Etiologic Factors

The primary etiologic factor in the development of furcation defects is bacterial plaque and the inflammatory consequences that result from its long-term presence. The extent of attachment loss required to produce a furcation defect is variable and related to local anatomic factors (e.g., root trunk length, root morphology)12,27 and local developmental anomalies (e.g., cervical enamel projections).^22,27 Local factors may affect the rate of plaque deposition or complicate the performance of oral hygiene procedures, thereby contributing to the development of periodontitis and attachment loss. Studies indicate that prevalence and severity of furcation involvement increase with age.^21,22,36 Dental caries and pulpal death may also affect a tooth with furcation involvement or even the area of the furcation. All of these factors should be considered during the diagnosis, treatment planning, and therapy of the patient with furcation defects.

Diagnosis and Classification of Furcation Defects

A thorough clinical examination is the key to diagnosis and treatment planning. Careful probing is required to determine the presence and extent of furcation involvement, the position of the attachment relative to the furca, and the extent and configuration of the furcation defect.³⁸ The Nabors probe may be helpful to enter and measure difficult to access furcal areas (Figure 62-1). Transgingival sounding may further define the anatomy of the furcation defect.²⁹ The goal of this examination is to identify and classify the extent of furcation involvement and to identify factors that may have contributed to the development of the furcation defect or that could affect treatment outcome. These factors include (a) the morphology of the affected tooth, (b) the position of the tooth relative to adjacent teeth, (c) the local anatomy of the alveolar bone, (d) the configuration of any bony defects, and (e) the presence and extent of other dental diseases (e.g., caries, pulpal necrosis).

The dimension of the furcation entrance is variable but usually quite small; 81% of furcations have an orifice of l mm or less, and 58% are 0.75 mm or less.5,6 The clinician should consider these dimensions, and the local anatomy of the furcation area,^11–13 when selecting instruments for probing. A probe of small cross-sectional dimension is required if the clinician is to detect early furcation involvement.

Local Anatomic Factors

Clinical examination of the patient should allow the therapist to identify not only furcation defects but also many of the local anatomic factors that may affect the result of therapy (prognosis). Well-made dental radiographs, although not allowing a definitive classification of furcation involvement, provide additional information vital for treatment planning (Figure 62-2). Important local factors include anatomic features of the affected teeth, as described next.

Root Trunk Length

A key factor in both the development and the treatment of furcation involvement is the root trunk length. The distance from the cementoenamel junction to the entrance of the furcation can vary extensively. Teeth may have very short root trunks, moderate root trunk length, or roots that may be fused to a point near the apex (Figure 62-3). The combination of root trunk length with the number and configuration of the roots affects the ease and success of therapy. The shorter the root trunk, the less attachment needs to be lost before the furcation is involved. Once the furcation is exposed, teeth with short root trunks may be more accessible to maintenance procedures, and the short root trunks may facilitate some surgical procedures. Alternatively, teeth with unusually long root trunks or fused roots may not be appropriate candidates for treatment once the furcation has been affected.

Cervical Enamel Projections

Cervical enamel projections (CEPs) are reported to occur on 8.6% to 28.6% of molars.26,27,35 The prevalence is highest for mandibular and maxillary second molars. The extent of CEPs was classified by Masters and Hoskins²⁷ in 1964 (Box 62-1). Figure 62-4 provides an example of a grade III CEP. These projections can affect plaque removal, can complicate scaling and root planing, and may be a local factor in the development of gingivitis and periodontitis. CEPs should be removed to facilitate maintenance.

Box 62-1

Classification of Cervical Enamel Projections

Grade I: The enamel projection extends from the cementoenamel junction of the tooth toward the furcation entrance.

Grade II: The enamel projection approaches the entrance to the furcation. It does not enter the furcation, and therefore no horizontal component is present.

Grade III: The enamel projection extends horizontally into the furcation.

From Masters DH, Hoskins SW: J Periodontol 35:49, 1964.

The form of the bony lesions associated with the furcation can vary significantly. Horizontal bone loss can expose the furcation as thin facial/lingual plates of bone that may be totally lost during resorption. Alternatively, areas with thickened bony ledges may persist and predispose to the development of furcations with deep vertical components. The pattern of bone loss on other surfaces of the affected tooth and adjacent teeth must also be considered during treatment planning. The treatment response in deep, multiwalled bony defects is different from that in areas of horizontal bone loss. Complex multiwalled defects with deep, interradicular vertical components may be candidates for regenerative therapies. Alternatively, molars with advanced attachment loss on only one root may be treated by resective procedures.

Other Dental Findings

The dental and periodontal condition of the adjacent teeth must be considered during treatment planning for furcation involvement. The combination of furcation involvement and root approximation with an adjacent tooth represents the same problem that exists in furcations without adequate root separation. Such a finding may dictate the removal of the most severely affected tooth or the removal of a root or roots (Figure 62-5).

The presence of an adequate band of gingiva and a moderate to deep vestibule will facilitate the performance of a surgical procedure, if indicated.

Indices of Furcation Involvement

The extent and configuration of the furcation defect are factors in both diagnosis and treatment planning. This has led to the development of a number of indices to record furcation involvement. These indices are based on the horizontal measurement of attachment loss in the furcation,14,17 on a combination of horizontal and vertical measurements,³⁷ or a combination of these findings with the localized configuration of the bony deformity.¹⁰ Glickman¹⁴ classified furcation involvement into four grades (Figure 62-6).