Clinical Examination for Caries

Contemporary caries management, which encompasses expanded non-operative approaches and conservative operative interventions, relies on enhanced risk assessment and improved lesion detection and classification. The objective of improved detection and classification systems is to accurately identify those early enamel lesions that are most likely to be reversed and remineralized. Therefore, appropriate non-operative care can be attempted, and lesions that require operative treatment can be identified as early as possible in the disease process. With this approach, the restoration will result in the removal of the minimum amount of tooth structure.

Caries lesions can be detected by visual changes in tooth surface texture or color or in tactile sensation when an explorer is used judiciously to detect surface roughness by gently stroking across the tooth surface. Current thinking finds that the use of an explorer in this manner might have some relevance for assessing caries activity. However, it cannot be over-emphasized that the explorer must not be used to determine a “stick,” or a resistance to withdrawal from a fissure or pit. This improper use of a sharp explorer has been shown to irreversibly damage the tooth by turning a sound, remineralizable sub-surface lesion into a possible cavitation that is prone to progression. Forcing an explorer into pits and fissures also theoretically risks cross-contamination from one probing site to another. In contrast, for assessment of root caries, an explorer is valuable to evaluate root surface softness. Additional methods used in caries detection are radiographs that show changes in tooth density from normal and adjunctive tests that use various technologies to aid in caries lesion detection and caries activity.

Caries lesions are most prevalent in the faulty pits and fissures of the occlusal surfaces where the developmental lobes of posterior teeth failed to coalesce, partially or completely (Fig. 3-3). It is important to remember the distinction between primary occlusal grooves and fossae and occlusal fissures and pits. Primary occlusal grooves and fossae are smooth “valley or saucer” landmarks indicating the region of complete coalescence of developmental lobes. Normally, such grooves and fossae are not susceptible to caries because they are not niches for biofilm and frequently are cleansed by the rubbing action of food during mastication. Conversely, occlusal fissures and pits are deep, tight crevices or holes in enamel, where the lobes failed to coalesce partially or completely. Fissures and pits are detected visually.

As noted earlier, sharp explorers were used to diagnose fissure caries. However, numerous studies have found that the use of a sharp explorer for this purpose did not increase diagnostic validity compared with visual inspection alone.5–8 The use of the dental explorer for this purpose was found to fracture enamel and serve as a source for transferring pathogenic bacteria among various teeth.^9,10 Therefore, the use of a sharp explorer in diagnosing pit-and-fissure caries is contraindicated as part of the detection process.

An occlusal surface is examined visually and radiographically.11,12 The visual examination is conducted in a dry, well-illuminated field. Through direct vision and reflecting light through the occlusal surface of the tooth, the occlusal surface is diagnosed as diseased if chalkiness or apparent softening or cavitation of tooth structure, forming the fissure or pit, is seen or a brown-gray discoloration, radiating peripherally from the fissure or pit, is present. In contrast, a nondiseased occlusal surface has either grooves or fossae that have shallow tight fissures, which exhibit superficial staining with no radiographic evidence of caries. The superficial staining is extrinsic and occurs over several years of oral exposure in a person with low caries risk. Pre-carious or carious pits are occasionally present on cusp tips (see Fig. 3-3, A). Typically, these are the result of developmental enamel defects or following loss of enamel from tooth due to erosion or abrasion. Carious pits and fissures also occur on the occlusal two thirds of the facial or lingual surface of posterior teeth and on the lingual surface of maxillary incisors. Occlusal enamel can be evaluated for loss of translucency and changes in color, which may be characteristic of a caries lesion (see Fig. 3-3, B). The color change can be dark gray and should not be confused with the noncarious fissures and pits that often become merely stained over time. These visual techniques of examining teeth are then translated into the codes used in the International Caries Detection and Assessment System (ICDAS).

Clinical caries lesion detection has been found lacking and improvement is needed.¹³ One means of addressing these concerns has been the development of a visual system for caries lesion detection and classification. The ICDAS was developed to serve as a guide for standardized visual caries assessment that could be used for clinical practice, clinical research, education, and epidemiology (Fig. 3-4). In the United States, the Caries Management by Risk Assessment (CAMBRA) movement, as discussed in Chapter 2 on cariology, embraces the principles of the ICDAS for visual examination and assessment of caries lesions.

The clinical examination for detecting caries lesions is aided by an assessment of the patient’s overall caries risk, along with the patient’s patterns of susceptibility. The patient’s medical history, dental history, oral hygiene, diet, and age, among other caries risk factors and indicators, can suggest a prediction of current and future caries activity. For example, caries lesions also tend to occur bilaterally and on adjacent proximal surfaces (see Fig. 3-3). During the clinical examination, every accessible surface of each tooth must be inspected for localized changes in color, texture, and translucency, as described in the ICDAS codes. This requires two minimum conditions for the examination to be properly conducted: (1)Teeth must be sufficiently air-dried so that the changes can be seen properly, and (2) biofilm or plaque must be thoroughly removed from teeth prior to the examination. The ICDAS uses a two-stage process to record the status of the caries lesion. The first is a code for the restorative status of the tooth, and the second is for the severity of the caries lesion. The status of the caries severity is determined visually on a scale of 0 to 6:

This severity code is paired with a restorative/sealant code 0 to 8:

See Fig. 3-4 for the ICDAS for examples of coding for restorative status and caries severity. The details of this system for detection and training to use the system with an online tutorial are available at www.icdas.org.

Proximal surface caries, one form of smooth-surface caries, is usually diagnosed radiographically (Fig. 3-5, A). It also can be detected by careful visual examination after tooth separation or through fiberoptic transillumination.¹⁴ When caries has invaded proximal surface enamel and has demineralized dentin, a white chalky appearance or a shadow under the marginal ridge may become evident (see Fig. 3-5, C). Careful probing with an explorer on the proximal surface may detect cavitation, which is defined as a break in the surface contour of enamel. The use of all examination methods is helpful in arriving at a final diagnosis.

Brown spots on intact, hard proximal surface enamel adjacent to and usually gingival to the contact area are often seen in older patients, in whom caries activity is low. These discolored areas are a result of extrinsic staining during earlier caries demineralizing episodes, each followed by a remineralization episode. These areas are no longer carious and are usually more resistant to caries as a result of fluorohydroxyapatite formation. Restorative treatment is not indicated. These inactive caries lesions sometimes challenge the diagnosis because of faint radiographic evidence of the remineralized lesion.

Proximal surface caries in anterior teeth can be identified by radiographic examination, visual inspection (with optional transillumination), or probing with an explorer. Transillumination is accomplished by placing the mirror or light source on the lingual aspect of teeth and directing the light through teeth. Proximal surface caries, if other than early enamel lesions, appears as a dark area along the marginal ridge when the light is directed through the tooth. In addition to transillumination, tactile exploration of anterior teeth is appropriate to detect cavitation because the proximal surfaces generally are more visible and accessible than in the posterior regions. Small early enamel lesions may be detectable only on the radiograph.

Another form of smooth-surface caries can occur on the facial and lingual surfaces of the teeth of patients with high caries activity, particularly in the cervical areas that are less accessible for cleaning. The earliest clinical evidence of early enamel lesions on these surfaces is a white spot that is visually different from the adjacent translucent enamel and partially or totally disappears with wetting. Drying again causes it to reappear. This disappearing–reappearing phenomenon distinguishes the smooth-surface early enamel lesion from the white spot resulting from nonhereditary enamel hypocalcification (see section on clinical examination for additional defects). Both types of white spots are undetectable tactilely because the surface is intact, smooth, and hard. For white spot lesions, nonsurgical remineralization therapies (discussed in Chapter 2) should be instituted to promote remineralization.

The presence of several facial (or lingual) smooth-surface caries lesions within a patient’s dentition suggests a high caries rate, which means that if the existing risk factors are not addressed, the patient is at high risk for developing more lesions in the future. In a caries-susceptible patient, the gingival third of the facial surfaces of maxillary posterior teeth and the gingival third of the facial and lingual surfaces of mandibular posterior teeth should be evaluated carefully because these surfaces are often at a greater risk for caries. Advanced smooth-surface caries exhibits discoloration and demineralization and feels soft to penetration by the explorer. The discoloration can range from white to dark brown, with rapidly progressing caries usually being light in color. With slowly progressing caries in a patient with low caries activity, darkening occurs over time because of extrinsic staining, and remineralization of the decalcified tooth structure occasionally may harden the lesion. Such an arrested lesion at times may be rough, although cleanable, and a restoration is not indicated except to address the esthetic concerns of the patient. The dentin in an arrested remineralized lesion is sclerotic. These lesions are inactive lesions but remain susceptible to new caries activity in the future.

In patients with attachment loss, extra care must be taken to inspect for root-surface caries. A combination of root exposure, dietary changes, systemic diseases, and medications that affect the amount and character of saliva can predispose a patient, especially an older individual, to root-surface caries. Lesions are often found at the cementoenamel junction (CEJ) or more apically on cementum or exposed dentin in older patients or in patients who have undergone periodontal surgery (see Fig. 3-3, F). Early in its development, root caries appears as a well-defined, discolored area adjacent to the gingival margin, typically near the CEJ. Root caries is softer than the adjacent tissue, and typically lesions spread laterally around the CEJ. Although no clinical criteria are universally accepted for the diagnosis of root caries, it is generally agreed that softened cemental or dental tooth structure compared with the surrounding surface is characteristic.¹⁵ Active root caries is detected by the presence of softening and cavitation.^16,17 Although root-surface caries may be detected on radiographic examination, a careful, thorough clinical examination is crucial. A difficult diagnostic challenge is a patient who has attachment loss with no gingival recession, limiting accessibility for clinical inspection. These rapidly progressing lesions are best diagnosed using vertical bitewing radiographs. Differentiation of a caries lesion from cervical burnout radiolucency is, however, essential.¹⁸

In addition to the traditional methods of caries detection, several new technologies have emerged and show promising results for the clinical detection and diagnosis of caries lesions. These devices may have the potential to replace the tactile portion of caries detection, where explorers are used to try to estimate the depth of the caries lesions into the pits and fissures. These devices have two limitations. The first is that they are only indicated for use on unrestored pits and fissures. The second is that their diagnostic accuracy has not been firmly established. The technologies currently approved by the U.S. Food and Drug Administration (FDA) include laser-induced fluorescence, light-induced fluorescence, and AC impedance spectroscopy.11,19

The DIAGNOdent device (KaVo Dental Corporation, Charlotte, NC) uses laser fluorescence technology, with the intention of detecting and measuring bacterial products and changes in the tooth structure in a caries lesion. This compact and portable device, which requires a clean, dry occlusal surface, yields a numerical score from 0 to 99. The manufacturer has recommended threshold scores that represent the presence and extent of a lesion. A systematic review found that the “device is clearly more sensitive than traditional diagnostic methods, but the increased likelihood of false-positive diagnoses limits its usefulness as a principal diagnostic method.”²⁰

Another system currently available for caries lesion detection is the Spectra Camera (Air Techniques, Melville, NY). The Spectra system claims to detect caries lesions by measuring increased light-induced fluorescence. Special LEDs project high-energy violet or blue light onto the tooth surface. Light of this wavelength supposedly stimulates porphyrins—metabolites unique to cariogenic bacteria—to appear distinctly red, while healthy enamel fluoresces to appear green. Using this fluorescent technology, the data captured by the Spectra system are analyzed by imaging software, which highlights the lesions in different color ranges and defines the potential caries activity on a scale of 0 to 5. Although this technology appears promising, as of the publication date of this textbook, no peer-reviewed randomized clinical trials have been reported.

The CarieScan PRO (CarieScan, LLC, Charlotte, NC) is a device for the detection and monitoring of caries by the application and analysis of AC (alternating current) impedance spectroscopy (ACIST). The CarieScan PRO claims to enable clinicians to evaluate demineralized tooth structure using ACIST by providing information about tissue being healthy, in the early stages of demineralization, or already significantly decayed. The device provides a color scale and a numerical scale to determine the severity of the caries lesion and is accompanied by management recommendations that range from therapeutic prevention to operative intervention appropriate for the extent of the demineralization.

As described earlier, an ideal diagnostic test accurately detects when a tooth surface is healthy (specificity); when a lesion or demineralization is present (sensitivity); and if demineralization is present, whether or not it is active and whether or not it has cavitated the surface. Except for the presence of frank cavitation and more advanced lesions, none of the available approaches to detecting caries or determining lesion activity is completely accurate. Thus, the clinician must take all of the available diagnostic information together—visual, tactile, radiographic, and so on—along with the respective reported levels of accuracy and combine that with an assessment of the patient’s overall caries status to make a final diagnosis to the presence and extent of a caries lesion.

After the clinical examination for detection of caries lesions is completed, the management and treatment of caries lesions discovered depends not only on a thorough assessment of the present activity of the lesions but also on an understanding of the future risk of the patient for increased activity of the lesions. Therefore, the next step is to determine the present activity of the lesions. Is the lesion progressing, or is the lesion arrested? If the lesion is determined to be progressing and the patient’s risk factors are not changed, some intervention, either surgical or nonsurgical, is indicated. If the lesion is determined to be arrested, or not progressing, and the risk factors have been controlled, no treatment is needed other than regular preventive dental care. Currently, a reliable and accurate gold standard test based on one examination at one point in time to accurately assess caries lesion activity is not available, so it is important for the clinician to use information from all the tests and risk assessment to judge which type of intervention is appropriate at the current time. The decision of surgical intervention or nonintervention carries some risk for the patient in either direction, but studies would conclude that all diagnostic doubts should benefit the tooth by choosing non-operative options over irreversible operative dentistry options.

Clinical Examination of Amalgam Restorations

Evaluation of existing restorations should be accomplished systematically in a clean, dry, well-lit field. Clinical evaluation of amalgam restorations requires visual observation, application of tactile sense with the explorer, use of dental floss, interpretation of radiographs, and knowledge of the probabilities that a given condition is sound or at risk for further breakdown. At least 11 distinct conditions might be encountered when amalgam restorations are evaluated: (1) amalgam “blues,” (2) proximal overhangs, (3) marginal ditching, (4) voids, (5) fracture lines, (6) lines indicating the interface between abutted restorations, (7) improper anatomic contours, (8) marginal ridge incompatibility, (9) improper proximal contacts, (10) improper occlusal contacts, and (11) recurrent caries lesions.

Discolored areas or “amalgam blues” are often seen through the enamel in teeth that have amalgam restorations. This bluish hue results either from the leaching of amalgam corrosion products into the dentinal tubules or from the color of underlying amalgam seen through translucent enamel. The latter occurs when the enamel has little or no dentin support, such as in undermined cusps, marginal ridges, and regions adjacent to proximal margins. When other aspects of the restoration are sound, amalgam blues do not indicate caries, do not warrant classifying the restoration as defective, and require no further treatment. Replacement of the restoration may be considered, however, for elective improvement of esthetics or for areas under heavy functional stress that may require a cusp capping restoration to prevent possible tooth fracture.

Proximal overhangs are diagnosed visually, tactilely, and radiographically (Fig. 3-6). The amalgam–tooth junction is evaluated by moving the explorer back and forth across it. If the explorer stops at the junction and then moves outwardly onto the amalgam, an overhang is present. Overhangs also can be confirmed by the catching or tearing of dental floss. Such an overhang can provide an obstacle to good oral hygiene and result in inflammation of adjacent soft tissue. If it causes problems, an overhang should be corrected, and this often indicates the need for restoration replacement.

Marginal gap or ditching is the deterioration of the amalgam–tooth interface as a result of wear, fracture, or improper tooth preparation (Fig. 3-7, A). It can be diagnosed visually or by the explorer dropping into an opening as it crosses the margin. Shallow ditching less than 0.5 mm deep usually is not a reason for restoration replacement because such a restoration usually looks worse than it really is.²¹ The eventual self-sealing property of amalgam allows the restoration to continue serving adequately if it can be satisfactorily cleaned and maintained. If the ditch is too deep to be cleaned or jeopardizes the integrity of the remaining restoration or tooth structure, the restoration should be replaced.¹² In addition, secondary caries is frequently found around marginal gaps near the gingival wall and warrants replacement.²²

Voids that are usually localized and are caused by poor condensation of the amalgam can also occur at the margins of amalgam restorations. If the void is at least 0.3 mm deep and is located in the gingival third of the tooth crown, the restoration is judged as defective and should be repaired or replaced. Accessible small voids in other marginal areas where the enamel is thicker may be corrected by recontouring or repairing with a small restoration.

A careful clinical examination detects any fracture line across the occlusal portion of an amalgam restoration. A line that occurs in the isthmus region generally indicates fractured amalgam, and the defective restoration that must be replaced (Fig. 3-8, A). Care must be taken to correctly evaluate any such line, however, especially if it is in the mid-occlusal area because this may be an interface line, a manifestation of two abutted restorations accomplished at separate appointments (see Fig. 3-8, B). If other aspects of the abutted restorations are satisfactory, replacement is unnecessary.

Amalgam restorations should duplicate the normal anatomic contours of teeth. Restorations that impinge on soft tissue, have inadequate embrasure form or proximal contact, or prevent the use of dental floss should be classified as defective, indicating recontouring or replacement (see Fig. 3-7, B).

The marginal ridge portion of the amalgam restoration should be compatible with the adjacent marginal ridge. Both ridges should be at approximately the same level and display correct occlusal embrasure form for passage of food to the facial and lingual surfaces and for proper proximal contact area. If the marginal ridges are incompatible and are associated with poor tissue health, food impaction, or the inability of the patient to floss, the restoration is defective and should be recontoured or replaced.

The proximal contact area of an amalgam restoration should touch the adjacent tooth (a “closed” contact) at the proper contact level and with correct embrasure form and possess the proper size. If the proximal contact of any restoration is suspected to be inadequate, it should be evaluated with dental floss or visually by trial angulations of a mouth mirror (held lingually when viewing from the facial aspect) to reflect light and see if a space at the contact (“open” contact) is present. For this viewing, the contact must be free of saliva. If the contact is open and is associated with poor interproximal tissue health, food impaction, or both, the restoration should be classified as defective and should be replaced or repaired. An open contact typically is annoying to the patients, so correcting the problem usually is an appreciated service.