ABSTRACT

Many systemic/local factors take part in the process of bone-remodeling. Nitric oxide (NO), an important intercellular signal modulator produced by osteoblasts, is a potent regulator of bone-remodeling. The objective of the study was to investigate the effects of different NO-isoforms on bone-remodeling during orthodontic tooth movement.

66-male, adult Sprague-Dawley rats were randomly divided into 11 groups to determine the effects of three different NO-synthase (NOS) inhibitors. All NOS-inhibitors (iNOS-inhibitor 1400W-dihydrochloride, eNOS-inhibitor L-NIO-dihydrochloride and nNOS-inhibitor Nu)-propyl-L-arginine) were administered in three different doses (10, 30 and 100μg/20μl); the remaining two groups served as control. Mandibular first molars were moved mesially with Ni-Ti closed coil-springs in all groups.

The results were evaluated histomorphometrically and parameters of trabecular bone volume (BV/TV), trabecular bone number (Tr.N) and trabecular separation (Tr.Sep) were analyzed at the interradicular bone area of the mandibular first molars. The outcomes of the WinTAS (Trabecular Analyze System, V. 1.2.9) revealed statistically significant alterations in BV/TV, Tr.N and Tr.Sep for the eNOS groups, especially for the 30\ig L-NIO dihydrochloride group.

Data suggest that eNOS could be the primary NO-isoenzyme involved in bone-remodeling during orthodontic tooth movement, and optimum dose is in a certain range.