I’ve been getting some dental work done, a bit at a time. Last week they put in my first onlay. While my mouth has had some trials throughout my life, I’ve never had a crown or an onlay. Apparently, an onlay is a permanant filling, one whole piece, molded out of porcelain or the like. They are used when a tooth has too little structure (or is too weak) for a composite filling, but there is still enough tooth left that a crown is not warranted.
In my case, I had a root canal and the removal of the pulp weakened the tooth, such that I needed extra support. So the surface of my tooth is now a bonded onlay. I am told that this is better than a crown, if the tooth structure will support it. My dentist is a big fan of conservative restorations and she tries hard to preserve as much of the tooth as possible.
My new onlay has a much “groovier” chewing surface that my other teeth, and since my bite doesn’t close on that size, she built it up a bit. It ain’t gold, but it’ll do.