Crown lengthening is used by dentists to increase the amount of tooth that is available for placing a crown on. Because this tooth needs a root canal, it probably is structurally going to be weak due to the access of getting to the canal and needs to be protected by a crown. Your tooth is probably a bit short (or the cavity is so large that there's not enough tooth left), so a crown lengthing procedure is recommended.
Crown lengthening can be done in two ways. The most common way is to surgically open the tissue and remove some bone. After removing the bone, the tissue is sutured back up and allowed to heal. The gums will recede to where the new bone height. Since the gums have receded, you have more access to the tooth for a crown.
The other way to crown lengthen is to place orthdontic brackets in place and pull the tooth out of the socket a little bit more to give more tooth structure. This isn't usually done but is a type of crown lengthening as well.
Generally the pain isn't too severe. I would probably expect your doctor to give you something like tylenol with codeine. 2 x 500mg of Tylenol may do the trick but it never hurts to have a strong prescription available in case you need it. The healing takes about 4-6 weeks I believe and then they should be able to start the crown.
You're welcome.
I wouldn't expect too much discomfort from a crown lengthening procedure. Also, as a dentist, we know that what we do is uncomfortable and we're usually very sensitive about the discomfort we cause. We don't want you to hate us so I'm sure he'll provide adequate pain medication and instructions afterwards.
Thank u so much 4 taking the time 2 explain everything 2 me{& he wrote down hard tissue} I feel so much better & less anxious about doing this :) I'm usually not so anxious but last time the told me an Apicoectomy wouldn't b so bad after lol so that's why I always ask around ;)