# Evaluation of the Effects of Locally Applied Resveratrol and Cigarette Smoking on Bone Healing
## 4 Discussion
Consistent with studies in the literature showing that CS inhibits osteogenesis and disrupts bone turnover by changing the balance between bone mineral content and osteoblast-osteoclast numbers [42], our study showed that CS reduces the number of osteoblasts. We found that RES given with CS increased the number of osteoblasts compared with the control group. At the same time, it is noteworthy that the study showed similar results to those of studies in the literature showing the effect of RES on osteoblasts at high and repeated doses (10 mg/kg-20 mg/kg) or low but repeated doses (10 umol/kg) with low- (50 umol) and single-dose local application. RES, acting as an aryl-hydrocarbon receptor antagonist, has been demonstrated in the literature to possibly have a positive effect on periodontal tissue regeneration and significantly reduce bone tissue loss [18]. However, due to its poor aqueous solubility, the use of RES for effective treatment is limited by its pharmacokinetic properties. In addition, RES has a short plasma half-life due to its extremely rapid and extensive metabolism [13; 43]. Therefore, it is important to develop a delivery system that can overcome biopharmaceutical barriers and fully realize the therapeutic potential of RES [44]. Vascularization provides bone tissue with the necessary nutrients, oxygen, growth factors, and hormones and plays an essential role in regulating bone formation [45]. In an animal study investigating early bone healing, [PERSON] et al. [46] examined angiogenesis and vascularization in rats exposed to CS for two hours per day. They showed a lower expression of VEGF in the smoking group at two and four weeks after surgery with Western blot analyses. They also reported that CS reduces the expression of the angiogenic factorsin the fracture callus, and after the fourth week of healing, in the control group, vWF expression was mainly observed around the cartilage area of the soft calluses, and in the smoking group, vWF expression and cartilage formation were low. There are many in vivo and in vitro studies in the literature that have evaluated the effects of RES on bone healing, but there is no study that has evaluated vascularization on bone defects. In a study conducted on rats, myocardial infarction occurred after pre-treatment with RES (1 mg/kg/day) for two weeks. After 24 h, it was observed that the size of the infarct decreased and the capillary density increased. Moreover, myocardium treated with RES after myocardial infarction showed that Trx-1, HO-1, and VEGF expression were observed to be significantly induced. It has been found that RES increases myocardial angiogenesis both in vitro and in vivo by accelerating the tubular morphogenesis of human coronary arteriolar endothelial cells and increasing capillary density in the peri-infarct myocardium [47]. Similar to studies in the literature, in this study, vascularization was observed to be higher in the local RES-applied group than in the control and smoking groups. The fact that vascularization was seen more in the CS + RES group than in the group in which only smoking was administered shows that RES application is effective in eliminating these negative effects of smoking. In the available literature, there are few articles investigating the effect of resveratrol and smoking on proliferation in bone healing. [PERSON] et al. [48] reported that mesenchymal stromal cells exposed to CS standardized for nicotine concentration exhibited impaired wound healing ability, and at high concentrations, increased cell death in an in vitro study. At lower concentrations, CS dose-dependently impaired proliferation and osteogenic differentiation. [PERSON] et al. [49] formed the healthy tooth extraction socket and investigated the effects of resveratrol for bone formation in vitro and suggested that resveratrol may improve the cellular physiology of periodontal ligament and osteoblasts, including proliferation and differentiation during wound healing after tooth extraction.