Often time patients and dentists are left to answer the above question. Dentists have been trained to keep teeth as long as possible, however there are certain clinical conditions where teeth cannot be saved. This a 3-part blog series that will examine the structural, periodontal and esthetic determinates of saving or extracting a tooth.
Structural & Periodontal
The structural issue relates to the amount of remaining tooth structure above the gums. There is a minimum biological space requirement between the proposed restoration margin and the bone level. This is called “Biological Width” (Figure 1) and it describes a peripheral gum “seal” around our teeth that measures on average 2mm. When there is less than 2mm between the apical extent of the cavity and the bone level, nature will try to reform these dimensions by way of an inflammatory (swelling and bleeding) reaction. If a cavity is deep and it extends close to the bone crest, it is often more practical to extract than to save the tooth. Additionally, when a tooth has a deep cavity and it extends to the nerve of the tooth, it may require root canal therapy. Many teeth that receive root canal therapy may require a post and core build up to replace the missing tooth structure from the deep cavity and the access hole placed into the tooth to reach the nerve. In order for a properly designed crown restoration, there must be an adequate “Ferrule” (Figure 2) defined as the amount of tooth structure between the margin of the crown and the margin of the build-up material. Based upon research and literature, there should be a minimum of 1.5mm -2mm of ferrule above the gum line and previously described biologic width, to ensure structural strength for long term retention and health of the permanent crown and tooth.
Sometimes there may not be this 2mm ferrule to properly retain a crown. A separate surgical procedure called “Crown Lengthening” (crown extension) can be completed, where tissue and bone gum are removed to obtain the proper ferrule on the tooth above the gum line. This surgical procedure to expose adequate tooth structure could compromise the gingival esthetics, especially on front teeth. Although, it may be possible to perform crown lengthening, the bigger question is what will the final tooth form look like if the surgical procedure is performed? If the proposed surgical procedure will not significantly alter the gingival esthetics on the compromised and adjacent teeth, it may be an acceptable way to save the tooth. On the other hand, if the gingival esthetics will be compromised, it may be best to remove the tooth and replace it with a dental implant. Dental implants can be a better long-term tooth replacement option that can preserve both the bone and gum tissue around the adjacent healthy teeth resulting in a higher esthetic result.
In summary, by understanding both the structural, periodontal and esthetic requirements to retain a tooth, one can make the best decision for themselves. When the decision is made to save or extract a tooth, it may require a multi-disciplined approach involving specialists to solve your specific need. We at PDG are specialists who routinely manage these types of cases and work together with dentists in the community to achieve a long term functional & esthetic result. In the next two parts of this blog, we will show clinical cases describing the results of these different choices. Your partner in dental health, Dr. Tassos Sfondouris.