Why Caries Detection is More than Just Looking for “Stickiness”

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Patients and dental professionals don’t always see eye to eye on dental needs, but carious lesions are one thing they often agree on. No one wants to hear the dreaded words that you, or your child, have a cavity. Through various lectures of my schooling, caries detection, both traditional and newer age techniques, have been addressed.

Traditionally, caries detection was accomplished by using the shepherd’s hook explorer to press into a suspicious area. If a stickiness or a grab was felt while pressing into the area, the lesion was considered carious. Subsequently, no stickiness meant caries were not present. Today, there is controversy surrounding that mindset. Some dental professionals believe that “poking” through the surface can actually cause more harm than good.

The traditional shepherd’s hook version of caries detection is used by many dentists and dental hygienists today even though newer research suggests the pressure can break through the surface of enamel and cause irreversible caries.

Caries are classified as cavitated and non-cavitated lesions. “A cavitated lesion is a lesion that has lost the outer surface layer of the crown or root, and a dental restoration is normally needed to repair a tooth surface with a cavitated lesion2.” Non-cavitated lesions, on the other hand, are a result of demineralization and are usually reversible or arrested by use of fluorides or placement of sealants2. The controversy today debates that once the surface of the lesion is penetrated, the hope for remineralization is lost, thus requiring a restoration.

Deb Spears, a long-time RDH, and instructor for the Illinois Central College Dental Hygiene program agrees. She states, “For decades, we were taught to push the explorer tip into a possible carious lesion to see if it was, in fact, caries. Now we know that using the tip with force on a lesion and breaking through the surface zone of the enamel is actually damaging and destructive to that surface. It prohibits that lesion’s ability to remineralize and ‘heal.’ The major problem is it can be difficult to change old habits; hence the pushing continues.” It has been expressed, “The use of a sharp explorer to diagnose caries in pit and fissure sites is no longer recommended2.”

Another side of the argument says if the enamel was fragile enough to be broken through in the first place, the lesion was already too advanced and would have required a restoration regardless. Although this argument exists, some old-school doctors still use the shepherd’s hook explorer to check for that sticky feeling in order to diagnose caries.

Another downside of traditional caries detection is it is said to have low-sensitivity and high-specificity. This basically means it is very specific to the location of the carious lesion, but not sensitive to how intense or severe the lesion is. Along with this, dentists’ opinions vary on whether or not a lesion is carious depending on how deep and how severe, which cannot be easily determined through shepherd’s hook exploration.

The best way to diagnose caries is by a combination of clinical and radiographical evidence, compiled and reviewed, by a diligent dental staff. Dental staff should always look for the tell-tale signs of a decaying tooth and avoid radiograph overlapping at all costs to ensure the earliest detection possible. Jill Gehrig, RDH, MA, states the best methods of early caries diagnosis are as follows, “Good lighting, clean tooth surface that is free of biofilm and deposits, a three-way syringe so that teeth can be viewed both wet and dry, sharp eyes, blunt explorer or periodontal probe, and bitewing radiographs2.” By practicing these techniques, the need for the potentially harmful shepherd’s hook method of caries detection might be eliminated.

As technology advances so does dentistry. Today there are several different products on the market to aid in caries diagnosis. One of the newer methods of detection is the Diagnodent. The Diagnodent, which detects enamel demineralization through infrared laser fluorescence, is opposite to the shepherd’s hook as it is low in specificity and high in sensitivity. The Diagnodent is able to detect how intense the demineralization is, but not how deep the lesion is. Instead, a more generalized area of the decay is determined. The Diagnodent is sensitive to its surroundings as the target tooth needs to be clean and dry.

To use the Diagnodent, a healthy “control” tooth is chosen to determine the patient’s enamel fluorescence reading, and the suspicious tooth’s fluorescence is compared to this. The infrared tip is rocked back and forth within occlusal pits and fissures, and also along smooth surfaces, to detect demineralization levels. A few downsides to this method include the inability to get accurate readings surrounding existing dental restorations, and the influence of plaque, calculus, saliva, certain colors of prophy paste, and stain. Despite this, the Diagnodent is able to detect a carious lesion in a noninvasive manner, which is not the case with the shepherd’s hook method.

Overall, we know caries is a gradual disease. One method of detection may not be enough, but a combination of visual, radiographical, and other detection aids can lead to a definitive diagnosis. To appease patients and to ethically complete your job as a hygienist, the knowledge of potential harm from the shepherd’s hook method must be addressed. Although sometimes it is hard to integrate newer methods into a daily routine, at the end of the day the health of the patient should be the driving force behind every adaptation to your office.




  1. General Knowledge from Illinois Central College / Dental Hygiene 228 Lecture notes / Debra Spears Instructor
  1. Nield-Gehrig, J. S., Sroda, R., & Saccuzzo, D. (2017). Fundamentals of periodontal instrumentation & advanced root instrumentation (8th ed.). Philadelphia: Wolters Kluwer.