• Sanutm Sutdhibhisal
• Suphot Tamsailom
• Sukanya Wanmahinthara
• Vipawee Bunruang

Objective: The purpose of this investigation was to study the morphology of bifurcation roof of mandibular first molars which cause difficulties in periodontal instrumentation and plaque control in teeth with furcation defects.

Materials and Methods: One hundred mandibular first molars were randomly selected from a collection of extracted human teeth. These molars were examined for the prevalence three morphologies of bifurcation roof: the intermediate bifurcation ridge, the bifurcation roof concavities and the flat bifurcation roof. Then, the dimensions of bifurcation roof were measured using the Digimatic Indicator by two examiners.

Results: Statistical analyses revealed that the intra-examiner and inter-examiner reliabilities were highly correlated (r = 0.9336; p < 0.001 and r = 0.9272; p < 0.001 respectively). The prevalence of the intermediate bifurcation ridge of mandibular first molars was 62% and the prominence of the ridges presented an average of 0.72 ± 0.42 mm and two distinct small pits were found in both lateral sides of the ridges. The distance from the buccal furcation entrance to the highest of the prominence of the ridges was at the average of 2.77 ± 0.36 mm. The prevalence of the bifurcation roof concavities was 4% and the depth of the concavities presented an average of 0.59 ± 0.09 mm. The distance from the buccal furcation entrance to the deepest of the concavities was at the average of 2.42 ± 0.86 mm. The flat bifurcation roof was found in 34% of the sampled teeth.

Conclusion: This study showed the complicated morphology of bifurcation roof which should be considered in the treatment of furcation lesions of the mandibular first molar.

(CU Dent J. 2006;29:119-126)