| disease | Dental Caries |
| alias | Tooth Decay, Tooth Decay |
Dental caries is a disease characterized by the gradual destruction of the hard tissues of the teeth. It begins in the crown of the tooth, and if left untreated, the condition progresses, forming cavities that eventually lead to the complete destruction and loss of the crown. Untreated cavities do not heal on their own, and the ultimate outcome is tooth loss. Dental caries is a bacterial disease, which can lead to secondary conditions such as pulpitis and periapical periodontitis, and may even cause inflammation of the alveolar bone and jawbone. Secondary infections from dental caries can form focal infections, leading to or exacerbating systemic diseases such as arthritis, pericarditis, chronic nephritis, and various eye diseases.
bubble_chart Epidemiology
Dental caries is a common and frequently occurring disease in children. The peak incidence of caries in deciduous teeth occurs around the age of 5, while the peak for permanent teeth is around 15 years old. According to survey data from Shanghai in 1981, among 15,059 kindergarten children and primary and secondary school students, 8,523 had caries in their deciduous teeth, resulting in a caries rate of 56.62%. At the age of 4, the caries rate reached 65.92%, and by 9 years old, it was 83.57%.
A 1983 survey of primary and secondary school students in Beijing showed that the average caries rate in permanent teeth for 7-year-old children in urban and suburban areas was 48.88%, 67.29% for 12-year-olds, and 73.61% for 17-year-olds. Generally, the incidence of caries in permanent teeth is lower in rural populations compared to urban areas. The data indicates that the average caries rate in permanent teeth for urban populations was 63.65%, with an average of 1.67 decayed teeth per person, while the rate for rural populations was 55.67%, with an average of 1.27 decayed teeth per person.
China is vast, and conditions vary across regions, leading to differences in caries prevalence. Therefore, caries prevention efforts should begin as soon as teeth erupt.Dental caries is a multifactorial disease, primarily involving three interrelated aspects: bacteria, diet, and teeth and saliva. The absence of any one of these factors prevents the occurrence of dental caries. Currently, scholars believe that saliva, as the external environment of teeth, is a significant factor influencing dental caries.
1. Bacteria In the occurrence and development of dental caries, bacteria play a dominant role. In recent years, it has been internationally recognized that dental caries is a bacterial disease. There are many types of cariogenic bacteria, with the most prominent being certain strains of Streptococcus mutans and Lactobacillus. These bacteria mix with mucoproteins in saliva and food debris, firmly adhering to the surfaces and fissures of teeth. This adhesive mass is called dental plaque. The large number of bacteria in the plaque produce acids, leading to demineralization and dissolution of the enamel beneath the plaque. Clinical studies have shown that children with more plaque in their oral cavities also have a higher incidence of dental caries.
2. Diet In the formation of dental caries, diet serves as a critical substrate for bacterial activity. Foods contain large amounts of carbohydrates and sugars, which not only provide energy for the bacteria in plaque but also, through bacterial metabolism, are fermented to produce organic acids. These acids remain on the tooth surfaces and fissures for extended periods, causing enamel demineralization and destruction. Subsequently, certain bacteria dissolve proteins, forming cavities. Among the various cariogenic sugars, sucrose is the most significant.
3. Teeth The morphology, structure, and position of teeth are clearly related to the occurrence of dental caries. The fissures on the occlusal surfaces of teeth are developmental defects where bacteria and food debris can easily accumulate and are hard to remove, making them prone to dental caries. Teeth with insufficient mineralization, particularly inadequate calcification, have less dense enamel and dentin, resulting in lower caries resistance and a higher susceptibility to dental caries. Although fluoride is present in trace amounts in the mineralized structure of teeth, it plays a crucial role in enhancing caries resistance. Teeth with adequate fluoride content are less likely to develop dental caries. The structure and calcification of primary teeth and young permanent teeth are not yet fully mature, making them more vulnerable to cariogenic factors and thus more prone to caries.
bubble_chart Clinical Manifestations
Dental caries most commonly occurs in the pits and fissures of molars and premolars, as well as on the contact surfaces between adjacent teeth. The former is called pit and fissure caries, while the latter is called proximal caries. Dental caries at the cervical area of teeth is rare in children and is only seen in cases of severe malnutrition or certain systemic diseases that cause extreme constitutional weakness. Based on the extent of caries destruction, it can be clinically classified into superficial caries, medium caries, and deep caries (Figure 1).
Figure 1 Dental caries and its complications
1. Superficial caries: The carious destruction is limited to the enamel. The initial stage [first stage] presents as brown or dark brown spots or patches on the enamel, with a rough surface. This is followed by surface destruction. Proximal caries begins below the contact surface, while pit and fissure caries often starts within the fissures, making both difficult to detect in the early stages. Only when it occurs at the entrance of the fissures can it be seen, but in children, the entrance of the fissures is prone to food pigment deposition, which can lead to misdiagnosis or fistula disease if the physician does not examine carefully. Superficial caries has no subjective symptoms.
2. Medium caries: The caries has reached the dentin, forming a shallow cavity in the dentin. The child may experience toothache when exposed to cold water, cold air, or sweet and sour foods, but the symptoms disappear immediately after the stimulus is removed. This is due to the hypersensitivity of the dentin to stimuli. Medium caries can be effectively treated if addressed promptly.
3. Deep caries: The caries has reached the deep layer of the dentin, close to the pulp, or has already affected the pulp. The child may experience pain from cold, heat, sour, or sweet stimuli, especially sensitivity to heat. Even after the stimulus is removed, the pain persists for a certain period before gradually subsiding. At this stage, pulp therapy is often required to save the tooth.
If deep caries is left untreated, the pulp may become secondarily infected or necrotic. Bacteria can reach the area outside the apical foramen through the root, causing periapical inflammation. This may lead to focal infection. If the crown is mostly destroyed or only the root remains, the tooth should be extracted.
bubble_chart Treatment Measures
The main treatment for dental caries is filling. This involves completely removing the decayed tissue, shaping a cavity, cleaning and disinfecting the area, then filling it with filling material to restore the tooth's damaged structure and prevent further decay. Superficial caries respond best to filling. For moderate and deep caries, after removing the decayed tissue, sometimes the cavity floor may be close to the pulp, requiring an additional layer of pulp-protecting agent before filling. In some cases of deep caries, the pulp may be exposed after removing the decayed tissue, necessitating pulp treatment before filling can proceed. The primary filling materials used are amalgam or composite resin. For deciduous teeth, which will eventually be replaced, glass ionomer cement (a temporary filling material) can be used.
Early-stage caries that have not yet formed cavities can be treated with medication, achieving certain therapeutic effects. Sodium fluoride paste is commonly applied to treat caries in permanent teeth, while silver diamine fluoride (which causes discoloration and is thus not used on permanent teeth) is used for deciduous teeth. After medication treatment, recurrence is possible, requiring follow-up every six months. Therefore, the earlier dental caries is treated, the better.
Preventing dental caries is a very important aspect of children's healthcare. The basic principle is to target the disease-causing factors and implement corresponding measures.
1. **Reduce or eliminate pathogenic irritants** Reducing or eliminating dental plaque and altering the oral environment to create clean conditions are crucial steps in preventing caries. The most practical and effective methods are brushing and rinsing. Public education should be strengthened to help children develop good oral hygiene habits from an early age and learn proper brushing techniques. Brushing can remove most bacteria in the mouth and reduce plaque formation. For young children, parents can use a soft towel or cloth to clean their teeth. Children can start learning to brush their teeth after the age of 3. Ideally, they should brush twice a day (morning and night) and rinse after meals. Brushing before bedtime is especially important because the long overnight interval allows bacteria to multiply rapidly. Brush vertically: "Brush the upper teeth downward and the lower teeth upward," ensuring both the inner and outer surfaces are cleaned. Pay special attention to the chewing surfaces of the back teeth. This method effectively removes food debris from between teeth and all tooth surfaces. Rinse after brushing. Avoid horizontal brushing, as it can injure the gums and fail to clean interdental debris properly. In 1975, the Ministry of Health, the Ministry of Light Industry, and the Ministry of Commerce jointly held a national toothbrush conference, establishing the "Interim Standards for Health Toothbrushes." In 1989, the Ministry of Health convened the National Health Standards Technical Committee, where the Toothbrush Subcommittee reviewed the "Interim Standards." The standards specify: - For young children: Toothbrush bristles should not exceed two rows, with 5–6 tufts per row, and the bristles should be soft. - For primary school students: Toothbrush bristles should not exceed three rows, with 6–7 tufts per row. - Standards for middle school students were also established, serving as a reference for adult toothbrushes.
Children's dietary habits should also be monitored. Introduce complementary foods on schedule and encourage the consumption of coarse, hard, and fibrous foods, which help clean tooth surfaces and reduce food residue buildup. Hard foods require thorough chewing, which strengthens the periodontal tissues and polishes the chewing surfaces, potentially making fissures shallower and reducing pit and fissure caries.
2. **Reduce or control sugar in the diet** As a country where grains are the staple food, controlling carbohydrate intake for caries prevention is challenging. However, in recent years, sugary foods and beverages have significantly increased. Parents should be educated to encourage children to limit snacks, candies, and pastries, avoid sugar before bedtime, and ensure balanced meals. From an early age, children should develop the habit of eating vegetables, fruits, and foods rich in calcium, phosphorus, and vitamins. Whole grains should be included whenever possible. Breastfeeding for infants is highly recommended. Internationally, there is a trend to control dietary carbohydrates and use sugar substitutes to reduce dental caries. However, this approach is currently impractical and uneconomical in China. Recently, reports have highlighted that a commonly used sugar substitute (aspartame) in the U.S. may contain toxic substances, drawing international attention.
3. **Enhance teeth's resistance to caries** This primarily involves increasing fluoride content in teeth, especially by altering the surface or subsurface structure of enamel to boost its resistance to caries. Modern effective methods include: - Central water fluoridation - School water fluoridation - Topical fluoridization (fluoride application to tooth surfaces) - Fluoride toothpaste brushing - Fluoride mouth rinse These methods are widely recognized for their effectiveness in caries prevention.
Water fluoridation for caries prevention involves the automatic addition of sodium fluoride by water supply centers to adjust the fluoride concentration in water to an optimal level for caries prevention. This is currently the most effective method. However, there are opposing views internationally and domestically regarding water fluoridation, so only a few countries and regions have adopted it. In China, Guangzhou once conducted a multi-year experimental observation of water fluoridation in a pilot area. Due to improper calculation of the fluoride dosage (using the reference amount recommended by the World Health Organization), children in Guangzhou developed dental fluorosis, leading to dissatisfaction among parents. As a result, comprehensive fluoridation has now been discontinued.
Our country is located across three geographical zones, with many high-fluoride areas. The fluoride content in water sources, climate, and crops varies by region, and dietary habits also differ. Therefore, children's daily fluoride intake must be carefully and accurately calculated. For this reason, emphasizing water fluoridation for caries prevention in our country is unrealistic.
In summary, fluoride-based caries prevention methods cannot be used in high-fluoride areas, and children with dental fluorosis should also avoid them.
Water fluoridation involves adding sodium fluoride to public drinking water in nurseries, kindergartens, and primary and secondary schools to achieve an optimal fluoride concentration for caries prevention. Since children consume relatively little water while at school or daycare, the fluoride dosage must be precisely calculated.
Both of the above methods are effective for both developing (unerupted) and erupted teeth.
Fluoride mouthrinse is suitable for kindergartens and primary/secondary schools. Under the supervision of medical staff or teachers, a 0.2% neutral sodium fluoride solution is recommended for rinsing once a week or every two weeks, held in the mouth for one minute without swallowing. This is a feasible method.
Fluoride toothpaste brushing, generally with a sodium fluoride concentration not exceeding 0.4%, when used by children twice daily (morning and evening), can effectively reduce dental caries. It is relatively easy to promote and is currently recognized internationally as the best supplementary method.
Any fluoride-based caries prevention method should only be used in areas with fluoride-free or low-fluoride water sources. High-fluoride areas must not use them.
In conclusion, the causes of dental caries are complex, and there is currently no single most effective method to entirely prevent new caries. Therefore, caries prevention requires a combination of control and treatment—both preventing new caries and ensuring early detection and treatment. Organized and systematic oral health initiatives should be carried out, including regular proactive prevention and early treatment in nurseries, kindergartens, and primary/junior high schools. At the same time, strengthening maternal and child health and nutrition programs to ensure overall and dental health can help reduce the incidence of dental caries.
