Aim  To evaluate and compare the response of pulps of rats capped with resin‐modified glass‐ionomer cement (RMGIC) or self‐etching adhesive system.

Methodology  Class I cavities were prepared on the occlusal surface of 54 maxillary first molars of 27 rats. Pulp exposure was performed on the cavity floor. The following resin‐based materials were applied as pulp‐capping agents: G1, Clearfil Liner Bond 2V (CLB 2V; Kuraray Co., Japan); G2, Vitrebond (VIT; 3M/ESPE, USA). In group 3 (control group), a calcium hydroxide/saline paste (CH; Labsynth, Brazil) was used. The cavities were restored with amalgam. After 7, 30 and 60 days, the animals were sacrificed and the jaws were processed for microscopic evaluation.

Results  Despite the inflammatory response caused by the experimental and the control materials at 7 days, pulpal healing associated with calcified barrier formation was observed at 60 days following the pulp therapy. Both resin‐based materials promoted a large zone of cell‐rich fibrodentine matrix deposition on the pulp horn related to the pulp exposure site, which was larger to VIT than to CLB 2V specimens. Tertiary dentine underneath the fibrodentine matrix was deposited by a layer of elongated pulpal cells. The remaining pulpal tissue exhibited normal histological characteristics. In the control group, healing and dentine‐bridge formation was observed at 30 days. Pulpal breakdown occurred only when bacterial infection occurred.

Conclusion  Both experimental pulp‐capping agents allowed pulpal healing characterized by cell‐rich fibrodentine and tertiary dentine deposition as well as calcified barrier formation.