Effect of Nd:YAG laser light on post-extractive socket healing in rats treated with zoledronic acid and dexamethasone

摘要

The effect of low level laser therapy (LLLT) on the healing process could be useful for the prevention of post-extractive Bisphosphonate-related Osteonecrosis of the Jaws (BRONJ). The aim of the study was to investigate the effect of LLLT on the post-extractive socket healing in rats treated with zoledronic acid and dexamethasone. Material and Methods Thirty male Sprague-Dawley rats were divided in 4 groups: control group (C, n = 5), laser group (L, n = 5), treatment group (T, n = 10) and treatment plus laser group (T+L, n = 10). Rats of group T and T+L received zoledronate 0,1 mg/Kg and dexamethasone 1 mg/Kg every 2 days for 10 weeks. Rats of group C and L were infused with vehicle. After 9 weeks the first maxillary molars were extracted in all rats. Rats of groups L and T+L received laser therapy (Nd:YAG, 1064 nm, 1.25W, 15Hz, 5 min, 14.37 J/cm2) in the socket area at days 0, 2, 4 and 6 after surgery. At 8 days from extraction, the sockets were clinically assessed with a grading score and the wound area was measured with a dedicate software. Histomorphometric evaluation and western blot analysis of osteopontin and osteocalcin expression were performed. Results Group T+L showed a trend toward a better clinical grading score compared to group T (grade Ⅰ 22% Vs 28 % - grade Ⅱ 56% Vs 28% - grade Ⅲ 22% Vs 44%, respectively). The average wound area was similar among the groups. Inhibition of osteoclastic alveolar bone resorption was found in groups T and T+L (P＜0.001). Rats of groups L and T+L showed a significant higher expression of osteocalcin compared to rats of groups C and T (C=0.3993; L=1.394; T=0.2922; T+L=1.156; P=0.0001). The expression of osteopontin did not show significant differences in the groups treated with Nd:YAG compared to the ones that did not receive laser irradiation. Our findings suggest that laser irradiation after tooth extraction can promote osteoblast differentiation, as demonstrated by the higher expression of osteocalcin. Thus, laser irradiation could be considered a way to improve socket healing in conditions at risk for MRONJ development.