Influence of occlusal interferences on the activation of trigeminal-spinal nucleus astroglia and microglia in rats

Objective To investigate the morphological changes in microglia and astroglia before and after the removal of occlusal interferences in rats and to further understand whether astroglia and microglia activation is involved in experimental occlusal interference-induced masticatory muscle pain.Methods Male Sprague-Dawley rats (200-220 g) were used. Crowns of two heights (0.2 mm and 0.4 mm) were bonded to the right maxillary first molars to establish experimental rat models of occlusal interference. The rats were randomly assigned to one of five groups of twelve rats each: sham-occlusal interference control group, 0.4 mm occlusal interference group, 6-day removal of 0.4 mm occlusal interference group, 0.2 mm occlusal interference group, and 6-day removal of 0.2 mm occlusal interference group. The rats were sacrificed by transcardiac perfusion after deep anesthetization on days 3, 5, 7, and 14. Brain stem sections were obtained and processed for immunofluorescence staining of GFAP and OX-42. Expression levels were