Choosing Between Onlays and Dental Crowns

There are a variety of restorative treatments for damaged and decayed teeth. For instance, dental crowns and onlays can restore teeth that have damage that is too extensive for fillings to address. Understanding the basics of each can give you a better idea of which option a general dentist is likely to recommend and why.

Dental crowns: What to know

A dental crown fits over a tooth, engulfing the entire structure. Their cap-like design makes crowns effective in restoring extensively damaged teeth, such as those damaged by tooth decay, dental abscesses, chips, or cracks. This also makes them an effective restoration for root canal-treated teeth. A general dentist typically has several crown options available, such as:

• Metal crowns. Such as silver crowns that contain an amalgamation of metals.
• Porcelain-fused-to-metal (PFM) crowns. Have a metal center and porcelain coating, combining maximum durability with a natural appearance.
• Pressed ceramic crowns. A nonmetal version of PFM crowns with a center of layered ceramic.
• All-ceramic crowns. Comprising ceramic materials, which the dentist closely matches with the surrounding natural teeth.
• All-resin crowns. Intended to be used as temporary crowns, as they comprise composite resin.

Each dental crown is custom-made for the patient to ensure a proper fit. An off-site dental lab fabricates all dental crowns except for all resin crowns. Thus, the general dentist often places an all-resin crown on the tooth until the permanent crown is ready. Most patients will need to wait a week or two for permanent crown placement.

What is an onlay?

Also known as 3/4 crowns, dental onlays restore teeth that have sustained damage to one or more cusps, the pointed part of a tooth. An onlay is another excellent choice for teeth damaged too much for a dental filling but not enough for a dental crown. They can comprise various materials, from silver and gold (i.e., metal) to porcelain.

However, like crowns, an off-site dental lab must fabricate the custom onlay. As a result, patients will need two appointments — one to take an impression of the tooth to create the onlay, then another in about two weeks to cement the onlay into place.

The bottom line

Whether a general dentist recommends an onlay or a crown typically depends on the extent of the damage. Both options restore a tooth's shape, rendering it fully functional. Additionally, restoring the tooth with either option protects it against further damage.

However, patients sometimes have a tooth that falls into a gray area and, therefore, could benefit from either an onlay or a crown. Patients looking for a more conservative treatment may prefer an onlay in these cases. Those looking for a longer-lasting, more comprehensive restoration may prefer a dental crown.