Dental caries, commonly known as tooth decay, remains a widespread chronic disease globally. Fortunately, significant advancements in diagnostic dentistry over the past century have led to the development of numerous tests for early detection. This progress allows for timely interventions, fundamentally improving the management and outcomes of caries.
For optimal patient care, dental professionals should employ a combination of diagnostic approaches. A thorough visual and tactile examination forms the cornerstone of initial Caries Diagnosis, often enhanced and validated by supplementary diagnostic tools tailored to individual cases. These diagnostic methods can be broadly categorized as qualitative and quantitative, depending on the nature of the information they provide. Following a clinical assessment, dental radiographs are frequently utilized as a primary qualitative diagnostic aid. Caries detection dyes are primarily valuable during caries removal procedures rather than for initial diagnosis. Fiber optic transillumination (FOTI), while versatile, is also significantly utilized for caries diagnosis.
Emerging diagnostic technologies, such as laser fluorescence and light-induced fluorescence, offer more precise insights into carious lesions. Light-induced fluorescence provides quantitative data, pinpointing the specific location, extent, and bacterial activity within a lesion.[1] Laser fluorescence detection excels in identifying demineralization and remineralization processes. This capability is particularly useful for diagnosing early lesions and evaluating the effectiveness of remineralization therapies, offering quantitative assessments through numerical values.[2]
Diagnostic Procedures for Dental Caries
Traditionally, dental explorers were employed to diagnose carious lesions. However, research has demonstrated that this method can cause irreversible damage to the enamel surface and potentially accelerate lesion progression.[3] Dental explorers can disrupt the remineralization process and facilitate the transfer of cariogenic bacteria to adjacent teeth. Furthermore, relying solely on explorers to assess occlusal surfaces can lead to misdiagnosis, where deep fissures might be mistakenly identified as caries simply due to a “sticky” sensation. The current recommendation is to limit the use of dental explorers to removing stains and soft plaque from tooth surfaces.[4] A visual examination, conducted on a dry tooth surface and potentially enhanced with magnifying loupes, should always be the initial step in caries assessment.
The International Caries Detection and Assessment System (ICDAS) is an invaluable tool for standardizing caries detection and recording. ICDAS categorizes carious lesions on a scale from 0 to 6, with higher scores indicating more extensive lesions. This system is instrumental in monitoring lesion progression and treatment outcomes. ICDAS is recognized for its specificity, accuracy, and reproducibility in caries classification.[5] Refer to the Table below for the International Caries Detection and Assessment System Caries Score Table.
Radiographic Caries Diagnosis
Visual-tactile examinations alone are often insufficient, especially for interproximal and occlusal surfaces. Radiography is a crucial adjunct for caries detection, providing practitioners with essential subsurface information about lesion progression.
Dental radiographs function by utilizing x-rays that are attenuated as they pass through tooth structures. Dense tissues like enamel and bone, due to their high mineral content, are radiopaque, meaning they absorb or block x-rays. Conversely, softer tissues with less mineralization are radiolucent, allowing x-rays to pass through more readily.[6]
Carious lesions manifest on radiographs as areas of reduced density within the tooth structure. These radiolucent areas represent demineralized and dissolved hard tissue. Interproximal caries typically appear radiographically as cone-shaped lesions originating apical to the contact point, with the base directed towards the tooth surface and spreading along the dentinoenamel junction. Occlusal caries, affecting the pits and fissures, initially present as a radiolucent dot at the fissure depth, evolving into thin radiolucent lines at the dentinoenamel junction.[7] Root and cemental caries are identified as notched radiolucencies interproximally, coronal to the alveolar bone crest, and apical to the cementoenamel junction.
Recurrent or secondary caries occur around existing restorations. These are characterized by radiolucent areas adjacent to or beneath restoration margins. It’s critical to differentiate recurrent caries from radiolucent lining materials, which can sometimes mimic caries radiographically.
Several radiographic techniques are employed in caries detection, with posterior bitewing, periapical, and panoramic radiographs being the most common.
Posterior bitewing radiographs, capturing the occlusal surfaces of premolars and molars, are the most frequently used view for caries detection, particularly for interproximal caries. They are often the initial radiographic examination for patients at low caries risk.[8] Periapical radiographs visualize the entire tooth, from crown to root, aiding in the detection of anterior proximal caries, periodontal disease, and periapical lesions. Panoramic radiographs offer a broad overview of the maxilla and mandible, useful for initial screening but lacking the detail required for detecting incipient caries. It is important to recognize that radiography alone is not a definitive method for caries diagnosis as it cannot reliably distinguish between cavitated and non-cavitated lesions, or active and arrested caries.[9]
Caries Detector Dyes
The use of caries detector dyes remains a topic of debate, yet many dentists utilize them as an adjunct for caries removal and occlusal caries diagnosis. These dyes function by staining the collagen associated with demineralized dentin. Importantly, they do not stain bacteria nor delineate the advancing front of infection.[10] Research by Yip et al. indicated that caries detector dyes stain areas with higher organic material concentrations, regardless of whether caries is present.[11] Therefore, indiscriminate use of caries detector dyes, without understanding their limitations, can lead to unnecessary removal of healthy dentin and potential pulp exposure.[10]
Many caries detector dyes produce irreversible staining. Their use for diagnosing occlusal caries is generally discouraged due to aesthetic concerns. However, the intensity of dye staining can offer a relative indication of demineralization severity, with deeper staining correlating to greater demineralization.[12]
Fiber Optic Transillumination (FOTI)
In dentistry, transillumination involves directing light through dental tissues to aid in diagnosis. While valuable for caries diagnosis, its applications extend to assessing developmental defects like fluorosis, locating root canal orifices, and identifying tooth fractures and cracks.[13]
Fiber-optic transillumination enhances clinical examination, often achieving specificity and sensitivity comparable to, or even exceeding, radiography, without exposing patients to ionizing radiation.[14]
Effective FOTI devices are compact, with small apertures (3 mm or less) to act as point light sources. Dental curing lights are not recommended for transillumination due to the risk of macular degeneration and retinal injury.[13]
Sound dental tissues exhibit a different light transmission index compared to caries, calculus, tooth discolorations, and restorative materials. This difference allows FOTI to distinguish these changes. Carious lesions appear as shadows within the tooth structure due to their lower light transmission index. Calculus presents as darker areas on the tooth surface.[15]
Proper FOTI Device Placement:
For anterior proximal caries assessment, position the probe on the vestibulo-cervical aspect of the tooth and examine from the lingual aspect using a mouth mirror. For posterior proximal caries, place the probe in the cervical region, either buccally or lingually.
Recent advancements include flexible, thin fiber-optic tips designed to access and assess interproximal caries in posterior teeth by gently sliding below the proximal contact.[13]
Advanced Technologies in Caries Evaluation
Emerging technologies in dentistry, leveraging fluorescence, electrical conductance, and lasers, enable earlier caries detection. These tools provide dentists with detailed information on the extent of demineralization, facilitating timely intervention.
Photothermal Radiometry and Modulated Luminescence (PTR-LUM)
PTR-LUM is an adjunctive technique to radiography that monitors caries-induced microstructural changes in teeth. It measures optical and thermal property changes using photodetectors and infrared detectors. The PTR-LUM response is quantified on the Canary scale (1-100). Scores of 1-20 indicate healthy mineralization, 20-70 suggest demineralization, and 70+ strongly indicate advanced decay requiring invasive treatment.[16] The Canary scale reading guides treatment decisions, differentiating between non-invasive and invasive approaches.
Laser Fluorescence Caries Detection Devices
Laser fluorescence devices offer a non-invasive method for early caries detection. They are highly accurate and sensitive in diagnosing dentinal caries and are widely adopted in dental practices. The procedure involves calibrating the device by irradiating a clean tooth surface with a diode laser. Subsequently, the device scans each tooth, measuring the fluorescence emitted and the light absorbed by dentinal metabolites, including bacteria and bacterial byproducts. Higher bacterial presence correlates with increased light absorption, indicating a higher likelihood of caries.
Beyond caries detection, laser fluorescence devices can pinpoint the location and extent of lesions, even detecting caries within grooves that radiographs may miss.[17] Laser fluorescence readings are also interpreted using the Canary Scale: 0-10 (healthy), 21-70 (decay), and 71-100 (advanced decay). Laser fluorescence technology is recognized for its simplicity and efficacy in early caries detection.[2]
Light-Induced Fluorescence
Light-induced fluorescence is effective in monitoring demineralization and remineralization, particularly when therapeutic agents like fluoride mouthwash are used. It quantitatively assesses the effectiveness of remineralization therapies.
This technique leverages the natural fluorescence of teeth to differentiate carious lesions from healthy enamel. Carious lesions exhibit lower fluorescence radiance than sound enamel.[1] Light-induced fluorescence provides quantitative parameters such as lesion size, percentage fluorescence loss (Delta F), lesion volume (Delta Q), bacterial activity and red fluorescence (Delta R), and staining intensity (Delta E). Demineralization increases fluorescence loss, while remineralization reduces it.
Limitations of light-induced fluorescence include potential interference from saliva and plaque. Staining can enhance lesion detection but can also be artificially reduced by tooth bleaching.[18]
Clinical Relevance
The field of dentistry is increasingly emphasizing conservative approaches to caries management. Modern diagnostic technologies facilitate the detection of early demineralization stages, enabling minimally invasive interventions to prevent further damage. This shift has significant positive implications for individual and community oral health. However, established methods like fiber optic transillumination remain valuable, supported by evidence of their high specificity and sensitivity in caries diagnosis.
Review Questions
Figure
International Caries Detection and Assessment System Caries Score Table Contributed by R Ghodasra
References
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