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.

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.

Collaborative WHO xylitol field studies in Hungary. I. Three-year caries activity in institutionalized children

The aim of this 3-year field study was to assess the value of partial substitution of sucrose with peroral xylitol (14-20 g/day) as a caries-preventive measure (X group) in comparison with systemic administration of fluoride (F group) and restorative treatment procedures solely (C group). An F dentifrice was used unsupervised in the X and F groups, the former containing 10% xylitol. The C group used customary, predominantly F-free dentifrices distributed by the local health authorities. The final material consisted of 689 institutionalized children (6-11 years). Caries was scored yearly in duplicate by two continuously calibrated teams. At base line the X group had a significantly higher caries prevalence than the F and C groups. The 3-year DMFS increment was 4.2 in the X group, 6.5 in the F group, and 7.7 in the C group. The corresponding ratio (RS) between caries incidence and the tooth surface population at risk was RSx, 4.9; RSF, 6.6; and RSC, 8.6. It is concluded that dietary xylitol in solid sweets resulted in a lower increment of caries than obtained in the F and C groups (p less than 0.001, covariance analysis, with base-line prevalence, number of permanent teeth, and visible plaque index as covariants).

Multifactorial modeling for root caries prediction

The study was part of a series of investigations aiming at the development of diagnostic caries tests for screening of risk subjects. The material consisted of 100 adult subjects (mean 62 yr, range 47-79 yr), 50 of these under chronic medication. The series of tests included two chairside registrations, i.e. incipient demineralization of exposed root surfaces without cavitation (RD 1) and quantitation of visible plaque (VPT%), three microbiological tests for mutans streptococci, lactobacilli, and candida/yeasts and three tests on stimulated saliva, i.e. secretion rate, buffering capacity and sucrase activity. A thorough clinical examination was conducted at the baseline and 1-yr registration phases, caries being registered at a tooth surface level according to WHO recommendations separately for coronal and root caries. Considerably more root caries than coronal caries developed during the observation period. For coronal caries increment, the predictive value of any of the tests was not significant. For root caries, however, the association between several tests and prospective caries increment was significant. Subsequent multifactorial modeling yielded the highest predictive value to the combination of Past Root Caries Experience (OR 25.0, Visible Plaque (OR 4.2), Candida (OR 8.0) and Lactobacilli (OR 5.8). A positive finding of Past Root Caries (RDFS) or the combination of the other three tests (Can, LB, VPT%) as criteria for selection in screening for root caries produced good accuracy (84.0) and a relative risk of 5.5.

Multifactorial modeling for root caries prediction: 3-year follow-up results

The study was part of a series aiming at the development of caries tests. The initial material (n = 104, age range 47-79 yr, mean 62 yr) was reduced to 96, who were observed for 3 yr. During the follow-up four subjects died, all due to myocardial infarction, and four refused to participate. Thorough oral examinations were conducted at the baseline, 1- and 3-yr registrations; coronal and root surface caries were registered separately according to WHO classification. The tests included salivary mutans streptococci, lactobacilli, candida/yeasts, secretion rate, buffer effect and sucrase activity, and quantitation of visible plaque. The association between prospective root caries increment and several tests was significant. Multifactorial modeling resulted in the combination of Past Root Caries Experience (OR 12.8), Lactobacilli (OR 8.6) and Candida (OR 2.8). At screening, the criterion "two or three positive tests" of these yielded acceptable accuracy (77.1) and a relative risk of 3.3.

Comparative effects of dexmedetomidine, propofol, sevoflurane, and S-ketamine on regional cerebral glucose metabolism in humans: a positron emission tomography study

INTRODUCTION

The highly selective α₂-agonist dexmedetomidine has become a popular sedative for neurointensive care patients. However, earlier studies have raised concern that dexmedetomidine might reduce cerebral blood flow without a concomitant decrease in metabolism. Here, we compared the effects of dexmedetomidine on the regional cerebral metabolic rate of glucose (CMR_glu) with three commonly used anaesthetic drugs at equi-sedative doses.

METHODS

One hundred and sixty healthy male subjects were randomised to EC₅₀ for verbal command of dexmedetomidine (1.5 ng ml^-1; n=40), propofol (1.7 μg ml^-1; n=40), sevoflurane (0.9% end-tidal; n=40) or S-ketamine (0.75 μg ml^-1; n=20) or placebo (n=20). Anaesthetics were administered using target-controlled infusion or vapouriser with end-tidal monitoring. ¹⁸F-labelled fluorodeoxyglucose was administered 20 min after commencement of anaesthetic administration, and high-resolution positron emission tomography with arterial blood activity samples was used to quantify absolute CMR_glu for whole brain and 15 brain regions.

RESULTS

At the time of [F¹⁸]fluorodeoxyglucose injection, 55% of dexmedetomidine, 45% of propofol, 85% of sevoflurane, 45% of S-ketamine, and 0% of placebo subjects were unresponsive. Whole brain CMR_glu was 63%, 71%, 71%, and 96% of placebo in the dexmedetomidine, propofol, sevoflurane, and S-ketamine groups, respectively (P<0.001 between the groups). The lowest CMR_glu was observed in nearly all brain regions with dexmedetomidine (P<0.05 compared with all other groups). With S-ketamine, CMR_glu did not differ from placebo.

CONCLUSIONS

At equi-sedative doses in humans, potency in reducing CMR_glu was dexmedetomidine>propofol>ketamine=placebo. These findings alleviate concerns for dexmedetomidine-induced vasoconstriction and cerebral ischaemia.

CLINICAL TRIAL REGISTRATION

NCT02624401.

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.

Assessment of single risk indicators in relation to caries increment in adolescents

Base-line data on a series of risk indicators were related to 11-month caries increment in 181 subjects with a mean age of 13 years and 3 months. A caries increment equalling or exceeding one tooth surface was recorded in 21% of the subjects. The risk indicators consisted of past caries experience, white spot lesions, visible plaque and gingivitis, and six salivary tests: secretion rate, buffer effect, sucrase, mutans streptococci, lactobacilli, and Candida. Significant associations between caries increment and past caries experience (p = 0.002), white spot lesions (p = 0.01), lactobacilli (p = 0.02), Candida (p = 0.006), and sucrase (p = 0.02) were observed. The ensuing odds ratios were thus recorded: past caries experience, 3.6; white spot lesions, 2.9; salivary sucrase activity, 2.9; lactobacilli, 2.5; and Candida, 2.8.

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.

Effect of a xylitol chewing gum on plaque quantity and quality

The aim of the present study was to further investigate the plaque-reducing effect of a xylitol-containing chewing gum. Ninety-six dental students were divided randomly into three groups: a sucrose group (n = 32), a xylitol group (n = 36) and a control group (n = 28), using a sucrose-containing chewing gum, a xylitol-containing chewing gum, or no chewing gum, respectively, during a three-day experimental plaque growth period with restricted oral hygiene. The fresh weight of plaque collected in the xylitol group was 40% lower than in the sucrose group, along with a significantly lower mean plaque index. The use of the xylitol chewing gum induced low invertase-like activity in plaque extra-cellular phase together with low carbohydrate content. These results concur to indicate advantageous effects through the use of a xylitol-containing chewing gum.

Effect on plaque of a xylitol-containing chewing-gum. A clinical and biochemical study

The effects on plaque induced by single or repeated use of xylitol- and sucrose-containing chewing-gums were studied on twenty subjects refraining from tooth-brushing for three days. Mechanical removal of plaque by chewing during a single period was shown to yield no significant differences between gravimetric values obtained before and after chewing. Daily use of a xylitol-containing chewing-gum reduced by 47% the weight of plaque formed in comparison to a sucrose-containing product, and by 20--41% in comparison to conditions when no chewing-gum was used. The use of a xylitol chewing-gum induced a lower invertase-like activity in plaque extra cellular phase. Results at variance with the gravimetric data were obtained by using a stained plaque scoring system; the eventual inadequacy of such plaque scoring systems was discussed.

Collaborative WHO xylitol field studies in Hungary. VII. Two-year caries incidence in 976 institutionalized children

The aim was to assess caries increment as influenced by partial substitution of sucrose by xylitol (X group) over a 2-year period in comparison with systemic fluoride (F group) and restorative treatment only (C group). The study differed from the 3-year field study of the same series primarily in that existing base-line differences were eliminated because the protocol required that all the new subjects entering the institutions in the 1st year were to be included for a 2-year trial. During this period the number of dropouts was 243 (19.9% of all subjects), the final material consisting of 976 children (6-12 years old). The 2-year DMFS increment was 3.8 in the X group, 4.8 in the F group, and 6.0 in the C group. The corresponding ratio (RS) between caries incidence and the tooth surface population at risk was RSX, 4.5; RSF, 5.5; and RSC, 7.5. The xylitol regimen resulted in a lower increment of caries than measured in the F and C groups (p less than 0.001; convariance analysis, with base-line prevalence, number of permanent teeth, and visible plaque index as covariants.

Collaborative WHO xylitol field studies in Hungary. IV. Saliva levels of Streptococcus mutans

Salivary Streptococcus mutans was quantified to detect possible age-, sex-, and group-dependent differences at the end of a 3-year field study assessing the value of partial substitution of sucrose with xylitol (X group) in comparison with systemic administration of fluoride (F group) and restorative treatment solely (C group). The material of this substudy consisted of 390 institutionalized children aged 9-14 years. S. mutans was determined through the spatula technique and grouped into categories 0, less than 10(5), 10(5)-10(6), and and greater than 10(6) CFU/ml saliva. Zero to less than 10(5) values included more than 80% of the subjects of the X group. The cross-sectional comparison between groups showed lower S. mutans values in the X group than in the F and C groups. These differences between groups were highly significant. S. mutans was not dependent on age or sex.

Multifactorial modeling for prediction of caries increment in adolescents

The purpose of the study was to develop a multifactorial model for the prediction of 11-month caries increment in adolescents. The mean age of the subjects (n = 181) at the base-line examination was 13 years and 3 months. The risk indicators consisted of past caries experience, white spot lesions, visible plaque, gingivitis, salivary secretion rate, buffer effect, sucrase, mutans streptococci, lactobacilli, and Candida. The multifactorial modeling included all the above risk indicators, age, and gender and resulted in different models in boys and girls, indicating the difficulty of caries prediction in adolescents. When boys and girls were combined, the final model included past caries experience, Candida, and salivary sucrase. Although the accuracy of the model was slightly below the 80% level recommended for screening purposes, the results provide clinically valuable information. The risk of caries increases with an increasing number of positive tests within the model.

Collaborative WHO xylitol field studies in Hungary. III. Longitudinal counts of lactobacilli and yeasts in saliva

The levels of salivary lactobacilli and yeasts were determined annually in half of the subjects of the xylitol (X) and fluoride (F) groups of a 3-year caries study. These measurements were carried out with Dentocult (DC) and Oricult (OC) dip-slide methods. A high level of lactobacilli prevailed throughout the study in these subjects. Significant changes were registered in some subgroups--that is, improvement in one of the X institutions and worsening in one of the F and one of the X institutions. At base line the counts of OC were worse in the X than in the F group. In the total material some improvement occurred during the course of the study, mainly in the X group. The changes associated with the preventive program should also be considered as related to the improvement in oral hygiene, restorative treatment, and the mere study effect.