Cavities are one of the most common reasons people end up in a dental chair, and one of the most preventable. The good news: with modern materials, a cavity caught early is a small, predictable filling that lasts years. At Dentist Pymble, we treat tooth decay for patients across the Ku-ring-gai region, and the conversations we have are almost always about whether it had to happen and what the best way is to fix it. This page covers what causes cavities, the treatment options, and the practical habits that keep them from coming back.
What causes cavities?
Cavities are caused by acid-producing bacteria in plaque that sit on the tooth surface. Every time we eat or drink anything containing sugar or starch, those bacteria ferment the sugars and produce acid as a by-product. The acid dissolves the minerals in enamel — a process called demineralisation. Saliva gradually neutralises the acid and starts putting minerals back, but if acid attacks happen more often than the saliva can repair, the enamel eventually breaks down into a cavity.
The four big drivers are sugar and acid in the diet, poor or inconsistent oral hygiene, dry mouth (which reduces saliva’s protective effect), and a lack of regular preventative dentistry such as fluoride treatments and fissure sealants. Tooth decay remains the most common preventable disease in Australia, affecting around one in three adults, and the picture is similar for children. The encouraging part is that the prevention toolkit is well established and works.
How do I know if I have a cavity?
The honest answer is that you often don’t, particularly in the early stages. Early decay is usually painless and only visible on an x-ray or as a chalky white spot on the tooth. As it progresses, the classic signs kick in: sensitivity to hot, cold, or sweet things; a dark spot or hole you can see or feel with your tongue; food packing in a particular spot; and eventually, a toothache that wakes you up at night.
By the time a cavity is causing pain, the decay has usually reached the dentine or the nerve, and the filling gets bigger or the tooth needs more involved treatment. This is why regular check-ups and cleans every six months are the single most useful thing — small cavities picked up on x-ray cost less, hurt less, and last longer.
How are cavities treated in Pymble?
Treatment depends on how far the decay has progressed. In the very early stages, before a true cavity has formed, we can sometimes halt or reverse the damage with fluoride, dietary changes, and better oral hygiene. Once a cavity has formed, the decayed tissue needs to be removed and the missing structure replaced with a filling. For most everyday cases — small to medium cavities — a direct composite filling is the right answer. The decayed tissue is removed with a bur, the cavity is shaped, an adhesive is applied, the composite is placed in layers and light-cured, and the restoration is polished to match the bite.
For larger cavities, particularly those that have undermined a lot of the tooth, a direct filling is no longer strong enough. The right answer is an inlay, an onlay, or a crown — a stronger, lab-made restoration that covers and protects the remaining tooth. If the decay has reached the nerve, a root canal plus a crown is usually required to save the tooth. We will always show you the x-ray and the tooth in the mouth before recommending a path, and we will give you a written treatment plan with item numbers and costs so you can make the call without any surprises.
Tooth-coloured fillings vs silver fillings
Most of the fillings we place at our Pymble practice are tooth-coloured composite. Composite bonds directly to the tooth, which means we can preserve more natural structure, and the result is essentially invisible. The main trade-off is that the placement is more technique-sensitive and takes a few minutes longer than an amalgam filling.
Silver (amalgam) fillings are still used in some situations — particularly for very large cavities in back teeth where moisture control is hard, or where the patient prefers them for cost reasons. They are extremely durable, but they are also more visible and require more healthy tooth to be removed to hold them in place. The honest answer for a Pymble patient: most people do best with composite in the visible parts of the mouth and amalgam only where it is genuinely indicated.
Can a cavity heal on its own?
True cavities — where the enamel has physically broken down and a hole exists — cannot regrow. They need to be filled. What can heal is the early stage of decay, when the enamel is demineralised but has not yet cavitated. At that point, fluoride, better brushing, and dietary changes can put minerals back and stop the lesion from progressing. This is what we mean when we say “we are watching that spot” — it is a real thing, and it works for the right lesion in the right patient. Once a hole is visible on an x-ray or in the mouth, however, the answer is a filling.
How much does a filling cost in Pymble?
The cost depends on the size of the filling, the material, and the tooth. A small one-surface composite runs at the lower end; a large multi-surface restoration on a back tooth is more. We will always provide a written quote and a health-fund check on the day, and the team can talk through the item numbers from the Australian Dental Association schedule so you know exactly what you are paying for.
How can I prevent cavities?
The basics, done consistently, are most of the battle. Brush twice a day with fluoride toothpaste, floss or use interdental brushes daily, drink tap water where it is fluoridated, limit sugary and acidic drinks (especially between meals), and see your dentist every six months for a check-up and clean. For children, fissure sealants on the permanent molars reduce the risk of decay in those teeth by up to 80% in the first two years, and they are a routine part of our children’s preventative dentistry service at the Pymble practice.
If you live in Pymble, Gordon, Turramurra, Wahroonga or anywhere else in the Ku-ring-gai area and you want a check-up or you have a tooth you are worried about, call our practice. We see neighbouring Gordon patients and other nearby residents, and we will always be straight with you about what is actually wrong and what the right next step is.
Frequently asked questions
How do I know if I have a cavity? Often you can’t, which is why regular check-ups matter. Symptoms like sensitivity to hot, cold, or sweet, a dark spot, food packing, or a toothache are all late signs. By then, the decay is usually more advanced.
Is a cavity a dental emergency? Most cavities are not emergencies and can be treated at a routine appointment. They become emergencies when there is severe pain, swelling, or a broken tooth with exposed nerve. If any of these apply, call our Pymble practice for a same-day slot.
Does it hurt to get a filling? No. The tooth is numbed with local anaesthetic, and most patients feel nothing more than some pressure and vibration. After the appointment, the tooth can be a little tender for a day or two, particularly if the cavity was deep.
How long does a filling last? A well-placed composite filling typically lasts 5-10 years, sometimes longer. Amalgam tends to last longer still. The lifespan depends on the size of the filling, your bite, your oral hygiene, and whether you grind your teeth.
Can children get tooth-coloured fillings? Yes. Composite is the standard filling material for children and adults at our Pymble practice. For very small cavities or baby teeth, other materials may be appropriate, and we will always discuss the options with you.