What is crown lengthening?

Actually this question can be a bit confusing. To understand it fully one must understand the terms. First, what is a crown? A crown is what dentists refer to as the visible tooth structure. So if you look in the mirror what you see are the crowns of the teeth. It is whatever is visible, so even if there is a short tooth or a longer tooth, what is visible is referred to as a crown.

Secondly, there is gum tissue or more specifically gingiva. Gum tissue covers portions of the tooth and the bone of the jaws. Sometimes there is excess gum tissue which a dentist can remove either with a laser or with a scalpel. This is NOT crown lengthening. While it will expose more crown and "lengthen" what is visible it is actually a procedure known as a gingivectomy (gin gi vec toe me). This simply means to remove gingiva or gum tissue. It may be done for cosmetic reasons, to access decay below the gum line, or to remove excess unhealthy tissue.

Finally, there is bone which holds the teeth in place. This is where actual crown lengthening is performed. When a tooth fractures it may fracture at the gum line or below. In order to fix or restore the tooth properly with a crown or cap, more tooth must be exposed or lengthened. To do so bone is removed from around the tooth. When the gum tissue heals it does so to the new lower level of the bone and lower than its original level. Therefore more tooth is now visible and hence the crown has been lengthened. 
Hyun J. Song, DDS
Crown lengthening is done to help retain crown longer. To give a "ferrule- more tooth structure" so that the crowns can stay longer and healthier.

Sometimes, it is done for the esthetic purpose to make a square looking tooth more natural in younger population after orthodontics.
Crown lengthening surgery (CLS) is a procedure that is done to uncover healthy tooth structure that is buried under the gumline. Sometimes it is done to change a "gummy smile" into a more esthetic smile that has a better balance between teeth and gums. Short, square teeth are not as pretty as teeth with a "golden proportion" ratio (about 3 units wide to 4 units tall). Esthetic crown lengthening can be the key to a more confident and beautiful smile. This is a form of plastic surgery, and is often (but not necessarily) done by a periodontist who specializes in gum treatments.

Crown lengthening may also be done to save a badly damaged tooth that would otherwise need to be extracted, or a short tooth that lacks the needed space for restoration. Broken or decayed teeth that have damage extending under the gumline often cause trouble with the gums in that area -- this is called a "Biologic width invasion" or BWI. When your dentist sees that the restoration of your tooth will cause a BWI, then you will be advised to have CLS. This service will enable you to avoid the unpleasant consequences of a BWI (BWI feels like you have a splinter under your gums; the pain and inflammation doesn't go away without treatment). Many teeth that would have to be extracted in the absence of CLS are saved by restorations that can only be done after CLS. This is a good mainstream treatment and it should always be considered before a tooth is extracted. That said, there are some limitations to what can be accomplished with this technique -- so ask about the risks, benefits, and alternatives that may apply to your particular situation and then make an informed decision about whether this treatment is right for you.
Some people have a "gummy smile" in which their teeth look too short. For these people, crown lengthening could help. A periodontist can remove excess gum tissue to reveal more of your natural teeth. This can dramatically improve your smile by exposing more of your teeth.
Crown lengthening is a periodontal (gum) procedure to increase the amount of tooth structure above the gum. This is necessary to have adequate tooth structure available to retain and support a crown (cap) that is being placed.

If crown lengthening is indicated it may also be necessary to build up the tooth (often with reinforced composite resin) above the newly exposed tooth structure. This is important for retention and to be able to fabricate a crown in the usual manner.

If crown lengthening is indicated but not performed, the crown would be seated only on build-up material, and it would not have sufficient grip on solid natural tooth structure to prevent fracture.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.