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DENTAL Caries – Etiology


 

Pathogenesis

 

Bacterial infections of teeth and gums (gingiva) begin early in life and continue to progress throughout life with the possibility of tooth loss. Caulfield et al showed that  mutan streptococci (MS) are transmitted by the mother to the child between 19 and 28 months of age.   (If during this “window of infectivity” the child does not acquire MS the child was caries free.)  It is important to note that mutan streptococci can be present without cavities being noted.  Less than 10,000 CFU’s of MS in saliva coincided with caries free children.  It is only when the infection overwhelms the host that demineralization of enamel begins.

 

The bacteria involved are many, but most frequently the species mutans streptococci is associated with the caries infection. The most often mentioned bacteria in gingival infections are gram negative anaerobes.  The bacteria form a complex community on the teeth.  This biofilm, called plaque, adheres to tooth surfaces and increases in amount unless disrupted daily.  The film is made up of bacteria that can ferment sugars and other carbohydrates producing lactic acids.  Continued production of acid can lead to demineralization of the enamel.  If preventive interventions are not in place or initiated early and daily, cavitation (a cavity) will result.  Therefore many preventive recommendations attempt to disrupt the process of demineralization, neutralize the acid attack and remineralize the early lesions.

 

In pediatric patients cavitation can begin as soon as teeth erupt (5-6 months of age) and increases in intensity especially in at-risk and vulnerable children.  If allowed to continue, severe destruction of teeth can occur.  Early childhood caries (ECC) is the presence of one or more decayed, missing or filled tooth surface in any primary tooth in a child 71 months of age or younger. ECC is associated with feeding practices that include prolonged use of the bottle during the day and night with carbohydrate containing liquids.

 

Not all children with habitual and prolonged use of the bottle are susceptible to this type of caries infection.  Other risk factors have been identified and include tooth enamel abnormalities, altered saliva production and composition, defects in immune defense mechanisms, insufficient or inappropriate exposure to fluoride, absence of daily oral hygiene, lack of professional dental intervention, frequent liquid medications, and finally a number of social, educational, and cultural factors.

 

 

Epidemiology

 

Since the 1970s national surveys have reported on the oral health status of US citizens.  For this study guide we will only report on findings of pediatric patients of both preschool and school age.

 

As background information, to measure oral health a number of indices are used.  The most common for dental decay is to count the number of decayed, filled, or missing teeth or surfaces.  With the primary dentition it is reported as dfmt or dfs.  In the permanent dentition it is reported as DFS or DMFT.

 

Because most studies use representative samples from schools, reports of children below age six are less available.  Studies from Head Start and WIC children reported that 6.4% of infants one year old had cavities; 20% of two year olds; 25% of three year olds, and 49% of four year olds.  In another study of Medicaid eligible children in a school clinic, 56% of children between 24 – 36 months had cavities.

 

Federally funded studies most often reported are the National Institute of Dental Research (NIDR) surveys.  The National Health and Nutrition Examination Surveys (NHANES I, II, and III), and the National Center for Health Statistics (NCHS) surveys. All give us a good idea of the prevalence of oral disease in given populations conducted by seasoned examiners at different time periods.  This allows us to track progress being made in community wide and professionally recommended preventive interventions.  The report stated that 97.3% of five year olds were free of decay in their permanent teeth while only 15.6% of seventeen year olds were free of decay, clearly demonstrating the progress of decay through the school years.

 

Over 40% of five year olds had decay in their primary teeth and by age nine the percent with decay was almost 60%, again demonstrating the progress of decay over time.

 

The good news is that since the 1960s reduction in decay in pediatric patients has been reduced dramatically probably due to the use of fluorides.  Nevertheless dental decay continues to be one of the most common diseases in children – more common than asthma.

 

Furthermore, we also know that some populations are at greater risk than others.  These include children of families living in poverty, young Mexican-American children, some immigrant children, Native American infants and toddlers and non-Hispanic black children.

 

Early childhood caries (ECC) is reported in six of ten children by age five.  A type of ECC, nursing caries or baby bottle tooth decay in up to 10% of children and 50% of native American and Eskimo children.

 

 

Other Infections

 

Decay that is not treated will progress through the enamel and into the dentin, the layer of tooth with sensory innervations.  Complaints of sensitivity and discomfort will follow.  Without intervention the disease process will progress through the dentin and into the pulp of the tooth.  Discomfort and pain will increase.  Pulpitis is a bacterial infection in the pulp, and in early stages, can be treated and the tooth restored.  If allowed to continue, the infection can progress out of the tooth into the surrounding bone.  It can further progress with the development of an intra or extra-oral fistula that allows for drainage of pus into the oral cavity.

 

If the infection spreads to the surrounding facial tissues, a cellulitis can result with swelling and inflammation.  The sites can be on the neck or on the face.  Cellulitis requires immediate intervention to prevent serious progression.  Treatment involves removal of teeth (if the cellulitis is tooth related), antibiotics and may require incision and drainage.

 

While water fluoridation, the use of fluoride products, dietary modification including sugar restriction, improved oral hygiene, and regular professional care have led to dramatic reductions in dental caries over the past 30 years, the disease remains a major public health problem.

 

Early phases of tooth decay are currently difficult to detect.  While radiographs, or x-rays, can disclose established cavities, particularly those that occur between the teeth, they are not effective in detecting early decay, or caries in the roots of teeth. The ongoing development of more sensitive diagnostic techniques to detect dental caries in its earliest phases will pave the way for the use of noninvasive treatment options to stop or reverse the caries process.  Current data support the following treatment options: fluorides, dental sealants, combinations of chlorhexidine, fluoride, and sealants; xylitol and health education.

 

Water fluoridation and the use of fluoridated toothpaste are highly successful in preventing dental caries.  There is also evidence to support the use of fluoride varnishes in permanent teeth, as well as fluoride gels, chlorhexidine gels, sealants, and chewing gum containing xylitol, a sugar substitute.  Combined interventions may be more effective in preventing caries in children.

 

Early identification of children at high risk for extensive caries is important so that they may receive early and intense preventive intervention.  Children at low risk also need to be identified to reduce unnecessary care and expenditures.  The most consistent predictor of caries risk in children is past caries experience.  Children who experience early childhood caries are more likely to develop caries on their permanent molars. Low socioeconomic status (SES) is also associated with higher caries rates.

 

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