The Effects Of Binge Drinking On Orthodontic Tooth Movement And Associated Root Resorption In Rats

Binge drinking,or heavy episodic drinking,is defined as consuming 60g or more pure alcohol in a short period of time,which usually overlaps with social drinking.Binge drinking could interfere the physiological remodeling and metabolism of bone.Various factors contribute to the pathological changes induced by alcohol,which involve a variety of molecular and cellular mechanisms.Alcohol could inhibit osteoblastogenesis and promote osteoclastogenesis by acting on osteoblasts and osteoclast directly or the indirect effects of increasing oxidative stress,decreasing the levels of vitamin D and parathyroid hormone et al.Orthodontic tooth movement(OTM)is a complex biological process.After the application of orthodontic force on the tooth,there would be a compressive side and a tension side in periodontal tissue.The osteoclasts mediate bone resorption at the compressive side,while osteoblasts mediate bone formation at the tension side.A wide range of biological mediators,like nuclear factor kappa B ligand(RANKL),osteoprotegerin(OPG)and inducible nitric oxide synthase(iNOS),have been confirmed to be important in the regulation of bone remodeling during OTM.Orthodontically induced inflammatory root resorption(OIRR)might lead to the permanent loss of tooth structure,which could seriously affect dental health and the stability of orthodontic treatment outcomes.It is one of the most common but unpredictable sequela of orthodontic treatment.90%of patients who underwent orthodontic treatment presented different extent of root resorption.Binge drinking could affect bone metabolism and remodeling,while alveolar bone remodeling plays a vital role during OTM.Thus,it could be estimated that alcohol exposure might have an impact on orthodontic treatment.Nevertheless,little is known about the effect of binge drinking on alveolar bone remodeling during orthodontic treatment and its influences on OTM and OIRR.Clarifying the impact of binge drinking on orthodontic treatment would be of great importance to orthodontic practice.Therefore,the present study will investigate the effects of binge drinking on OTM and OIRR,and explore the related mechanism.Objective:The present study was performed to investigate the effects of binge drinking on tooth movement and associated root resorption in rats by the models of binge drinking and OTM,and explore the possible mechanism.Methods:64 male Wistar rats aged 6 weeks were randomly divided as ethanol group and control group with 32 animals per group.All rats received orthodontic appliance.Two maxillary incisors of the rat acted as anchorage,while the maxillary right first molar was moved mesially by the closed coil nickel-titanium spring at a force of 50g.The orthodontic appliance and weight of the rat were monitored every day.Each rat in ethanol group received a single daily intraperitoneal injection of 20%ethanol/saline solution at a dose of 3g/kg.The rats in control group received the same volume of saline by intraperitoneal injection.Ethanol and saline injections were administrated for 3 consecutive days,and no injections were given during the remaining 4 days each week.Each group was divided into two subgroups of 16 animals each.One subgroup from ethanol group and one from control group were sacrificed at day 14 and day 28,respectively.Tooth movement was measured at day 14 and day 28,while the root resorption was analyzed by scanning electron microscope(SEM)evaluation.Hematoxylin and eosin(H&E)staining was performed to observe histological change.Tartrate-resistant acid phosphatase(TRAP)staining was performed to observe the change of osteoclasts.Additionally,the expressions of RANKL,OPG and iNOS was observed by immunohistochemistry staining.Results:1.During the experiment,the orthodontic appliances did not show any breakage,and there was no significant difference in the weights between groups.2.The amount of tooth movement in rats treated with ethanol was relatively smaller than control group at 14 day and 28 day,but the difference was not statistical significantly.3.The resorption area was detected on the compressive surface of distobuccal root apparently after application of orthodontic force with SEM.There was no significant difference in the ratio of root resorption between ethanol group and control group.4.The disorientation and diminution of periodontal ligament were observed at the compressive side of distobuccal root with H&E staining,while some cell-free hyalinization area was observed in rats injected with ethanol.5.The number of TRAP-positive cells was significantly higher in ethanol group than control group at both day 14(P<0.01)and day 28(P<0.05).6.Compared with control group,the expression of RANKL increased significantly in ethanol group at day 14(P<0.01)and day 28(P<0.05).In contrast,the immunoreactivity of OPG was weaker in rats treated with ethanol at both two time points(P<0.01).The expression of iNOS was significantly increased in ethanol group at each time point(P<0.01).Conclusion:The binge drinking could increase the osteoclastogenesis and the expression of iNOS,but the tooth movement and root resorption in rats were not affected by binge drinking.