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Periodontal-Restorative Interrelationships: Ensuring Clinical Success

horizontal and vertical dimensions. Horizontal furcation involvements are defined as follows: A. Class I: Entrance into the furcation proceeds less than half of the horizontal dimension of the tooth (Fig. 3.1). B. Class II: Entrance into the furcation proceeds greater that half of the horizontal dimension of the tooth, but less than the full horizontal dimension of the tooth (Fig. 3.2). C. Class III: Entrance into the furcation proceeds along the complete horizontal dimension of the tooth, connecting both the buccal and lingual furcation entrances (Fig. 3.3).

Fig. 3.3 Class III furcation involvements are noted on both the first and second molars.

Vertical furcation involvements are defined as follows:

Fig. 3.1 Class I furcation involvements are noted on both molars.

Fig. 3.2 Class II furcation involvements are present on both the first and second molars. The greater vertical component of the furcation involvement on the first molar renders treatment of this area more problematic than the Class II furcation on the second molar.

A. Subclass a: Loss of attachment apparatus along less than 25% of the vertical component of the furcation of the tooth. B. Subclass b: Loss of attachment apparatus along more than 25% but less than 50% of the vertical component of the furcation of the tooth. C. Subclass c: Loss of attachment apparatus along more than 50% of the vertical component of the furcation of the tooth. Although the vertical component of a furcation involvement has significant ramifications in the treatment of Class II furcations, it plays a minimal role in the treatment of Class I furcations, unless the vertical involvement either extends to such a degree as to render attainment of appropriate osseous morphologies impossible, or reaches the apices of the tooth in question. In such situations, regenerative therapy or molar extraction and implant placement must be effected, depending upon the extent of the problem. Examination of the root morphologies facing involved periodontal furcations demonstrates the difficulty, and often futility, of attempting to thoroughly debride these areas through the use of curettes and/or ultrasonic instrumentation, either through a closed or open-flap approach (Fig. 3.4). Molars presenting with additional roots, whether they be fully formed or vestigial in nature, pose an even greater challenge to the treating clinician (Fig. 3.5).