Crown lengthening is a surgical procedure performed by a dentist to expose a greater amount of tooth structure for the purpose of subsequently restoring the tooth prosthetically.[1] This is done by incising the gingival tissue around a tooth and, after temporarily displacing the soft tissue, predictably removing a given height of alveolar bone from the circumference of the tooth or teeth being operated on. While many general dentists perform this procedure, they frequently refer such cases to periodontists.
The biologic width is patient specific and may vary anywhere from 0.75-4.3 mm.
Biologic width is the distance established by “the junctional epithelium and connective tissue attachment to the root surface” of a tooth.[1] This distance is important to consider when fabricating dental restorations, because they must respect the natural architecture of the gingival attachment if harmful consequences are to be avoided.
This distance is 2.04 mm (on average), of which 1.07 mm is occupied by the connective tissue attachment and another approximate 0.97 mm being occupied by the junctional epithelium.[1] Because it is impossible to perfectly restore a tooth to the precise coronal edge of the junctional epithelium, the roughly 1 mm depth of the sulcus is often included together with the biologic width when leaving a certain amount of tooth structure remaining, thus establishing a margin of safety. When restorations do not take these considerations into account and violate biologic width, three things tend to occur:
The alveolar bone surrounding one tooth will naturally surround an adjacent tooth, and removing bone for a crown lengthening procedure will effectively damage the bony support of adjacent teeth to some inevitable extent, as well as unfavorably increase the crown-to-root ratio. Additionally, once bone is removed, it is almost impossible to regain it to previous levels, and in case a patient would like to have an implant placed in the future, there might not be enough bone in the region once a crown lengthening procedure has been completed. Thus, it would be prudent for patients to thoroughly discuss all of their treatment planning options with their dentist before undergoing an irreversible procedure such as crown lengthening.
TREATMENT PLAN
Crown lengthening is often done in conjunction with a few other expensive and time-consuming procedures of which the combined goal is to improve the prosthetic forecast of a tooth. If a tooth, because of its relative lack of solid tooth structure, also requires a post and core, and thus, endodontic treatment, the total combined time, effort and cost of the various procedures, as well as the impaired prognosis due to the combined inherent failure rates of each procedure, might combine to make it reasonable to have the tooth extracted. If the patient and the extraction site make for eligible candidates, it might be possible to have an implant placed and restored with more esthetic, timely, inexpensive and reliable results. It is important to consider the many options available during the treatment planning stages of dental care.
A better alternative to surgical crown lengthening is orthodontic forced eruption, it is simple, it is non-invasive, does not remove or damage the bone and cost effective. The tooth is extruded a couple of millimeters with simple bracketing of adjacent teeth and using light forces this will only take a couple of months. A simple fiberotomy is performed after crown lengthening and is easily performed by the general dentist. In many cases such as this one shown, surgery and extraction may be avoided if patient is treated orthodontically rather than periodontally.
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