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 in 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 long-term 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 xylitol-containing 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.