Tā de zhìchǐ ( zuì hòumian de jiùchǐ) xūyào bádiào.
His wisdom tooth (the rearmost molar) needs to be extracted.
Tips
memory
臼 means a mortar - the bowl-shaped tool used for grinding. 臼齿 are your 'mortar teeth' - the flat back teeth designed for grinding food, just like a mortar grinds grain.
