The aim of this 3-year longitudinal study was to analyze caries increment and the caries-preventive effect of sealants in adolescents in the setting of the German national health system. 434 pupils (193 male, 241 female) took part in compulsory school examinations at age 12 (mean 12.3 ± 0.4 years) and 15 (mean 15.6 ± 0.3 years) according to WHO criteria, including the examination of sealants. Mean DMFT increased from 1.78 (± 2.15) to 3.97 (± 3.68), mean DMFS from 2.79 (±4.07) to 6.94 DMFS (± 8.34), respectively. Logistic regression analysis showed that high caries incidence at the individual level was mostly associated with the type of school (’Gymnasium’, RR = 0.3), gender (female, RR = 2.08) and high baseline DMFS (RR = 1.2 per surface), but not with the number of sealants. In an interaction model, adolescents with high baseline DMFS values had an even higher risk of caries increment with an increasing number of sealants compared to adolescents with fewer sealants (p = 0.047). At the tooth level, this effect was detected for first permanent molars, while sealants in premolars and second permanent molars did not result in a statistically significant caries-preventive effect due to the low caries incidence on these surfaces. Thus, sealants on occlusal surfaces of first permanent molars were only protective in individuals with low or moderate caries activity (p = 0.006), which indicates the need for other measures to reduce caries activity in high risk adolescents. In addition, rates of 19% lost sealants and 18% carious or filled surfaces in 3 years suggest a discrepancy between sealant retention under real-life conditions and the results of controlled clinical trials.

The aim of this in vivo study was to assess the association between caries prevalence and activity parameters and the properties of etched sites measured with quantitative light-induced fluorescence (QLF). In a clinical method, two areas of a deciduous tooth were etched in each of 44 children (mean age 8.23 years ± 1.45) with 36% phosphoric acid gel for 1 min and 4 min, respectively. ΔQ of the etched site was measured immediately after the etching (ΔQ₁) and 24 h later (ΔQ₂) with QLF. In addition, deft/DMFT, approximal plaque (API), bleeding on probing (mod. PBI), active carious lesions and currently used fluorides were recorded. In a regression analysis for the deft, the use of fluoridated salt (standardized coefficient SC = –0.25) and fluoride gel (SC = –0.37) showed the greatest effect, as did the fluoride gel (SC = –0.26) and gingival bleeding (SC = 0.50) for the number of active carious lesions. The deft and the number of active carious lesions correlated significantly (r = 0.70, p < 0.001). ΔQ₁ and ΔQ₂ showed a significant statistical correlation with the age-adjusted deft (0.39 < r < 0.52, p < 0.01) and with the number of active lesions (0.42 < r < 0.59, p < 0.01). Correlations between ΔQ and the API, PBI and the fluoride scores were slightly weaker but also statistically significant. In a principal-component analysis, these parameters were approximately identical, indicating a strong relationship between the different variables and ΔQ. This relationship was especially strong for the deft and the active carious lesion scores. In conclusion, these data suggest that the degree of demineralization by etching and its changes with time are associated with caries activity and that this method might be used for the early assessment of caries activity.