Patient age 35, routine exam. Tooth #30 has a small, shallow amalgam restoration that does not contact the opposing tooth. The amalgam appears fractured clinically but NOT on X-ray. What is the MOST LIKELY cause of restoration fracture, EXCEPT:

Correct answer: A. Hyper-occlusion

• A. Correct (the exception). Since the restoration does NOT contact the opposing tooth, hyper-occlusion (excessive occlusal contact/loading) cannot be the cause of its fracture.
• B. An inadequately thick, shallow, or poorly designed restoration IS a plausible cause of fracture, independent of occlusal contact.