Comment

This paper addresses a topical subject in which there is a resurgent interest. The NMAB chemical discussed in this paper was the main active ingredient in the Caridex system was time consuming, expensive, involved noisy and expensive equipment, and was slow; it is not available on the market today. However, extensive research show its clinical efficacy, safety, patient acceptance and compatibility with filling materials.^{1, 2, 3, 4} Caridex was not consistently efficacious for caries removal, used large volumes of solution, took too much time to employ, had a poor shelf-life, and needed a heated reservoir and a pump solution delivery.

As also mentioned in the paper, a new method of chemomechanical caries removal CCR has been developed called Carisolv. The major differences from Caridex are a different amino acid composition, an increased sodium hypochlorite concentration, the solution consistency (and colour) and new instruments. Despite using much greater volumes of liquid, none of the three solutions in the present study has resulted in better caries removal than Carisolv. Although addition of 2M urea improved caries removal compared with saline, urea toxicity might be a problem clinically.

Chemomechanical caries removal is particularly suited for:

• Patients with phobias to either needles or drills
• Patients where conservation of tooth tissue is a prime requirement
• Patients for whom local anaesthesia is contra-indicated such as those with severe medical complications
• Children and adolescents especially when they would require an inferior dental block
• Older patients with root caries.

The achievement of local anaesthesia can take about 5 minutes. If this can be avoided, as is the case in about 95% of patients treated with CCR, then the increased time required for the CCR method as compared with conventional drilling, is probably not significant. As it is possible to work in several quadrants of the mouth with CCR this can further reduce potential discomfort. It is notable that patients' perception of the time taken for the caries removal is that the CCR takes a shorter time compared with drilling and this could be described as an extension of wishful thinking.

In addition there are many clinical situations which are particularly suited for the use of CCR. These include root carious lesions, open caries lesions, very deep carious lesions where we wish to attempt to avoid the creation of a traumatic exposure, secondary caries around the margins of crowns or bridges and carious lesions in deciduous teeth.

The paper also comments on the fact that the prepared cavity surface structure following CCR is very different from that seen after conventional cavity preparation when using a drill. The topography is highly irregular, as has previously been shown with the Caridex system. This may increase the surface area for bonding and thus possibly improve bond strengths to certain adhesive materials.

Work has proven that CCR significantly reduces cariogenic micro-organisms, probably due to the oxidants within the product, as well as the high pH. This antimicrobial effect may well also be significant in the management of deep carious lesions. This paper adds to our knowledge of CCR, a topic of increasing interest to both practitioners and patients.