IL1B and periapical periodontitis: IL-1β may play vital roles in bone loss in periapical periodontitis: IL1B gene polymorphisms are involved in the risk of periapical periodontitis development (263); IL-1β production is increased in periapical periodontitis in vivo (264); and IL-1β levels and osteoclast differentiation are upregulated in an in vitro coculture system of osteoblasts and osteoclasts (186).