Risks and Problems

What Problems can you get with Fillings?

We were told at dental school never to call a filling ‘permanent’ because it won’t last forever and will at some point in the future need replacing. Even in a normal mouth, these materials take immense stress during chewing.

Those of you who are bruxists and grind your teeth, place your teeth under considerable extra force; teeth are much more likely to chip and fillings are more likely to break and fail. The importance of wearing a mouth guard to prevent problems cannot be emphasised enough.

Whenever you have something hot or cold to eat or drink, fillings expand and contract. Ideally this would occur at the same rate as your tooth, to help the filling maintain its integrity. Whilst technology is improving rapidly and we are pretty close to achieving this – your mouth is a hostile environment- failures do and will happen.

What are the Ways in which a Filling can Fail?

What are the ways in which a filling can fail?

Poor bonding

On occasions, fillings just fall out. It is very important when placing a white filling that moisture- that’s your saliva- and blood, are kept out during the bonding procedure otherwise the filling may simply not stick properly and come out.

This is most common with children’s teeth as they have small mouths and buckets of saliva. It can happen sometime after the filling was placed, as when the filling sets it shrinks and often even without successful bonding, this shrinking effect can hold it in place. We isolate teeth in various ways to the control moisture in your mouth and make bonding successful.

Broken fillings- fillings can need to be replaced because of:

  • Too much pressure. You can fracture or break a piece off your filling it you bite down too hard or catch it precisely at the wrong angle. Sometimes the extra pressure can be because the filling has been left high in your bite. At other times, the force is just too much for a large filling to cope with.
  • Not enough tooth. The more tooth you have available to support a filling the stronger the tooth is. Very large fillings often have quite weak walls or less surface for bonding and this makes a break more likely. In these circumstances an inlays/onlay or a crown may prove to be a better long- term solution.
  • Recurrent decay. Whilst the filling material itself will not decay (it can only wear down), the tooth around the filling can- so it is important that you see a dentist regularly to make sure that this is not happening. At every check up the dentist will check all your fillings to make sure they are doing their job and don’t need to be replaced.
  • Leaking fillings. If the sides of the filling don’t sit firmly against your tooth, the small gap can allow saliva, debris and bacteria between the filling and the tooth leading to sensitivity, staining and decay. If this occurs, when a gap is not visible or probe-able by the dentist, you may get what is called ‘micro leakage’. This generally occurs with white fillings that have not bonded properly and sealed the tooth, either because saliva contaminated the filling, or because shrinkage away from the walls occurred. Sensitivity following a filling is the most common sign and often settles after a few weeks, especially after use with a sensitive/ fluoride toothpaste. If the problem persists, the filling may need to be replaced. Amalgam corrodes naturally at the walls of the tooth but this in fact helps to seal the tooth- just because an amalgam looks a bit worn doesn’t mean it needs to be replaced.
  • Un-aesthetic fillings. Fillings rarely continue to look as good as the day they were placed, unless they are made of our dear friend ‘gold’. Wear and diet will cause them to slowly deteriorate over time and staining around the sides of white composite fillings is pretty common. This stain can come from things you are eating and drinking, from poor cleaning or because the margin is not smooth against the tooth. White fillings also often go yellower and darken with time. A good clean from your dentist can improve the staining significantly and some simple polishing and re-surfacing can often work wonders without the need to replace the filling.
  • Cracked teeth. Fillings made of both composite and amalgam filling can crack. This can occur if the cavity prepared to receive the filling is not ideal- sharp angles in walls of the cavity or there is less than the minimum thickness of material needed for strength. Sometimes the crack occurs shortly after the filling is put in- for example: if you have an amalgam and close down too hard when the dentist is checking your bite with the blue bite paper. It can also occur as a result of pressure over time.

Does my Filling need Replacing or Repairing?

It is not always necessary to replace a whole filling. Each tooth situation is different so your dentist will need to assess it and discuss the various options and materials with you. If you change dentists regularly, this will probably lead to more fillings being replaced.

Staying with a dentist for a long time and visiting them regularly allows little things to be monitored to see if they genuinely need to be replaced instead of replacing them immediately.

New dentists are unable to see how things have changed in your mouth over time, so when they first see you they might find something that looks like it needs replacing, when in fact the reality it that it has been exactly like that for a number of years.

Your choices are:

  • If it is very small and not causing or going to cause any problem, it may just be smoothed.
  • If there is a lot of decay around and under a filling, the whole filling will need replacing.
  • If part of a tooth pings off – generally the side of a molar tooth with a large filling in the middle, the tooth can often be repaired if the remaining filling is solid.
  • If the filling that remains is loose, it will certainly need taking out and replacing.
  • Repairing a white filling (composite) by bonding more composite to it or using a sticky glass ionomer cement (GIC) is often possible instead of replacing the whole thing. This is good because it preserves as much tooth as possible, however once a composite filling has been set for some time this becomes more difficult and unless some natural tooth is available for bonding, it may be stronger to replace the whole thing.
  • Repairing an amalgam, if enough tooth is present to get a good strong bond, can also be done with composite or GIC. That said, in general, I personally find it is better to repair amalgam with amalgam by cutting a little mechanical lock to hold it in place, though if you want to swap to a white filling this might be a good time to consider it.
  • If most of the tooth is gone, or is weak it may be necessary to progress to an inlay/onlay or a crown instead to restore the tooth.