CLINICAL PROCESS: CARIES DETECTOR
I have found caries detector to be one of the most effective and helpful products to produce high quality composite restorations. Red below to see its benefits.
Academia has confounded the benefits of this product by defining detector-stained dentin as either “Affected” or “Infected” This is a useless distinction. You cannot see bacteria so you cannot”Infected Dentin”. It is known that caries invades tooth structure by acid dissolution. So any black and white description drawn along lines that ae not perceivable by the clinician is a waste of our cerebral capacity. More valuable are distinguishing between hard red dentin and soft red dentin. Soft dentin is not structural and cannot be retained. Hard dentin may be retained, because, dear friends, are we not going to acidify and hybridize dentin as the first step in restoration? Therefore, the fact that the bacteria have acidified the dentin to any given depth merely opens up the age old question of how deeply do you remove carious tissue? That clinical judgement has to be made in every prep and the relevant questions are answered by how close one is to the pulp, how healthy this pulp is, how much capacity does it have to regenerate dentin, how large are the tubules and how numerous in terms of tubule area per sq mm of dentin.
In all cases the clinical goal is to maintain the health of the pulp and minimize pulpal inflammation and control unavoidable inflammation post operatively.
Caries detector cannot make those judgement calls for you but it can provide a lot of information.
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 flexural modulus of this boundary layer, which to my knowledge , has not been measured. Its function is to distribute stress within the DEJ of the natural tooth.
Caries often tracks along this less-mineralized layer and undermines the enamel. Without Detector it can be clandestine and difficult to identify because it is often not discolored. Routine use of Detector identifies carious mantle dentin undermined cusps and weakened CEJs.
The second place where it is helpful is when approaching deep caries that appears close to exposing the pulp. Repeated staining allows the perimeter of the most deeply carious area to cleaned so that the near-exposure site can be approached with suitable caution. If an exposure does occur, it is obviously better to do it in a field that is 98% clear of caries rather than in a gooey mess of surrounding caries fulminating with microorganisms.
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. I believe one reason that clinicians do not adopt caries detector is because it is so messy- the plastic dispensing bottle quickly gets a layer of detector between the bottle and its top. From there it spreads to the assistant’s gloves, the instruments, the tray- yuck! The above syringe with a small tip keeps the assistant’s gloves pristine.
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 other steps using these pellets in the 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?
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. What is the reality? -a continuum of mineral density.
Here are procedural rules that this writer recommends:
- Remove all red and pink when remote from the pulp. No pink gingival margins, no pink undermined cusp arms, no pink mantle dentin along DEJs. With impunity, cleanse these areas 100%of caries.
- 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 is not 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
DISPENSING CARIES DETECTOR CHAIRSIDE
- 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.