What is the most common cause of pulpal damage during cavity preparation?

Correct answer: C. Frictional heat generated by the bur

• A. Noise is a patient-comfort issue with no bearing on pulpal health.
• B. Vibration is uncomfortable for the patient but is not the principal cause of pulpal injury.
• C. CORRECT. FRICTIONAL HEAT is the principal iatrogenic insult. A temperature rise of about 5.5 °C at the pulp is enough to cause irreversible damage, and cutting dentine dry can exceed that within seconds. Adequate air-water spray serves both as coolant and lubricant, and is the single most important protective measure during preparation.
• D. Excessive pressure contributes indirectly by generating more heat, but heat is the mechanism of damage.

Note: Heat generation rises with: no water spray, a dull bur, heavy pressure, high speed with a large-diameter bur, and prolonged continuous contact. Use light intermittent pressure, sharp burs and copious water.