Inlays and onlays are examples of what we call an “indirect” restoration i.e made outside the mouth and then glued in, as opposed to a filling that is placed directly in the mouth.
There are a number of advantages because they are “laboratory made” and are a very effective way to restore your tooth, particularly if a large amount of tooth has been lost.
An inlay as the name suggests sits inside the tooth as opposed to an onlay that sits on top of a tooth replacing some or all of its biting surface – this is quite similar to a partial coverage crown.
They are both generally used in posterior teeth, that is your premolars and molars.
Why would I need an Inlay/Onlay?
Inlays and onlays are used instead of fillings or crowns for numerous reasons, such as:
- To restore a large cavity and weakened tooth due to dental caries, failed fillings or a cracked tooth
- Instead of a filling such as composite
- Instead of a crown, as inlays/onlays are less invasive and require less tooth preparation
- To avoid root canal, post and crown in case insufficient tooth is present
- In deep cavities that go under the gum level to ensure a good marginal seal.
What types of Inlay/Onlay are available?
- Porcelain (of which there are different subtypes)
Most inlays are now made of porcelain, as the desire for more natural looking teeth increases and the ability to bond these restorations to your tooth improves.
How long do Inlays/Onlays last?
Inlays and onlays are regarded as a long term solution for restoring your teeth. In general they would be expected to last a similar number of years to crowns (around 10-15 years) and considerably longer than conventional fillings – provided you have good oral hygiene.
What are the advantages of an inlay/onlay?
- Appearance They have a very attractive and natural appearance, unlike silver amalgam and are much less prone to picking up stain and discolouring than white filling materials. The porcelain cannot only be shaded to mimic the natural tooth but the patterns on the biting surface can be recreated with a little staining added effect.
- Strength They are not as destructive to the remaining tooth as crowns and by preserving much of the natural tooth, they increase the strength of the tooth.
Wear The materials used to make the inlays/onlays are extremely durable and will not wear like fillings, even under the stress of grinding.
- Decay They are less prone to decay at the margins because they are custom fit and they achieve a good seal.
- Durability They are more durable and last longer than fillings.
- Hygiene Because they are custom made for individual teeth, they do not trap plaque in the same way as fillings and can this be easier to keep clean.
- Stability They don’t expand and contract in the same way as filling materials reducing the stresses on the tooth.
During the first visit, the tooth/teeth will be prepared; this involves reshaping the tooth/teeth and removing any decay or reshaping a fractured tooth to allow the inlay/onlay to be placed. Impressions are taken, these will allow the laboratory to construct your inlay/onlay. Your dentist will place a temporary filling to protect your tooth/teeth while your inlay/onlay is being made.
During the second visit, your temporary filling will be removed and the new inlay/onlay will be checked and adjusted if needed. Then the dentist will bond the restoration in your tooth.