Osteoclastogenesis and matrix metalloproteinase-9 expression in apical and periapical repair following root canal treatment

Abstract

Matrix metalloproteinases (MMPs) are enzymes capable of tissue degradation during inflammatory events. These enzymes are expressed in human periapical cysts and granulomas in high concentration. However, MMP modulation following root canal treatment is not known. Therefore, the aim of this study will be to evaluate the expression of MMP-9 in periapical area in teeth with apical periodontitis and following root canal treatment using several clinical protocols. Then, the expression of MMP-9 will be correlated to periapical osteoclastogenesis. Apical periodontitis will be induced in dog’s teeth then the root canal treatment will be performed in a single visit or using calcium hydroxide as root canal dressing. Vital teeth submitted to root canal treatment, teeth with apical periodontitis not treated and healthy teeth will be used as controls. One hundred and eighty days following root canal filling, the animals will be euthanized and the tissues will be removed and submitted to histopathological evaluation. To investigate if tissue destruction is associated with MMP-9 expression, immunohistochemistry and western blotting will be performed. The presence and activity of osteoclasts will be determined by cell counting using tartarate-resistant acid phosphatase labeling (TRAP). Groups will be compared using one-way ANOVA or Kruskal-Wallis and by Fisher exact test (alpha = 0.05). (AU)