A patient has multiple cervical carious lesions on the mandibular canines and premolars, some extending SUBGINGIVALLY onto the root. Which restorative material would you NOT choose for these Class V restorations?

Correct answer: C. Composite resin

• A. RESIN-MODIFIED GLASS IONOMER is an excellent compromise, combining chemical adhesion and fluoride release with better aesthetics, higher strength and command set. It is widely regarded as the best all-round choice for subgingival cervical lesions.
• B. AMALGAM is durable and remarkably tolerant of a slightly damp field, so it remains a reasonable functional choice for a subgingival Class V where aesthetics do not matter — though it requires mechanical retention and releases no fluoride.
• C. CORRECT — this is the material to avoid. COMPOSITE RESIN requires strict MOISTURE CONTROL and a reliable bond to enamel to perform well, and a subgingival root-surface margin provides neither. There is little or no enamel at the margin, the bond to cementum and root dentin is weak, crevicular fluid and haemorrhage contaminate the field, and the polymerisation shrinkage stress at a low C-factor-unfavourable Class V cavity leads to marginal gaps and recurrent caries. Composite also releases no fluoride, which matters in a patient with multiple active root lesions.
• D. GLASS IONOMER is the material of choice here. It bonds CHEMICALLY to dentin and cementum without requiring a bonding agent, is far more tolerant of moisture, and releases FLUORIDE continuously — an important advantage in a high-caries-risk patient with multiple root lesions. Its lower aesthetics and wear resistance are acceptable trade-offs in this location.

Note: The underlying principle: match the material to the SUBSTRATE and the FIELD. Enamel margins with good isolation favour composite; root surface margins with compromised isolation favour glass ionomer. In a patient with multiple new root lesions, also address the cause — salivary flow, medications, diet, and consider high-fluoride toothpaste (5000 ppm) and silver diamine fluoride.