Regeneration of periodontal tissues requires orchestration of several cell types. Two cell types, gingival fibroblastic cells (gingival fibroblasts) and cells from the periodontal ligament (PDL cells), were studied to compare the effects of supplemental addition of TGF-beta 1 and PDGF on proliferation. Cells obtained from healthy donors were cultured in 10% FBS supplemented with either 10 ng/ml TGF-beta 1, 20 ng/ml PDGF, or both. Thymidine incorporation was measured after 24, 48, or 72 hours. Data from PDL (analyzed by ANOVA) showed the following relations: at 24 hours TGF beta 1/PDGF = PDGF > TGF-beta 1 = control; at 48 hours TGF beta 1/PDGF > TGF-beta 1 > PDGF > control; at 72 hours TGF beta 1/PDGF > TGF-beta 1 > PDGF = control. Gingival fibroblast cultures showed the following relations: at 24 and 48 hours TGF beta 1/PDGF = PDGF > TGF-beta 1 = control; at 72 hours, TGF beta 1/PDGF = PDGF > control with TGF beta 1 not different from control or factor combinations. Both TGF-beta 1 and TGF-beta 1/PDGF showed a significantly greater increase in proliferation of PDL cells than in gingival fibroblasts at 48 and 72 hours (Student t test P < 0.05). In contrast, PDGF stimulated proliferation of gingival fibroblasts was significantly greater than PDL cells at 72 hours (P < 0.05). Thus, supplementation of complete cultures (containing 10% FBS) with TGF-beta 1 alone or combined with PDGF stimulates proliferation of PDL cells to a significantly greater extent than proliferation of gingival fibroblasts.(ABSTRACT TRUNCATED AT 250 WORDS)