What is it? Caries detector is an acidophilic dye that is absorbed by acidified carious structure; the most popular commercial products are red, formulated from acid red 52 in propylene glycol. Other dyes-green, blue and black are available for operators who have a red color-blindness.

What does it do? It is absorbed into acidified tooth structure where, unlike sound structure, it will not wash off.

Where is it particularly helpful? At the DEJ, the dentin is known as Mantle Dentin and it is less mineralized than elsewhere. The  histological function of Mantle Dentin is to join the enamel, which is very stiff with a  Flexural Modulus of 80GPa, to coronal dentin, which is much more elastic at a range of 12GPa to 16GPa. The flexibility of this boundary layer  helps distribute stress within the natural crown. Caries often tracks along this less-mineralized layer to undermine the enamel. Routine use of Detector identifies  undermined cusps and weakened CEJs.

How to dispense it and bring it to the mouth? In the method of this Handbook,Caries Detector is  kept chairside in a 3cc syringe fitted with a 22 gauge tip. The syringe is housed vertically in a composite syringe organizer, and a plastic 50cc cup sits beneath it to accept drips without mess. At the outset of the procedure, detector is dispensed in a well in a four-well dispensing block. In its well lies a Voco Pele Tim #1 pellet, which is  carried to the preparation with   cotton pliers. The pledglet is returned to the bonding block. As the caries is washed,  the tips of the pliers are placed in the A/W stream so caries detector residue will not remain on the cotton pliers to potentially contaminate  the acid etch and primer stages, in which the same cotton pliers are used.

Does it affect bonding? Studies have shown no reduction in bond strength. See EL-HOUSSEINY AND JAMJOUM, J CLIN PEDIAT DENT 2000, KAZEMI ET AL, OPER DENT 2002

What are the conventional terms used in discussing caries detector?

The terms “caries infected” and “caries affected” are the norm in discussions of what one sees when applying it to carious structure. These terms are histological and of no use in clinical practice, as we cannot see microscopically. Clinically these terms are inferential, an attempt to discern what is revealed when the dye is applied. A more useful description would be bright red vs pink.

In the images below you can see  areas of bright red  prior to excavation, and in the second photo only one small portion is red and the rest is surrounded by pink. The pink areas feel hard to an spoon excavator or slow speed round bur. The red is soft. Soft is not structural and must be removed.


  • Bright red is always soft, demineralized, and structurally worthless. It is mushy. Must go.
  • Pink is a lesser extent of demineralization. It feels harder to the operator using a slow speed round bur, or a spoon excavator. As caries is a progressive disease from initial acid dissolution to complete acid dissolution, there is a continuum of mineral density. There is no real clinical correspondence to the terms infected/affected. There is a continuum of mineral density.

Here are procedural rules that this writer recommends:

  1. Remove all red and pink when remote from the pulp. No pink gingival margins, no pink undermined cusp arms, no pink DEJs along box walls. With impunity, cleanse these areas 100%of caries.
  2. When in closer proximity to the pulp, accept that we must respond to what nature has created; if caries has progressed to exposure, no amount of tiptoeing will reverse that.

The path to excellence is to develop a predictable pulp cap procedure rather than to avoid excavating cavities thoroughly.See Pulpal Encroachment and Pulp Cap

Learn to deal with minimal tooth structure by developing better prep designs when tooth structure becomes lessened from ideal. Learn to deal with the histological needs of pulp tissue in composite resin restoration by studying biocompatibility. See Pulp Protection and Biocompatibity

Longitudinal studies on the efficacy of leaving caries are usually only short term and based on pedodontic and young adult populations. That excludes 75% of the population; to suggest we leave caries in older populations is without scientific proof.

Longitudinal studies of pulp cap using MTA has large international literature support in a wide range of age groups. Post-op periods of 5 to 10 years show retained vitality and freedom from apical disease.

Standard of care: According to a study by Clinician’s Report in January 2010, only 3% of practitioners surveyed were using MTA at that time. The use of silicate-based materials has gained ground since then, but the variety of methods used in pulp cap is still probably indicative of wide variation in standards of care in managing deep caries and pup cap. See Resin Pulp Cap Materials


  • Dropper bottles of caries detector often collect product under the screw cap and after a few uses the CDA will contaminate her gloves each time caries detector is dispensed. This can distribute detector on the countertop and onto instruments- wherever she subsequently touches with the gloves. Messy.
  • A convenient fix is to decant the solution into a 3cc Luer-lock syringe fitted with a 22-gauge needle.
  • Store the syringe vertically in a stable position, with a 50cc plastic medicine cup (commonly available from a pharmacy) below the tip.
  • Dispensing detector will then leave gloves clean
  • Chairside deployment works well with a 4-well block for holding the bonding products. A very suitable block is sold with Kurarary’s Clearfil Photobond kit, this writer’s recommended MDP based adhesive.
  • The detector is dispensed into one well holding a Voco #1 foam pellet; from there it is carried to the preparation with cotton pliers for generous and rapid deployment
  • The pellet will fit into all sizes of preparation except the very smallest of preps, efficiently flooding large preparations without undue loss of time.
  • In smaller preps, caries detector can be carried with a Bendabrush or Microbrush.
  • Clinical tip: When the detector is being washed off, also wash the cotton pliers in the water flush stream to avoid contaminating the etch and primer stages using the same cotton pliers.
  • Clothing and operatory staining are a risk with this product and with this method of transfer. Try to be careful, like a brain surgeon, for example.