Furcation defect

In dentistry, a furcation defect is bone loss, usually a result of periodontal disease, affecting the base of the root trunk of a tooth where two or more roots meet (bifurcation or trifurcation). The extent and configuration of the defect are factors in both diagnosis and treatment planning.

A tooth with a furcation defect typically possessed a more diminished prognosis owing to the difficulty of rendering the furcation area free from periodontal pathogens. For this reason, surgical periodontal treatment may be considered to either close the furcation defect with grafting procedures or allow greater access to the furcation defect for improved oral hygiene.

The distance between the cementoenamel junction (CEJ) and the furcation entrance is called the root trunk length. This distance plays an important role in furcation defects because the deeper the furcation entrance is within the bone, the more bone loss necessary before the furcation becomes exposed.

For mandibular first molars, the mean root trunk length is 3 mm on the buccal aspect and 4 mm on the lingual aspect. The root trunk lengths for mandibular second and third molars are either the same or slightly greater than for first molars, although the roots may be fused.

For maxillary first molars, the mean root trunk length is 3-4 mm on the buccal aspect, and 4-5 mm on the mesial aspect and 5-6 mm on the distal aspect. As with mandibular molars, the root trunk lengths for maxillary second and third molars are either the same or slightly greater than for first molars, although the roots may be fused.

For maxillary first premolars, there is a bifurcation 40% of the time and the mean root trunk length is 8 mm from both mesial and distal.

Because of its importance in the assessment of periodontal disease, a number of methods of classification have evolved to measure and record the severity of furcation involvement; most of the indices are based on horizontal measurements of attachment loss in the furcation.

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