Dr. Kassai Tibor szerk.: Parasitologia Hungarica 1. (Budapest, 1968)

Table 2 The frequency of mouth protozoa according to oral hygiene Szájprotozoonok előfordulásának gyakorisága a szájhlgiéne foka szerint Rate of oral hygiene - Száihi-' gl

éne foka Number of Individuals - Vizsgált személyek száma Number of infected persons - 'Fertőzött személyek száma * group 0 .102 . .65 63.7 group I 205 134 65.4 group II 246 198 80.5 group III 178 153 86.0 the case of healthy mucous membrane and the presence of some carious teeth (group I), in 65.4 The increase was considerably higher in group II (gingivitis) and III (stomatitis-ulcerosa)

; 80.5 fo and 86.0 respectively .The evidence implies that it is not the teeth but the mucous membranes — and mainly diseased ones which are a suitable substrate and medium for the mouth protozoa, favouring their introduction and proliferation. The examinations also resulted in observations concerning the technique of demonstrating oral protozoa. It was found that reliable demonstration of infection turns on careful sampling. In the case of a rather careless sampling, only 33 $> infection was demonstrable in a community of individuals. Having repeated the sampling by a suitably careful technique

,the number of Infections increased to 73 According to our observations, the time of sampling is immaterial but should be prior to eating or the brushing of teeth. WESTPHAl's (14) statement that culture is the most suitable method of demonstrating mouth protozoa found ample corroboration also in our experiments. For the culture of both E. gingivalis and T. te nax , the easily producible CRAIG medium and all mono- or biphasic substrates are suitable; they are favourable also for E. histolytica . It is advisable to check the cultures after 48 hours; only