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Profile in Oral Health Trisha E. O'Hehir, RDH, MS

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by Trisha E. O'Hehir, RDH, MS
Dental caries remains a significant problem responsible for pain, suffering, disfigured smiles, impaired function, lost hours of school and work, and of course, considerable expense, worldwide. Today, our understanding of the complex caries process has led to earlier diagnosis, before cavitation occurs. Early diagnosis of demineralization opens up opportunities for remineralizaton of tooth surfaces, avoiding the need to amputate part of a tooth in order to place a restoration.

With this new understanding of demineralization and remineralization, diagnosis doesn't wait for the patient to report pain and is no longer a simple yes-no decision of whether the tooth surface is cavitated. Diagnosis today involves measuring early, subclinical caries activity in the enamel and dentin and new technology is making that task easier and more objective.

The Caries Process
cay beginning on the inside of the tooth and working their way out. That idea has more truth to it than we realize. There are no tooth worms, but the acid-produced demineralization of the enamel does in fact begin below the outer enamel surface. Acid from several sources penetrates the enamel and begins the demineralization process. This is a dynamic process that moves from demineralization to remineralization and back. As long as there is sufficient saliva to remineralize and the acid load can be balanced, no break in the enamel will occur. When the acid levels overwhelm the salivary remineralization, the demineralization process continues to undermine the enamel surface, eventually leading to a break or cavitation in the enamel surface. This allows acid and acid-producing bacteria access to deeper areas and protection from routine daily cleaning and salivary neutralization.

Caries Detection
Diagnosis classifications D1-D4 differentiate carious lesions based on progression. D1 are clinically detectable enamel lesions with intact enamel, D2 are cavitated lesions within the enamel, D3 are both cavitated and non-cavitated lesions into the dentin and D4 are lesions into the pulp. Carious lesions pass through each of these stages, from subclinical demineralization to lesions into the pulp, if they go that far.

Traditional caries lesion detection uses radiographs, a sharp explorer, light and unwaxed dental floss. Radiographs show lesions only after they have progressed at least 30 percent into the enamel. A sharp explorer is now considered obsolete and harmful rather than helpful, as it can break through softened, demineralized enamel, causing cavitation and eliminating the option of remineralization. Even narrow diameter explorers cannot reach the base of deep pits or fissures to detect decay. Air, light and magnification are more effective for evaluating enamel surfaces, specifically occlusal surfaces. Researchers suggest that sharp explorers no longer be used to detect stickiness on occlusal surfaces. Although sharp explorers are still widely used this way, they can actually create cavitation before it occurs, moving the lesion to a level that can no longer benefit from remineralization therapy. Research does not support the use of sharp explorers and because of this, some dental schools now teach that it is unethical to use a sharp explorer to look for initial lesions in occlusal pits and fissures.

Diagnosis classification D1-D4 do not identify subclinical lesions that are in a dynamic state of progression and regression, demineralization and remineralization. Technology now provides many options for detecting the early demineralization of enamel and determining how far lesions have progressed. When used after remineralization therapy, these technologies provide valuable information on the success of those efforts.

Caries Diagnostic Systems
Digital Radiography
Visual inspection of film radiographs is no longer the most effective means of diagnosing early caries. In a study published in The Journal of the American Dental Association (JADA) by Dr. S. White showed the depth of caries was misdiagnosed up to 40 percent of the time and healthy teeth were misdiagnosed as having caries 20 percent of the time when looking at film radiographs. Other studies showed no difference between film and digital when visually diagnosing caries. The advantage of digital is the ability to enlarge the image and change contrast for better visualization. Now there is a software program available as an optional component of the Kodak RVG system that analyzes tooth density and demineralization patterns. Logicon Caries Detector Software uses a database of histologically validated caries cases to compare images for diagnosis. Graphics and visual aids provide a Tooth Density Variation Chart and a Lesion Probability Chart.

Light Illumination
Transillumination enhances vision by passing intense incandescent yellow-to-white light through tooth surfaces. Because healthy tooth enamel has a light transmission index greater than decay or calculus, differences will be seen visually. These products provide greater light than overhead or headlamps for caries diagnosis. Many devices can transilluminate a tooth: standard light for ear, nose and throat examinations, composite curing lights, small light probes used in electronics that look like tiny flashlights and the fiber optics built into handpieces.

Microlux Transilluminator Diagnostic System from AdDent, Incorporated, illuminates tooth structure to detect changes in enamel. Aiming light through the teeth from facial to lingual and viewing the surface with a mouth mirror shows defects in the enamel as dark shadows.

Audible Signal Plus and Light
DIAGNOdent and the DIAGNOdent Pen from KaVo use laser fluorescence technology for detecting occlusal caries. A baseline reading is taken from each patient just prior to evaluating surfaces for decay. Both an audible signal and digital number measure laser-reflected light. Quantified laser-reflected light can be used to detect a carious lesion. The DIAGNOdent quantifies the lesion based on the following reading:
• 0-10 healthy
• 10-20 early caries in the outer enamel
• 20-30 caries extending into the inner enamel
• 30+ dentinal caries

The Midwest Caries I.D. utilizes LED light and contains three separate fiber-optic fibers. One fiber emits green light, one emits red and the third is the receiving fiber. The light passes through the enamel rods and if the surface is healthy, the LED light is absorbed into the tooth and the green light remains on. When the enamel is demineralized or caries is present, the LED light will be reflected, refracted or scattered. The receiving fiber captures this light as red. The message to the clinician is either the green light, indicating healthy tooth structure or red, indicating demineralization or caries. Color indicators are accompanied by an audible tone.

The level of involvement is indicated by the rate of pulsed light. A rapid, medium or slow pulse corresponds to high, medium or slight decalcification. Interproximal caries can be detected by scanning the mesial or distal marginal ridges.

Visual Imaging Diagnostics
Spectra Caries Detection Aid from Air Techniques, Inc., connects to your computer through the USB port. It uses light-induced fluorescence produced by LEDs that project high energy violet blue light. Images of sound enamel appear green. Light of this wavelength stimulates metabolites of cariogenic bacteria to appear as red.

Soprolife from Acteon Imaging is an intraoral camera and caries-detection device in one. It combines Sopro video imaging and light-induced fluorescence to provide images magnified 30- to 100-times actual size. Soprolife offers two views, one using blue light and the other using white light. Blue lights allow observation of the tooth structure and white lights show the periodontium.

CarieScan Pro from 3D Diagnostic Imaging in the U.K. is the first to use electrical Impedance Spectroscopy Technology. Using six blue LED lights, the CarieScan Pro produces a computer image much like Doppler radar used for weather reporting. The device is small, lightweight, battery-operated, automatically calibrated and Bluetooth-enabled to capture readings wirelessly. A low-amplitude microamp current passes through the tooth structure penetrating enamel, dentin and pulp to provide mineral density changes. Electrical impedance is measured and compared to a map of reference teeth collected from six years of research at universities in Scotland. Probability of disease is given with scores from 0 to 100 and a colored inDECAYtor. The impedance of a healthy tooth structure is greater than demineralized tooth structure, including dentin. Readings over time monitor disease progression and the effectiveness of remineralization therapy.

Future Products
Canary Dental Caries Detection System by Quantum Dental Technologies, a Canadian company uses Photothermal Radiometry and Modulated Luminescence (FDPTR and LUM) or a low-power, pulsating laser light that can provide information to a depth of 5mm. As the laser light is absorbed by the tooth, two phenomena are observed. First, the laser light is converted into luminescence and secondly, heat of less than one degree Celsius is released, which does not harm the tooth. Demineralization is measured by combining data on the reflected heat and the reflected light. This information is displayed on a touch screen monitor in an Odontogram showing both Canary numbers and color codes depicting the level of demineralization or remineralization. The higher the Canary numbers, the greater the level of demineralization. The Canary System comes from Canada and should be available in the United States before the end of 2011.

Conclusion
These new caries detection technologies provide cutting edge tools for dentists and hygienists that provide non-invasive methods for determining the level of health and disease in teeth. The dental industry is changing to encompass a more preventive model rather than the more traditional repair or amputation model. New detection methods like these and those soon to be introduced to the dental market help pave the way for clinicians to intervene earlier and thus save natural tooth structure. Early intervention for prevention will allow many to maintain healthy tooth structure for a lifetime rather than following a lifelong path of tooth repair.
Dentaltown Magazine
September 2025
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