Effect of intercellular adhesion molecule 1 deficiency on the development of apical periodontitis

Aim To evaluate the specific role of ICAM‐1 in host responses against endodontic infection. Methods Apical periodontitis was experimentally induced in the mandibular first molars of ICAM‐1 knockout and wild‐type (WT) mice by pulp exposure to the oral environment. At 7, 21 and 42 days following pulp infection, the animals were euthanized and the jaws were prepared for analysis under conventional and fluorescence microscopy (histopathologic and morphometric analysis), immunohistochemistry (polymorphonuclear leucocytes), enzyme histochemistry (osteoclasts and cementoclasts) and RT‐PCR (IL‐1 α, TNF‐α, INF‐γ, IL‐10, RANK, RANKL and OPG). A generalized linear model with GLIMMIX procedure with Satterthwaite approximation method of degrees of freedom, Tukey–Kramer, pseudo‐ranking nonparametric, Bonferroni–Holm multiple testing adjustment, analysis of variance (ANOVA) and the Tukey's multiple comparisons tests were used to evaluate the statistical differences between the groups using SAS 9.4 and the GraphPad Prism 5.0 software (α = 0.05). Results Compared to WT mice, ICAM‐1 knockout mice had significantly greater bone resorption (P