how does a dentist decide between a filling and a crown

Patients often ask why one tooth gets a filling and the next one needs a crown. The answer is mostly engineering. A filling repairs a hole in a tooth that is still strong. A crown (a cap) covers and holds together a tooth that has become weak.

What your dentist weighs up

• How much tooth remains. Once the decay or old filling is removed, the dentist looks at the remaining walls. As a rough rule, if more than about half the width of the biting surface is missing, or a cusp (one of the pointed corners of a back tooth) is thin and unsupported, the risk of fracture rises sharply.
• Cracks. Fine cracks spread under chewing forces. A crown wraps the tooth and resists that splitting; a filling can act like a wedge.
• Root canal treatment. Back teeth that have had a root canal have usually lost much of their internal structure and are more likely to break. Most need a core build-up and a crown. Front teeth with minimal loss can sometimes manage with a filling.
• Bite forces. Heavy grinders and people who chew hard foods like supari put more strain on large fillings.
• Where the tooth is. Molars take much more force than front teeth.
• Gum and bone health. A crown on a tooth with weak support may not be worth it; that needs assessing first.

The middle option: onlays

Between a filling and a full crown is an onlay, a lab-made piece that covers one or more cusps while preserving the healthy sides of the tooth. It is useful when a filling is too weak but a crown would cut away more healthy tooth than necessary.

Why not just crown everything to be safe?

Because a crown is not free of cost to the tooth. Preparing a tooth for a crown removes healthy enamel all round, and once done it cannot be undone. Crowned teeth can still decay at the edges and occasionally need a root canal later. If a filling can do the job, it is usually the better choice. Equally, an oversized filling on a weak molar often fails by breaking the tooth, sometimes below the gum, which can mean an extraction.

Comparing costs honestly

Our current published fees, listed in our online store, are: composite fillings from ₹3,500 (back teeth) to ₹6,000 (front teeth); onlay ₹8,000; core build-up ₹3,000; crowns from ₹3,000 (metal) through ₹9,000 (PFM) and ₹12,000 (zirconia) to ₹16,000 for an advanced aesthetic zirconia crown. The final cost is confirmed after examination. A filling is cheaper today, but a filling that breaks the tooth can cost much more later. Ask your dentist to show you the remaining tooth on the X-ray or a photograph so you can see the reasoning.

Questions to ask

• How much healthy tooth is left after the decay is removed?
• Is there a crack, and where does it run?
• What is the realistic risk if I choose a filling?
• Would an onlay work here?

See our pages on fillings and crowns and bridges.