Trimac Dental Centre offers a variety of dental treatments performed by general dentists. The information below is formatted for your printer so you can have this information on hand. Click the button to the right to view an animation of the procedure.

Inlay       Onlay

An inlay or onlay is a type of tooth restoration that restores the broken and/or decayed tooth back to its original form and function. This conservative restoration allows the dentist to make the tooth strong and also preserve the remaining tooth structure. Most fillings are made in the mouth by packing and curing filling material into a cavity in the tooth. This process is adequate for smaller fillings but when a larger filling is fixed there are problems that arise leading to questionable fit and longevity. Inlays/Onlays are made out of the mouth and then cemented or adhered into place. Thus the fit of an inlay or onlay is very accurate and extends the longevity of the restoration. The strength and properties of the inlay/onlay (modulus of elasticity � coefficient of expansion) are similar to natural tooth structure which improves the marginal integrity (fit of edges) of the restoration. The compressive and tensile strength are also better then composite resin fillings. Trimac Dental Centre does not place amalgam fillings due to the mercury content (50% mercury). Inlays/onlays are great restorations for those teeth that are too large for typical white composite fillings (cured in the mouth). Many times an inlay or onlay can be placed instead of a crown. This also makes some root canals unnecessary since the inlay/onlay can be hermatically sealed and bonded against very little tooth structure.

What is the difference between an inlay and an onlay?
An inlay sits inside a tooth. An onlay partially covers the top of the tooth and replaces one or more of the cusps of the tooth. A onlay is typically a bigger inlay that covers one or more of the cusps.

Why can you avoid some root canals doing inlay/onlays?
When placing crowns, many times if there is little tooth structure left above the gum then we do an elective root canal therapy to make space for a post and core. The post and core is used to keep the crown in place since it is "cemented" instead of "bonded". Since the success of inlays/onlays restorations is dependant upon the bonding the inlay /onaly with an assortment of new dental materials it opens a new area to do conservative dentistry. Quite typically a root canal can be prolonged for many years or completely avoided by placing an inlay/onlay. Furthermore the structural integrity of the tooth is maintained since the root canal procedure does take away some of the internal root structure. Your dentist will assess the root canal potential before doing an inlay/onlay by taking an x-ray to see if the canal looks problematic and by doing testing to check the health of the tooth. A root canal can always be completed at a latter date through the inlay/onlay if the tooth becomes abcessed.

How are they different then composite plastic fillings?
The porcelain inlay has an elasticity very similar to enamel. When the tooth is biting then it flexes back and forth. The porcelain filling flexes very similar to the tooth. This helps to support the edges of the tooth that are in contact with the inlay/onlay. The porcelain also offers a precise fit that does not have any shrinkage upon curing. Composite plastic filling shrink slightly due to the polimerization (hardening process) process.

What are Inlays/Onlay made of?
Inlays can be made of:
1. Porcelain
2. Resin
3. Gold

Are the materials safe to use in the mouth?
Yes the fillings are inert and very safe. They contain no mercury or silver. The porcelain and indirect resin fillings are tooth colored. The gold fillings are gold!

How many appointments does it take for inlays and onlays?
Porcelain inlays and onlays can be made in one visit using the CEREC computer machine. Resin can also be used in the CEREC. The fit of these restorations is extremely accurate (42 microns = marginal fit). Gold inlays and onlays take 2 visits to fabricate. An impression is taken and the dental lab will fabricate the restoration typically within two weeks. Gold inlays/onlays are great for heavy grinders.