Lactoperoxidase (LPO)/H₂O₂/SCN^--system-generated hypothiocyanite ions (OSCN^-) and hypothiocyanous acid (HOSCN) are inhibitory against a number of oral bacteria, including mutans streptococci. A commercially available toothpaste (Biotene®) comprises the complete LPO system. Generation of HOSCN/OSCN^–– by Biotene was studied in vitro both in sterilized and nonsterilized saliva of 10 healthy subjects. The HOSCN/OSCN^–– yield ranged from 100 to 300 μM with Biotene, while the salivary levels of HOSCN/OSCN^–– before the addition of Biotene were 30.1 ± 25.1 μM. Two in vivo trials were carried out-In the first study, resting saliva was collected from 12 individuals before immediately after, and 2,5 10 and 20 min after brushing with Biotene to evaluate the in vivo generation and decomposition of HOSCN/OSCN^-. In the second study, 26 healthy individuals attended a 1-month crossover trial with Biotene and a control toothpaste, Vademecum® (no LPO system), both containing F^- and xylitol. The salivary counts of total streptococci, mutans streptococci (MS), lactobacilli and the total flora (TF), as well as the peroxidase, thiocya-nate ion and HOSCN/OSCN^- levels were determined before and after 2 and 4 weeks daily use of the toothpastes. Twice-a-day use of Biotene for 1 month resulted in an elevation of ‘resting levels’ of HOSCN/OSCN^-. No such effect was found with the control toothpaste. No significant changes were found in the salivary levels of total streptococci, MS, lactobacilli or TF after 1-month use of either toothpaste. The results show the capability of the LPO-system-containing toothpaste to elevate the salivary levels of HOSCN/OSCN^-, although no bactericidal effect was observed.

Plaque and whole saliva samples were collected from initially 11- to 12-year-old children randomly chosen from two groups which participated in a 2- to 3-year field trial designed to test the efficacy of xylitol chewing gums in caries prevention. No initial differences were observed between the groups with regard to the plaque levels of Streptococcus mutans, but at the end of the 2-year xylitol gum regimen, the levels were smaller (p < 0.05) in children using xylitol gum than in control children. In a similar follow-up study on children who were considered to be at high risk with regard to dental caries and who continued the study over a 3rd year, the xylitol-consuming subjects showed at the end of the study significantly smaller (p < 0.004) salivary S. mutans counts than the control children. These effects were achieved after using up to 3 xylitol gums/day (daily xylitol dose per child was 7–10 g). Salivary flow rate and several salivary chemical parameters did not change.

The association of flow rate and biochemical and microbiological characteristics of saliva with diet was studied in 83 12-year-old children and in 127 adults (84 in the age group 35–44 years, 43 in the age group 65–74 years) living in rural and urban communities in Tanzania. No significant differences were observed between the salivary flow rates of the rural and urban subjects. The mean salivary flow rates were slightly lower in women than in men and significantly lower in the 12-year-old children than in the two older age groups (p < 0.05). The buffer effect was higher in the rural than the urban population. Further, it was lower in women than in men (p < 0.001). Salivary protein, IgG, and sialic acid concentrations were significantly higher in the rural than in the urban population, whereas amylase activity and IgA concentrations were lower. Microbiological studies showed mutans streptococci in 97% of the rural and in 91% of the urban subjects (n.s.). Lactobacilli grew significantly less often in the rural than urban samples (p < 0.01). Analyses of 24-hour dietary recalls showed that the rural and urban diets differed. The proteins in the rural diet were largely of plant origin, while in the urban diet animal proteins dominated. The rural diet contained also less sucrose but more fibre (mainly from grain) than the urban diet. Intake of energy and protein were for some subjects slightly below the recommended dietary allowances in both rural and urban groups, but none of the study subjects showed clinical signs of malnutrition. Our results suggest that differences in the composition of saliva in rural and urban Tanzanians are more closely associated with differences in absolute and relative amounts of nutrients than with the energy content of diet. The high buffer effects of saliva in the Tanzanian subjects appear to be associated with their exceptionally grain fibre rich diet.

Continuously increasing proportion of elderly people in the human population creates new challenges for the dental care. Because the microbial etiology of the most common oral diseases, dental caries, endodontal and periodontal diseases, is not substantially different in different age groups, the altered host response during aging may modify the progression of these diseases. Most prevalent and severe change in the oral defense is hyposalivation or xerostomia but aging as such does not seem to reduce neither parotid nor whole salivary flow rate. However, submandibular and minor salivary glands produce less saliva at old age which may be the reason for the frequently reported symptoms of oral dryness even if the stimulated flow rate is normal. Concomitantly to the changes in the flow rate the daily output of many saliva-mediated defense factors declines but age-related impairment has been described only for specific IgA response to external antigens, for salivary opsonic activity, and for T-lymphocyte function. The non-immunoglobulin defense factors seem to act with full capacity over the entire life-span. Therefore, elderly people with normal salivary flow rate possess no special risk group for the development of oral diseases.

A new buffering lozenge (sucking tablet) was developed for patients susceptible to dental caries and erosion, in particular for those with reduced salivary secretion. As active ingredients this lozenge comprises of a combination of xylitol, fluoride, calcium, phosphate, zinc and buffering compounds. To test the lozenge's activity /« vivo, the release of ingredients was monitored in 19 healthy subjects for 22 min after sucking the lozenge was completed. In subjects with a normal salivary secretion rate the lozenge caused only a slight stimulation of saliva flow, but a significant elevation both in salivary pH and buffer effect was observed.Furthermore, fluoride, calcium and phosphate were effectively released into whole saliva with peak values 2-4 min after use. The same salivary parameters were also quantitated after 1 month's regular use (3 lozenges/day) but no consistent longterm changes were found. Salivary mutans streptococci and total anaerobic microflora did not change significantly during the long-term use. The results show that the buffering fluoride-and xylitolcontaining lozenge, which also releases calcium and phosphate, is active in vivo but its serviceability as a remineralizing agent, in particular for elderly patients with reduced salivary flow rate, has to be analysed separately.