DIAGNOSTIC ACCURACY IN SELECTIVE CARIES REMOVAL: An In Vitro Comparison Between DIAGNOcam Vision Full HD Fluorescence Imaging and Caries Detector Dyes Using Histological Validation

For decades, the standard approach to fixing a cavity was to drill away until the dentist felt the tooth was hard and clean, often removing more healthy structure than necessary. Modern dentistry has shifted toward a gentler philosophy called minimal intervention. The goal is to remove only the soft, infected part of the tooth that is rotting, while leaving behind the softer, but still salvageable, dentin that can heal itself if sealed properly. This delicate balance relies entirely on the dentist's ability to tell the difference between tissue that must go and tissue that should stay. In the real world, this decision is made by looking at the tooth and feeling its texture with a tool, a process that varies from one dentist to another and can lead to either removing too much or leaving too much decay behind.

To help dentists make this choice more consistently, researchers have developed tools that act like extra senses. One common tool is a special dye that stains infected tissue a bright color, acting like a highlighter for rot. Another newer technology uses a camera that captures the natural glow, or fluorescence, of the tooth when lit with specific light; bacteria and decay change this glow, making them visible to the camera even when they are invisible to the naked eye. However, it was unclear how well these two methods worked together, or if using the dye first would mess up the reading from the camera. A team of researchers at the Universidad Complutense de Madrid, working with colleagues from the University of Florida and the University of Salamanca, set out to test these tools side-by-side in a controlled laboratory setting to see which method helped dentists agree on what to remove and how accurately they could judge the remaining damage.

The researchers gathered forty-four extracted human teeth that had natural cavities, mimicking the deep lesions often found in patients. They carefully drilled out the decay in a way that simulated a real clinical procedure, stopping when the tooth felt firm enough to be safe but not so hard that healthy tissue was lost. Once the drilling was done, two trained observers examined the inside of the cavity four different ways. First, they looked and felt the walls with their eyes and tools. Second, they used a high-definition camera that captures the tooth's fluorescence. Third, they applied the caries detector dye, waited thirty seconds, rinsed it off, and looked for the remaining stain. Finally, they took another fluorescence picture after the dye had been applied to see if the dye changed the camera's reading. After all these assessments, the researchers sliced the teeth in half and examined them under a microscope to measure exactly how much decay remained, using this microscopic view as the ultimate truth against which to judge the other methods.

The results showed a clear difference in how reliable the methods were. When the two observers looked at the same tooth, they agreed most often when using the fluorescence camera or when combining the camera with the dye. Their agreement was almost perfect with these tools. In contrast, when they relied on the dye alone, their opinions disagreed more frequently, and when they used only their eyes and touch, their agreement was moderate. The study found that the dye did not just highlight the decay; it actually changed the way the fluorescence camera saw the tooth. The numbers the camera gave before the dye was applied were significantly different from the numbers it gave after the dye was used. This means that if a dentist uses the dye and then immediately looks with the camera, the reading is no longer the same as a fresh, clean reading. The two measurements are related, but they are not interchangeable.

Despite these differences in how the tools behaved, all four methods shared one important trait: they all got better at detecting decay as the actual amount of remaining decay increased. When the microscopic slices showed a larger area of rot, every method—whether it was the camera, the dye, or the human eye—assigned a higher score to the problem. The researchers found that the size of the decay did not make one method work better than the others; the relationship between the decay size and the score was consistent across the board. The study concludes that the fluorescence camera is a highly reliable tool that helps dentists see residual decay with much more consistency than looking alone. However, it also warns that if a dentist chooses to use the dye, they must understand that it alters the fluorescence signal. The camera can still be used after the dye, but the reading must be interpreted as a new signal, not as a direct replacement for the initial view. This work suggests that while these tools can help standardize care and prevent the unnecessary removal of healthy tooth structure, they work best when their specific behaviors and limitations are understood.