The Christian O'Connell Show: Filling in the name of

Media item: radio segment

Programme: the Christian O'Connell show, Melbourne commercial radio

Date broadcast: 12 September 2024

Subject: dental fillings

This page records the media item. The audio is the property of the broadcaster and is not reproduced here.

No individual's dental treatment is described here, and section 133 of the National Law prohibits testimonials about clinical care in advertising a regulated health service. What follows is general information. The service page is Tooth Fillings.

The single most important thing about fillings

No filling lasts forever, and every replacement removes more tooth than the last. How long do dental fillings last? puts numbers to it.

That is the whole shape of the problem. A small filling at twenty becomes a larger one at thirty-five, an onlay or crown at fifty, possibly a root canal at sixty, and eventually an extraction. Each step is driven by the previous one, and the cycle is called the restorative death spiral in the literature for good reason. The stages of dental decay is the start of it.

Which produces two rules that are worth more than any material comparison:

1. The best filling is the one you never need. Fluoride toothpaste twice daily, spit don't rinse, and attention to sugar. On sugar, the Australian Dental Association's policy does not single out one variable — its position is that "the form, frequency, timing and total amount of sugar intake are significant in the initiation of the caries process", with particular emphasis on snacking on sugary drinks and sugar-rich foods of limited nutritional value. The World Health Organization puts a number on the quantity side: limiting free sugars to less than 10 per cent of total energy intake, and ideally less than 5 per cent, "minimizes the risk of dental caries throughout the life course". See How do I prevent dental decay?

2. Age alone is not a reason to replace a filling. A twenty-year-old amalgam that is intact, sealed and caries-free should generally be left alone. Replacing it restarts the cycle for no benefit. 'Watch and monitor' is a legitimate clinical decision — Can you reverse tooth decay & do I need a filling?

The materials

Dental fillings: porcelain, amalgam or composite resin? covers the same comparison, and Porcelain fillings and composite fillings the costs.

A note on what follows. The comparison below reflects settled clinical practice rather than a document we can quote at you. We hold no regulator statement, guideline or trial on the safety or longevity of composite resin or amalgam among our independent sources, so nothing in this section is presented as an externally established figure — and where you see a durability claim on any dental site stated as a number of years, ask what published source it came from.

Composite resin (tooth-coloured, 'white fillings')

The default in Australia now, for good reasons.

How it works: it is bonded to the tooth — chemically and micromechanically attached — which means the cavity is cut to remove disease, not cut to create mechanical retention. Less tooth is removed than for an equivalent amalgam, which is the substantive advantage. See Composite bonding and Composite bonding: will it look natural and how long will it last?

It is placed in layers and set with a blue light on command.

Realities: it is technique-sensitive — it must be kept dry while placed, which is why isolation matters. It stains and wears at the margins over years. It shrinks very slightly on setting, which is why layering technique matters. Longevity in large posterior cavities is generally shorter than amalgam, though it has improved substantially, and modern materials in well-placed small-to-moderate restorations perform well.

Amalgam (silver fillings)

Durable, cheap, tolerant of moisture, and long-lived — particularly in large posterior restorations, where its survival data remain strong.

Why its use has declined: appearance, and the Minamata Convention — an international treaty on mercury, which is an environmental instrument, not a finding of patient harm.

On safety: there is no good evidence that intact amalgam fillings harm health. Major regulators and health bodies have reviewed this repeatedly — see Dental Myths Exposed and What is holistic dentistry?

And the corollary that matters more: removing sound amalgam fillings to 'detoxify' is not supported by evidence. It destroys tooth structure, costs money, and releases more mercury vapour than leaving them alone.

Its structural drawback: amalgam is not bonded. It requires an undercut cavity for retention — more tooth removed — and it does not support the remaining cusps, which is one reason heavily amalgam-filled molars crack. See Why does a cracked tooth hurt so much? and Chipped or Cracked Teeth.

Glass ionomer cement

Bonds chemically to tooth structure and releases fluoride.

Weaker and less wear-resistant than composite, so it is not a first choice for load-bearing surfaces in adults.

Where it is genuinely valuable: root surface cavities, high-caries-risk patients, children's teeth, temporary and interim restorations (what do I do if a temporary filling comes out?), and anywhere moisture control is difficult — including community and outreach settings, and treatment for people who cannot tolerate long appointments. It was also the mainstay during pandemic restrictions on aerosol-generating procedures — Rafa's dental day at Smile Solutions.

Indirect restorations: inlays, onlays and crowns

Made outside the mouth — in a laboratory or by chairside milling — and then cemented in.

Materials: ceramic, composite, gold, or metal-ceramic. Gold remains, by durability, one of the best materials ever used in dentistry; it is used far less now purely because of appearance. What types of dental crowns are available? compares them.

When they are indicated: where the cavity is so large that a direct filling would leave thin, unsupported cusps.

Onlays and crowns cover the cusps, and on a cracked tooth that is the decision that matters most — but the evidence is more qualified than it is usually presented. The European Society of Endodontology's 2024 position on cracked teeth states that "there is no clear evidence on the most suitable restorative treatment approach", while also finding that a cracked tooth restored with a direct bonded composite "may be more likely to require root canal treatment and/or further repair of fractured restorations compared with" one managed with cuspal coverage, and that "early management, cuspal coverage restorations, and absence of deep periodontal probing depth of non-endodontic origin increase the survival rate". Its instruction on how to choose is explicit: the decision "must be tailored to each patient's unique characteristics, rather than taking a 'one fits all' approach", weighing the extent of the crack, any history of spontaneous pain, the amount of tooth left, pain on biting, existing restorations, proximal contacts, the bite and any grinding habit. See How will my cracked tooth be treated? Crowns are covered at Dental Crowns, and their cost at How much does a dental crown cost in Melbourne?

The trade: more expensive, at least two appointments (unless milled chairside), and a crown removes substantially more tooth than an onlay. The modern preference is for the most conservative option that will work — which is often an onlay rather than a full crown. See What is restorative dentistry?

What actually determines how long a filling lasts

More than the material:

What to ask

And the aftercare nobody mentions

Related pages: Tooth Fillings, Dental Crowns, General Dentistry, Fighting decay, Molar Power, and the rest of the media record.

Common questions

How would I know if a tooth is cracked?

Often you would not, which is the difficulty. A practice-based study of 2,858 cracked teeth seen by 209 dentists in the United States found that only 45 per cent were symptomatic at all; among those that were, the commonest complaints were pain to cold (37 per cent), pain on biting (16 per cent) and spontaneous pain (11 per cent). The pattern worth recognising is specific: a short sharp pain on biting something hard or clenching, which stops when the pressure is released. That is what a bite test in the surgery is trying to reproduce. The European Society of Endodontology notes that early-stage diagnosis "can be challenging due to poorly localised symptoms, which may be misdiagnosed" as other dental or non-dental problems, and that a crack is sometimes an asymptomatic, incidental finding. Finding one properly takes more than a look: existing restorations may have to come out, fibre-optic transillumination and stains such as methylene blue are recommended, and "the use of a dental operating microscope or loupes is critical in detecting dentinal cracks, as well as distinguishing them from craze lines". That last distinction matters to you financially: craze lines are confined to the enamel, occur naturally through chewing and become more prominent with age, and treatment of them "is not indicated, except for aesthetic reasons". Later signs of a real crack include tenderness when one particular cusp is tapped, a visible line on a marginal ridge, a cusp that breaks away — and an isolated, deep, narrow gum pocket beside an otherwise healthy tooth. See Chipped or Cracked Teeth and Why does a cracked tooth hurt so much?

My dentist says my cracked molar needs a crown. Is that automatic?

No, and the published guidance says so. The European Society of Endodontology's 2024 position is that "there is no clear evidence on the most suitable restorative treatment approach" for a cracked tooth, and that the choice "must be tailored to each patient's unique characteristics, rather than taking a 'one fits all' approach" — weighing how far the crack extends, whether there has been spontaneous pain, how much sound tooth remains, pain on biting, the bite and any grinding habit. What the same document does find is that a cracked tooth restored with a direct composite may be more likely to need root canal treatment or further repair than one given cuspal coverage, and that early management improves survival. So a crown or onlay is often the right answer; it is a reasoned answer, not a reflex, and an onlay is frequently more conservative than a full crown.

A crack was found and nothing hurts. Can it just be watched?

Sometimes, and the honest position is that nobody knows for how long. The ESE's statement is that "shallow cracks and/or low risk of crack propagation may be periodically reviewed", followed immediately by the admission that matters: "it remains unclear for how long asymptomatic, untreated CT can remain stable and without further crack propagation, as current studies have only monitored cracks for 1–3 years." So monitoring is legitimate, but it is monitoring on a short evidence base rather than a settled interval — which is an argument for keeping the review appointments rather than for relaxing. Two things belong in the plan alongside it: advice on managing parafunctional habits, and management of occlusal interferences to limit the crack extending, which the ESE notes may need a multi-disciplinary approach. And there is a point past which watching stops being an option: where the fragments are completely separated, or separate under pressure — a split tooth — the ESE states that it "has an unfavourable prognosis, and timely extraction should be considered to minimise the development of acute symptoms and limit bone loss." The practical reading: a watched crack is a decision with a review date, not a decision to do nothing.

A root-filled tooth of mine might be cracked. Will a cone beam CT show it?

Less reliably than you would hope, and this is the most important caveat on the whole subject: a negative scan does not clear the tooth. A systematic review of 20 studies published between 2000 and 2022 assessed how well CBCT detects vertical root fractures in root-filled teeth. Where the canal held root-filling material but no post, mean sensitivity was 71.5 per cent (SD 22.2) and specificity 75.6 per cent (SD 19.4), with accuracy 78.5 per cent (SD 17.2) — and the spread across studies is the real finding: sensitivity ranged from 32 to 100 per cent and accuracy from 40.6 to 99 per cent. Where a post was also present, sensitivity averaged 72.8 per cent (range 30 to 92) and specificity 75.4 per cent (range 45 to 100). The review's own conclusion names the weakness plainly: further clinical research is needed "given the low sensitivity, significant heterogeneity of studies, and lack of in-vivo studies on the subject" — of 17 experiments in the no-post group, only one was a clinical trial; the rest were laboratory studies on extracted teeth, which usually flatters a diagnostic test. Metal in the canal also produces artefacts that make the images harder to read, which is precisely the situation you are scanning in. So a CBCT is worth doing when it will change the plan, and it is not a test that rules a fracture out. See How safe are dental X-rays? and Root Canal Treatment

Practical details

Smile Solutions, Level 1, 220 Collins Street, Manchester Unity Building, Melbourne VIC 3000. Phone 13 13 96, or theteam@smilesolutions.com.au. Monday–Friday 8.00am–6.00pm, Saturday 8.30am–1.30pm, Sunday by appointment. Directions are on Location; enquiries go through Contact Us.

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This page records a broadcast and its date, with general information. It is not a diagnosis, a treatment plan or a promise of any particular outcome; restoration longevity varies widely with the individual case. Figures quoted are from the publishers named and apply to the populations and measurement conditions those publishers described. No individual's clinical information is published here. Third-party broadcast content is not reproduced.

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