# Heterologous Fibrin Biopolymer as a Key Scaffold for Bone Regeneration: Synergistic Effects with Photobiomodulation and Membrane Therapy

## TL;DR

This study explores how combining a fibrin biopolymer with photobiomodulation and a biological membrane can enhance bone healing in rats with large skull defects.

## Contribution

The study demonstrates that combining regenerative strategies can influence early bone healing patterns without a direct causal effect.

## Key findings

- Combined treatments showed higher early bone formation compared to single treatments.
- Biological membranes contributed to greater bone repair at 42 days regardless of photobiomodulation.
- Photobiomodulation influenced early healing but not long-term outcomes.

## Abstract

Bone regeneration remains a clinical challenge, particularly in critical-size defects, motivating the investigation of biomaterials and adjuvant therapies that may support tissue repair. This experimental study evaluated bone healing in critical-size calvarial defects created in rats, using different combinations of regenerative strategies, including heterologous fibrin biopolymer gel, bovine cortical bone biological membrane, and photobiomodulation. Standardized 5.0 mm calvarial defects were surgically created in sixty Wistar rats, which were randomly allocated into six experimental groups according to the filling material and the application or absence of photobiomodulation. The treatments included clot alone, fibrin biopolymer gel, biological membrane, photobiomodulation, or their respective combinations. Animals were euthanized at 14 or 42 days, and bone repair was evaluated by histomorphometric analysis. At 14 days, differences in the extent of newly formed bone were observed among the experimental groups, with higher bone formation values detected in groups receiving combined treatments and lower values in groups treated with fewer regenerative components. At 42 days, all groups showed progression of bone repair, with greater bone formation observed in groups in which a biological membrane was used, regardless of photobiomodulation. Overall, the findings indicate that the association of different regenerative approaches was related to variations in bone repair patterns over time, suggesting that photobiomodulation, when applied in combination with biomaterials, may be associated with differences in early bone healing, without implying a direct causal effect.