Strategies for prevention and control of caries based on plaque ecology hypothesis
According to the plaque ecology hypothesis, low pH (less than 5) will promote overgrowth of aciduric microorganisms, such as the cariogenic mutans streptococci and lactobacilli, at the expense of less acid-tolerant plaque microorganisms, such as S oralis, which are associated with healthy tooth surfaces.
Therefore the treatment strategy would be to increase plaque pH and thereby promote reestablishment of the harmless normal microflora of the tooth surfaces.
Increased pH can successfully be achieved by a combination of the following preventive measures:
1. Frequent mechanical removal of the plaque from all tooth surfaces: “Clean teeth never decay,” and frequent removal of plaque (once or twice a day) limits the thickness of reaccumulated plaque, ensuring that saliva has accessibility for diluting and buffering the acid that is formed.
2. Reduction of sugar clearance time by reducing the intake of sticky sugar-containing products.
3. Use of sugarless chewing gums containing fluoride and chlorhexidine as a “dessert” for 15 to 20 minutes directly after every meal (including between-meal snacks).
Use of this kind of gum has several beneficial effects:
1. Salivary flow is increased and the acid formed during the meal is diluted and buffered.
2. Fluoride will reduce acid formation by the acidogenic microorganisms at low pH.
3. Chlorhexidine has not only a nonspecific antiplaque effect but also a specific effect on mutans streptococci and acid formation by acidogenic microorganisms.
4. Fluoride ions and minerals from the increased salivary flow will accelerate remineralization directly after the acid attack during the meal.
This recommendation is very important for caries-susceptible patients, particularly those with xerostomia (for reviews on plaque ecology related to caries etiology, see Bowden, 1997; Bowden and Edwardsson, 1994; Marsh, 1993.)
