The Effect Of Neostigmine On Orthodontic Tooth Movement In Nicotine-associated Periodontitis Rats

Orthodontic tooth movement is a process of biological response including bone resorption in pressure side and bone deposition in tension side.The position of the tooth changes in the alveolar bone in this way,which depends on osteoclasts and osteoblasts.In recent years,people’s awareness of oral health and improvement of living standards increased the number of patients with nicotine-related periodontitis who ask for orthodontics treatment.The loss of bone in patients with periodontitis is closely related to the function of osteoblasts and osteoclasts.Force,inflammatory periodontal tissue and nicotine may jointly participate in the process of osteoclast activation,differentiation and maturation in different ways.These factors can also affect each other,which is not conducive to periodontal tissue health.Therefore,how to move teeth efficiently and safely and protect bone tissue at the same time has become an urgent problem.Studies have shown that inhibitors of a7-acetylcholine receptors,such as mecamylamine and coral snake poison,can antagonize the increase in the expression of inflammatory cytokines and bone loss which induced by nicotine.Neostigmine is an a7nAChR antagonist.We suggest that its role in regulation of bone remodeling and inhibition of the damaging effect of nicotine is similar to a-BTX.Therefore,this experiment study the effect of neostigmine on the orthodontic tooth movement in patients with nicotine-associated periodontitis,and probed into possible molecular biological mechanisms to provide new ideas for clinical treatment.Purpose:This study explored the effect of neostigmine,a a7nAChR antagonists,on bone remodeling during orthodontic tooth movement in rats with nicotine-associated periodontitis,in order to provide a new and effective experimental basis on OTM in rats.Method:Thirty-six 6-month-old male Wistar rats were randomly divided into three groups:control group(A group),low concentration nicotine group(0.83mg/kg/d,group B)and high concentration nicotine group(1.67mg/kg/d,group C).Establish rats periodontiti model and intraperitonea injecte nicotine solution with different volumes in two experimental group three days before,while the control group was given 0.5ml normal saline.After 2 weeks,remove the ligation silk and establish the rat model of OTM,intramuscular inject neostigmine infusions of 1ml/kg or 0.5ml 0.9%saline every day.7,14,and 21 days after stressing,four rabbits in each group were sacrificed and the maxillary specimens including the right molars were obtained.The distance of the first molars was measured.All specimens were made into tissue sections after decalcification.Observe the remodeling of bone tissues by hematoxylin-eosin staining and anti-tartaric acid alkaline phosphatase of rats.Result:1.OTM distance:OTM distance gradually increased after stressing.There was no significant difference between the low-dose nicotine group and the control group on the 7th and 14th day after intramuscular injection of neostigmine(P>0.05),but the difference in the 21th day was significant(P<0.05).The high-concentration nicotine group compared with the two groups at three time points are different(P<0.05).The movement distance in seven days of the three groups increased first and then decreased.The high concentration group move further in three weeks compared with the control group(P<0.05),while in two weeks compared with the low concentration group(P<0.05).2.HE staining:HE staining showed that the periodontal ligaments in the pressure side were compressed.Fibers showed disorder.Howship lacunae appeared on the surface of the alveolar bone.In the control group,osteoclasts were observed and increased at 7 days,and decreased sequentially at 14 days and 21 days.The trend of the number of osteoclasts in the low-concentration nicotine group and high-concentration nicotine group was the same as that in the control group.The periodontal ligaments in the tension side were stretched,new bone was observed either.3.TRAP staining:At the three time points of 7,14 and 21 days,The counts of osteoclasts were highest in the high concentration nicotine group while lowest in the control group.On the 7th day after stressing,the osteoclast count peaked in three groups.The level of osteoclasts tended to decline to a similar level on the 21th day.The difference between the high concentration group and the control group was statistically significant at three time points(P<0.05).But no significant difference was observed between the low concentration group and the control group on the 7th and the 14th day(P>0.05).Conclusion:1.Neostigmine can antagonize nicotine effects on a7nAChR,which can promote osteoclast activation,differentiation,maturation.Besides,neostigmine can make the process of OTM safer.2.This process may relate to the regulation of NF-κB pathway and the RANKL/RANK/OPG axis.