Dental caries is an infectious-contagious disease of multifactorial origin and requires simultaneous interaction of three factors for establishment: microorganisms, host and diet^1-3. Prevention of this pathology requires interference on these etiologic factors by means of strengthening of the host, which occurs in the presence of fluorides; control of the microorganisms through professional prophylaxis and antimicrobial agents; and restriction of dietary carbohydrates, especially sugar.

Within this preventive context, the utilization of xylitol is highlighted, which is a polyalcohol known by organic chemistry since 1890. Xylitol may be found naturally in some fruits and vegetables and may also be industrially produced⁴. The dental studies concerning xylitol were initiated in 1969, aiming at a possible substitution of sucrose because of the similar sweetening power. Later it was also employed in other forms for prevention, allowing interference on the metabolism of cariogenic microorganisms and improving the protective mechanisms of the host against tooth decay⁵. Xylitol is currently available in many forms such as chewing gums^6-10,toothpastes^11-13, fluoridated mouthrinses^14-15, milk¹⁶ and it may also be associated to the use of fluoride^17-18.

The utilization of xylitol in chewing gums allows an increase in the salivary flow, yielding an increase in the buffering capacity of saliva and a larger and faster increase in the salivary pH, therefore making the de/remineralization process more favorable¹⁹. The studies on the literature display possible anticariogenic²⁰ and cariostatic²¹ properties of xylitol, which render this sweetener greatly interesting and important to Preventive Dentistry. However, its utilization in public services is partially impaired by one of its disadvantages, namely the high cost²¹. However, this may be overcome because of the preventive benefits it provides to oral health, reducing the expenses with therapeutic procedures. There is also the gastrointestinal side effect, caused by the intake of doses above 20g, which can lead to osmotic diarrhea. Nevertheless, it is known that high doses of fluoride, which is currently the most widely spread and used preventive method, can bring about even death of individuals, a risk that xylitol²² does not present.

The aim of this work is to describe how xylitol can be used as an anticariogenic agent by means of a review of the specialized literature, demonstrating its properties and possible mechanisms of action in the control and prevention of tooth decay.

Literature Review

Studies using xylitol in chewing gums revealed a reduction of 40% in dental plaque, compared to a group that used chewing gums containing sugar⁶.

When chewed between meals, the gums can stimulate the natural defenses of the organism, which help in the decrease of caries prevalence together with the non-fermentability of xylitol by the bacteria⁷, besides the decrease in the speed of progression of the lesion²⁰ and reduction in the amount of cariogenic bacteria²³.

Comparison of xylitol chewing gums and pit and fissure sealants demonstrated no significant difference between these two preventive methods²⁴.

The utilization of xylitol was also investigated in toothpastes containing it and NaF/silica, which produced a significant increase in the anti-caries benefit when compared to a similar toothpaste without xylitol¹³. This can be attributed to the remineralization capacity of human enamel surfaces by means of toothpastes with fluoride and xylitol¹², showing that it is an efficient association.

Utilization of xylitol in solutions associated or not to fluoride was also observed, and the results showed that xylitol isolatedly did not reduce the level of demineralization, yet such reduction was present when xylitol was associated to fluoride¹⁴ Therefore, mouthrinses containing xylitol seem not to have anticariogenic effects over the dental plaque²⁵. Further benefits were observed when xylitol was used in pills associated to fluoride and sorbitol, which yielded a reduction in the colonization of S. mutans, leading to a lesser amount of plaque and less carious lesions in the deciduous dentition. A reduction in the amount of S. mutans was also observed when xylitol pills were used in dummies²⁶.

The utilization of substances to avoid dental plaque formation and adhesion to the dental structure is of great importance for the maintenance of oral health. Within this context, xylitol has been playing an important role because of the following properties: non-fermentability by the cariogenic bacteria, ability to stimulate certain natural defenses of human beings⁷, reduction in the amount of bacteria⁹ and their adherence²⁷, which make it a cariostatic and anti-cariogenic agent³.

Some disadvantages are reported, such as the high cost²⁸ and possible gastrointestinal alterations when consumed in high doses¹.

The utilization of xylitol as a sugar substitute has been mainly performed in chewing gums, with better results when chewed between meals^2,7 and no differences as to the total or partial substitution of sugar. The main advantages of the chewing gum include the great acceptability by children^29-30, extended period of contact with the teeth and saliva² and permanence below the critical pH for a very short period¹⁶. The reduction in dental plaque was quantitatively demonstrated through the utilization of xylitol chewing gums^6,27, which revealed a reduction of 40%⁶, collaborating with the reduction in tooth decay⁸ and prevention of periodontal disease². Further, there was remineralization of incipient carious lesions^4,19,21.

Regarding the reduction in the levels of S. mutans, some studies demonstrated a positive effect of xylitol^4,27, differently from another on which such reduction was not observed11. Some species of S. mutans may adapt themselves to xylitol; however, these are less pathogenic than those that metabolize the sucrose. The reduction in the amount of S. mutans and Lactobacillus occur either with the isolated utilization of xylitol²⁸ or in association with chlorhexidine²⁰.

The fluoride-xylitol complex demonstrated to be beneficial for caries prevention in the deciduous dentition, by means of the utilization of tablets with this complex in babies aged 8 to 16 months old, through the reduction in the amount of S. mutans^26,31.

Being fluoride an acknowledged relevant agent for caries prevention, several studies were conducted to compare it to the use of xylitol in toothpastes, which demonstrated the induction of cariostatic mechanisms¹⁰ and provided an optimal concentration of available fluoride³².

The three-year employment of a toothpaste containing fluoride and xylitol reduced the number of new restored surfaces, presenting to be better than the isolated use of fluoride¹³.

When mouthrinses containing xylitol were used, a smaller reduction in salivary pH³ was observed, however other studies demonstrated that xylitol was not able to reduce the level of demineralization¹⁴ nor did it have any effects on the dental plaque¹⁵.

In conclusion, xylitol can be presented in many forms such as chewing gums, tablets, mouthrinses, and associated to fluoride in toothpastes. Its anticariogenic power is due to the impairment of growth of cariogenic bacteria and consequent reduction in the acidity of plaque. Besides, it helps in the remineralization of initial carious lesions, is specific to S. mutans, well accepted by children and may be used with beneficial effects in all ages.

References

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