Fillings restore, crowns protect
A filling replaces missing tooth structure but does not hold the tooth together. A crown wraps the tooth and redistributes chewing force, which is what prevents a cracked cusp from splitting off.
The tipping point
Once a cavity or old filling spans more than about half the width between the cusps, or a cusp is undermined, a large filling becomes a wedge that can fracture the tooth. Teeth after root canal therapy on back teeth almost always need cuspal coverage.
Middle-ground options
Onlays and partial-coverage restorations protect the weak cusps while preserving more natural tooth than a full crown. Ask whether one is possible in your case.
Key takeaways
- •Remaining tooth structure decides, not cavity size alone.
- •Root-canal-treated molars need cuspal coverage.
- •Ask about onlays as a conservative alternative.
This article is general information, not a diagnosis. Your situation deserves an exam.