Relationship between buccal bone and gingival thickness revisited using non-invasive registration methods

Objective: To determine the relationship between buccal bone and soft tissue thickness at teeth in the premaxilla by means of non-invasive registration methods. Materials and Methods: Buccal bone thickness at central incisors, lateral incisors and canines was measured at five reference points (1-5 mm from the top of the alveolar crest) on CB-CT scans of 21 patients. The corresponding buccal gingival thickness was measured by the use of an ultrasonic device. Spearman's correlation coefficient was calculated to assess the correlation between buccal bone and soft tissue thickness at each tooth type. Results: Mean buccal bone thickness (SD) at central incisors, lateral incisors and canines was 1.07 mm (0.34 mm), 1.16 mm (0.54 mm) and 0.98 mm (0.37 mm), respectively. For central incisors, 68% of all sites had a thickness <1 mm and 32% had a thickness between 1.0 and 2.0 mm. At lateral incisors, 44% demonstrated buccal bone thickness between 0 and 1.0 mm, 48% between 1.0 and 2.0 mm and 8% ≥2 mm. For canines, 57% of the sites were <1 mm thick; 41% were between 1.0 and 2.0 mm thick, and 2% demonstrated ≥2 mm thickness. Mean gingival thickness (SD) at central incisors, lateral incisors and canines was 1.37 mm (0.32 mm), 1.33 mm (0.32 mm) and 1.08 mm (0.25 mm), respectively. The correlation between buccal bone and soft tissue thickness was moderately positive (ρ = 0.406; P < 0.001). Conclusions: A thin buccal bone wall (<1 mm) may be expected in over half of the central incisors and canines. The correlation between buccal bone and soft tissue thickness was moderately positive.