Introduction
Tooth surfaces with pits and fissures are particularly
vulnerable to caries development [Manton and Messer,
1995]. Ripa [1973] observed that although the occlusal
surfaces represented only 12.5% of the total surfaces of
the permanent dentition, they accounted for almost 50%
of the caries in school children. This can be explained
by the morphological complexity of these surfaces,
which favours plaque accumulation to the extent that
the enamel does not receive the same level of caries
protection from fluoride (F) as does smooth surface
enamel [Ripa, 1973; Bohannan, 1983; Ripa, 1990]. The
plaque accumulation and caries susceptibility are
greatest during the eruption of the molars [Carvalho et
al., 1989], and caries susceptible individuals are
therefore vulnerable to early initiation and fast
progression of caries in these sites. Brown et al. [1996]
and Kaste et al. [1996] showed that in fluoridated
communities over 90% of dental caries is exclusively
pit and fissure caries