Many problems can occur to damage or destroy teeth. Cavities are the most common culprit. Tooth fractures are another common complication. When decay or cracks damage a tooth, dental treatment is necessary to restore it to normal function.
This is why we call crowns, inlays and onlays “dental restorations”. They restore teeth to normal function.
Specifically, crowns, inlays and onlays are indirect restorations because the process of creating them occurs outside of the mouth. This contrasts a direct restoration, like a composite filling, in which all forming, contouring, and finishing takes place inside the mouth.
What Do Indirect Restorations Involve?
Indirect restorations involve a process of replicating the prepared tooth outside of the mouth. Dentists accomplish this replication through either a 3D digital scan or a dental impression. Both methods produce an exact model of the prepared tooth.
All indirect restorations are a result of one of two methods: CAD/CAM milling or the handiwork of a certified dental lab technician. CAD/CAM milling is a digital process that can occur either in the dental office or in the lab. Dental lab technicians make indirect restorations by hand through metal casting and porcelain stacking.
After indirect restorations have the correct shape and contour for their specific tooth, lab technician or dentist polishes them to a high shine. This prevents the buildup of plaque and food debris on the surface.
We verify the proper fit and adaptation to the tooth with a dental x-ray before permanently placing the restoration with a dental cement. All indirect restorations use cement to keep them in place.
A crown is an indirect restoration made of metal, porcelain, or a combination of the two.
A crown covers all exposed surfaces of a tooth, replacing any broken, decayed or missing pieces.
Crowns are necessary to restore a tooth when less than half of original tooth structure remains above the gums.
The most common cases requiring crowns are teeth with large, old fillings that have new decay or cracks. When the dentist removes the old filling material and the decayed or cracked tooth structure around it, very little remains to support normal function.
Rebuilding the tooth with a crown provides the necessary strength to withstand chewing forces.
An inlay is an indirect restoration that replaces a small portion of the biting surface of a tooth.
We call it an inlay because it goes into the tooth.
An inlay is an alternative way to restore a tooth that needs a filling.
An inlay made from composite or porcelain has an excellent fit inside the tooth. A perfect fit lowers the risk of cavities and breakdown at the edges of the restoration. It also creates a beautiful cosmetic restoration.
Inlays show increased strength over a traditional filling. They are easy to clean and provide a glossy surface that is resistant to plaque buildup.
An onlay is an indirect restoration that replaces a larger portion of the tooth, extending over the biting surface onto the sides of the tooth. We call it an onlay because it rests on top of the tooth.
An onlay is smaller than a crown and covers less of the tooth surface. An example of a good indication for an onlay is a healthy molar that has broken off one of its cusps. (The cusps are the raised portions on the biting surface that interlock with pits and grooves on an opposing tooth to chew food.)
Onlays consist of either metal or porcelain and completely restore the biting surface of a tooth back to normal function.