How far does a D3 interproximal caries penetrate the dentin?

• A. More than one-third of dentin thickness
• B. Less than one-third of dentin thickness
• C. Entire dentin thickness
• D. Through enamel only

Answer: (A)

Depth into dentin is used to gauge how far an interproximal caries has progressed and to guide treatment. D3 denotes a deep dentin caries lesion, defined as caries that penetrates more than one-third of the dentin thickness. This level of dentin involvement signals substantial progression toward the pulp, increasing the risk to the pulp and often prompting more conservative or protective restorative approaches and closer consideration of pulp status. If the caries were less than one-third into dentin, the lesion would be shallower and sometimes amenable to simpler management; if it spanned the entire dentin thickness, it would indicate very extensive involvement near or into the pulp.