Boron-Doped Nano Hydroxyapatite Grafts for Bone Regeneration in Rat Mandibular Defects

The aim of this study was to evaluate the potential effects of boron-doped nano hydroxyapatite grafts on craniofacial bone regeneration in critical bone defects in the mandibular corpus of rats, in terms of scintigraphic and histopathological aspects. Forty Wistar albino rats, with an average weight of 200-220 g, aged 16-18 weeks, and all male, were used in the study. The rats were randomly assigned to five groups, each containing 8 rats, as follows: group C1 (no procedure applied to the mandible), group C2 (surgical defect created in the mandible but no treatment applied), group nHA (nano hydroxyapatite applied to the surgical defect area), group nHA + B1 (nano hydroxyapatite + 1% boron applied to the surgical defect area), and group nHA + B2 (nano hydroxyapatite + 2% boron applied to the surgical defect area). A standard 4 × 4 mm full-thickness transosseous bone defect was created in the mandibular corpus of all rats, except for those in group C1. The bone defect in the rats in group C2 was left to heal naturally. Nano hydroxyapatite (nHA), nano hydroxyapatite + 1% boron, and nano hydroxyapatite + 2% boron were applied to the surgical defect areas of the other three groups, respectively. Bone scintigraphy was performed on all rats on days 0 (following the surgical procedure) and 28 of the experimental period. At the end of the 28th day, the animals were sacrificed, and tissue samples were collected for histological examination. A standard grading system was used to evaluate fracture healing. When the groups were compared in terms of bone healing histopathological scores, a statistically significant difference was observed between group C1 and the other groups (p < 0.005). In the statistical evaluation made according to the histopathological mean scores, the least improvement was observed in group C2. No statistically significant difference was observed between group nHA and group nHA + B1 and group C2 and between group nHA and group nHA + B1 in terms of bone healing scores (p > 0.005). A statistically significant difference was found between group nHA + B2 and group C2 (p = 0.026). Although there was no statistically significant difference in histopathological scores, the mean score closest to group C1 was observed in group nHA + B2. A statistically significant difference was observed between the groups in the scintigraphic evaluation performed on the 28th day of the experimental procedure, and the difference was between group C1 and group nHA + B1 and between group nHA and group nHA + B1 (p = 0.004; p = 0.028, p < 0.005). In the comparison of the values obtained on days 0 and 28 within the group, a statistically significant change was observed in group nHA + B1 and group nHA + B2 (p < 0.005). When the results of the present study were evaluated, it was thought that the boron-doped nHA graft biomaterials may have positive effects on bone healing. Providing a different perspective for the development of an alternative new treatment modality that can be locally applied in the treatment of fractures a serious and common health problem can be interpreted as an important outcome of the present study. We believe that this study will serve as a preliminary study for more comprehensive future studies on this subject.