Clinical significance of furcation anatomy of the maxillary first premolar: A biometric study on extracted teeth
The purpose of this study was to determine the frequency of bifurcation, the proximity of bifurcation to the CEJ, the depth of concavities on the root trunk and the furcal aspect of the root, the diameter of the furcation entrance, and the extent of root divergence.
One hundred maxillary first premolars were selected at random from a collection of extracted human teeth and identified based on the crown and root morphology. The following measurements were taken: distance from the CEJ to the furcation, distance from the furcation to the apex of the root, and distance from the CEJ to the apex of the root. The depth of the concavity on the root trunk was measured using a digital gauge. The width of the furcation entrance and the extent of the root divergence also were determined using a profile projector. The results showed that 63 out of 100 teeth had fused roots and 37 had bifurcated roots. The position of the furcation in relation to the CEJ and its level on the root was evaluated on 37 teeth. Of these, 13 (35%) had bifurcation at the apical third; 14 (38%) had bifurcation at the middle third; and 10 (27%), at the cervical third. The minimum length of the root trunk (CEJ to furcation) was 4 mm and the maximum was 14.6 mm. The mean length of the root trunk was 7.9 mm on the mesial and 7.6 mm on the distal. The minimum root length recorded was 10 mm and the maximum was 17.1 mm. The teeth had deeper concavities on the mesial than the distal aspect. The concavities on the cervical third were significantly deeper on the mesial aspect than on the distal; however, the depth of the concavity was more or less the same on the mesial and on the distal of the middle third. A furcation concavity was seen on the palatal aspect of the buccal root in 62% of the teeth with bifurcated roots. The mean depth was 0.46 mm. No such concavity was seen on the palatal root. The furcation width was 0.71 mm; the mean root divergence was 3.0 mm.
In conclusion, the concavities on the root trunk and furcation concavities act as niches for plaque and calculus. These areas are not reached by scaling and root planing. Maintenance of these areas after treatment is also difficult. In the present study, 21 of the 37 teeth with bifurcated roots (57%) had a furcation entrance of less than 0.75 mm. This implies that the standard Gracey curette may not be suitable for this area, and a miniature variety may be needed for thorough root planing. [C.C.]
Joseph, I., B.R.R. Varma, and K.M. Bhat, J Periodont, 67:386,1996