A “failed crown” is one that is no longer doing its job — protecting the tooth, sealing out bacteria and distributing biting forces predictably. At our Adelaide dental practice, Mend Dental on Glynburn Rd, we replace failed crowns regularly, often with a CEREC same-day crown so the patient does not need a second visit with a fragile temporary in between.

This post explains how we assess a failed crown, what the replacement options are, and what to expect at Mend Dental. It is written for adults in Adelaide, Firle, Payneham, Glynde, Magill and surrounding Adelaide suburbs who have been told their crown is failing.

What is a “failed” crown?

A crown is failing when one or more of its key functions is compromised:

• Marginal seal failure — decay or staining at the margin between the crown and the tooth, meaning bacteria can leak in.
• Mechanical breakdown — fracture of the crown itself (a chip or a full break), or a crack running through the underlying tooth.
• Loss of retention — the crown has come loose or fallen out.
• Cusp or tooth fracture adjacent to the crown, requiring a more extensive rebuild.
• Biological complications — decay under the crown, infection of the nerve, or gum disease around the margin.

In Australian adults, the Australian Institute of Health and Welfare’s National Adult Oral Health Survey 2017–18 reports that adults 35–54 have an average of 11.7 decayed, missing or filled teeth (DMFT), with crown-bearing teeth included. Each crown has a finite service life, and the larger and older it is, the more likely it is to be approaching failure.

What causes a crown to fail?

The main causes:

• Recurrent decay at the margin — the most common cause. Bacteria, time and a marginal gap are a losing combination.
• Cement seal failure — particularly with older glass-ionomer cements under metal-ceramic crowns.
• Crown material fracture — porcelain chipping, zirconia fracture.
• Cusp or tooth fracture around the crown.
• Endodontic complications — a tooth under a crown develops an infected nerve requiring root canal through the crown.
• Trauma or parafunction — a blow, or chronic grinding (bruxism), that overloads the crown.
• Gum recession or periodontal disease around the margin, exposing the root and compromising the seal.

How we assess a failed crown at Mend Dental A thorough assessment includes:

• Clinical examination of the crown, the tooth, the bite and the gum.
• High-resolution intra-oral photographs.
• A digital scan or impression of the area.
• A CBCT scan where there is a question of root fracture, infection or bone support.
• A bite (occlusal) analysis where the failure might be load-related.

The point is not just to find the failed crown but to understand why it failed. A crown that failed because of recurrent decay needs a different replacement plan than a crown that failed because of a vertical root fracture under it.

Treatment options for a failed crown in Adelaide

CEREC same-day replacement (our preferred option for most cases)

For adults with a failed crown where the underlying tooth is still restorable, a CEREC same-day replacement is fast and predictable. The old crown is removed, the tooth is re-prepared, scanned, and a new crown is milled and cemented — all in a single visit.

Mechanism. Old crown sectioned and removed; tooth re-prepared; digital scan; in-house mill; cement.

Evidence base. Long-term CEREC studies report 10-year survival of 90–95% in healthy non-smokers.

Ideal patient. Adults with a failed crown where the underlying tooth is healthy or restorable.

Treatment timeline. Single visit (typically 90–120 minutes).

Effect on neighbouring teeth. None.

Considerations. See our crowns and bridges service page for the materials we use.

Lab-fabricated crown (for complex aesthetic cases)

For anterior teeth or complex aesthetic cases, a lab-fabricated crown may give a better aesthetic result. The process is two visits: preparation and impression, then crown fit 2–3 weeks later.

Ideal patient. Adults with a failed crown on a front tooth where colour match and shape are critical.

Crown lengthening + crown (when there is not enough tooth above the gum)

If decay or fracture extends below the gumline and there is not enough tooth above for a ferrule, a small surgical procedure (crown lengthening) can be done to expose more tooth structure before placing the new crown.

Ideal patient. Adults with a failed crown where the underlying tooth has lost gum height.

Build-up + crown (when the underlying tooth has lost structure)

When the underlying tooth has lost structure since the old crown was placed, a bonded build-up (composite or glass-ionomer) is added first to give the new crown something to hold onto.

Extraction + implant (when the tooth cannot be saved)

When the failure extends below the gumline, when there is a vertical root fracture, or when periodontal support is inadequate, extraction is the right choice. Replacement options include dental implants, bridges, or partial dentures.

Insurance trust block: Mend Dental accepts all funds and is a preferred provider for BUPA Platinum and HCF More for Teeth. Medibank members are welcome. CDBS bulk-billing for eligible kids.

Sedation trust block: Inhalation sedation (laughing gas) is available at Mend Dental for anxious patients and longer procedures — particularly useful for crown removal where the old crown is firmly cemented.

How to choose between the options

1. Why did the old crown fail? Marginal decay → CEREC replacement. Vertical root fracture → extraction. Tooth structure lost → build-up + crown.
2. Tooth position. Posterior → CEREC. Anterior with aesthetic demand → lab-fabricated.
3. Remaining tooth structure. Adequate → direct replacement. Compromised → build-up + crown, possibly crown lengthening.
4. Patient preference. Same-day (CEREC) vs traditional (lab).

Treatment process at Mend Dental

1. Comprehensive assessment with photographs and digital scan.
2. Treatment plan with options — written, with timeline, costs and risks.
3. Old crown removal and tooth re-preparation in the same visit.
4. CEREC scan, mill and cement — new crown fitted the same day.
5. Bite check and review.

Our practice is at Unit 3/219 Glynburn Rd, St Morris SA 5068, between Bella Donna Laser Skin Body and Sunrise Speech Pathology. Phone (08) 8364 6780 for bookings.

Long-term outlook

A CEREC or lab-fabricated replacement crown, on an adequately prepared tooth in a patient with good oral hygiene, has a 10-year survival of 90–95% in published studies. The most common reasons for re-failure are similar to the original failure: marginal decay, fracture, cement seal failure and parafunctional overload.

A custom night-guard is recommended for patients who grind or clench, particularly for the new crown. How to look after a replacement crown

• Six-monthly check-ups and hygiene visits.
• A custom night-guard if you grind.
• Avoid very hard foods on the crown.
• Treat any grinding or clenching if it worsens.
• Address any gum or periodontal issues promptly.

Frequently asked questions

Can a failed crown always be replaced?

Most can, as long as the underlying tooth is still healthy or restorable. Teeth with vertical root fractures or advanced gum disease usually need extraction.

How long does a CEREC replacement crown take?

Same day, typically 90–120 minutes for the whole procedure including removal of the old crown and fitting of the new one.

Will the replacement last longer than the original?

With proper home care and regular reviews, yes — but the same risk factors (grinding, decay) apply. A custom night-guard helps if you grind.

Can I have the new crown done at a different dentist?

Yes. Mend Dental will provide records and a treatment summary on request.

Book a consultation in Adelaide

If you have a crown that is failing — chipped, decayed at the margin, loose, or causing sensitivity — our team at Mend Dental sees patients from Adelaide, Firle, Payneham, Glynde, Magill and surrounding suburbs. We are at Unit 3/219 Glynburn Rd, St Morris SA 5068 — phone (08) 8364 6780.

The first step is a comprehensive assessment. You will leave with a written plan — whether to repair, replace, or take a different approach — and why. For adults missing teeth due to past crown failures, see our dental implants service page for the implant-replacement options. Our Adelaide dentist home page sets out the full scope of our general and cosmetic services. You can request a consultation through our contact page.

Disclaimer

This article is for general information only and does not substitute for a clinical examination or a tailored treatment plan.