Tomographic Evaluation of Bone Regeneration by Photothermal Stimulation in a Rat Calvarial Defect

Abstract

The effect of controlled photothermal stimulation on new bone formation ability using a calvarial defect model in rats over 40 weeks old was evaluated. Photothermal stimulation was carried out using a photothermal device composed of an alginate-gel-containing carbon nanotubes (CNT-Alg gel) and an irradiator supplying near-infrared light. Photothermal stimulation (42°C, 15 min) was repeated every day for up to 3 months to assess the effect of thermal stimulation on bone healing of defects treated with commercially available collagen sponge. Photothermal stimulation accelerated bone regeneration with collagen sponge treatment compared with treatment without photothermal stimulation. There were no significant differences in microhardness values between the newly formed bone, with or without photothermal stimulation. Microhardness measurement revealed that the regenerated bones were sufficiently mature. The results of this study suggested that photothermal stimulation enhanced bone regeneration induced by expression of heat shock-related molecules.