This study aimed to compare the effectiveness of xenogeneic demineralized bone matrix (DBM), chitosan (CS), and polymethylmethacrylate (PMMA) on the regeneration of the critical-sized radial bone defects in rats after eight weeks. Fifty bilateral radial bone defects were randomly divided into five groups including untreated defects and those treated with autograft, CS scaffold, PMMA, and DBM. The defects were evaluated by diagnostic imaging, histopathology, histomorphometry, scanning electron microscopy, and biomechanical testing. Compared with the defect, CS, and PMMA groups, the autograft and DBM treated defects showed significantly higher new bone formation, bone volume, ultimate mechanical strength, and stiffness, but significantly lower inflammatory cells, fibroblasts, fibrocytes, and strain. Moreover, DBM showed significantly superior biocompatibility, biodegradability, osteoconductivity, and osteoinductivity to the CS scaffold and PMMA. In conclusion, both CS and PMMA alone were non-biocompatible polymers with slow biodegradation which retarded bone regeneration, whereas DBM significantly improved bone healing close to the gold method. However CS was not osteoconductive or osteoinductive alone, it can be combined with other biomaterials and molecules considering the excellent properties of this carbohydrate biopolymer for bone healing and regeneration.

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