Use of cone beam imaging to assess inter-root distance in molar furcations

This study used cone beam computed tomography (CBCT) to evaluate distances among root surfaces in molar furcations and assess the congruence between inter-root distances in molar furcations and curette blade widths. Distances among root surfaces at 1 and 3 mm from the fornix of molar furcations (points A and B, respectively) were measured with standardized CBCT images and analyzed using computer software. Periodontal curette widths were evaluated by digital caliper and stereomicroscope (magnification 10x). Forty CBCT images (containing a total of 141 molar teeth and 354 furcations) were evaluated; 19 furcations (5.4%) with fused molars were excluded. Mesial furcations of the first molars had the highest average inter-root distances (point A: 3.81 ± 0.87 mm; point B: 5.30 ± 0.92 mm), while buccal furcations of the maxillary second molars had the smallest average distances (point A: 1.49 ± 0.37 mm; point B: 1.90 ± 0.65 mm). Analysis of 107 curettes revealed statistically significant differences among curette types and manufacturers. Pearson's coefficient revealed a strong and significant correlation for curette measurement using digital caliper and stereomicroscope (r = 0.86, P < 0.01). In most cases, the curettes tested allowed access for scaling and root planing of teeth with furcation involvement.