Visual method used in general practiceThe visual method, a combination of light, mirror, and the probe for detailed examination of every tooth surface, is by far the most commonly applied method in general practice worldwide. Although sensitivity is low and specificity is high, it may be possible to detect:1. Noncavitated enamel lesions (D1) on the free smooth surfaces (buccal and lingual), most anterior approximal surfaces, and the opening of some fissures 2. Clinically detected "cavities" limited to the enamel (D1, D2)3.

Diagnosis and Registration of Carious LesionsIntroductionThe coronal carious lesion starts as a clinically undetectable subsurfacedemineralization. With further progression, it will eventually become clinicallydetectable, and can then be classified according to type, localization, size, depth, andshape (see Table 15).Apart from for the occult fissure lesion penetrating deeply into the dentin, dilemmasin clinical detection and registration arise not with the advanced lesion, but primarilywith the early lesion (confined to the outer enamel), the noncavitated lesion of dentin,recurrent caries (around the margins of restorations), and subgingival root caries.

Root cariesAccording to Hix and O'Leary (1976), root surface caries is defined as "a cavitationor softened area in the root surface which might or might not involve adjacent enamelor existing restorations (primary and recurrent lesions)." Nyvad and Fejerskov (1987)introduced the definitions of active and inactive carious lesions of the root. Rootcaries may be classified as primary or secondary, cementum or dentin, active orinactive, and with or without cavitation (see Table 15). The lesions can also beclassified according to the texture (soft, leathery, or hard) and the color (yellow, lightbrown, dark brown, or black).

Dentin cariesWhether or not an active, noncavitated carious lesion in enamel will progress into thedentin and the rate of progression are determined by many factors:1. The overall estimated caries risk (C1 to C3) of the individual2. The rate at which the enamel lesion has developed3. The size, depth, and site of the enamel lesion4. The posteruptive age of the enamel5. The future efficacy of self-care and supplementary needs-related preventiveprogramsOn the approximal surfaces of the posterior teeth, the progression of a carious lesionthrough the enamel into the dentin can easily be followed on serial bitewingradiographs.

ArrestFluoride and plaque controlArrest of enamel carious lesions is a reality, as shown in the studies by Backer-Dirks (1966) and von der Fehr et al (1970). In vitro as well as in vivo studies have shown that carious lesions in enamel can successfully be arrested by plaque control or topical use of fluoride. The most efficient means is a combination of both, as exemplified in Fig 156. On the left is an active, noncavitated enamel lesion on the mesiolingual surface of a mandibular second molar.

Development of Carious LesionsEnamel cariesDevelopmentThe physicochemical integrity of dental enamel in the oral environment is entirely dependent on the composition and chemical behavior of the surrounding fluids: saliva and plaque fluids. The main factors governing the stability of enamel apatite are pH and the free active concentrations of calcium, phosphate, and fluoride in solution.  The development of a carious lesion in enamel involves a complicated interplay among a number of factors in the oral environment and the dental hard tissues.

Development and Diagnosis of Carious LesionsIntroductionA carious lesion should be regarded not as a disease entity, but as tissue damage or a wound caused by the disease dental caries. The coronal lesion begins as clinically undetectable subsurface demineralization of enamel, visible only at microscopic level, and gradually progresses, first to visible demineralization of the enamel surface and to cavitation of the dentin, and finally to complete destruction of the tooth crown despite restoration, but without prevention (Fig 145).

ConclusionsCaries riskFrom a cost-effectiveness aspect caries-preventive measures should be applied strictly according to predicted caries risk. In populations with very high caries prevalence and caries incidence (where almost everyone develops new lesions every year) the traditional whole population strategy would be cost effective. The number of such populations is dwindling, however, particularly in the industrialized countries where caries prevalence was high 20 to 30 years ago.

Cariogram ModelA new model, the Cariogram, was presented in 1996 by Bratthall for illustration of the interactions of caries-related factors. The model makes it possible to single out individual risk or resistance factors. A special interactive version for the estimation of caries risk has been developed.The original Cariogram was a circle divided into three sectors, each representing factors strongly influencing carious activity: diet, bacteria, and susceptibility. The development of the model was based on a need to explain why, in certain individuals, carious activity could be low in spite of, for example, high sucrose intake, poor oral hygiene, high mutans streptococci load, or nonuse of fluorides.

Detailed risk profiles for dental cariesIf a patient is at high risk predominantly for either caries or periodontal disease, a more detailed risk profile is available for the specific disease. Box 19 shows a list of abbreviations for the most important variables related to caries risk.  Figure 138 illustrates how a high-risk patient (C3) has been transformed to a low-risk patient (C1) by improved self-care supplemented by professional preventive measures. The greater the difference between the solid line and the dotted line, the greater the improvement.

Risk ProfilesIntroductionBy combining the symptoms of disease (prevalence, incidence, treatment needs, etc); etiologic factors; external modifying risk indicators, risk factors, and prognostic risk factors; internal modifying risk indicators, risk factors, and prognostic risk factors; and preventive factors, it is possible to present risk profiles for tooth loss, dental caries, and periodontal diseases in graphic form. This can be done manually or by computer. The degree of risk, 0, 1, 2, or 3, is visualized using green, blue, yellow, and red, respectively.

Key-risk surfacesAs mentioned earlier, depending on the age and caries prevalence of the population, there may be pronounced variations in the pattern of both lost teeth and decayed or filled surfaces. Figure 130 shows caries prevalence and the pattern of decayed or filled surfaces in 12-year-old children in the county of Varmland, Sweden, in 1964, 1974, 1984, and 1994. The molars are clearly the key-risk teeth. In a toothbrushing population, the key-risk surfaces are the fissures of the molars and the approximal surfaces, from the mesial aspect of the second molars to the distal aspect of the first premolars.

Key-risk teethThe factors determining future tooth loss are related to age, dental caries, periodontal  diseases, iatrogenic root fractures, trauma, orthodontic therapy, and so on. Therefore, it may be argued that it is difficult to analyze the true reasons for tooth loss in the adult, particularly in the elderly. The reasons for tooth loss may vary not only among different age groups but also among different populations and countries, depending on differences in prevalence of dental caries and periodontal diseases as well as the availability of resources for dental care.

Individual RiskBy combining etiologic factors, caries prevalence (experience), caries incidence (increment), external and internal modifying risk indicators, risk factors, and prognostic risk factors, as well as preventive factors, caries risk may be evaluated at the individual level, as no risk (C0), low risk (C1), risk (C2), and high risk (C3). As discussed earlier in this chapter, these conditions may vary in different age groups.  Therefore, the criteria for C0, C1, C2, and C3 should be defined for at least the following general groups: preschool children (primary teeth), schoolchildren (permanent teeth), adults, and the elderly.

Risk GroupsRisk age groupsRecent studies have shown that carious lesions are initiated more frequently at specific ages. This applies particularly to children but also to adults. In children, the key-risk periods for initiation of caries seem to be during eruption of the permanent molars and the period during which the enamel is undergoing secondary maturation.  In adults, most root caries develops in the elderly, partly because of the higher prevalence of exposed root surfaces.

Prediction of Caries Risk and Risk ProfilesIntroductionFor successful prevention and control of dental caries in both children and adults,  some basic principles must be adopted: For example, the higher the risk of developing caries (new carious surfaces) in most of the population, the greater the effect of one single preventive measure. This may be illustrated by the Swedish experience, where 30 to 35 years ago, caries prevalence was extremely high. Almost every child developed several new lesions every year, mainly because of very poor oral hygiene.

Tooth-related factorsPhysical characteristics of the teeth may increase the risk for caries: tooth size, tooth morphology, cusp and fissure patterns, enamel structure (defects, opacities, mottling, and roughness of the surface), the morphology of the cementoenamel junction, and exposed root surfaces. In addition, the chemistry of the enamel, dentin, and root cementum may influence caries susceptibility. Studies to date indicate that large teeth in crowded mouths are more likely to develop caries, but this cannot be predicted on an individual basis.

Systemic and immunologic factorsOf the chronic systemic diseases, by far the most important risk factor and prognostic risk factor for dental caries is Sjogren's syndrome, because of its extremely depressive effect on both the salivary secretion rate and the quality of the saliva. Indirectly, reduced SSR is associated with other chronic diseases in which medical management involves regular use of drugs with side effects on the salivary system. Some other general chronic diseases, such as leukemia, acquired immunodeficiency syndrome, diabetes mellitus, and Down's syndrome, impair the immune system generally or specifically.

ConclusionsIntroductionThe most important internal modifying factors related to dental caries are salivary  hypofunction, some chronic diseases, impaired host factors, and unfavorable macroanatomy and microanatomy and eruption stage of the teeth that favor plaque retention. Of utmost importance is impaired salivary function, particularly stimulated salivary secretion rate. Salivary factorsSalivary secretion rate, the buffering effect, and possibly the in vivo concentrations of some salivary constituents, such as fluoride, hypothiocyanite, and agglutinins (possibly including IgA), seem to be the most important determinants of caries susceptibility and/or activity.

Exposure of root surfacesIn the young, healthy adult, root surfaces, like the cementoenamel junctions, are not exposed to the oral cavity. At the population level, the prevalence of exposed root surfaces is strictly age related and is attributed to the long-term effects of trauma from toothbrushing (buccal surfaces) and gingival recession associated with periodontal disease. With the decline in prevalence and severity of enamel caries, and hence the preservation of an intact dentition into old age, root caries is becoming an increasing problem in clinical practice.