Assessing the Impact of 2D:4D Ratio on Oral Hygiene Performance and Gingival Health in Turkish Adults.

PURPOSE: To investigate the relationship between the second-to-fourth digit ratio (2D:4D), a marker of prenatal hormone exposure, and oral hygiene performance and gingival health. MATERIALS AND METHODS: A cross-sectional study was conducted with 126 adults aged 18-55 years (71 males, 55 females) at Istanbul Okan University's Periodontology Clinic. Participants were classified by sex, hand dominance, and 2D:4D ratio (cut-off: 1). Oral hygiene was assessed using the Turesky Modification of the Quigley-Hein Plaque Index (QHPI) and Gingival Index (GI) at baseline and one week after standardised oral hygiene education. Finger lengths were measured to calculate 2D:4D. Statistical analyses included t-tests, repeated-measures ANOVA, Pearson's correlation, and Bonferroni post-hoc tests (α=0.05). RESULTS: No statistically significant difference in 2D:4D ratio was found between sexes (p=0.395) or hand dominance (p=0.730). QHPI and GI scores statistically significantly improved across all groups after education (p0.001). No statistically significant association was found between 2D:4D ratios and changes in QHPI or GI. However, left-handed individuals showed statistically significantly lower QHPI scores at both time points (p 0.05), and males with 2D:4D 1 reported more frequent brushing habits, though this was not reflected in clinical indices. The highest GI values were observed in males with 2D:4D ≥1, while the lowest were in females with 2D:4D<1. CONCLUSIONS: The 2D:4D ratio was not a reliable predictor of oral hygiene status or gingival health. However, handedness may influence oral hygiene performance. Standardized oral hygiene education led to comparable improvements regardless of biological variability.