A two-year longitudinal study of dental caries in permanent first molars of Korean elementary schoolchildren

Difference in virulence and composition of a cariogenic biofilm according to substratum direction

The aim of this study was to investigate the difference in composition and virulence of Streptococcus mutans biofilms according to substratum direction. S. mutans biofilms (46-h-old) were formed on three different saliva-coated hydroxyapatite (sHA) disc direction groups: downward (discs placed in the direction of gravity), vertical (discs placed parallel to gravity direction), and upward (discs placed opposite to gravity). The 46-h-old biofilms on sHA discs in the upward direction showed the highest biofilm accumulation, colony forming unit (CFU) count, and extracellular polysaccharide (EPS) amount, followed by those in the vertical and downward directions. In the confocal laser scanning microscopy (CLSM) study, the biofilms in the upward direction also showed the highest bacterial count (live or dead cells) and EPS biovolume. Scanning electron microscopy (SEM) analysis confirmed the microbiological and biochemical results. In addition, biofilm density and acid production were higher in the upward direction than those in the other directions. Our findings suggest that substratum direction, which might be related to gravity, strongly influences the formation and virulence of cariogenic biofilms and subsequent initiation of dental caries. Collectively, the differences in the formation and virulence of cariogenic biofilms are related to the direction of tooth surface (occlusal surfaces of mandibular teeth > proximal surfaces > occlusal surfaces of maxillary teeth).

Clinical evaluation of DIAGNOdent in detection of occlusal caries in newly erupted noncavitated first permanent molars in caries-active children

OBJECTIVE

The aim of this study was to compare the in vivo diagnostic ability of a laser fluorescence system (DIAGNOdent, KaVo, Biberac, Germany) with that of visual inspection in the early detection of occlusal caries in newly erupted noncavitated first permanent molars among caries-active children.

MATERIALS AND METHODS

A total of 505 mandibular first permanent molar teeth in 307 children aged 6 to 7 years with decayed, missing, and filled tooth surfaces (DMFS)>8 were examined. Visual examination and DIAGNOdent measurement of caries were compared for teeth with intact occlusal surfaces or varying degrees of fissure discoloration, but with no radiologic evidence of enamel or dentin caries. Teeth were classified according to caries status as sound, enamel caries, or dentin caries using visual examination and DIAGNOdent scoring systems corresponding to histologic definitions of caries depth. Analysis of the results was performed using Cohen's unweighted kappa statistic.

RESULTS

Statistical analysis revealed "poor" agreement between the two diagnostic methods (κ=0.231).

CONCLUSION

Clinical results suggest that the DIAGNOdent device does not seem to be suitable for accurate diagnosis of early caries lesions in newly erupted first permanent molars.

Caries prevalence and severity in urban Fijian school children

OBJECTIVES

To determine the prevalence and severity of dental caries in a sample of urban Fijian school children.

DESIGN

Cross-sectional.

SAMPLE AND METHODS

Children aged between 6 and 8 years who attended one of four primary schools in different localities of Suva completed self-report questionnaires and were examined for dental caries.

RESULTS

A total of 704 children (response rate = 72.4%) returned questionnaires and were examined dentally. The prevalence of dental caries in the primary dentition was 87.6% and in the permanent dentition, 46.7%. The mean dfs and mean DFS were 8.43 (SD 7.82) and 2.38 (SD 1.37), respectively. High caries prevalence and severity were associated with infrequent brushing, snacking on sugar-containing foods, having seen a dentist before, and having last visited a dentist because of pain.

CONCLUSIONS

The caries prevalence of the sample was comparable with findings from a national oral health survey conducted in 1985/86, but the caries severity was greater. As in other developing countries, this may be due to an increased availability of refined sugar products without a concurrent rise in oral health awareness. The study findings contribute to the overall picture of Fijian school children's dental health.