Influence of soft drink intake on the salivary pH of schoolchildren

Abstract

Objective: To evaluate the influence of Coca-Cola® consumption on the salivary pH of 12-year old children. Material and Methods: The convenience sample was composed of forty-five 12-year old students of both genders from public schools of Itatiba, state of São Paulo, Brazil. Salivary pH was measured with pH colorimetric tape indicator (Merck). The reading of the colorimetric method was made by an experienced evaluator under uniform lighting conditions. The colorimetric tape was positioned in the back of the student’s tongue, which remained with the mouth shut for 30 Seconds. For control, the first measurement (T0) was performed before the intake of the soft drink (baseline pH). Subsequently, students were instructed to slowly drink 100 ml of Coca-Cola® using a plastic disposable cup. Immediately after ingestion, the pH was measured again with the colorimetric tape (t1). The oral pH values were also measured 5 minutes (t2), 10 minutes (t3) and 15 minutes (t4) after the soft drink intake, keeping the tape positioning always the same in all measurements. The statistical SAS software was used for data analysis. Comparisons of oral pH values at different times were performed by the Tukey-Kramer test adopting 5% significance level. Results: Immediately after soft drink intake, the salivary pH significantly decreased (pH = 6.26) (p <0.05) compared to baseline (pH = 7.23) (p <0.05). Fifteen minutes after ingestion, although an increase in the pH was observed (pH = 6.64), it had not yet returned to baseline (T0) (p <0.05). Conclusion: Coca-Cola® intake caused a significant reduction in salivary pH, without, however, reaching critical pH for enamel demineralization.