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Do you really need that filling?

Jun 13, 2026Dr. Dillon

When we point out an early spot of decay, the first thing many people want to know is whether it really needs fixing right now.

For a long time the answer was almost always "drill it and fill it." We now know early decay can be stopped or reversed, and we can see how far a cavity has gone. Not every spot needs a filling right away.

A cavity is a process

A cavity doesn't flip from "fine" to "needs a filling." It's a slow back-and-forth: minerals leave the enamel, and with saliva, fluoride, and time, minerals can move back in. Early on, decay is a soft or chalky spot that hasn't broken through yet, and a tooth at that stage can often re-harden. Once decay collapses into a hole, it can't grow back, and a filling becomes the right call.1 (We walk through that repair process in Can you actually reverse a cavity?.)

What we do depends on where it sits

  • Caught early, before it's broken through — we can often watch it on purpose. Rechecking an early spot at your next visit, to see whether it's stable or re-hardening, is a real plan.
  • Active, but not yet a hole — some decay can be stopped without a drill.2 We cover the gentler options, and what the evidence does and doesn't support, in When a cavity doesn't need the drill.
  • Broken through into the softer layer beneath — here a filling is the conservative choice. Waiting only lets it grow, and a small filling now heads off a root canal later.

How we decide, and why we show you

If we recommend a filling, we'll pull up the scan and show you why this tooth, and why now. If a spot is early enough to watch or help along, we'll tell you that too, even though it means less to do today. We treat the least-invasive way first. If you want a second opinion, we'll send your scans over.

If you have a "keep an eye on it" spot, ask us to pull it up on the screen next visit.

References

  1. The National Institute of Dental and Craniofacial Research (NIH) describes early decay as reversible before a cavity forms: "Enamel can repair itself by using minerals from saliva and fluoride from toothpaste." The Cleveland Clinic describes the other side: "Once a hole forms in your tooth, a dentist drills out the decayed tissue and fills the hole." A Cochrane review of in-office fluoride varnish (Marinho et al. 2013) found it produced "a 43% reduction in decayed, missing and filled tooth surfaces." NIDCR — Tooth Decay · Cleveland Clinic — Cavities · Cochrane: Marinho 2013 ↩

  2. American Dental Association, on silver diamine fluoride (SDF): it "offers the possibility of arresting or slowing progression of caries lesions in primary and permanent teeth without removal of sound tooth tissue." A Cochrane review (Worthington et al. 2024) found SDF "likely prevents new root caries" and "may help arrest caries in the primary dentition". American Dental Association — Silver Diamine Fluoride · Cochrane: Worthington 2024 ↩

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