Understanding the pH of the mouth
One of the most important factors in maintaining healthy teeth is pH. First, consider what pH means. It is a measure of acidity or alkalinity. The pH scale goes from 1 to 14, 1 being the most acidic, 14 being the most alkaline, and 7 being neutral (like most water). A pH of 5.5 is an important pH level for teeth as the teeth begin to dissolve or demineralize at a pH in the mouth below 5.5. At a pH above 5.5, the teeth begin to remineralize.
Dental plaque that is kept at a pH of 7.0 or greater does not experience this shift in the bacterial species to aciduric and acidogenic (cavity-causing) bacteria even during exposure to sugar. If the pH in the mouth can be maintained at a neutral or alkaline pH, regardless of sugar, food, or acidic drink consumption, the healthy bacteria within the dental plaque biofilm will not die and the shift to cavity-causing bacteria will not occur.
A healthy pH balance in the mouth can explain why many people—family members, coworkers, friends, etc.—can consume lots of sugary food and drink, seemingly take little care of their mouth, and yet do not have cavities. At the same time, many people who are extremely diligent about their diet and home care continue to get cavities because the bacteria in their biofilm are primarily cavity causing bacteria. These people continue to be very susceptible to small changes in pH.