What are dental inlays and onlays, and how do they differ from fillings or crowns?

Inlays and onlays serve the same purposes as a filling or a crown: to protect your tooth after damage or decay while restoring its shape and function. However, there are some key differences:

• Fillings are used to fill small cavities, and crowns are used when a large portion of the tooth needs to be protected, such as when the tooth has broken or there is deep decay. Inlays and onlays are perfect for the “in-between” cases where a filling would be too small, but a crown is too intensive.
• A filling is typically made from composite resin placed in your tooth during the same visit that the decayed/damaged area is removed. Inlays and onlays are more like dental crowns in that the tooth is typically prepared in one visit, and dental impressions are used to fabricate your custom restoration out of high-quality dental porcelain in a laboratory. After it is ready, you then come back into the office to have your final restoration placed.
• Inlays and onlays preserve more of your natural tooth than a crown and can often be adjusted or repaired over time if needed, whereas crowns are more difficult to repair because the natural tooth is less stable.
• While they cost more than fillings due to their larger size, inlays and onlays tend to be much less expensive than a crown while offering many of the same benefits.