Summary In 1996 and 2006, recruits of the
Swiss army participated in a dental survey.
Similarly in 1995/96 and 2004/05, randomly
selected schoolchildren from 16 rural communities
of the Canton of Zurich participated
in a dental survey. As part of these surveys,
color slides were taken of the incisor teeth of
all recruits, as well as of third and fourth grade
schoolchildren. The slides (N = 2049) were
examined for the presence of fluoride-associated
enamel opacities (FOP), using the Thylstrup-
Fejerskov (TF) index. Two examiners (A
and B) assessed all slides. The examiners were
blind as to the year of survey. Examiner A recorded
prevalences of FOP between 18% and
27% depending on population; examiner B
recorded prevalences between 7% and 12%.
The examiners’ influence on the estimation of
the prevalence was obvious. The prevalences
reported should, therefore, be considered as
rough estimates. FOP of TF score 2 were only
observed in approximately 1% of the participants.
One examiner recorded a TF score 3 in
a single individual. FOP therefore are not a
cosmetic problem and certainly not a public
The prevalence of FOP decreased slightly
during observation period I (recruits born
1975–77 vs 1985–87) and period II (schoolchildren
born 1985–87 vs 1994–96). However,
the decline was statistically supported
in only one instance (Period I, Examiner B).