Frequency Of Intake Or Exposure

Increased snacking increases the risk of caries because increasing the frequency of sugar intake extends the duration of acid production and exposure, thereby tipping the scale toward the development of caries.6 This can be demonstrated simply by measuring plaque pH (which would be the immediate environment of the tooth) throughout the day. In the example below it can be clearly seen that in A, increasing the frequency of eating and drinking increases the episodes when the pH of plaque falls below 5.5. In B, restricting between-meal snacks and drinking non-sugared drinks reduces the time that plaque pH falls below 5.5.

Figure 4.
fig04
Frequent sugar-containing snacks between meals cause more episodes of the oral pH falling under 5.5, increasing caries risk. (B.) Fewer sugar-containing snacks between meals cause fewer episodes of the oral pH under 5.5, reducing caries risk.
From: Marsh PD, Martin M. Oral Microbiology. 5th ed. Churchill Livingstone Elsevier, London, UK. 2009:12.

An interesting observation is that it can be less beneficial to eat one sweet than it is to eat five sweets in immediate succession. With five in succession, the levels of sucrose may be toxic to bacteria and there may be a greater salivary stimulatory effect. Furthermore, if five sweets are spread out throughout the day, oral pH would be depressed for more episodes.5 The message for patients: Consume all sweets in one episode, and preferably following a meal, rather than spreading them throughout the day.

Figure 5.
fig05
Plaque pH after eating 1 sweet or 5 sweets in succession.
Adapted from: Edgar WM. Duration of response and stimulus sequence in the interpretation of plaque pH data. J Dent Res. 1982;61(10):1126-1129.