This study evaluated the attachment of cultured explants of human periodontal ligament fibroblasts and gingival fibroblasts to different root-end-filling materials. Although periodontal ligament and gingival fibroblasts initially attached avidly to Geristore, these same cells displayed no significant attachment to ProRoot, Tytin amalgam, or SuperEBA. With further incubation on Geristore, the attachment of both periodontal ligament and gingival fibroblasts improved and these cells proliferated. In contrast, no improvement in attachment or proliferation was observed for cells incubated for greater times with ProRoot, Tytin amalgam, or SuperEBA. Because the attachment characteristics of these two groups of fibroblasts were identical, we examined the potential role of the extracellular matrix family of receptors (integrins) on the attachment of gingival fibroblasts. Gingival fibroblast attachment to collagen type I was determined to be dependent on alpha1beta1 and alpha2beta1 integrins, whereas their attachment to the RGD-binding sequence of fibronectin and vitronectin was partially inhibited by antibodies to the beta1 and alphaV integrin subunits. However, attachment of gingival fibroblasts to Geristore was not reduced by the addition of any of the attachment-perturbing anti-integrin antibodies examined. Thus, gingival fibroblasts attach to Geristore, but this attachment was mediated by mechanisms other than integrins.