Candida albicans is the most numerous commensal and potentially pathological yeast in the human oral cavity. Here we investigate the ability of C. albicans to form a biofilm on human root tip surfaces (RTs) in the presence of periodontal ligament (PDL) cells, and we compare the expression of cytokines in PDL cells induced by biofilm on RTs compared to that induced by planktonic C. albicans. PDL cells were added at the adhesion phase of C. albicans, or after C. albicans cells were allowed to attach to RTs for 90 minutes. The whole mixed culture was allowed to form a biofilm.