ADA Caries Classification System (2015): four lesion stages, sound to advanced, so the chart says what the tooth needs

What it says#

The problem the report sets out is a charting one. A caries lesion, in the report's words, is the cumulative result of an imbalance in demineralization and remineralization over time, and a system that records a lesion's location, site of origin, extent and, where possible, activity level, consistently over time, is what a clinician needs to decide which treatments are appropriate. In 2008 the ADA convened a group of experts to build an easy-to-implement version of that; the Council on Scientific Affairs compiled the discussions into the ADA Caries Classification System and published it in JADA in February 2015.

The system runs from clinically unaffected (sound) tooth structure, through noncavitated initial lesions, to extensively cavitated advanced lesions, with a moderate stage between. The ADA's own topic page describes how it is meant to be used: on clean teeth, with compressed air, adequate lighting and a rounded explorer or ball-end probe, and with radiographs available. The CCS incorporates ICDAS and other systems into a broader one that also takes in the radiographic presentation of the approximal surface, and it is designed to include both noncavitated and cavitated lesions and to describe them by clinical presentation without reference to a specific treatment approach. What sets it apart from some other systems, the ADA says, is that it links clinical lesion presentation to radiographic findings and gives a way to identify, when possible, lesion activity over time.

The report's authors were explicit that this was a first release. The abstract says the CCS is available for implementation in clinical practice to evaluate its usability, reliability and validity, and that feedback from practitioners and researchers will improve it. It also anticipated technology: the ADA topic page quotes the report on light-based and fluorescence caries detection tools as emerging and, as they are developed, clinically tested and validated, possibly contributing to a more precise placement of lesions within the CCS categories.

The stage names have since become the ADA's working vocabulary. The 2018 evidence-based guideline on nonrestorative treatments, whose chairside guide defines noncavitated lesions as ICDAS 1 and 2 and cavitated lesions as ICDAS 5 and 6, sorts its fluoride, sealant, resin infiltration and silver diamine fluoride recommendations by that split. The 2023 guideline on restorative treatments defines a moderate caries lesion as ICDAS codes 3 and 4 and an advanced caries lesion as ICDAS codes 5 and 6, and builds its carious-tissue-removal and material recommendations on those two stages. The ADA's topic page gives the ICDAS scale itself: 0 clinically sound; 1 to 2 clinically detected intact enamel lesions (initial stage decay); 3 to 4 clinically detectable early, shallow or microcavitations (moderate decay); 5 to 6 clinically detectable late or deep cavitations (extensive decay).

Who it applies to#

Anyone who charts caries: the dentist doing the exam and the hygienist doing the recall. The system is per surface and per lesion, and it assumes the exam conditions above, which means it is as much a protocol for the operatory setup as it is a set of labels.

It does not choose the treatment. The ADA describes the CCS as a description of lesions without reference to a specific treatment approach; the decision between watching, remineralizing, sealing or cutting comes from the guidelines that use its stages. It is also not a legal requirement. It is a Council on Scientific Affairs report, not a board rule or a CDT code, and an office that charts in ICDAS or another validated scheme is not out of step. Where the ADA's guidelines do reach a chart is in the ICDAS code ranges above, since those are what "moderate" and "advanced" mean in the 2023 restorative guideline and what "noncavitated" and "cavitated" mean in the 2018 nonrestorative one.

What changed#

The report's stated reason for existing was consistency: a way to record a lesion's location, site of origin, extent and, when possible, activity, the same way over time, so that the choice of treatment follows from the record. The CCS gave the noncavitated lesion a stage name and gave the activity judgment a place in the chart, which is what makes a decision to remineralize rather than restore defensible when the same surface is looked at three years later.

The larger change came after the report, when the ADA's guideline program adopted the stages. A recommendation such as the 2018 panel's suggestion to prioritize 38% silver diamine fluoride, applied twice a year, for advanced cavitated lesions on coronal surfaces of primary teeth, or the 2023 panel's suggestions on selective versus nonselective carious tissue removal for moderate and advanced lesions, only works if the lesion in front of you has been staged. The classification was the first edition; the guidelines are what made it operational.

Where the source is#

The report is Young et al., JADA 2015;146(2):79-86; the DOI link under the title opens the publisher's article page, and the full text, including the classification table, is behind JADA access, so the stage definitions above are taken from the published abstract, the ADA's caries risk assessment topic page (which describes the system and quotes it), and the ADA's 2018 and 2023 caries guideline chairside guides, which define the lesion categories by ICDAS code. An erratum ran in the June 2015 issue. The chairside guides are free PDFs from the ADA and may be copied for noncommercial use.