Transcript Chapter 7 Body Systems

Dental Caries
Chapter 13
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Chapter 13
Lesson 13.1
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Learning Objectives
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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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Learning Objectives
(Cont’d)
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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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“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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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.
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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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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.
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Dental Caries: A Bacterial Infection
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Two specific groups of bacteria found in the
mouth are responsible for dental caries:
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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.
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Transmission of Caries-Causing
Bacteria
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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.
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Dental Plaque
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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.
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Fig. 13-1 Dental plaque made visible with the use of a
disclosing agent.
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Structure of Enamel
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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.
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Fig. 13-3 Chemical interchange in the formation of
dental caries.
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The Caries Process
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For caries to develop, three factors must be
present at the same time:
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A susceptible tooth
A diet rich in fermentable carbohydrates
Specific bacteria (regardless of other factors,
caries cannot occur without bacteria.)
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Areas for Development of Caries
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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.
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Stages of Caries Development
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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.
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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)
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Stages of Caries Development
(Cont’d)
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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.
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Fig. 13-4 A, Early carious lesion, or white spot
of demineralization.
(Courtesy of Dr. John Featherstone, University of California, San Francisco, School of Dentistry.)
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Fig. 13-4 B, Overt carious lesion.
(Courtesy of Dr. Frank Hodges, Santa Rosa, Calif.)
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Fig. 13-4 C, Rampant caries.
(Courtesy of Dr. Frank Hodges, Santa Rosa, Calif.)
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Fig. 13-5 Severely decayed molar in a child.
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Fig. 13-6 Decay on the lingual surface of a
maxillary lateral incisor.
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Chapter 13
Lesson 13.2
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Learning Objectives
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Explain the remineralization process.
Distinguish between root caries and smoothsurface 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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Root Caries
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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.
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Fig. 13-7 Root-surface caries.
(Courtesy of Dr. John Featherstone, University of California, San Francisco, School of Dentistry.)
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Secondary, or Recurrent, Caries
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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.
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Fig. 13-8 Radiograph showing recurrent decay (arrow) under
an amalgam restoration.
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The Role of Saliva
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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.
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Diagnosis of Dental Caries
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Detectable explorer “stick”
Radiographs
Visual
Laser caries detector
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Laser Caries Detector
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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.
Fig. 13-11
(Courtesy of KaVo America,
Lake Zurich, Ill.)
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Fig. 13-12 Visual and radiographic appearance
of seemingly intact molar.
(Courtesy of KaVo America, Lake Zurich, Ill.)
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Fig. 13-13 Cross section of molar showing decay.
(Courtesy of KaVo America, Lake Zurich, Ill.)
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Methods of Caries Intervention
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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.
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Fig. 13-14 Preventive measures against caries.
A, Fluoride rinse. B, Chlorhexidine rinse. C, Xylitol gum.
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Risk Assessment for Dental Caries
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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.
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Patients in Whom a Caries-Risk Test
Is Indicated
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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)
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Indication for Using a Caries-Risk
Test
(Cont’d)
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Patients about to undergo chemotherapy
Patients who frequently consume fermentable
carbohydrates
Patients suffering from diseases of the
autoimmune system
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