Objective

To evaluate the role of nitric oxide synthases (NOS) isoforms influence during tooth movement with different forces.

Settings and sample population

100 male Wistar rats (n=10/group) were divided into a Sham group (animals not submitted to device installation nor Induced Toot Movement [ITM]), Negative Control Group (NCG) (animals submitted to device installation but not to ITM), and three experimental groups (F1, F2, and F3) (submitted to ITM with forces of 25, 50 and 100 gF, respectively).

Materials and methods

A daily count of biting and scratching on the vibrissae and the Grimace scale were applied. After 4 (D4) and 11 (D11) days, the molar diastema was measured, and the animals were euthanized for histological (vascular parameters) and immunohistochemistry (iNOS, eNOS and nNOS) in the dental pulp.

Results

On D4, there was significant movement in the F3 group (p=0.001) and on D11 in F1, F2, and F3 (p<0.001). The number of bites (p<0.001) and scratching (p=0.006) were higher in F2-F3 and F3 had higher Grimace-scores (p<0.001) and weight loss (p<0.001). At D4, there was an increase in pulp ectasia in F2-F3 (p=0.021) and a reduction in the number of vessels in F3 (p=0.005). In D4 and D11 there was a significant increase in immunostaining for iNOS and eNOS in F1 (p=0.025 and p<0.001, respectively) and F2 (p=0.007 and p<0.001, respectively). At D4, F2 and F3 showed higher immunostaining for nNOS (p=0.027)

Conclusion

Thus, IDM induced inflammatory changes in the dental pulp reflecting in force-dependent pain/suffering signs.