportion among populations. Material and methods: A systematic search based on the Patient, Intervention, Comparison, Outcome (PICO) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted in PubMed, Cochrane, Scopus, Web of Science, and Embase in January 2021 without any time limitations and included English and non-English-language articles. Additional studies were identified by searching the reference lists of the retrieved articles. Two reviewers independently performed the literature search and data extraction, selecting articles based on the inclusion and exclusion criteria. Eligible studies were selected based on the inclusion criteria, and quality assessments were conducted. Descriptive statistics were applied for a number of outcome measures. Using a meta-analysis software program, data extracted from each selected study were statistically combined by using weighted mean differences and 95% confidence intervals, and heterogeneity was calculated for each measurement. Results: A total of 566 articles were retrieved based on the keyword search. After the articles were assessed based on the inclusion and exclusion criteria, only 6 articles were included in the meta-analysis. Conclusions: The outcomes of the review and analyses demonstrate that evidence supporting the existence of the golden proportion in natural smiles is lacking and that the existence of the golden proportion in dentistry is a myth and not a fact. However, the golden percentage theory can be applied with modified percentages that consider critical aspects of esthetic dentistry.