FURCATION MORPHOLOGY RELATIVE TO PERIODONTAL TREATMENT - FURCATION ROOT SURFACE ANATOMY

Internal furcation root surface morphology was studied in a sample of 114 maxillary and 103 mandibular first molar teeth sectioned transversely at a level 2 mm apical to the most apical root division. The morphology was found to be complex. The most significant findings were: Maxillary first molar teeth. The furcal aspect of the root was concave in 94% of mesiobuccal roots, 31% of distobuccal roots, and 17% of palatal roots. The deepest concavity was in the furcal aspect of the mesiobuccal root - mean concavity 0.3 mm. The furcal aspects of the buccal roots diverge toward the palate in 97% of teeth - mean divergence 22°. Mandibular first molar teeth. Concavity of the furcal aspect was found in 100% of mesial roots and 99% of distal roots. Deeper concavity was found in the mesial root (mean concavity 0.7 mm) than the distal root (mean concavity 0.5 mm). The maximum internal mesiodistal dimension of the furcation was larger than the mean mensiodistal root separation at the buccal and lingual (mean difference 1.2 mm). Wider root separation is associated with larger furcation entrance diameter. Little indication of internal furcation morphology can be gained from mesiodistal tooth size. The distribution of cementum over the furcal aspects of the roots was studied in a sample of 92 maxillary and 85 mandibular first molar teeth which are also part of the former sample. The most significant findings were: Cementum distribution was not uniform. Teeth with concavity of the DCJ toward the furrcation have more cementum over the concavity than over the adjacent convexities. Greater concavity of the DCJ is associated with increased net reduction of concavity due to the presence of cementum. The likely significance of such complex morphology on instrumentation and plaque control in the furcation has been discussed.