Aim: To assess the biocompatibility of an experimental endodontic paste based on the ethyl acetate fraction of Pothomorphe umbellata + calcium hydroxide, using propylene glycol as vehicle, in connective tissue of rats.
Materials and methods: Fifteen rats had four polyethylene tubes implanted in their backs, with each one containing the experimental paste. The tube side was considered the control group. After 7, 21, and 42 days, animals were euthanized.
Results: Intense inflammatory reaction was noticed after 7 days for experimental paste and it was moderate for control group. At 21 days, the inflammatory reaction was moderate for experimental paste and discrete for control group; and at 42 days, it was discrete for experimental paste and control group. Statistical analysis (Dunn's test, P < 0.01) demonstrated significant difference between the fibrous capsule area at 7 and 42 days (P > 0.01) for experimental paste.
Conclusions: Experimental endodontic paste presented satisfactory tissue reaction in the connective tissue of rats.
Keywords: Biocompatibility; Pothomorphe umbellata; calcium hydroxide; filling material.