Pediatric Dental Health
November 10, 2004
Management and Prevention of Dental Caries In Children
There has been remarkable progress in the reduction of tooth decay in the U.S. over the past 30 years. Nevertheless, dental caries continues to be a significant problem for many children. Dental caries continues to be the most common infectious disease of childhood.
During the past few decades, changes have been observed in the prevalence and distribution of dental caries in the population. This disease is endemic in specific sectors of the population, especially the economically disadvantaged. Some children seem to have a mouthful of cavities, while other children have beautiful teeth. Eighty percent of the dental caries is found in only 25 percent of the children. More than half of all children in the U.S. have dental caries by the second grade of school. By the age of 17, approximately 80% of young people have had a dental cavity.
WHAT IS DENTAL CARIES?
Dental caries is an infectious, communicable disease, which causes destruction of teeth by acid-forming bacteria found in dental plaque. The most important concept to remember is that caries is a dynamic disease process, and not a static problem. Secondly, before a cavity is formed in the tooth, the caries infection can actually be reversed!
Caries progression or reversal is determined by the balance between protective and pathological factors in the mouth. The development of dental caries is a dynamic process: Demineralization of the hard dental tissue by the acidic products of bacterial metabolism – alternating with periods of remineralization.
The development of the carious lesion is episodic, with periods of demineralization alternating with periods of remineralization The lactic acid produced by the cariogenic bacterial dissolve the calcium phosphate mineral of the tooth enamel in a process call demineralization. Baby teeth have thinner enamel than permanent teeth, making them very susceptible to caries.
Dental caries in children is typically first observed clinically as a “white spot lesion.” If the tooth surface remains intact and non-cavitated, then remineralization of the enamel is possible. If the subsurface demineralization of enamel is extensive, it eventually causes the collapse of the overlying tooth surface, resulting in a “cavity.”
Saliva has a critical role in the prevention of dental caries. Saliva provides calcium, phosphate, proteins, lipids, antibacterial substances, and buffers. Saliva buffering can reverse the low pH in plaque, and with a higher pH, calcium and phosphate can be driven back into the tooth enamel. One factor that lowers the risk of cavity formation is normal salivary flow. Anything less than 0.7 ml/minute increases the risk for cavity development.
WHAT IS EARLY CHILDHOD CARIES?
Early childhood caries is a “virulent” form of dental caries that can destroy the teeth of preschool children and toddlers. Early childhood caries can also be defined as the occurrence of any sign of dental caries on any tooth surface during the first 3 years of a child’s life. Economically disadvantaged children are the most vulnerable to ECC.
Early childhood caries is an infectious disease, and the Streptococcus mutans bacteria is the main causative agent. Not only does S. mutans produce acid, it also thrives in acid. High sugar levels in the mouth increase the acid levels on the teeth. In children with ECC, oral Streptococcus mutans levels routinely exceed 30% of the cultivable dental plaque flora.
The clinical pattern of ECC is rampant and characteristic: First affecting the primary upper anterior teeth, followed by the upper primary molar teeth. The initial appearance of early childhood caries is white areas of demineralization on the surface of the enamel along the gum line of the upper incisor teeth. These white spot lesions progress such that they later become cavities that have been discolored. The mandibular incisors are protected by saliva and the position of the tongue during feeding. The ECC process may be so rapid that the teeth appear to have cavities “from the moment they erupt.”
The first event in the natural history of ECC is primary infection with S. mutans. The second event is the accumulation of S. mutans to pathologic levels, due to prolonged exposure to sugars. The third event is demineralization of enamel, which leads to cavity formation in teeth.
Early infection with S. mutans is a significant risk factor for future development of dental caries. Colonization of an infant’s mouth with this bacteria is usually the result of transmission from the child’s mother. S. mutans can apparently colonize the mouths of infants even before their teeth erupt. Children at high risk for early childhood caries may develop carious lesions on their upper front teeth soon after they erupt into the mouth. As the disease progresses, decay appears on the biting surfaces of the primary upper first molars.
New strategies for combating the infectious component using topical antimicrobial therapy appear promising.
THE CAUSES OF DENTAL CARIES - PATHOBIOLOGY
The caries process must be thought of as a dynamic alteration between demineralization and remineralization phases. This represents a competition between the pathologic factors (such as bacteria and carbohydrates) and the protective factors (such as saliva, calcium, phosphate and fluoride). They Keyes diagram (above) shows that cavities are the result of the interaction between a susceptible tooth, a dietary substrate (sugar), a chronic bacterial infection, and time.
Streptococcus mutans is the major cariogenic bacterium. S. mutans forms glucan and levan polymers that are adhesive. The bacteria, along with the polymers, work together to form a biofilm – called dental plaque. The bacteria use a substrate (sugar) to produce acids that dissolve dental enamel. Repeated demineralization by these acids leads to dental cavities.
S. mutans has been highly associated with dental caries. The proportion of S. mutans in plaque associated with ECC can be 30% to 50% of the total viable bacterial counts in dental plaque. In contrast, S. mutans usually constitutes less than 1% of the plaque flora in non-caries active children. Lactobacilli are highly acidogenic microorganisms, associated more with deep cavities in dentin than with the initiation of the disease. Lactobacilli counts alone are not considered reliable enough in predicting dental caries activity, however.
RISK FACTORS FOR DENTAL CARIES
The causes of caries are multifactorial, and the individual risk factors associated with ECC are therefore not necessarily causative.