Neutrophils: A Double Edged Sword in Periodontics

Oral tissues are constantly exposed to damage from the mechanical effort of eating and to microorganisms. In healthy gingiva tissue remodeling and a balance between bacteria and innate immune cells are maintained. However, excess of bacteria biofilm creates an inflammation state that recruits more immune cells, mainly neutrophils to the gingiva. When neutrophils are insufficient, bacteria thrive causing more inflammation that has been associated with systemic effects on other conditions But paradoxically when neutrophils persist, they can also promote a chronic inflammatory state that leads to periodontitis. How a neutrophil balance is needed for maintaining healthy oral tissues is the focus of this review. We present recent evidence on how alterations in neutrophil number and function can lead to inflammatory bone loss, and how some oral bacteria signal neutrophils to block their antimicrobial functions and promote an inflammatory state.