Turku sugar studies. I. An intermediate report on the effect of sucrose, fructose and xylitol diets on the caries incidence in man

Effect of xylitol on Porphyromonas gingivalis: A systematic review

OBJECTIVE

This review was conducted to assess the effectiveness of xylitol against Porphyromonas gingivalis anaerobic species, a key microbe contributing to periodontal disease pathogenesis.

MATERIAL AND METHODS

Relevant studies published on seven online databases (Cochrane, Ovid, Pubmed, Pubmed Central, Scopus, Google Scholar, and Web of Science) were included in accordance with the PRISMA guidelines. Inclusion criteria allowed all study designs involving xylitol and P. gingivalis, literature published since the year 2000, and all xylitol delivery forms.

RESULTS

The initial search yielded 186 papers. After the removal of duplicates, five reviewers screened every article for eligibility and seven articles were selected for data extraction. Four out of seven included studies assessed the dose-dependent effect of xylitol on P. gingivalis growth, two studies assessed the effect of xylitol on P. gingivalis-induced cytokine expression, and one study assessed both domains.

CONCLUSIONS

From the in vitro studies included in this systematic review, there is some evidence of xylitol's inhibitory effect on P. gingivalis. However, more evidence derived from in vivo studies is required to confirm its effectiveness warranting their routine use.

Improving Clinical Visual Detection—Potential for Caries Clinical Trials

It has been the norm in caries clinical trials to measure caries increment by several different caries-recording systems, including the crude DMF-S/T index. However, there is a reserved attitude as to whether to subdivide the non-cavitated lesions and use arrested lesions in clinical trials. This has been due to the belief that it is not possible to achieve reliable data of the early stages of the disease (Radike, 1972). However, recently, Ekstrand et al. (1997, 1998) showed that it was possible: (1) to differentiate between different stages of non-cavitated occlusal lesions, (2) to differentiate between active and inactive occlusal lesions, and (3) to predict the depth of the lesion. In at least 4 other clinical studies, the reproducibility of recording initial active lesions, cavitated active lesions, and arrested lesions was found to be adequate (Carvalho et al., 1989; Nyvad et al, 1999; Ekstrand et al., 2000; Machiulskiene et al., 2001). Since caries today is a more slowly developing disease in many countries in the world, this will result in prolongation of the duration of the clinical trial, which will increase the costs. As indicated above, there is now sufficient evidence that caries can be clinically diagnosed accurately and reliably in earlier stages as well as in an arrested stage. If such stages of caries are used as outcome variables in caries clinical trials, they may have a positive influence on the trials’ duration and costs.

Sugar alcohols, caries incidence, and remineralization of caries lesions: a literature review

Remineralization of minor enamel defects is a normal physiological process that is well known to clinicians and researchers in dentistry and oral biology. This process can be facilitated by various dietary and oral hygiene procedures and may also concern dentin caries lesions. Dental caries is reversible if detected and treated sufficiently early. Habitual use of xylitol, a sugar alcohol of the pentitol type, can be associated with significant reduction in caries incidence and with tooth remineralization. Other dietary polyols that can remarkably lower the incidence of caries include erythritol which is a tetritol-type alditol. Based on known molecular parameters of simple dietary alditols, it is conceivable to predict that their efficacy in caries prevention will follow the homologous series, that is, that the number of OH-groups present in the alditol molecule will determine the efficacy as follows: erythritol >/= xylitol > sorbitol. The possible difference between erythritol and xylitol must be confirmed in future clinical trials.

Health potential of polyols as sugar replacers, with emphasis on low glycaemic properties

Abstract Polyols are hydrogenated carbohydrates used as sugar replacers. Interest now arises because of their multiple potential health benefits. They are non-cariogenic (sugar-free tooth-friendly), low-glycaemic (potentially helpful in diabetes and cardiovascular disease), low-energy and low-insulinaemic (potentially helpful in obesity), low-digestible (potentially helpful in the colon), osmotic (colon-hydrating, laxative and purifying) carbohydrates. Such potential health benefits are reviewed. A major focus here is the glycaemic index (GI) of polyols as regards the health implications of low-GI foods. The literature on glycaemia and insulinaemia after polyol ingestion was analysed and expressed in the GI and insulinaemic index (II) modes, which yielded the values: erythritol 0, 2; xylitol 13, 11; sorbitol 9, 11; mannitol 0, 0; maltitol 35, 27; isomalt 9, 6; lactitol 6, 4; polyglycitol 39, 23. These values are all much lower than sucrose 65, 43 or glucose 100, 100. GI values on replacing sucrose were independent of both intake (up to 50 g) and the state of carbohydrate metabolism (normal, type 1 with artificial pancreas and type 2 diabetes mellitus). The assignment of foods and polyols to GI bands is considered, these being: high (> 70), intermediate (> 55–70), low (> 40–55), and very low (< 40) including non-glycaemic; the last aims to target particularly low-GI-carbohydrate-based foods. Polyols ranged from low to very low GI. An examination was made of the dietary factors affecting the GI of polyols and foods. Polyol and other food GI values could be used to estimate the GI of food mixtures containing polyols without underestimation. Among foods and polyols a departure of II from GI was observed due to fat elevating II and reducing GI. Fat exerted an additional negative influence on GI, presumed due to reduced rates of gastric emptying. Among the foods examined, the interaction was prominent with snack foods; this potentially damaging insulinaemia could be reduced using polyols. Improved glycated haemoglobin as a marker of glycaemic control was found in a 12-week study of type 2 diabetes mellitus patients consuming polyol, adding to other studies showing improved glucose control on ingestion of low-GI carbohydrate. In general some improvement in long-term glycaemic control was discernible on reducing the glycaemic load via GI by as little as 15–20 g daily. Similar amounts of polyols are normally acceptable. Although polyols are not essential nutrients, they contribute to clinically recognised maintenance of a healthy colonic environment and function. A role for polyols and polyol foods to hydrate the colonic contents and aid laxation is now recognised by physicians. Polyols favour saccharolytic anaerobes and aciduric organisms in the colon, purifying the colon of endotoxic, putrefying and pathological organisms, which has clinical relevance. Polyols also contribute towards short-chain organic acid formation for a healthy colonic epithelium. Polyol tooth-friendliness and reduced energy values are affirmed and add to the potential benefits. In regard to gastrointestinal tolerance, food scientists and nutritionists, physicians, and dentists have in their independent professional capacities each now described sensible approaches to the use and consumption of polyols.

Breast-feeding and sugar intake in babies with cleft lip and palate

OBJECTIVE

To investigate the pattern of breast-feeding and sugar intake among babies with cleft lip and palate.

PARTICIPANTS

Caretakers of 200 babies with cleft lip and palate enrolled at the Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo, Bauru, Brazil.

RESULTS

A low prevalence of breast-feeding was found. The most reported reason was the sucking inability of the baby. Complete cleft lip and palate was the primary cause affecting sucking. The first contact with sugar occurred mainly through the baby bottle with milk during the first month of life. For nutritional supplement, the children were given sugar and fruit juices in the bottle.

CONCLUSIONS

It was observed that dietary habits in babies with cleft lip and palate are more risky. This highlights the role played by early education and constant oral hygiene follow-up for prevention in these patients.

Methodological issues in longitudinal epidemiologic studies of dental caries

As longitudinal epidemiologic studies of dental caries address increasingly complex research questions, approaches to analysis of data from those studies have become more sophisticated. This review examines methods available for analyzing and reporting data from such studies. Traditional analytic methods utilize the DMFS increment as the outcome measure in longitudinal studies of caries. However, two other outcome measures may be needed to address some research issues: cumulative incidence, which quantifies caries risk; and incidence density, which quantifies caries rate. Four major analytic decisions have to be addressed when computing DMFS increment: examiner misclassification ("reversals"), teeth lost due to caries, findings from more than two examinations, and multiple events such as caries initiation and progression. We present a uniform approach for enumerating caries events that permits the same analytic decisions made in calculating DMFS increment to be applied to cumulative incidence and incidence density calculations. In view of the variety of analytic decisions that must be made when enumerating events in longitudinal studies of caries, authors should specify how all potential changes in caries status were handled. Furthermore, if a study uses more than one outcome measure, the same decisions for enumerating events should be used when computing those measures.

Xylitol in caries prevention: what is the evidence for clinical efficacy?

Xylitol has attracted much attention as an alternative sweetener. Essentially all clinical studies concerning the effect of xylitol on caries development consent to its non-cariogenicity and to the beneficial effect of substituting sucrose with xylitol in chewing gums and sweets. However, claims of anti-caries or therapeutic effects, and superiority of xylitol over other polyols are still to be confirmed by well designed and conducted studies from independent research groups.

Skewed distributions--new outcome measures

The traditional measure of caries, the DMF index, either as prevalence or incidence of disease, has become highly positively skewed among children and young adults. Most discussion of skewed distributions has focused on the properties of statistical analyses using such data or the implications for sample sizes and subject selection in clinical trials. This paper examines the full range of epidemiologic studies, their aims and constitutive interest in order to identify the measurement problems associated with skewed DMF index data. Constitutive interests include: description; documentation; explanation and prediction; evaluation; advocacy; and, experimentation. 'New' outcome measures that would assist in reaching the aims and constitutive interests of the epidemiology of caries include caries severity grading, variants of prevalence, extent and severity and their combination into case definitions, and weighting of the components of the DMF index. Research questions for each area of 'new' outcome measures are identified as steps in the codifying of their use in the epidemiology of caries.

Management for the highly caries-susceptible patient

Despite dramatic improvement in caries treatment during the past 30 years, a substantial number of patients remain highly susceptible and do not respond to conventional treatment. It is possible, using simple chairside caries-susceptibility tests, to identify the etiologic factors responsible for the disease and to design a rational approach to treatment that addresses the specific needs of the patient.

Effect of Pentoses and Pentitols on Fermentation of Hay by Mixed Populations of Ruminal Microorganisms

Consecutive batch culture, a technique which involves sequential transfer of cultures to fresh medium at regular intervals, was used to establish mixed ruminal-microbial populations in an anaerobic medium containing highly digestible hay. Once volatile fatty acid production was stable, perturbations were imposed in consecutive cultures by the addition of one of each of the following pentoses or analogous pentitols: l -arabinose, d -lyxose, d -ribose, d -xylose, l -arabitol, d -arabitol (lyxitol), ribitol, and xylitol. With the exception of d -lyxose, the addition of pentoses caused marked increases in propionate and valerate production, and except for d -arabitol, pentitol addition caused increases in butyrate and valerate production. On transfer to and continued incubation in the control medium, volatile fatty acid production reverted to preperturbed levels. The presence of pentitols and pentoses significantly reduced the endpoint pH of cultures and the proportion of hay that was fermented. With all added substrates, the response to the perturbation was at its maximum within one incubation (i.e., within 48 h). Similarly, the variables being monitored all returned to control levels within one incubation. On the basis of these results, it is suggested that changes were related to the need to maintain a redox balance within anaerobic cultures rather than any significant changes in the microbial population that was present.

Xylitol metabolism in xylitol-sensitive and xylitol-resistant strains of streptococci

The metabolism of xylitol in xylitol-sensitive strains (strains whose growth is inhibited by xylitol) and xylitol-resistant strains (growth not inhibited) of oral streptococci was compared. Both xylitol-sensitive and xylitol-resistant strains took up xylitol. In the sensitive cells, the xylitol was probably transported via a phosphotransferase system. This resulted in intracellular accumulation of xylitol-5-phosphate and xylulose-5-phosphate. These metabolites were not detected in the xylitol-resistant strains, which probably transported xylitol via a permease system. It appeared that the resistant strains were able to utilize xylitol as carbon and energy source in the absence of other carbohydrates.

Enamel microhardness change and plaque pH measurements in an intra-oral model in humans

Changes in plaque pH and microhardness of bovine enamel slabs were evaluated with a seven-day intra-oral cariogenicity test (ICT). The test enamel slabs were mounted in prosthetic appliances with a Dacron mesh cover for enhancement of microbial colonization. Three percent solutions of sucrose, sorbitol, and xylitol were evaluated as four daily extra-oral immersions of 10 min each, for seven days, and the results were compared with baseline experiments (no daily immersions). The pH was measured with antimony electrodes on one-day and seven-day ICT plaque samples that were challenged with a one-minute immersion in the studied substrates. Plaque samples in the baseline experiments were challenged with 3% sucrose. The enamel softening was assessed with measurements of microhardness. Sucrose challenge caused pH depression with both the baseline and the sucrose-immersed plaque. Sorbitol and xylitol challenge did not depress the plaque pH. Compared with the baseline, sucrose immersions caused enamel softening; sorbitol and xylitol did not.

Caries prevalence in Turner's syndrome (45,X females)

Dental caries prevelance in permanent teeth (DFS) was studied in 50 patients with Turner's syndrome (45,X females) and 41 normal first-degree female relatives. Caries prevalence was lower in 45,X women than in controls, and this difference was more pronounced in the incisor region than in pre-molar and molar teeth.

Enamel dissolution and fluoride uptake from sugar solutions

Solubility studies and fluoride uptake by enamel powder in xylitol-buffered solutions versus sucrose- and glucose-buffered solutions were carried out. The studies were done at a pH range of 4-8. The enamel solubility in the xylitol media was similar to the enamel solubility in the other sugar solutions--increasing with a decreasing pH. The solubility of enamel in the buffered sugar solutions was significantly lower as compared to the solubility in the sugar-free buffered solutions--up to the pH of 6. At the pH values of 7 and 8 the amounts of solubility were similar for the experimental and control solutions. No significant differences were found in the fluoride uptake by the enamel powder from the fluoride-containing sugar solutions at the pH values of 6 and 7.5 respectively. The results point to the conclusion that the xylitol does not differ from sucrose and glucose in its effect on enamel powder solubility and the uptake of fluoride ions by enamel.

Further studies on the growth inhibition of some oral bacteria by xylitol

The growth in Brain Heart Infusion medium containing glucose or sucrose of Streptococcus mutans strain OMZ 176, two strains of Strep. sanguis (ATCC 10556 and No. 39) and Actinomyces viscosus type ATCC 27044 was inhibited by xylitol but not by D-arabitol or ribitol. When fructose was substituted for glucose, xylitol had no growth-inhibiting effect. It was also shown that the bacteria produced less acid in the presence of xylitol, as measured by the pH of the cultures or by neutralization with alkali.

Effect of the sweet-tasting protein monellin on growth of a cariogenic bacterium: a microbiological study

Monellin is a protein with an intensely sweet taste and could be considered as a potential alternative sweetener to sucrose. The effect of monellin on the in vitro growth of the cariogenic microorganism Streptococcus mutans was investigated.

Effect on plaque growth of xylitol and sucrose-containing chewing gums

Two experiments tested the effects of xylitol or sucrose-containing chewing gums on plaque formation. In the first experiment the 18 subjects maintained their normal dietary habits, and in the second they received a sucrose-free diet during the 3-day experimental periods. Plaque formation was assessed gravimetrically and/or planimetrically. When the dietary habits were not altered, neither the sucrose nor the xylitol-containing chewing gums had significant effects on the plaque scores. When sucrose was almost eliminated from the diet, plaque formation was significantly higher in the sucrose than in the xylitol and the placebo groups. Although plaque formation was lower in the xylitol group than in the placebo group, the differences were not statistically significant.

Xylitol and D-arabitol toxicities due to derepressed fructose, galactitol, and sorbitol phosphotransferases of Escherichia coli

d-Arabitol was observed to be toxic to many laboratory strains of Escherichia coli K-12, and xylitol was found to be toxic to an existing E. coli C mutant strain. Fructose-specific components of the phosphoenolpyruvate:sugar phosphotransferase system are required for xylitol toxicity. Selection for xylitol resistance results in Fru(-) strains blocked in fructose phosphotransferase. Introduction of the ptsF or ptsI mutation into a xylitol-sensitive strain eliminates sensitivity. [(14)C]fructose uptake experiments imply that the mutation to xylitol sensitivity, which is co-transducible with ara and leu, results in derepression of normally inducible fructose phosphotransferase. Wild-type strains also become xylitol sensitive if induced by (and then removed from) fructose. Xylitol toxicity is prevented by fructose in both wild-type and mutant strains. Circumstances causing xylitol, a new food additive, to become toxic to an otherwise insensitive wild-type organism have not been reported previously. The d-arabitol-sensitive laboratory strains are galactitol (dulcitol) utilizers, although most other strains are not. Selection for d-arabitol resistance results in Gat(-) strains blocked in a constitutive galactitol-specific component of the phosphotransferase system. A mutation causing d-arabitol sensitivity occurred many years ago in AB284, the parent of AB311, AB312, AB313, and many other strains. d-Arabitol sensitivity also occurs in sorbitol-constitutive strains and is shown, like the previous two instances of pentitol toxicities, to result from a constitutive phosphotransferase, which is blocked in mutants selected for resistance.

Conceptions of Finnish people about the etiology and prevention of dental caries and periodontal disorders

Conceptions among the general public in Finland regarding the etiology and prevention of dental caries and periodontal disorders were surveyed in two interviews in 1971 and 1972. Both population samples interviewed comprised about 1,000 people aged 15 years and over. Inadequate oral hygiene was the most common (65%) possible cause chosen by the subjects among the causes of dental caries. Only 44% of the interviewees considered sugar to be a cause of cariers. Thorough cleaning of the teeth (83%) and dentist's check-ups twice a year (67%) were the factors most frequently chosen in caries prevention. Avoidance of sugar (56%) ranked as the third in frequency. As regards symptoms of periodontal disorders, tender gingiva, gingival bleeding, and loosening of the teeth were correctly suggested as symptoms by 62, 61 and 45%, respectively. Poor oral hygiene (77%) was the cause of gingivitis most commonly chosen by the interviewees, while simultaneous systemic disease (37%) was considered more important than, for example, dental calculus (31%). As regards treatment of periodontal disorders, careful toothcleaning (73%) received most support. However, this factor was closely followed by misconceptions regarding the supposed advantageous value of drug and rinses (50%), chewing of fibrous foods (45%), and vitamin therapy (38%).

Xylitol binding in human dental plaque

Human dental plaque and whole saliva sediment were tested for their ability to bind 14C-labeled sucrose, fructose, glucose, sorbitol, and xylitol. Sucrose, glucose, sorbitol, and fructose were bound to all materials tested, in this decreasing order. The binding was strongest with plaque given a five-second ultrasonic shock, and lowest with salivary sediment. Xylitol was only insignificantly bound, indicating that plaque microorganisms possess specific recognition sites for xylitol to a very restricted extent.

Xylitol-induced increase of lactoperoxidase activity

Whole saliva samples of volunteers who ate a strict diet for two years with regard to the type of sweeteners used (sucrose, fructose, and xylitol) showed considerable differences in the lactoperoxidase activity. The consumption of a xylitol diet increased the activity of this enzyme fourfold to tenfold when compared to the other two test groups. Lactoperoxidase belongs to the natural defense mechanisms of the oral cavity. However, the consumption of a xylitol diet also leads to a strong reduction in the incidence of dental caries. It is suggested that the xylitol-induced elevation of the salivary lactoperoxidase activity and the cariostatic properties of xylitol are partly interrelated phenomena.

Turku sugar studies XI. Effects of sucrose, fructose and xylitol diets on glucose, lipid and urate metabolism

The effect of chronic consumption of sucrose, xylitol and fructose on lipid, carbohydrate and urate metabolism was studied in conjunction with a clinical trial on the effects of these sugars on dental caries. No consistent differences were found in serum triglycerides, glucose, insulin, urate, lactate, or pyruvate concentrations or in the urinary excretion of urate between the groups using sucrose, fructose or xylitol as the dietary sweetener. Serum cholesterol tended to be lower in the fructose than in the xylitol group, but the difference disappeared when subjects with initial high serum cholesterol in the baseline examination were excluded from the calculations. The results suggest that the effects of peroral fructose and xylitol on the metabolic parameters studied in this investigation do not differ from that of sucrose.

Turku sugar studies. VI. The administration of the trial and the control of the dietary regimen

125 voluntary subjects, divided into three groups, were originally chosen to participate in a two-year trial in which the dental and general effects of the consumption of sucrose (S 35), fructose (F 38) and xylitol (X 52) were elucidated through an extensive clinico-chemical analysis plan. Additionally 2 edentulous subjects were included in the X-group for survey of the general metabolic effects only. The subjects were given free of charge a versatile assortment of foodstuffs sweetened with either S, F or X. Using special distribution and control systems, the subjects were handled and controlled so that an almost comparable consumption of the products was achieved throughout the trial. The mean individual monthly intake of S, F and X was 2.2, 2.1 and 1.5 kg, respectively. The highest daily amounts of S, F and X per person varied between 200--400 g. The cooperation of the subjects completing the study in the F- and X-groups was 97%, expressed as the intake frequency of the correct sugar. Ten persons discontinued or were otherwise excluded for a diversity of reasons. No health problems were observed, except for transient osmotic diarrhoea in the X-group. These symptoms gradually disappeared and occurred later in the trial in the X-group almost to the same extent as in the S- and F-groups.

Turku sugar studies XII. The effect of the diet on oral peroxidases, redox potential and the concentration of ionized fluorine, iodine and thiocyanate

Detailed biochemical analyses of peroxidases in saliva, plaque and gingival exudate samples were carried out in view of the preliminary findings that the peroxidase activity of centrifuged oral fluid was considerably higher in the xylitol group than in the fructose or Sucrose groups. Chromatographic experiments revealed the activity which was increased due to the intake of xylitol, to be attributed to the involvement of the salivary lactoperoxidase, and not to enzymes formed in plaque or leucocytes. There were no significant differences between the sugar groups in the concentration of thiocyanate ions (mean 92 mg/l) and ionized iodine (mean 1.6 mug/l), but the concentration of ionized fluorine in saliva was lower in the xylitol group (0.128 mg/l) than in the other groups (0.150 mg/l). There were no clear differences in the salivary redox potential between the sugar groups. It is evident that various sugars selectively affect the enzyme and other production of the salivary glands. Xylitol-induced elevation of the salivary lactoperoxidase activity and the cariostatic properties of xylitol may partly be interrelated phenomena due to the antibacterial properties of lactoperoxidase.

Turku sugar studies. V. Final report on the effect of sucrose, fructose and xylitol diets on the caries incidence in man

The purpose was to study differences in the caries increment rate as influenced by various sugars. The trial involved almost complete substitution of sucrose (S) by fructose (F) or xylitol (X) during a period of 2 years. There were no significant initial differences as to caries status between the prospective sugar groups; 35 subjects in the S-group, 38 in the F-group, and 52 in the X-group. During the entire study 10 subjects discontinued or were excluded. The clinical and radiographical observer error was reported and discussed. After 2 years the mean increment of decayed, missed and filled tooth surfaces was 7.2 in the S-group, 3.8 in the F-group, and 0.0 in the X-group. The weakness of the DMFS-index in not showing the development of new secondary caries and the increase in size of the lesions was overcome by expressing the caries activity in terms of indices showing the total quantitative and qualitative development. The results showed a massive reduction of the caries increment in relation to xylitol consumption. Fructose was found to be less cariogenic than sucrose. It was suggested that the non- and anticariogenic properties of xylitol principally depend on its lack of suitability for microbial metabolism and physico-chemical effects in plaque and saliva.

Turku sugar studies X. Occurrence of polysaccharide-forming streptococci and ability of the mixed plaque microbiota to ferment various carbohydrates

Dental plaque samples collected from the subjects during the last 20 months of the 2 year trial were subjected to quantitative and qualitative analysis of the occurrence of S. mutans, S. sanguis, S. salivarius and the total growth on phenol red agar. Lyophilized plaque samples were homogenized and incubated on a sucrose containing medium under anaerobic conditions. In addition, the pH-values were measured after incubation of the mixed plaque flora in media containing 1% respectively xylitol(X), sorbitol, sucrose (S), fructose (F) or no carbohydrates. The results show a significantly lower incidence of S. mutans in the X-group relative to the S- and F-groups. The corresponding difference could not be observed between the S- and F-groups. The logarithmic means and standard deviations of the colony counts of S. sanguis, S. salivarius and total bacteria yielded no significant differences between the 3 sugar groups during the test period. Repeated pH-measurements, carried out at the 4, 12, 18 and 24 month phases, showed that, except in the presence of X, the mean values all fell below the pH-limit of 5.5. In the course of the study, no evidence was obtained of adaption of mutation enabling acidogenic decomposition of X. These findings emphasize the importance of low acidogenic potential in dental plaque, generally paralleled by a low incidence of dental caries.

Turku sugar studies. VII. Principal biochemical findings on whole saliva and plaque

Plaque and whole saliva samples of the subjects of the Turku sugar studies were analyzed for several enzymes and biochemical compounds. Strict xylitol diet maintained throughout the study a 50% lower quantity of plaque than the sucrose of fructose diets. Decreased plaque and whole saliva lactate concentration, diminished activity of salivary amylase, and reduced hydrolysis rate of sucrose in plaque and whole saliva were observed in relation to xylitol consumption. The xylitol diet also reduced the ratio of glucose to proteins in plaque. On the other hand, increased activity in plaque of alpha- and beta-glycosidases (against p- and o-nitrophenyl derivatives), fucosidase and aspartate transaminase, as well as increased activity of proteinases and lactoperoxidase in saliva were found in connection with xylitol consumption. The fructose diet caused less clear differences when compared to sucrose, but the experiments indicated a selectivity of the effects of dietary carbohydrates on the biochemistry of whole saliva, plaque and salivary glands. The results contribute in explaining the cariostatic effects of xylitol and the lower coriogenicity of fructose when compared to sucrose.

Turku sugar studies XVIII. Incidence of dental caries in relation to 1-year consumption of xylitol chewing gum

A longitudinal study was carried out in order to evaluate the caries incidence as affected by partial substitution of dietary sucrose (S) with xylitol (X), the effects of S- or X-containing chewing gums being compared during one year. The material comprised initially 102 young adults, predominantly dental and medical students, divided randomly into S- and X-groups. During the study 2 subjects were excluded, one due to lack of cooperation, the other not being allowed to enter the assigned S-group due to excessive caries prevalence. The subjects consumed 4.0 chewing gums per day in the S-group and 4.5 in the X-group. The frequency of sucrose intake was 4.2 times per day in the S-group, and 4.9 in the X-group. The caries incidence, assessed independently by clinical and radiographical means, expressed as the mean increment of decayed, missed and filled tooth surfaces, was 2.92 in the S-group, and --1.04 in the X-group. The corresponding values, when considering additionally the secondary caries reverals, were 3.76 in the S-group, and 0.33 in the X-group. The caries incidence was also expressed in combined quantitative and qualitative terms by considering in addition to the above parameters, also the changes in lesion size. The caries activity index thus calculated was 4.96 in the S-group, and 0.88 in the X-group. The results show a profound difference in the caries increment rate between the two experimental groups. The findings clearly indicate a therapeutic, caries inhibitory effect of xylitol.