Background: The last few years have detailed a number of surgical materials and techniques to stimulate guided bone regeneration (GBR). Polypropylene has been used as a mechanical barrier, intentionally designed to be exposed to the oral environment, isolating the regeneration area, and allowing the blood clot to remain protected in a confined space while pluripotent mesenchymal cells regenerate the alveolar bone tissue.

Aim: Due to the lack of studies on polypropylene barriers (PB) (Bone Heal– Bone heal ind. e Com. LTDA – São Paulo, Brazil), this study aimed to evaluate the histological repair process of critical defects (7 mm) made in the rodent cranial vaults comparing its efficacy in GBR and modified GBR.

Materials and Methods: A total of 30 rats were divided into three groups. The control group consisted of 10 rats, wounds covered with just a blood clot.The second group consisted of an exposed/uncoated PB at the edges of the wound, and it was removed after 3 days. The third group used submerged PB with coaptation of the wound edges, and it was not removed. Five animals of each group were euthanized at 30 and 90 days postoperative and submitted to microscopic analysis and histomorphometric evaluation.

Results: Modified GBR (membrane exposed to the oral medium) provided earlier tissue organization at 30 days; however, the third group presented better bone neoformation at 90 days.

Conclusion: Modified GBR provided earlier tissue organization compared with the control group, as well as promoting improved bone neoformation, while regeneration with the submerged membrane presented better bone neoformation in the long term.

Keywords: Bone regeneration, Guided bone regeneration, Polypropylene