The Michigan Xylitol Programme

Xylitol Chewing Gum Plays a Valuable Role in Caries Prevention and Stabilisation

The aim of the Michigan Xylitol Programme (1986-1995) was to study the use of xylitol-containing saliva stimulants in the prevention of dental caries. The studies undertaken in this programme consisted of several clinical trials and laboratory investigations and were carried out in Belize, (Central America), Michigan, Ohio, Finland, and Estonia.

The results of the ten-year research project confirm that a chewing gum sweetened 100% with xylitol plays a valuable role in caries prevention and stabilization. Such chewing gum used in The Michigan Xylitol Programme was provided by Leaf Finland. The gum was developed and launched as a result of the programme.

The Belize Xylitol Chewing Gum Trials

In a chewing gum trial on permanent dentition (1989-1994), effects of chewing gum use on the increment of dental caries were compared as a function of sweetener type, proportion of specific sweeteners in the gums, and frequency of chewing, initially in 10-year-old subjects in a 40-month double-blind cohort study.

This study was carried out in Belize, Central America. The caries prevalence in Belize has been high. The chewing gums had comparable organoleptic properties and essentially the same aggregate percentages of polyols or sugars, comprising either xylitol, sorbitol, or sucrose. The chewing gums in the form of either sticks or pellets were chewed either 3 or 5 times/day, during the school year.

Gum with high xylitol content has a remineralising effect

In long-term dental trials in Belize, the regular consumption of xylitol chewing gum with the highest xylitol content has been shown to have a clear remineralizing effect. The xylitol content is evidently in direct relation to the degree of caries reduction: the higher the xylitol content, the more effectively caries reduction was achieved. There was also a correlation between frequency of use and results.

Nine groups were studied, comprising 1277 subjects. One control group was provided with no gum at all; four xylitol gum-chewing groups received either pellet- or stick-shaped gum for either 3 or 5 supervised sessions/school day; one group used sorbitol pellet gum for 5 sessions/school day; two groups used either xylitol or sorbitol pellet gums 5 times/school day; one group used sucrose gum 5 times/school day. The primary response variable was the development of frank carious surface lesions, which were detectable by the physical loss of enamel and probable extension of lesions to the dentine for those tooth surfaces, which were not cavitated at the baseline or which had not erupted at the baseline. Statistical comparisons were made according to the relative risk for caries associated with the use of each of the chewing gum types, when compared to the ‘No-gum’ group.

The use of 100% xylitol chewing gum had the most significant caries- preventing effect

The findings of the research show that there is an anti-caries hierarchy among polyol-sweetened chewing gums. Although sorbitol-sweetened gum is clearly less cariogenic than sugar gum, combination with xylitol decidedly enhances its anti-caries effectiveness, which becomes much greater when the ratio of xylitol to sorbitol is increased to 3:2 (See table below)

DMFS Scores Marin health and smiles

DMFS scores refer to the number of decayed, missing or filled surfaces of teeth. The DDMFS scores show changes in the caries index over a 28-month follow-up period. Positive scores mean an increase and negative scores a decrease in the incidence of caries.

The largest caries reductions were observed in a group receiving 100% pellet- shaped xylitol chewing gum. The sorbitol and xylitol/sorbitol mixture gums were less effective than the 100% xylitol gum, but they still reduced caries rates significantly when compared to the ‘No-gum’ or sucrose gum. All xylitol- containing gums reduced the relative risk of caries increment compared to sugar, ‘no-gum’ and sorbitol gum.

References:
Isokangas,P., Alanen,P. Tiekso,J., Mäkinen K.K. Xylitol chewing gum in caries prevention: a field study in children. JADA 1988 117:315-320.
Hujoel P.P., Isokangas, P., Tiekso, J., Davis S., Lamont R.J., DeRouen T.A., Mäkinen K.K. A re-analysis of caries onset rates in a preventive trial using Poisson regression models. Journal of Dental Research 1994 73:573-579.
Pape H.R.jr., Mäkinen K.K. Verification and maintenance of dental explorer sharpness. Oper. Dent. 1994 19:221-223.
Hujoel P.P., Mäkinen K.K., Bennet C.A., Isokangas P., Isotupa K.P. Pape H.R. jr., Do caries explorers transmit infection within persons? An evalution of second molar caries onsets. Caries res. 1995 29:461-466