This article notes that “dental erosion is a multifactorial condition: The interplay of chemical, biological and behavioral factors is crucial and helps explain why some individuals exhibit more erosion than others. The erosive potential of erosive agents like acidic drinks or foodstuffs depends on chemical factors, e.g. pH, titratable acidity, mineral content, clearance on tooth surface and on its calcium-chelation properties. Biological factors such as saliva, acquired pellicle, tooth structure and positioning in relation to soft tissues and tongue are related to the pathogenesis of dental erosion. Furthermore, behavioral factors like eating and drinking habits, regular exercise with dehydration and decrease of salivary flow, excessive oral hygiene and, on the other side, an unhealthy lifestyle, e.g. chronic alcoholism, are predisposing factors for dental erosion.”

Danielle added that many factors determine individual dental health, including the types of food consumed, the level of oral hygiene, access to professional dental care and access to fluoridated water. Phosphates — like any substance that is acidic (lemons, citrus fruit, tomatoes etc.) — lower plaque pH. When plaque pH falls enough, tooth enamel begins to demineralize, which leads to tooth decay.

However, the natural action of saliva reverses this situation by remineralizing the teeth and neutralizing the pH. The frequency of eating and the length of contact with the teeth are some of the most important factors in determining whether or not there is decay. Carbonated soft drinks have a relatively low pH partially because of phosphate content. However, if consumed rapidly the low pH of the mouth would be very temporary as the saliva is basic and would rapidly neutralize the acids found in soft drinks.

The carbohydrates in soft drinks can come into contact with teeth and lead to demineralization, but since the duration of contact between a drink and teeth is usually very short that is rarely the case. Sticky foods like soft cookies that tend to stay in the mouth longer and/or cling to teeth are much more likely to be a significant source of dental cavities. If liquids were constantly sipped throughout the day (as in a toddler cup or baby bottle), then carbohydrate containing liquids would be more likely to lead to tooth decay.

I can't offer you much advice on how to seem trustworthy to other folks, but I can tell you what works with me. Numbers. The natural folks tell me that phosphate levels in soft drinks are high. “How high?”, I wonder. “Very High”, they tell me. “How high, and high in relation to what?”, I wonder. “Very high, unhealthily high”, they reassure me. So I take a closer look at the propaganda from those corporate tools at Pepsico. “Soft drinks provide less than 3% of phosphorus of the normal daily phosphorus intake.”
Yay! An actual quantitative number. 3%. But wait. “3% of what? What is the numerator and what is the denominator? Is this an estimate for a population? What population? How much soft drink is consumed by this population? And who/what is the source of this statistic?” Reading further I find that 3% number again (Yay, numbers!) being contrasted to a 60% number (Double yay, comparisons between numbers!), but still no clarity as to what these numbers mean or citations indicating where they come from.

But eventually, I reached closure on this issue when I found this resource which satisfied my craving for numbers. And guess what. I believed these numbers, even though their source was an evil corporation. I believed them because it was clear exactly what claims were being made, and therefore also clear how those claims might be falsified and their purveyors demonstrated to be liars. I don't think a big bad corporation would take that risk. Hence, I believe them. If the “natural” folks had put out numbers instead, I might have believed them. But they didn't. So it is PepsiCo ftw. But that is just me. Your results with other readers may vary.