Furcation entrance anatomy of the fourth maxillary premolar in dogs.

Tooth surface and interradicular area (furcation) measurements were determined for 20 fourth maxillary premolar teeth obtained randomly from canine cadavers. The palatal furcation entrance had a mean width of 1.2 +/- 0.1 mm. The coronal roof of the palatal furcation was located at the cementoenamal junction (CEJ). The buccal furcation entrance had a mean width of 0.9 +/- 0.2 mm. The horizontal attachment area between the CEJ and the coronal roof of the buccal furcation was 1.3 +/- 0.3 mm. The mesial furcation entrance had a mean width of 0.4 +/- 0.1 mm. The horizontal attachment area between the CEJ and the coronal roof of the mesial furcation entrance was 1.7 +/- 0.3 mm. The mean coefficient of variation for variables measured was 10.3%. Tooth size did not have a significant effect on furcation entrance measurement. All teeth had a fluted area between the CEJ and mesial furcation, a concavity coronal to the furcation area, a distal concavity of the mesial root trunk between the mesiopalatal and mesiobuccal roots, and a mesial furcation concavity of the distal root extending apically for a mean distance of 60% of the distal root length. The complexity of furcation entrance anatomy may be a factor in the manifestation of periodontal disease involving the furcation of the fourth maxillary premolar in dogs.