Effect of Kissing on Salivary pH Recovery After Consumption of Acidogenic Beverages: A Randomised Clinical Trial

To evaluate whether kissing is associated with salivary pH recovery after consumption of acidogenic beverages in young adults. This 3-arm parallel randomised clinical trial randomised 33 couples to control, Experimental Group 1, or Experimental Group 2. One participant per couple was randomly selected for salivary measurement and analysis (11 per group). Coca-Cola and Cifrut sessions were available for all 33 selected participants; 24 completed the non-alcoholic beer session. Salivary pH was recorded at baseline, 1 minute after beverage intake, and every 5 minutes through 40 minutes. Recovery was analysed using beverage-specific linear mixed-effects models. No significant group effect or group-by-time interaction was found for Coca-Cola, Cifrut, or non-alcoholic beer (all P > .05). Bonferroni-adjusted pairwise mean differences were also non-significant, and all corresponding 95% confidence intervals included zero. Baseline pH and the initial pH decrease were not significantly different among groups for any beverage. The 1-minute post-beverage pH differed among groups for non-alcoholic beer (F(2,21) = 7.074; P = .004), but not for Coca-Cola or Cifrut. The minimum observed absolute pH was 5.70; no value was below 5.5. Under the conditions evaluated, the analyses did not provide evidence that kissing modified salivary pH recovery. Estimates were imprecise, particularly for the non-alcoholic beer session, and the findings should be interpreted as exploratory. Salivary pH recovery is a physiological marker after acidic exposure; however, these findings do not support kissing as a preventive or clinically protective strategy. ClinicalTrials.gov NCT06501729.