In cases where a patient’s tooth has extensive decay or has been fractured, a typical amalgam (silver) or composite (tooth-coloured) filling is inadequate to secure the structural integrity of the tooth. In such cases an inlay or onlay is used to restore the tooth. This type of filling is called an indirect restoration and is fabricated from a mold as opposed to a direct restoration such as the fillings mentioned above.
Inlays and Onlays are essentially the same and there is little difference except for what part of the tooth they fill in or cover. As in the name implies, an inlay fills the center of the tooth between the cusps, which are sides or raised parts of your tooth. An onlay will cover a larger part of the tooth and will include the cusp, typically used to repair a chipped tooth or fracture.
Inlays can be made of material such as gold, porcelain, or a cured composite resin. While porcelain materials are improving and are becoming stronger, gold has a great track record for durability and has been used for many years. Inlays and Onlays offer superior resistance to occlusal forces (biting) and protection from further decay. A direct filling usually shrinks when cured which can be completely avoided by choosing an inlay.
An inlay is used when there is no damage to the cusps of the tooth and the inlay can be placed right on the tooth. An onlay is used when the damage is a little more extensive, such as cuspal fracture.
Inlays and onlays are often referred to as partial crowns. They use the existing tooth as a base and fit the inlay or onlay onto the tooth. This is done to strengthen the tooth, restore its shape, and prevent further damage. Inlays and onlays can last from 20 to 30 years, making them a very reliable option for restoring your teeth. In fact, inlays / onlays allow for great conservation of the healthy part of the tooth.
Inlays or Onlays Procedure
The procedure for getting inlays or onlays to repair a cavity usually involves two visits to your dentist. During your first visit, the decayed area of the tooth is first removed during the procedure. If the cavity is large this may take a little longer as your dentist will want to make sure all infected parts of the tooth are removed. Local anesthetic may be used to help numb the tooth and eliminate any discomfort. A mold of the tooth is then taken and sent to a dental lab.
The lab will then create a restoration made from porcelain, gold, or a composite resin. The restoration takes about 2-3 weeks to make, so a temporary inlay or onlay will be placed on the tooth for that time. It is important to take care of the temporary onlay by avoiding lifting it or eating foods that might displace it. If the temporary onlay is removed it may expose nerves and cause pain.
During your next visit your dentist will remove the temporary inlay or onlay. The permanent inlay or onlay will be placed into your mouth and set with cement. Your tooth will look natural and you or anyone else won’t be able to tell the difference.
This is a very reliable and durable restoration and will last you many years.