“A sharp explorer should be used with some pressure and if a very slight pull is required to remove it, the pit should be marked for restoration even if there are no signs of decay.”
This is a quote from GV Black in 1924. Caries is not a simple to diagnose today as it was decades ago when there were large, bombed, out teeth. With the increase use of fluoride, the detection of caries is not as simple as it used to be. Yet in 2009, many of us are still diagnosing caries the same way GV Black did. The goal is now to be minimally invasive—catch caries at its earliest stages and attempt to remineralize incipient caries.
Decay is difficult to detect in radiographs unless larger than 2 to 3 mm deep into dentin, or 1/3 the bucco-lingual distance. Because an explorer has high specificity for caries but low sensitivity, a lot of incipient caries can be missed by relying on an explorer or radiographs alone.
There is a call in the literature to stop using the dental explorer for caries detection. Some dental schools are now teaching reduced reliance on the explorer. An explorer may actually cause more harm by breaking the enamel rods when forced in to an incipient carious lesion. At this early stage of caries, remineralization should be considered. The problem is detecting the initial stage of caries. So what improved ways exist for detecting caries?
There are a number of different modalities for detecting caries, the most popular of which use fluorescence. Normal healthy tooth structure produces little or no fluorescence. Carious tooth structure fluoresces proportionately to the degree of caries. The devices that use fluorescence have a high sensitivity to caries, but low specificity—the devices will measure the fluorescence of anything. Therefore, these systems are an adjunct tool to aid in the diagnosis of caries, and should be combined with conventional tools and good professional j judgment. The devices can be used to monitor caries progression and help the practitioner decide on treatment—prevention, remineralization, or restoration.
One system is KaVo’s DIAGNOdent, which uses a 655-nm laser to detect fluorescence of decay.
The DIAGNOdent provides a numeric value for caries progression. |
A similar device, Dentsply Midwest’s Caries I.D, uses an LED instead of a laser to measure the caries reflection signature; instead of a numerical readout like the DIAGNOdent, the Caries I.D. offers red and green indicators (complicating the process of monitoring caries progression and remineralization).
Midwest Caries I.D. uses LEDs to measure the caries reflection signature. |
Another device using fluorescence is Air Techniques’ Spectra that uses a 405-nm LED; caries fluoresce red and health tooth structure fluoresces green. The Spectra creates a graphic and a numeric display; the graphic can be saved to imaging software for monitoring caries over time.
In this Spectra scan, green is healthy enamel, blue is incipient caries, and red is enamel caries. |
Scheduled for launch in 2010, Quantum Dental Technologies’ Canary system uses a low-power, pulsating laser light to scan teeth for the presence of caries. The laser light is absorbed by the tooth and two phenomena are observed: the laser light is converted into luminescence and there is a release of heat (less than 1 degree Celsius). This heat does not harm the tooth but provides information on the tooth up to a depth of 5 mm below the surface. Simultaneous measurement of the reflected heat and light determines the presence and extent of tooth decay below the tooth surface.
Another technology on the horizon for caries detection (and other diagnostic applications in dentistry) is optical coherence tomography (OCT). Capable of scanning both hard and soft tissues, Lantis Laser’s OCT Dental Imaging System features a hand-held scanner that captures tomographic slices up to 3-mm deep. The cross-sectional images are displayed individually in real-time and can be saved . this system can detect recurrent caries around restorations and can examine marginal integrity of restorations bonded to tooth structure.
An OCT image of a molar with a failing composite. |
These and future methods are improving our ability to detect caries at its earliest stages. With this enhanced knowledge, we’ll be able to establish better protocols for caries intervention and treatment.
This article originally appeared in GC Europe’s MID e-magazine.