Chapter 3 Dental Caries to Carious Lesions

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Primary Preventive DentistrySeventh Edition

Primary Preventive Dentistry, Seventh EditionNorman O. Harris, Franklin García-Godoy, and Christine N. Nathe

Chapter 3Dental Caries to Carious Lesions




Introduction

•Dental caries–One of the most common diseases in humans–Causes pain and disability–Can lead to infection, tooth loss, and

edentulism




Historical Perspective

•One of the oldest theories of caries and toothache was that of a tooth worm that lived in the center of the tooth

•Treatments included henbane seeds, magical formulas, and oaths

•Then caries were thought to be caused by erosion of the enamel and recommended that the caries be smoothed by a file




Historical Perspective (Continued)

•Then in the 1800s caries were theorized to be caused by the presence and proliferations of organisms

•Then an American dentist teaching in Germany published a chemicoparisitic theory of caries

•Dr. G.V. Black, the founder of modern dentistry, then added that microbic plaque was the source of the acids, which is still believed today




Multifactorial Disease Process

1. There must be a susceptible tooth and host

2. Cariogenic microorganisms must be present in a sufficient quantity

3. There must be frequent excessive consumption of refined carbohydrates

4. This process must occur over a sufficiently long period of time




FIGURE 3–1

Dental caries: multifactorial disease process.




FIGURE 3–2

Oral disease risk assessment worksheet. (Baylor School of Dentistry, Texas A&M Health Science Center, Dallas. Used with permission.)




Dental Caries Description

•Carious legions occur in four general areas of the tooth:–Pit and fissure caries–Smooth surface caries–Root surface caries–Secondary/recurrent caries (on tooth surface

adjacent to an existing restoration)




Physical and Microscopic Features of Incipient Caries

•Three distinct stages of caries: –Incipient lesion

The initial stage of tooth decay that has not penetrated the outer surface of the tooth

The lesion looks like a white spot on the enamel–The progress of demineralization toward the

dentinoenamel junction–Overt or frank lesion which is characterized by

actual cavitation




FIGURE 3–3

Development of a carious lesion. (Retrieved June 27, 2007, from http://www.gsbs.utmb.edu/microbook/ch099.htm. Used with permission.)




FIGURE 3–4

Incipient caries in an occlusal fissure. The bilaterality of the lesion is evident in the

microradiograph. (Courtesy of J. S. Wefel, University of Iowa College of Dentistry,

Iowa City.)




FIGURE 3–5

The bilaterality of caries development. Note coalescence of two lateral carious areas at base of fissure. (From Konig, K. G. (1963). Dental morphology in relation to carious resistance

with special reference to fissures as susceptible areas. J Dent Res, 42:461–76.)




Physical and Microscopic Features of Incipient Caries (Continued)

•Rampant decay occurs:–If the development of overt elsions is rapid or

extensive (on more than one tooth) –After excessive and frequent intake of sucrose

and/or presence of xerostomia




Incipient Lesion Zones

•Surface zone

•Body of lesion

•Dark zone

•Translucent zone




Pore Spaces of the Different Zones

•The translucent zone has a 1% pore space

•The dark zone has a 2%-4% pore space

•The surface zone has a pore space of approximately 1%

•A body of a lesion ranges from 5%- 25% pore space




Direct Connection of the Bacterial Biofilm to the Body of a Lesion

•Demineralization

•Remineralization




FIGURE 3–6

Diagram of a trichotomized lesion attributable to diffusion of acids in both directions under the enamel and directly into the body of the lesion in the dentin. T, translucent zone; B, body of the lesion; R, reactionary dentin; P, pulp. (From Silverstone L. M., & Hicks, M. J. (1985). The structure and ultrastructure of the carious lesion in human

dentin. Gerodontics, 1:185–93.)




Mutans Streptococci and Caries

•Mutans streptococci and caries–Considered to be the major pathogenic

bacterial species involved in the caries process–Usually found in relatively large numbers in the

placquethat forms immediately over developing smooth-surface lesions




Lactobacilli and Caries

•Lactobacilli are cariogenic, acidogenic, and aciduric

•Are not required for caries development




Adherence of Bacteria to Teeth

•Continous adherence of the bacteria to the solic tooth surface is necessary both before and after initial colonization

•The first bacteria must establish a foothold on the acquired pellicle on the tooth surface

•Then they must maintain their positions while other bacteria continue to colonize




Ecology of Caries Development: Caries Transmission

•It has been suggested that an effective means of preventing caries in your children would be to reduce the number of MS in the parents’ and siblings’ mouths before a child’s birth




Dental Caries

•Coronal dentin caries

•Root caries

•Secondary/recurrent caries




FIGURE 3–7

Root caries. The darker staining of the coronal half of the root indicates considerable gingival recession, which is a prerequisite to lesion development.




Measuring Plaque pH, and The Stephan Curve

•There is a continuous pH change in plaque every time food is consumed

•Stephan Curve is the term for the immediate drop in pH when sugar or sugary snacks are eaten, followed by a longer recovery period when other foods are eaten




FIGURE 3–8

Stephan curves. These curves show the typical plaque pH response to an oral glucose rinse (indicated by the screened area). An immediate fall in the pH is followed by a gradual return to resting values after about 40 minutes. Each curve represents the

mean of 12 subjects; the pH was measured by sampling method and therefore is an average value for the whole-mouth plaque pH. In individual sites away from the

salivary buffers, the pH values may fall close to 4.0. The upper curve was obtained from reconstituted skim milk and the lower one from an apple-flavored drink, showing a

large difference in the acidogenicity of these two drinks.

(Courtesy of M. W. J. Dodds, University of Texas Dental School, San Antonio.)




Relationship of Saturation to pH

•The concentration of calcium and phosphate ions in plaque fluid bathing the tooth at the plaque-tooth interface is extremely important because these are the same elements that compose the hydroxyapatite crystal found in the enamel




Demineralization and Remineralization Principles

•Demineralization is caused by plaque acid, which dissolve the tooth minerals making up the basic calcium, phosphate, and hydroxyl crystals of the enamel, dentin, and cementum

•Remineralization requires the same ions, preferably with fluoride as a catalyst




Relationship of HAP, FHA and CaF₂

•After an attack by plaque acid(s), CaF2

disolves first, followed in a sequence by HAP and FHA




Depth of Remineralization

•Topical procedures are successful in stimulating surface remineralization

•Some researchers believe that remineralization is a reasonable objective even for lesions reaching the dentin




Summary

•Multifactorial process

•Dental caries description

•Plaque bacteria

•Demineralization

•Remineralization

Chapter 3 Dental Caries to Carious Lesions

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