Ethics & Law · patient case question
Which anatomical feature distinguishes the maxillary first premolar from the second?
Patient case: Behaviour, communication and quitting
demo: Adult patient in a health-promotion consultation
chief: Attends for a check-up and mentions he would like to stop smoking.
history: Smokes 15 cigarettes a day and has done so for twenty years. He has tried to quit twice before without support.
meds: None.
findings: Generalised staining and halitosis. No mucosal lesions on careful examination.
Show answer and explanation
Correct answer: B. A mesial concavity in the cervical third of the root and crown
- A. Both maxillary premolars have a lingual cusp; the first premolar's buccal cusp is notably longer and sharper than its lingual.
- B. Correct. The maxillary first premolar has a distinct mesial developmental depression running from the crown onto the root, and it is most often two-rooted. That concavity is clinically important because it complicates scaling, root planing and crown margin placement, and it predisposes to furcation involvement.
- C. The maxillary first premolar is most commonly two-rooted, with buccal and palatal roots, while the second is usually single-rooted.
- D. A distal marginal ridge groove is a feature of the maxillary first premolar in some descriptions but the mesial concavity is the definitive distinguishing feature.