A filling is the most common treatment in dentistry, and it is the one where the material choice actually matters to the person in the chair. Composite, glass ionomer, amalgam and ceramic all behave differently, cost differently and last for different lengths of time.
Most pages leave that comparison until the end, so we have put it first, because choosing between the materials is the decision you are actually being asked to make.
Which filling material suits your tooth?
There is no single material that wins on every count. The right choice depends on which tooth it is, how much structure has been lost, whether it shows when you smile, and what your budget allows.
Material | Appearance | Typical lifespan | Suits |
Composite resin | Matched to your tooth | Around 5 to 10 years | Front teeth, small to medium cavities, anywhere visible |
Glass ionomer | Slightly duller white | Around 3 to 5 years | Children, below the gum line, temporary repairs |
Amalgam | Silver | Often 10 to 15 years or more | Large cavities in back teeth, heavy chewing loads |
Ceramic inlay or onlay | Matched to your tooth | Around 10 to 15 years | Large cavities where a standard filling is not enough |
Composite resin
Composite is the material behind most fillings placed today. It is a tooth-coloured resin bonded directly to the tooth, shaped by hand and set hard with a curing light, all within a single visit.
Because it bonds to the tooth, less healthy structure has to be removed to hold it in place. It can stain slightly over many years, particularly in heavy coffee, tea or red wine drinkers, and it tends to wear faster than amalgam under heavy grinding.
Glass ionomer
Glass ionomer bonds chemically to the tooth and releases a small amount of fluoride over time, which can help protect the surrounding surface.
It is less hard-wearing than composite. That makes it a common choice for children's teeth, for cavities near or below the gum line, and as a longer-term temporary repair.
Amalgam
Amalgam is the traditional silver filling, and it remains the most durable option under heavy chewing load. Its use has declined considerably, partly for appearance and partly because more tooth has to be removed to lock it in place.
It is still occasionally the sensible choice for a large cavity in a back molar, particularly where keeping the area dry during placement is difficult.
Ceramic inlays and onlays
Where a cavity is too large for a standard filling but the tooth does not yet need a crown, a ceramic inlay or onlay can be made to fit the prepared space precisely.
These are made outside the mouth and then bonded in, which gives better strength and a more accurate bite than a very large direct filling. They cost more and usually take two appointments.
How to tell if you have a cavity
Early decay is silent, and by the time a tooth actually hurts the decay has usually reached the inner layer, which is why routine check-ups find cavities long before any symptoms do.
What you might notice
A dull ache or twinge when eating something sweet, hot or cold
Food consistently catching between two particular teeth
A rough edge or small hole you can feel with your tongue
A visible brown, grey or white mark on a tooth surface
A tooth that has become tender to bite on
An unpleasant taste or persistent bad breath from one area
What an examination picks up first
Decay between teeth, visible on an x-ray before it is visible in the mouth
Softening beneath an old filling where the seal has failed
Early demineralisation that may still be reversible with fluoride
Cracks that have let bacteria in underneath the surface
The last point in that first list is worth acting on quickly. A tooth that hurts to bite has usually moved past a simple filling.
What causes decay
Decay is the result of a straightforward process repeated many times. Bacteria in plaque feed on sugars and produce acid, that acid dissolves minerals from the enamel, and saliva gradually repairs the damage between meals.
Problems arise when acid attacks outpace the repair. Frequent snacking, sipping sweet or acidic drinks across the day, and anything that reduces saliva all tip the balance. How often you eat sugar matters more than how much you eat at once.
Dry mouth from medication is a commonly missed contributor, as are deep grooves in back teeth, crowded areas that are hard to clean, and the margins around older fillings.
What happens when a filling is placed
A straightforward filling takes around 20 to 40 minutes, while larger ones, or several placed in a single visit, will take longer than that.
Assessment. The tooth is examined and an x-ray taken if the extent of the decay is not clear from the surface.
Numbing. Local anaesthetic is given unless the cavity is very shallow, and time is allowed for it to take full effect.
Removing the decay. The softened, infected tooth structure is cleared away, leaving sound tooth behind.
Preparing the surface. The cavity is cleaned and conditioned so the filling material can bond properly.
Placing and shaping. Composite is added in layers, each one set with a curing light, then shaped to match the tooth's natural contours.
Checking the bite. You bite on marking paper and the filling is adjusted until it meets the opposing tooth correctly.
Will it hurt?
Very little in most cases, since the anaesthetic does the work here, and the injection itself is usually the least comfortable part of the whole appointment.
You may feel vibration and pressure while the decay is being removed, which is normal, though you should not be feeling sharp pain. If you do, say so and more anaesthetic can be given before continuing.
Shallow cavities confined to enamel sometimes need no anaesthetic at all, since enamel contains no nerve endings, and that is something we discuss with you rather than simply assume.
Sensitivity afterwards, and when to call
Some sensitivity to cold in the first week or two is common, particularly after a deep filling, because the nerve inside the tooth has been irritated by the work. It usually settles on its own.
Sensitivity that is easing week by week is generally a good sign and worth waiting out. Worth a phone call: sensitivity that is getting worse, pain lingering more than 30 seconds after something cold, throbbing that wakes you at night, or a filling that feels high when you bite.
Most of these have straightforward explanations and equally straightforward fixes, so please ring us rather than assuming the problem will settle by itself.
How long fillings last, and why they fail
No filling lasts for life, because every one of them has a margin where the material meets the tooth, and that margin is where decay eventually finds its way back in.
Lifespan varies with the material, but it varies more with the individual. Heavy grinding shortens the life of any filling considerably, as does a high-sugar diet, dry mouth and inconsistent cleaning. A large filling in a molar also works harder than a small one in a front tooth.
Fillings typically fail in one of three ways: the margin leaks and decay develops underneath, part of the filling or the tooth around it chips away, or the tooth cracks under load. Replacing one early is usually simple, whereas leaving a failing filling often means the next repair has to be considerably larger.
Should you replace old silver fillings?
This question comes up often, so here is a straight answer rather than a sales pitch.
An amalgam filling that is intact, sealed and causing no problems does not generally need replacing. Australian health authorities regard existing amalgam as safe, and removing a sound filling unnecessarily means cutting away healthy tooth and leaving the tooth weaker than it was.
There are perfectly reasonable grounds to replace one. Decay underneath it, a crack in the filling or the tooth around it, a broken margin, or simply disliking the look of silver when you smile. Appearance is a legitimate motivation where the filling is visible.
If you would like old fillings replaced for cosmetic reasons, we will tell you honestly which ones are worth doing, which are better left alone, and what each would cost.
When a filling is no longer enough
There is a point where a cavity is too large for a filling to be the right repair. Fill too large a space and the remaining walls of the tooth become thin enough to crack, which is a worse outcome than the original problem.
Past that threshold, a ceramic inlay, an onlay or a crown restores the tooth more reliably, because those cover and support the remaining structure rather than just plugging a hole. Where decay has reached the nerve, root canal treatment is usually needed before the tooth can be rebuilt.
None of this gets decided without showing you first. You will see the x-ray and the tooth itself. You will hear why a filling is or is not the right answer here, and get the options with costs attached before anything proceeds.
Fillings for children
Baby teeth still need treating, because they hold space for the adult teeth coming through underneath. Decay in a baby tooth can also cause pain, infection and problems for the adult tooth forming beneath it.
Glass ionomer is often used for children because it releases fluoride and is quicker to place, which matters when a child's patience is finite. Small cavities in a baby tooth close to falling out are sometimes monitored instead, and that call is made tooth by tooth.
The approach we take with an anxious child is to keep the first visit simple and unhurried. Building some trust at a check-up makes the treatment appointment considerably easier for everybody.
Looking after a new filling
Wait until the numbness has fully worn off before eating, which generally takes 2 to 4 hours
Composite is set hard immediately, so you can eat normally once sensation returns
Go gently on that side for the first day if the tooth feels tender
Clean between your teeth daily, since the margin of a filling is exactly where decay returns
Ease off very hard foods such as ice and hard nuts, which chip fillings and teeth alike
Mention any grinding, because an unprotected habit will shorten the life of every filling you have
Keep your check-ups, as a failing margin is far easier to repair when it is found early
Get a cavity checked before it grows
If a tooth has become sensitive, food keeps catching in one spot, or it has been a while since your last examination, a check-up will tell you exactly where things stand.
The number here is (02) 6241 5941, and there is an online booking form if that suits you better. Either way you will be seen at Gwydir Square.
