Abstract
The author undertook a survey in order to set guidelines for the dental health care of school children, which are to be used to check the progress of dental caries. One hundred seventy-three students of N Elementary School in Gifu Prefecture, Japan, who had not received restoration treatment (fillings), were the subjects of the survey. We took photos of occlusal surfaces of 599 permanent first molars of the students using an oral camera and a reflecting mirror at intervals of six months or one year from 1990 to 1996. Judging from the pictures, the pits and fissures of the teeth were classified by 4 criteria I white areas, stains, the area of stains, and plaque. Follow-up observations were carried out to monitor the progress of dental caries as the students grew up. The following are our findings and conclusions. 1. White areas in pits and fissures were observed in 84.0% to 97.8% of the surfaces at the age of 6, remained unchanged until the age of 8, and started to decline at the age of 9. 2. White areas were observed slightly more frequently in the mandible than in the maxilla. White areas remained unchanged both in the maxilla and in the mandible until the age of 8, then started to decline from the age of 9 to the age of 11. 3. Stains were observed in 26.0% to 42.0% of the subjects at the age of 6, and the frequency increased as they grew up. 4. As for the degree of stains, light brown stains were most frequently observed both in the mandible and in the maxilla at the age of 6. From the age of 8 onward, black-brown and black stains increased in terms of proportion, with black stains forming the largest proportion at the age of 11. 5. As for the area of stains, spot stains formed the largest proportion at the age of 6, then remained relatively unchanged. Stains covering one-third of the surface area and two-thirds of the surface area increased from the age of 6 towards the age of 8, and presented a gradual increase afterward. At the age of 11, stains covering one-third of the surface in the maxilla, and stains covering two-thirds of the surface in the mandible formed the largest proportion. Stains covering the whole surface remained unchanged regardless of age. 6. Plaque presented its highest rate at the age of 6, then presented a sharp decline towards the age of 9. 7. As for the correlation between cloudiness and the changes in stains, white areas in the mandible at the age of 10 were significantly correlated to the changes in stains at the ages of 10 and 11. White areas and the changes in stains in the maxilla, however, presented no significant correlation. 8. As for the correlation between white areas and the changes in the area of stains, while the mandible possessed no significant correlations between factors, the maxilla presented a correlation between white areas at the ages of 9,10 and 11, and the changes in the area of stains at the ages of 8 to 11. 9. The changes in stains were significantly correlated to the changes in the area of stains, regardless of age. 10. Plaque and white areas both in the maxilla and in the mandible presented no significant correlation regardless of age. 11. Plaque at the ages of 9 and 10 was significantly correlated to the changes in stains at the ages of 9 to 11. 12. While plaque in the mandible was not correlated to the changes in the area of stains, plaque in the maxilla at the age of 10 was significantly correlated to the changes in the area of stains at the ages of 8 to 11. The findings of our survery show that white areas and plaque, frequently observed in younger students aged 6 to 8, turned into a high incidence of black stains as the students grew up to be 9 to 11. This dose not imply progress in dental caries, rather the consequences of remineralization. Therefore, there is no urgent need of restoration at these ages. Instead, the emphasis should be placed on the prevention and control of dental caries.
