Density and Diameter of Bovine Dentinal Tubules by SEM

Objectives: Bovine teeth have been widely used in studies focusing adhesion to dentine over the last years. Although a number of studies involving bond strength analyses have shown values that appear to be comparable to those obtained with human dentine, little is known about main structural aspects of bovine dentine, especially regarding density and diameter of its tubules. Methods: Thirty bovine incisors were randomly divided into two groups. In Group I, teeth were sectioned in transversal cuts at three depths: outer, middle and inner; the outer dentinal surface was etched with 35% phosphoric acid for 90 sec. For Group II, the teeth were fractured at the same depths. All the specimens were processed and examined in a Jeol 6100 SEM. Fifteen micrographs from each depth were obtained for the two groups at the same magnification (2500X). To determine the diameter of the dentinal tubules, the LEICA Q500 MC program was used. All the results were statistically processed in the EXCEL software. Results: The dentinal tubules were wider at the outer regions (GI: 5.21±0.64µm; GII: 2.30±0.09µm) than that at the inner regions (GI: 2.71±0.72µm; GII: 1.77±0.06µm). Tubular density was higher at the inner regions (GI: 50310±11178/mm2; GII: 44901±8427/mm2) than that at the outer regions (GI: 18772±2951/mm2; GII: 35756±6174/mm2). The data between groups I and II indicated that peritubular dentine was wider at the outer regions than that at the inner ones. Conclusions: Our results showed that bovine dentine possesses some structural aspects different from those previously reported for human dentine, mainly related to the diameter of dentinal tubules, as well as to thickness of peritubular dentine at the several depths.