Analysis of the effects of concentrated growth factor and low-level laser therapy on the bone healing

Abstract

Purpose: The aim of this study is to evaluate whether concentrated growth factor (CGF) and photobiomodulation (PBMT) can show synergistic effect on bone healing process.

Methods: In vivo osteogenesis studies were performed in a rabbit critical-sized calvarial defect model. Four 8 mm critical-sized bone defects were created on each rabbit calvarium, and these 4 defects were randomly divided into 4 groups: 1-control (defect filled with autologous blood clot); 2-CGF (defect filled with CGF); 3-LLLT (defect filled with autologous blood clot and received Nd:YAG low-level laser irradiation); 4-CGF + LLLT (defect filled with CGF and received LLLT). 15 Japanese big-ear white rabbits were operated on using the same procedure in this study. Then, 5 rabbits were selected randomly and sacrificed at 4th, 6th and 8th week postoperatively and respectively. The calvariums were harvested and scanned by micro-CT. The volumes of new bone formation of these defects were calculated by analyzing the micro-CT image. Data were analyzed as mean values of each group, comparisons were made for statistical analysis with the group and among the 4 groups using analysis of variance (ANOVA, P < 0.05).

Results: At the 4th, 6th and 8th weeks, compared with the control group, the volume of new bone formed in each experimental group was significantly increased. Both CGF and LLLT can accelerate bone healing, but the effect of LLLT is better than that of CGF, and the difference between the two is statistically significant (P < 0.01). There was no statistically significant difference in the osteogenic effect between the combined application of CGF + LLLT and the application of CGF alone. And the osteogenic effect of the former two groups was weaker than that obtained by laser irradiation alone.

Conclusions: Both CGF and LLLT can promote osteogenesis effectively, but the combination of the two did not show a synergistic effect. The pro-osteogenic effect of Nd:YAG low-level laser irradiation is superior to that of CGF, and also superior to the combined effect of the two.

Keywords: CGF, concentrated growth factor; Calvarial defect; Concentrated growth factor; LLLT, low-level laser therapy; Low-level laser therapy; Nd:YAG laser; PBMT, photobiomodulation; Photobiomodulation.

Fig. 1

Prepare of four 8 mm critical-sized bone defects on rabbit calvarium. (A) 8 mm diameter trephine used in our operation. (B) Calvarial bone defects without dural perforation were created. (C) Bone defects filled with CGF. (D) The wound was closed, and Nd:YAG laser irradiation was performed on the marked bone defect area according to the experimental design.

Fig. 2

Demonstration volume of the new bone formed. (A) Calvaria harvested from the rabbit. (B) Calvaria scanned by micro-CT and then reconstructed. (C) A cylinder with a diameter of 8 mm was created. (D) The volume of new bone was obtained through Boolean operation. (E) New bone formed in the defect area is isolated. (F) New bone formed in the defect area is calculated.

Fig. 3

General view of new bone volume of different group and different time. Three representative rabbits were selected from each of the 5 rabbits sacrificed at 4 W, 6 W and 8 W for display.

Fig. 4

Compared with every group, except CGF and CGF + LLLT, the other groups had statistical difference. (A) New bone volumes at 4 W. (B) New bone volumes at 6 W. (C) New bone volumes at 8 W. (D) Comparison of overall new bone volumes.