Effect of different dental burs for experimental induction of pulpitis in mice.

OBJECTIVE: To evaluate the effect of using different dental burs on the development of pulpal inflammation after pulpal exposure in mice.

DESIGN: Eighty-eight C57 BL/6 mice were randomly assigned to group A (n=40), group B (n=40) and control group (n=8). The pulps of the maxillary first molars were occlusally exposed using ¼ round burs and polishing burs in group A and B respectively. Animals were sacrificed randomly at 0h, 4h, 8h, 12h and 24h after pulpal exposure. Micro-CT scanning was used to determine the success rate of sample preparation. Pulpal tissue changes were evaluated by histopathologic and immunohistochemical analyses.

RESULTS: The success rates of sample preparations were 85% in group A and 90% in group B. The mean maximum diameter of pulpal exposure area was 625.6±30.6μm in group A and 402.7±18.0μm in group B (p<0.05). In addition, the mean of the minimum remaining dentine thickness at the marked region of interest was 133.2±29.9μm in group A and 261.4±16.3μm in group B (p<0.05). Histopathologic staining demonstrated more signs of inflammation in both groups, as the duration of pulpal exposure increases. However, the rate of inflammatory progress was higher in group A, even spreading to the root pulp tissue within a few hours. For group B, the progress was relatively slow.

CONCLUSIONS: Pulpal exposure with different sizes of dental burs affects changes in the development of pulpal inflammation in mice.