to detect lesions, to assess surface integrity, and to assess lesion activity to support clinical decision making. The first and most important diagnostic method is meticulous visual-tactile inspection. This is the only method that potentially contributes to all 3 diagnostic requirements. All other methods that are presented in this chapter, i.e., bitewing radiography, fluorescence-based technologies, and transillumination methods, are limited to assessing lesion depth in surfaces that are not visible to the eye and thus contribute to lesion detection only. At the end of the chapter, recent developments in objective lesion activity assessment are presented.
© 2018 S. Karger AG, Basel
Detection versus Diagnosis of Caries
In general, most dental practitioners’ use the term “caries diagnosis” synonymously with “caries detection” [1]. This might derive from the fact that the therapeutic step is indirectly linked to the diagnostic step [2, 3]. Because therapy is remunerated, and operative intervention more so than non-operative intervention, a dichotomous “caries yes/no thinking” is often employed in daily practice – although this is not sufficient. However, it is worthwhile considering the distinct differences between these two terms.
“Caries detection” means the discrimination between a healthy tooth surface and a tooth surface affected by a carious lesion to a certain degree. To a great extent the different methods of caries detection aim at staging the caries process in order to facilitate treatment decision making: initial stages of caries usually require different treatment options than further progressed stages. In this respect, caries detection also and most importantly involves the assessment of surface integrity of a tooth. Once a frank cavitation occurs on a tooth surface, removal of the biofilm in that place is hampered. Thus, non-operative intervention is usually not recommended anymore, and the dental practitioner treats the lesion by cleaning, restoring, and sealing the cavity in order to facilitate plaque removal at the restored tooth surface [4].
Detecting a carious lesion does not say anything about whether the lesion is in a progressing or in a stagnating stage [5]. The lesion’s specific behaviour over time is referred to as “lesion activity” [6]. Lesion activity assessment is a crucial factor because its outcome contributes to clinical decision making [7]. Furthermore, in a broader perspective “caries diagnosis” also considers the local environment in which the respective tooth is embedded. Several patient-specific factors (location/position of the tooth or the lesion, saliva, microbiota, fluoride availability, cleaning habits, diet) that contribute to individual caries risk also play a significant role in the decision-making process of caries diagnosis. However, this chapter deals with the first two aspects, caries detection and lesion activity assessment.
Caries Detection Methods
Visual-Tactile Inspection
The first and most important method to detect and to diagnose caries is visual-tactile inspection [8]. The eyes are able to discriminate by colour matching all clinically relevant caries stages from sound tooth surfaces to dental restorations. The eyes are also capable of seeing surface discontinuities, ranging from microcavities to large cavities. Further advantages include clinical visual inspection being fast, inexpensive, radiation-free, and helping to establish doctor-patient contact. As a prerequisite, the eyes should be functioning perfectly [9]. It is known that after the age of about 40 years the eyes have lower accommodation capabilities, the reflection glare increases, and the visual acuity decreases [10, 11]. Therefore, the use of moderately high magnification loupes (about ×2.5) [12] is recommended to compensate for reduced vision at increased age [13]. It has been shown that magnification greater than ×2.5 significantly decreased specificity, irrespective of the duration of clinical experience [13]. Additional illumination is helpful, but if too intense (>20,000 lx) it might actually reduce the accuracy of caries detection [14]. Lastly, a visual caries detection system should be used that takes into account the different stages of carious lesion development, and not only those that have reached a stage of cavitation. Several main caries detection and notation systems are available (Nyvad system [6], The International Caries Detection and Assessment System (ICDAS) [15], and the Caries Assessment Spectrum and Treatment (CAST) [16]). CAST covers the total spectrum of dental caries and has been designed for epidemiological purposes, whereas ICDAS and the so-called Nyvad criteria can be used also in the private office. For epidemiological data acquisition, ICDAS and Nyvad criteria have their limitations [see the chapter by Frencken; this vol., pp. 11–23]. It has been shown that proper training is needed to use either system to increase reliability, validity, and accuracy. The outcome of visual caries detection trials is dependent on the circumstances under which clinical visual inspection takes place, on the caries prevalence of the respective patients/subjects or, in laboratory experiments, on caries levels [17], and caries detection thresholds [18, 19]. Thus, in a recent review, a moderate to high degree of heterogeneity was found in visual caries detection studies [20]. In visual caries detection studies assessing initial and more advanced caries lesions, pooled sensitivities and specificities were reported to be 0.27–0.81 and 0.73–0.99, respectively, with a tendency towards lower sensitivity and higher specificity in clinical settings [20].
Visual-tactile inspection works well on visible surfaces, but the detection of carious lesions in the approximal surface is more difficult, and therefore more biased [20]. Furthermore, dentine carious lesions in occlusal surfaces with seemingly intact fissures (so-called “hidden caries”) is usually detected at a relatively late stage when discolouration of dentine shines through the enamel [21]. Approximal surfaces and occlusal grooves and fissures are the sites where most carious lesions are found. On approximal surfaces, a small hook-like probe might add information on a present cavitation, but this test is reliable only when the cavitation itself or the area beneath the contact zone of two adjacent teeth are large enough for the probe to enter. A sharp-ended probe should only be used to gently touch the surface of the tooth to assess lesion roughness, but this test seems to be not reliable [22]. Firm pressing of a sharp probe in order to test the “stickiness” of a fissure should be refrained from because irreversible damage occurs that results in more invasive treatment [23]. The use of a periodontal probe is recommended to scan the surface for irregularities, such as microcavities [