Rationale and methods for crown lengthening.

Surgical crown lengthening should not be attempted when tooth fractures extend into the middle third of the root. Excessive bone reduction on the fractured tooth and necessary blending of osseous contours over adjacent teeth may result in mobility or furcation involvement. In addition, the necessary osseous surgery may create precipitous changes in the bony architecture that will be bridged by soft tissues. This results in increased pocket depth and an unhealthy situation. If the tooth in question has a hopeless prognosis or the osseous surgical procedure would create a poor crown-root ratio, furcation involvement, mobility, or esthetic problems, crown lengthening should be avoided. In cases such as these, extraction may be indicated.