Hans R. Mühlemann

Oral Starch Degradation and Its Influence on Acid Production in Human Dental Plaque

Enzymatic hydrolysis of starch by salivary α-amylase, its time dependence and influence on plaque acid production was investigated. Analysis of the composition of starch digests was performed with gel filtration chromatography. Wheat starch in solution, in bread and in biscuit was hydrolyzed rapidly mainly to maltose, maltotriose and limit dextrins. In vivo enzymatic degradation of wheat starch caused marked drops in interdental plaque pH to 4.75 measured by intraoral plaque pH telemetry, most probably as the result of the fermentation of low molecular weight maltodextrins by plaque bacteria. On this basis starch may contribute to cariogenesis.

Cariogenic effects of cooked wheat starch alone or with sucrose and frequency-controlled feedings in rats

Abstract Twenty-day-old Osborne-Mendel rats, super-infected orally with Streptococcus , mutans OMZ-176 and Actinomyces viscosus Ny 1, received 111 mg of one of the following diets 18 or 36 times daily for 33 days from a programmed feeding machine: (1) powdered sucrose × 36; (2) powdered sucrose × 18; (3) cooked wheat starch × 36; (4) a 1:1 mixture of cooked wheat starch : powdered sucrose × 36; (5) alternating meals of powdered sucrose and cooked wheat starch × 36; or (6) powdered sucrose × 18/cooked wheat starch × 18. During the 33-day experimental period the animals were administered 2 ml of a balanced liquid diet by stomach-tube twice daily. Cooked wheat starch alone was cariogenic, but less so than sucrose. Thirty-six alternating meals of powdered sucrose and cooked wheat starch were as cariogenic as 36 meals of sucrose. The 1:1 mixture of cooked wheat starch : powdered sucrose was as cariogenic or more cariogenic than an equal number of sucrose meals. The additive or synergistic effect was time-dependent; the block-feeding of 18 powdered sucrose/18 cooked wheat starch meals was less cariogenic than 36 sucrose meals.

Caries and Plaque Inhibition by Mutanase in Rats

The effects of mutanase (α-1,3 glucan 3-glucanohydrolase, free of 1,6 activity produced by Trichoderma harzianum OMZ 779) and dextranase (α-1,6 glucan 6-glucanohydrolase obtained from Penicillium funiculosum) on plaque formation and caries incidence were investigated in two groups of 36 rats each. The first group was kept in relative gnotobiosis with Streptococcus mutans OMZ 176 E, the second group harboured its indigenous flora. During the entire 28-day experimental period the animals were housed in a feeding machine and fed 18 meals per day. For the first three experimental days both groups received diet 2,000 (56% sucrose). Thereafter each of the two groups was distributed among the following treatments: O: diet 2,000; M: diet 2,000 containing mutanase (100 MU/ g); D: diet 2,000 containing dextranase (150 DU/g); M+D: diet 2,000 containing both enzymes (100 MU and 150 DU/g). Blood for white cell counts was collected prior to sacrifice by heart puncture. Extent of plaque on the smooth surfaces of the upper molars was scored under a dissection microscope after staining with erythrosin. Fissure caries was assessed on serial sections of the first and second lower molars.

Some Dental Effects of Xylitol under Laboratory and in vivo Conditions

In vitro, xylitol was not fermented by S. mutans and A. viscosus and had no effect on cell growth. Xylitol neither interfered with the utilization of sucrose by the two bacterial species nor inhibited bacterial colonization of rat molar surfaces in sucrose-containing broth. In a rat caries test, xylitol added to starch diets and starch-sucrose diets did not affect formation of bacterial agglomerates on rat molars. Rinsing with 10% xylitol solutions did not interfere with early plaque formation in young adults consuming their habitual diet. Telemetric recordings of interdental plaque pH showed that 10% xylitol rinses and xylitol chewing gum were non-acidogenic. Xylitol did not prevent rapid sucrose glycolysis. In a 40-day rat caries test, xylitol was non-cariogenic and seemed to reduce the cariogenic potential of sucrose administered simultaneously, however, the animals consuming xylitol diets suffered from severe diarrhoea and gained less weight. In another experiment, rats drank less when xylitol was added to the drinking water.

Effect of topical application of urea peroxide on caries incidence and plaque accumulation in rats.

100 μl of 10.00/o aqueous solutions of the test substances were applied topically 3 times daily to molar teeth in 23-day-old CARA rats previously inoculated with Streptococcus mutans

Effect on rat caries of endogenous and exogenous hydrogen peroxide.

A toothpaste containing sodium fluoride and enzymes activating the anti-glycolytic lactoperoxidase-thiocyanate system was without inhibitory effects in 3 independent rat caries studies on formation of

Effects of the Topical Application of Mutanase on Rat Caries

The effect of topically applied mutanase (α-1-3-glucan, 3-glucanohydrolase) on plaque formation and caries in rats was studied in two experiments. Compounds known to strongly inhibit dental caries whe

Oral telemetry of fluoride ion activity.

Abstract A method for continuous in vivo measurement of fluoride ion activity of human oral fluid is described. An electrochemical fluoride sensor and short range radiotelemetry were employed to study clearance of salivary fluoride after use of fluoride-containing tablets and dentifrices. A miniature transmitter including power supply and reference electrode was mounted on a removable partial denture. The fluoride sensor, a modified Ionalizer fluoride ion activity electrode, was fixed to the denture so that it replaced the buccal surface of a lower first molar. Dissolution of a sodium fluoride tablet (0.7 mg F) placed in the vestibular fold on the electrode side resulted in an increase of fluoride ion activity to a maximum of 150 ppm F within 12 min and in a gradual decrease to the original activity level in 40 min. The same procedure with the tablet placed in the vestibular fold on the opposite side was followed by a small rise only in the range of single ppm F units. Regular toothbrushing with dentifrices containing aminefluoride, sodium fluoride or monofluorophosphate was followed by fluoride activity increases of different magnitudes.

Effect of the length and number of intervals between meals on caries in rats.

Rats, orally inoculated with Streptococcus mutans OMZ 176 and Actinomyces viscosus Ny-1, received 18 meals daily of either sucrose, cooked wheat starch or a 1:1 m

Daily Variations in Mitotic Activity of Adrenal Cortex, Thyroid and Oral Epithelium of the Rat.∗

Summary Daily periodicity characterizes mitotic activity in the adrenal, the thyroid and the oral epithelium of male Sherman albino rats, kept under standardized environmental circumstances. The daily times of “high” and “low” in number of mitoses are roughly synchronized for the thyroid and the oral epithelium, while the 24-hour periodicity in mitotic activity of the adrenal cortex shows a different timing.