Ten individuals were each supplied with a new toothbrush of the same t
ype and brand, together with identical tubes of fluoridated toothpaste
. After a three-week period, during which subjects were asked to follo
w their usual oral hygiene practices, the toothbrushes were collected
and assayed for microbial contamination using a range of selective gro
wth media. The total microbial load per toothbrush was found to be 10(
4) to 10(6) colony forming units. Staphylococci were found on all toot
hbrushes and streptococci on all but one. These two genera were also q
uantitatively dominant. Candida, corynebacteria, pseudomonads and coli
forms were identified in 70, 60, 50 and 30 per cent of toothbrushes, r
espectively. However, mutans streptococci, lactobacilli and black-pigm
ented Gramnegative anaerobic rods were not detected on any of the toot
hbrushes. For each individual, information on variables such as toothb
rush rinsing practices and post-brushing storage methods and environme
nt was collected. No obvious relationship between such variables and m
icrobial load was apparent but it is suggested that more extensive stu
dies are needed, taking into account additional parameters such as age
and degree of toothbrush wear and the use of pre-brushing mouthwashes
.