Turku sugar studies XXI: Xylitol-, sorbitol-, fructose- and sucrose-induced physico-chemical changes in saliva

The aim was to study eventual physico-chemical changes occurring in whole saliva due to sweetened and unsweetened stimulators. The assay was carried out in 10 female subjects with regard to changes of pH, buffering capacity and electrolytes in saliva as influenced by chewing of fructose, sucrose, sorbitol and xylitol gum, gum base and paraffin. The flow rate of saliva was measured in relation to use of xylitol and sucrose chewing gum and unsweetened gum base. These sweeteners increased significantly the salivary flow rate in comparison to the unsweetened gum base. Generally, xylitol and sorbitol on one hand, and sucrose and fructose on the other, behaved in an almost similar way. Increased buffering capacity and elevation of pH in saliva was found in the presence of the polyols tested.     

Turku sugar studies XXI. Xylitol, sorbitol-, fructose- and sucrose-induced physico-chemical changes in saliva.

The aim was to study eventual physico-chemical changes occurring in whole saliva due to sweetened and unsweetened stimulators. The assay was carried out in 10 female subjects with regard to changes of pH, buffering capacity and electrolytes in saliva as influenced by chewing of fructose, sucrose, sorbitol and xylitol gum, gum base and paraffin. The flow rate of saliva was measured in relation to use of xylitol and sucrose chewing gum and unsweetened gum base. These sweeteners increased significantly the salivary flow rate in comparison to the unsweetened gum base. Generally, xylitol and sorbitol on one hand, and sucrose and fructose on the other, behaved in an almost similar way. Increased buffering capacity and elevation of pH saliva was found in the presence of the polyols tested.     

Turku sugar studies. VIII. Principal microbiological findings.

The possible qualitative and/or quantitative alterations in the proportions of cultivable groups of oral microorganisms were analysed during a clinical trial involving the consumption of fructose (F) or xylitol (X) in comparison to sucrose (S). Supragingival plaque samples and paraffin-stimulated saliva were collected from 115 subjects. The samples were dispersed by sonication, diluted stepwise, plated on blood sugar, Mac Leod agar, Mac Concey agar, Rogosa S.L. agar, and Sabouraud agar plates and incubated anerobically and/or aerobically. The number of the total colony forming units (CFU) on blood agar plates in anaerobic incubation was about 1-3 X 10(9)/ml saliva and 1-4 X 10(8)/mg plaque and in aerobic respectively 5-18 X 10(8)/ml saliva and 10(8)/mg plaque. The total CFU on Mac Leod agar was of a similar order of magnitude. The variation between subjects and consecutive determinations was of a similar order of magnitude. The variation between subjects and consecutive determinations was relatively large. The arithmetic mean of the total CFU on Mac Concey agar was about 1-5 X 10(5)/ml saliva, on Rogosa S.L. agar 6-130 X 10(3)/ml saliva and on Sabouraud about 1-2 X 10(3)ml saliva, all in aerobic incubations. Replacement of dietary sucrose with xylitol did not affect the proportion of major microbial categories in saliva or dental plaque. The percentage of typical streptococcal colonies on blood agar was of a similar order of magnitude (about 60-70%) during the diets. The arithmetic and geometric means of the total CFU values on Rogosa and Sabouraud agar plates were significantly lower in the X-group than in the S- or F-groups after a diet period of some months. It was thought that the reason for the reduction of acidogenic and aciduric oral flora in the X-group was partly due to the fact that xylitol is generally not metabolized by these microorganisms.     

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.     

Incidence of dental caries among a group of university students in Turku

The aim of the present study was to estimate the incidence of dental caries in a group of university students during a 4-year interval between registrations. Eventual differences in the periodontal and oral hygiene conditions were also examined. In addition, the reasons for high prevalence of caries in freshmen were investigated. The material consisted of 116 students, initially examined clinically and radio-graphically in 1967, and later in 1971. The amount of untreated caries diminished from originally 15.0 to 9.9 decayed surfaces per student. Untreated caries was constantly less frequent among females than males. The caries incidence was 1.9 surfaces per year which corresponds to previous estimations of the caries increment in Finland. An improvement in the gingival conditions, eventually due to the decrease of untreated carious lesions, was registered. The difference between mean PH-values in 1967 and 1971 was not significant. Classification in subgroups according to gingival and oral hygiene conditions showed, however, that the group possessing poor oral hygiene conditions diminished in size. The indices of GI and PII were higher among males than females.

The poor dental conditions among the freshmen could be attributed to a mean of 6.4 years since the termination of previous regular dental treatment.     

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^o₀ lower quantity of plaque than the sucrose or 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 α and β-glycosidases (against p₂- and 2-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 cariogenici-ty of fructose when compared to sucrose.     

Turku sugar studies XIII. Effect of the diet on certain clinico-chemical values of serum.

Pooled and individual serum samples of subjects on long-term sucrose, xylitol and fructose diets were analyzed for Ca, Mg, K, Na inorganic phosphate, bilirubin, ascorbate, alkaline and acid phosphatase, amylase, transaminases, lactate dehydrogenase, and amino acids. Most serum samples were obtained from the last phases of the two-year dietary regimen. Significant differences between the three experimental groups were not found with regard to any of the compounds or enzymes studied. Almost significant differences were observed for amylase which was lower in the xylitol and the fructose groups than in the sucrose group, all these values being within the normal range. The results indicate that xylitol and fructose do not induce significant changes in liver function tests, nor in serum level of electrolytes, ascorbate or serum enzymes when their oral administration takes place in the same scale as that of sucrose.