1. Dental Caries
Chapter 13
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2. Chapter 13
Lesson 13.1
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3. Learning Objectives Pronounce, define, and spell the Key Terms.
Name the most common chronic disease in children.
Recognize dental caries as an infectious disease.
Describe the modes of transmission of dental caries.
(Cont’d)
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4. Learning Objectives
(Cont’d)
Identify the infective agent in the caries process.
Explain the process of dental caries.
Describe the relationship between diet and dental caries.
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5. “The mouth is the gateway to the rest of the body, a mirror of our overall well-being.”
Harold C. Slavkin, DDS Former director of the National Institute of Dental and Craniofacial Research and dean of the University of Southern California School of Dentistry
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6. Every day in the United States, millions of people—including children, working families, and the elderly—live in constant pain as a result of oral disease or injury to the mouth.
The development of dental caries is a complex multistage process. Even though many younger patients do not exhibit caries, tooth decay still affects a large portion of patients (20% of patients have 80% of the tooth decay), regardless of sex, age, and ethnicity. However, caries tend to affect low-income individuals more frequently than it does members of other demographic groups.
What are the signs and symptoms of the disease? (In most cases there is tooth sensitivity to sweet foods and to hot and cold food or drinks. A tooth that is sensitive to heat frequently requires a root canal. There may be no symptoms until a cavity becomes very large or a tooth abscess forms. An abscess can cause pain, swelling, and fever. )
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7. Introduction
Dental caries is an infectious bacterial disease that has plagued human beings since the beginning of recorded history. What is dental caries? Simply stated, it is tooth decay.
Today, because of scientific advances and new technologies, dentistry is developing new strategies for managing dental caries. These strategies emphasize prevention and early intervention.
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8. You cannot be healthy without oral health
You cannot be healthy without oral health. Oral health and general health should not be interpreted as separate entities. Oral health is a critical component of general health.
Many patients do not understand this concept because oral health is usually not viewed as connected to the general health of the body.
It is important for the dental healthcare team to believe this concept and to reinforce it with patients.
For this reason it is important that dental healthcare professionals try to see the “whole” patient and not think that it is only the mouth that is being treated.
Many important factors involved in the patient’s oral health and disease are lost when only a narrow focus to oral health is considered.
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9. Dental Caries: A Bacterial Infection
Two specific groups of bacteria found in the mouth are responsible for dental caries:
Mutans streptococci (Streptococcus mutans)
Lactobacilli
They are found in relatively large numbers in dental plaque.
The presence of lactobacilli in the mouth indicates a high sugar intake.
The earliest recorded reference to oral disease is found in an ancient Sumerian text (c BC) that describes "tooth worms" as a cause of dental decay.
The skulls of Cro-Magnon peoples, who inhabited the earth 25,000 years ago, show evidence of tooth decay.
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10. Transmission of Caries-Causing Bacteria
Mutans streptococci are transmitted through saliva, most frequently the mother’s, to the infant.
When a mother has a high count of mutans streptococci in her mouth, the baby has a high count of the same bacteria in his or her mouth.
Women should be certain that their own mouths are healthy.
When the number of caries-causing bacteria in the mouth increases, the risk of dental caries also increases.
How does a mother transmit her saliva, with its bacteria, to her infant? (It can be transmitted by kissing and touching the child after the mother’s hands have picked up bacteria from her mouth. Remember: No one advocates not kissing or touching babies; rather, the mother must be encouraged to keep her mouth healthy. This may include dietary counseling, professional cleanings, oral hygiene instruction, topical fluoride application, and removal of any caries. If necessary, an antibacterial, such as chlorhexidine, can be prescribed and placed in the mouth daily for about 2 weeks.)
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11. Dental Plaque
Dental plaque is a colorless, soft, sticky coating that adheres to the teeth.
Plaque remains attached to the tooth despite movement of the tongue, water rinsing, water spray, and less-than-thorough brushing.
Formation of plaque on a tooth concentrates millions of microorganisms on that tooth.
Many healthcare professionals are now stressing that plaque is a biofilm.
What is a biofilm? (Biofilms are composed of microbial communities that are attached to an environmental surface. These microorganisms usually encase themselves in an extracellular polysaccharide or slime matrix. Therefore plaque is an outstanding biofilm.)
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12. Fig. 13-1 Dental plaque made visible with the use of a disclosing agent.
Usually the patient rinses with or chews tablets of a nontoxic disclosing agent, and plaque is revealed as a red stain on the teeth. This stain is subsequently removed by brushing and flossing. This is an easy aid to help patients look for areas they are missing in their daily oral care.
Care must be taken to cover areas of tooth-colored fillings with petroleum jelly to protect them. Areas of hardened plaque or tartar (calculus) will remain stained until they are removed professionally or wears off. The tongue will also appear stained, but plaque forms on it, too, and needs to be gently brushed off.
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13. Structure of Enamel
Enamel is the most highly mineralized tissue in the body.
It is stronger than bone.
Enamel consists of microscopic crystals of hydroxapatite arranged in structural layers or rods, also known as prisms.
The enamel crystals are surrounded by water.
The water and protein components in the tooth are important because that is how the acids travel into the tooth, the minerals travel out, and the tooth structure dissolves.
How mineralized is enamel? (Enamel is composed of 95% calcium minerals. )
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14. Fig. 13-3 Chemical interchange in the formation of dental caries.
How can fluoride be provided to the patient to aid in remineralization? (It can be contained in water, toothpaste, and oral rinses. It can also be applied as a treatment at a dental office or used at home by the recommendation of the dentist.)
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15. The Caries Process
For caries to develop, three factors must be present at the same time:
A susceptible tooth
A diet rich in fermentable carbohydrates
Specific bacteria (regardless of other factors, caries cannot occur without bacteria.)
Caries can also develop as a result of constant intake of acidic foods. This is called erosion.
What types of food or drink could be considered risky to the tooth because of their acid content? (This category could include soft drinks or lemon cough drops.)
If a patient only drinks diet soda rather than regular soda, does this have a positive effect on tooth health? (It does not. Acid breakdown of the tooth can occur with bacteria in the caries process or with acidic foods. Diet soda is more acidic than nondiet soda.)
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16. Areas for Development of Caries
Pit and fissure caries occurs primarily on the occlusal surfaces and the buccal and lingual grooves of posterior teeth, as well as in the lingual pits of the maxillary incisors.
Smooth-surface caries occurs on intact enamel other than pits and fissures.
Root-surface caries occurs on any surface of the root.
Secondary, or recurrent, caries occurs on the tooth surrounding a restoration.
No surface is really safe from decay. Many patients believe that once a tooth has been restored, it cannot become decayed again. What type of decay can occur in these teeth? (Secondary or recurrent caries.)
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17. Stages of Caries Development
It usually takes some time, months to years, for a carious lesion to develop.
Caries is an ongoing process characterized by alternating periods of demineralization and remineralization.
Demineralization is the dissolution of the calcium and phosphate from the hydroxyapatite crystals.
Remineralization is the redeposition of calcium and phosphate in previously demineralized areas.
It is possible for the processes of demineralization and remineralization to occur without any loss of tooth structure.
(Cont’d)
Minerals that are replaced during remineralization actually make the tooth stronger against acid attack than the original.
It is important to note that newly erupted teeth are especially vulnerable to acid attack because they have fewer minerals present at the surface (hypomineralization); this is similar to the exposure of roots, with their layers of less mineralized tissue.
What can be done in the dental office to help promote remineralization of teeth that are newly erupted?
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18. Stages of Caries Development
(Cont’d)
An incipient lesion develops when caries begins to demineralize the enamel.
An overt, or frank, lesion is characterized by cavitation (the development of a cavity or hole in the tooth).
Rampant caries describes the time between the onset of the incipient lesion and the development of the cavity; it is rapid and there are multiple lesions throughout the mouth.
At what stage of caries development should the teeth be protected from demineralization? (Incipient.)
At what stage does the patient usually first notice the lesion? (Overt or frank.)
At what stage is it most difficult for the dentist to restore good health to the mouth? (Rampant.)
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19. Fig. 13-4 A, Early carious lesion, or white spot of demineralization
Fig A, Early carious lesion, or white spot of demineralization. (Courtesy of Dr. John Featherstone, University of California, San Francisco, School of Dentistry.)
The chalky white area in the photo is called the “white spot.” It is an area of decalcification, the earliest sign of decay. This is incipient caries.
How would it feel if a dental assistant went over this area with a dental instrument such as an explorer? (It would feel rough, an indication that the enamel structure has broken down.)
Is this lesion very painful to the patient? (There is generally no pain with this lesion other than sensitivity to sweet foods and hot and cold food and drinks.)
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20. Fig. 13-4 B, Overt carious lesion. (Courtesy of Dr
Fig B, Overt carious lesion. (Courtesy of Dr. Frank Hodges, Santa Rosa, Calif.)
Where are the dental caries located in this patient’s mouth? (They appear as dark-stained areas between the anterior teeth and the areas in the pits and fissures of the posterior teeth that do not polish or scale off. Appearance is not always an exact way to diagnose caries.)
Are these early signs of decay?
The occlusal surface that is decayed will “stick” when the dentist presses an explorer into the pits and fissures with a dental explorer to diagnose decay, but this method of examination is not as effective once the teeth have been exposed to fluoride.
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21. Fig. 13-4 C, Rampant caries. (Courtesy of Dr
Fig C, Rampant caries. (Courtesy of Dr. Frank Hodges, Santa Rosa, Calif.)
What type of decay is in this patient’s mouth? (This is rampant decay. Multiple lesions are always present with this type of caries.)
Note that some of the carious lesions look as if they were prepared for restorations at one time. These lesions could also be considered secondary or recurrent caries.
How could this have happened to the patient? (Poor diet, poor dental care, or xerostomia [dry mouth].)
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22. Fig. 13-5 Severely decayed molar in a child.
This may be an example of “baby bottle” tooth decay, which is caused by frequent exposure of a child’s teeth for long periods to liquid that contains sugars. It can occur when a baby falls asleep with a bottle containing formula, milk, or juice; with the use of a pacifier dipped in honey; or even with breastfeeding.
Primary teeth have thinner layers of tooth tissue overlying the pulp, so they decay easily compared with thicker-layered permanent teeth.
The teeth most likely to be damaged are the maxillary anterior teeth. They are some of the first teeth to erupt and therefore are exposed the longest to the sugars in bottles.
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23. Fig. 13-6 Decay on the lingual surface of a maxillary lateral incisor.
Why caused this lesion? (It could be due to the patient’s having a natural pit in this area of the tooth that was susceptible to the carious process.)
The dentist will use an explorer to visually check for any natural pits and fissures in the teeth or may use a laser device.
How can the patient protect natural pits and fissures from decay? (The patient can perform good oral hygiene, watch his or her diet, use fluoride products, and have the pits and fissures sealed in the dental office.)
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24. Chapter 13
Lesson 13.2
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25. Learning Objectives Explain the remineralization process.
Distinguish between root caries and smooth-surface caries.
Explain the role of saliva in oral health.
Explain the purpose of caries-activity tests.
Describe the advantages and disadvantages of the laser caries-detection device.
Identify the risk factors for dental caries.
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26. Root Caries
Root caries is becoming more prevalent and is a concern for members of the elderly population, who often have gingival recession, exposing the root surfaces.
People are living longer and keeping their teeth longer. Older people often take medications known to reduce saliva flow.
Carious lesions forms more quickly on root surfaces than coronal caries does because the cementum on the root surface is softer than enamel and dentin.
Like coronal caries, root caries has periods of demineralization and remineralization.
Recession may be seen on an older person’s front teeth.
Why does the root surface become exposed? (Many factors are involved. Two of them are age and periodontal disease; others include hard brushing and tooth placement.)
One factor that may be involved in recession is “abfraction,” which occurs when the enamel structure breaks down and chips off, causing recession and deep cervical cuts. Abfraction occurs with oral habits such as grinding and clenching of the teeth.
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27. Fig. 13-7 Root-surface caries. (Courtesy of Dr
Fig Root-surface caries. (Courtesy of Dr. John Featherstone, University of California, San Francisco, School of Dentistry.)
Would these root carious lesions cause as much pain as other types of lesions already reviewed? (Usually root caries are slow to form and do not cause much pain until most of the tooth’s neck or cervix has been undermined. However, rampant decay can lead to extensive pain and suffering.)
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28. Secondary, or Recurrent, Caries
Secondary, or recurrent, caries starts to form in the small spaces or gaps between the tooth and the margins of a restoration.
Bacteria thrive in these areas.
When dental restorations need to be replaced, it is because there is recurrent caries under the existing restoration.
New restorative materials that are bonded to the tooth structure eliminate the gap between tooth and filling where microleakage can occur. Restorative materials that slowly release fluoride help prevent secondary caries.
Today there are many choices in sealant surface protection.
The old stand-by is the unfilled resin system that has been available for years.
One of the relatively new types is the glass ionomer sealant. It releases high levels of fluoride to aid remineralization of the surrounding area.
Another new sealant incorporates the latest system of amorphous calcium phosphate to release these important minerals to aid in remineralization.
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29. Fig. 13-8 Radiograph showing recurrent decay (arrow) under an amalgam restoration.
What indicates to the dentist that decay is present on this radiograph? (It is a dark area located interproximally, as indicated by the arrow. You can see that the radiograph must have good contrast to allow the dentist to see any carious lesions.)
Note that decay is often two times deeper and more widespread than it appears on radiographs. Therefore, using a radiograph alone is not the best way to diagnose decay, but a visual exam using an explorer would not show this lesion.
Would it be possible to see early decay on the occlusal surface on a radiograph? (No, only extensive decay of the occlusal surface on a radiograph would be seen.)
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30. The Role of Saliva
Physical protection involves a cleansing effect. Thick, or viscous, saliva is less effective than a more watery saliva in clearing carbohydrates.
Chemical protection contains calcium, phosphate, and fluoride. It keeps calcium at the ready, to be used during remineralization. Chemical protection includes buffers, bicarbonate, phosphate, and small proteins that neutralize the acids after we ingest fermentable carbohydrates.
Antibacterial substances in saliva work against the bacteria.
If salivary function is reduced for any reason, perhaps as a result of illness, medication, or radiation therapy, the teeth are at increased risk for decay.
Currently there are fluoride varnishes that are safer and easier to use than gels or foams because less systemic intake is required by the patient for remineralization. New toothpastes, candies, and rinses incorporate this type of remineralization; however, they must be studied further in relationship to the overall processes occurring in the mouth.
New antibacterials are expected to become available in the form of rinses, gels, and varnishes.
What is another name for dry mouth? (Xerostomia.) What types of medications cause dry mouth? (Prescribed medications for high blood pressure, allergies, and mental anxiety.) How will you know if your patient has dry mouth?
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31. Diagnosis of Dental Caries
Detectable explorer “stick”
Radiographs
Visual
Laser caries detector
Which is the best method for the dentist to use to diagnose caries? What are the pros and cons to each method of caries detection?
Even the latest approach, the laser caries detector, has limitations. At the current level of technology, it cannot detect caries interproximally or under sealants or restorations, but it is useful in nonrestored areas and around the margins of restorations.
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32. (Courtesy of KaVo America, Lake Zurich, Ill.)
Laser Caries Detector
The laser caries detector is used to diagnose caries and reveal bacterial activity under the enamel surface.
Carious tooth structure is less dense and gives off a higher reading than noncarious tooth structure.
One other method that may soon move from the lab to the office is the quantitative light-induced fluorescence method, which uses the autofluorescence of teeth.
When teeth are illuminated with harmless high-intensity blue light, they start to emit light in the green part of the spectrum, with the data going to a computer.
The fluorescence of the dental material is directly related to the mineral content of the enamel. A loss due to caries would be easily detected on any exposed tooth surface, including the root.
Fig
(Courtesy of KaVo America, Lake Zurich, Ill.)
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33. Fig Visual and radiographic appearance of seemingly intact molar. (Courtesy of KaVo America, Lake Zurich, Ill.)
As you can see, the molar appears intact but the readings from the laser tell another story. The readings indicate to the dentist that decalcification is occurring on the occlusal surface of this tooth.
The laser comes with a chart that helps the dentist determine what treatment needs to be performed on the tooth surface.
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34. Fig. 13-13 Cross section of molar showing decay
Fig Cross section of molar showing decay. (Courtesy of KaVo America, Lake Zurich, Ill.)
The tooth must be clean for consistent readings to be obtained with the laser.
At the specific wavelength at which the laser operates, clean, healthy tooth structure exhibits little or no fluorescence, resulting in very low-scale readings on the display.
Carious tooth structure will exhibit fluorescence, proportionate to the degree of caries, resulting in increased scale readings on the display.
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35. Methods of Caries Intervention
Fluoride: A variety of types are available to strengthen the tooth against solubility to acid.
Antibacterial therapy: Products such as chlorhexidine rinses are effective.
Fermentable carbohydrates: These reduce the amount and frequency of ingestion.
Salivary flow can be increased by chewing sugarless gum—for example, one with a nonsugar sweetener such as xylitol.
How can the dental office help a patient with caries intervention?
Patients can consider several risk interventions in the area of caries prevention, especially protection and remineralization.
It is important to note that preventive strategies are more effective when two or more are combined.
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36. Fig. 13-14 Preventive measures against caries. A, Fluoride rinse
Fig Preventive measures against caries. A, Fluoride rinse. B, Chlorhexidine rinse. C, Xylitol gum.
Which of these preventive measures would be the easiest for the patient to use on a daily basis? (Sugar-free gum.)
What is compliance? (The extent to which a patient follows the recommendations of a doctor or healthcare professional, particularly with respect to medication and other treatments.)
Compliance with a preventive that does not taste good may be poor, so manufacturers try to provide rinses that have a pleasant taste.
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37. Risk Assessment for Dental Caries
If the patient’s risk for dental caries can be determined, it is possible to prevent the caries from developing by beginning appropriate preventive treatment.
Risk-assessment tests for caries are based on the amount of mutans streptococci and lactobacilli present in the saliva.
High bacterial counts indicate a high caries risk, and low counts indicate a low risk for caries. If the preventive measures are not provided, carious lesions are likely to develop.
An important shift has taken place with regard to strategies for caries control because we now have the ability to promote remineralization and protection of the tooth surface.
Today the emphasis is on a prevention model and is moving away from a repair model.
Restoring the teeth does nothing to control caries.
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38. Patients in Whom a Caries-Risk Test Is Indicated
New patients with signs of caries activity
Pregnant patients
Patients experiencing a sudden increase in the incidence of caries
Individuals taking medications that may affect the flow of saliva
Xerostomic patients
(Cont’d)
What is your caries risk? What factors can promote or even reduce the incidence of decay? (A dental professional should seek ways to take care of his or her own mouth as an example to the patients. Consider taking the caries-risk test.)
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39. Indication for Using a Caries-Risk Test
(Cont’d)
Patients about to undergo chemotherapy
Patients who frequently consume fermentable carbohydrates
Patients suffering from diseases of the autoimmune system
What is chemotherapy, and why is it a risk factor for caries? (Chemotherapy is treatment with anti-cancer drugs. The teeth should be protected before this treatment is undertaken because the patient may vomit as a result of using these drugs, resulting in acid contact with the teeth.)
What are fermentable carbohydrates? (There is a considerable range in the ease with which different carbohydrates can be attacked by microorganisms. The most vulnerable are sugars and cooked starches.)
Why do autoimmune diseases indicate a risk for caries? (Many diseases of the autoimmune system have a side effect of xerostomia or dry mouth.)
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