TLR2 and periodontitis: Clinical observations not only showed an enhancement of TLR‐2 and TLR‐4 expression in oral tissues during periodontitis, but also a crucial role of these receptors for periodontitis progression.12‒14 Interestingly, animal studies with different periodontitis models show that TLR‐2 deficient mice exhibit lower levels of alveolar bone loss and proinflammatory cytokine expression compared to wild‐type and TLR‐4‐deficient mice, which underlies the important role of TLR‐2 in periodontitis.15, 16 In contrast to TLR‐2 and TLR‐4, the role of TLR‐3 in periodontitis is much less investigated.