caries. In general, the more plaque present, the higher the risk for plaque pH to drop to levels where dissolution of enamel can occur. Both salivary and plaque pH begin to fall as plaque levels increase. Thus, efforts at reducing plaque levels will contribute to increasing plaque pH and decrease the chances of demineralization and caries. Saliva, our natural buffer solution, is stimulated with eating and drink-ing and serves to neutralize acid attacks. If dietary or hygiene measures are not carefully controlled, the body’s defense mechanism can be overridden, and cavity risk can remain high. Enamel is in a constant battle between demineralization and remineralization in the oral envi-ronment because this is where the plaque adheres. Frequency of sugar consumption, especially sucrose, can create an acidic environment that shifts the balance toward demineralization that results in caries. Both fructose and sucrose were found to be highly acidogenic in a study on acidogenicity. 1 Acido-genicity is a measure of the drop in plaque pH after exposure to a fermentable carbohydrate. Both frequency of ingestion and type of fermentable carbohydrate will determine cariogenicity (cavity causing potential). Sucrose is known to be highly acidogenic, and its association with caries is well estab-lished. It is desirable to limit consumption of sugar based foods and drinks, especially between meals, to prevent prolonged periods of acid attack on enamel. A high frequency of consumption of sugar based foods and drinks keeps plaque and salivary pH low (high acido-genicity), and cavity risk high. Acidic pH levels, below 5.5 will result in demineralization. As mentioned above, a consis-tently low pH levels created by frequent sugar consumption will override the saliva’s natural buffer-ing capacity. Thus, the neutraliza-tion effect of the saliva is ineffective to raise the pH to levels that are not damaging. Sweeteners that are non-acidogenic are desirable, as these will not cause a decrease in plaque pH. Sweeteners with low acido-genicity will have less cariogenicity (potential to cause caries). Polyols (xylitol in particular) are a class of sweeteners that have reduced acido-genicity and thus are considered less cariogenic. Background of Polyols Polyols were discovered in the late 1800s but remained unstudied in the dental field until 1970 when the “Turku Sugar Studies” began. 2,3,4 These studies initially reported reduction in the amount of dental plaque formed after xylitol was consumed for four or five days. Subsequently, long term studies (over a period of two years) that replaced sucrose in the diet with fructose or xylitol showed a huge decrease in caries rates with the xylitol diets. 2,3 The caries reduction was reportedly greater than 85%. Eventually, studies with partial substitution (rather than total replacement) of sucrose in the diet using xylitol gum carried out over a one year period clearly indicated a therapeutic caries inhibitory effect for xylitol. 4 This sparked the inter-est of the dental community to further research the effects of xylitol as a preventive measure. Use of Xylitol in Orthodontic Patients The aim of this article is to review studies that examined the use of xylitol in active orthodontic patients; to discuss the unique properties of xylitol that make a useful adjunct in the preventive care of orthodontic patients; and to encourage the widespread use of xylitol for orthodontic patients. A Pub-Med search for use of xyli-tol in active orthodontic patients revealed 4 articles. The first study of the effects of xylitol gums and rinses on plaque acidogenesis in patients with fixed orthodontic appliances was published in 1982 and was funded by the William Wrigley Company and Kenilworth Dental Research Foundation. 5 The research was divided into four phases and tested the effects of sucrose, sorbitol, and xylitol sweeteners on plaque pH, acidogenicity of the plaque from areas traditionally susceptible to decalcification in orthodontic patients, plaque composition, and effects on supporting soft tissues in active orthodontic patients. Orthodontic patients chewed letter-coded packages of gum three times per day, one stick at a time, after each meal. No adverse orthodontic problems such as increased breakage or loose attach-ments occurred with any signifi-cance during the study, despite the fact that the patients chewed gum with their appliances. Only the xylitol group had a significant increase in plaque pH, and it appeared that there was less gingi-val proliferation in the xylitol group. The implications from the study were that gum chewing is favorable to soft tissue health. The study concluded that xylitol-sweet-ened chewing gum, together with proper prophylaxis, should prevent damage to the teeth and investing tissues during fixed orthodontic treatment. www.orthodontics.com Winter 2014 37
Journal of the American Orthodontic Society Winter 2014: Page 37
