How does the acidity from carbonic acid in unflavored sparkling water contribute to dental erosion compared to colas?
Sparkling water ($ ext{pH}$ 3 to 4) is generally less severe than a typical cola (easily below 2.5) because colas contain compounding strong acids.
While the carbonic acid in plain sparkling water is sufficient to soften tooth enamel over time, leading to dental erosion (often resulting in a $ ext{pH}$ around 3 to 4), commercial colas present a much greater danger. Colas incorporate powerful, non-volatile acids like phosphoric and citric acid in addition to the carbonic acid derived from carbonation. These added acids significantly drive the $ ext{pH}$ much lower, often dipping below 2.5. Therefore, the risk from carbonated water alone is less severe than the compounded risk posed by highly acidic soft drinks that utilize both carbonation and strong organic/inorganic additives.
