Effects Of Different Force Values On Orthodontic Tooth Movement And The Expression Of OPG In Periodontal Tissue Of Rats With Long-term Drinking Carbonated Drinks

Objectives Established of orthodontic tooth movement model by long-term drinking carbonated rats,to test the bone density at different time points,the moving distance of maxillary first molar,the condition of root resorption,and the expression of osteoprotegerin(OPG)in rat periodontal tissues.To investigate the effect of different force values on orthodontic tooth movement and the expression of OPG in periodontal tissues of long-term drinking carbonated beverages rats.To provide experimental basis for orthodontic treatment of patients who have the habits of long-term drinking carbonated beverages.Methods 60 female SD rats aged one month,210 ± 10 g,and clean grade were selected.After three months of feeding with Coca-Cola,the rats were randomly divided into 4 groups: group A(group 0g),group B(group 30g),group C(group 50g),group D(group 80g).Each group were divided into three sub-groups based on the periods of 7 days,14 days,21 days,with 5 in each sub-group.B,C,D group were to establish rat model of orthodontic tooth movement according to different group,each sub-groups rats were killed on the last day of each period.Bone mineral density(Bone mass density,BMD)of the left side of proximal tibia was measured at 0 day,the end of three months(90 days),afterburner for 21 days.Use the vernier caliper to measure the tooth movement distance after the afterburn.The right maxillary first molars were isolated with the periodontal tissue,and the root condition of the rats was observed by CBCT after fixation.Histological sections were prepared in the mesial and distal directions after decalcification.Calculated the root resorption index and the number of osteoclast in root resorption after HE staining and TRAP staining.The Image-Pro Plus 6.0 software was utilized to conduct semiquantitative analysis to the expression situation of OPG at the tension side of the first molar after immunohistochemical staining.The statistical analysis to mean optical density(MOD)of OPG expression of periodontal cell was conducted on the basis of histological observation and image analysis.Results 1 With the increase of the feeding time,the BMD of each group decreased and the difference was statistically significant(P<0.05),but there was no significant difference among the groups at the same time point(P> 0.05).2 The orthodontic tooth movement distance was group B > group C > group D,the difference was statistically significant(P<0.05).3 The root resorption degree was group D >group C >group B(P<0.05),the difference of group B and group A was not statistically significant(P>0.05).4 The results of immunohistochemistry showed that OPG was positive in the periodontal tissues of rats,and was mainly expressed in the lacunae of osteoblast(OB),periodontal ligament fibroblasts(PDLF),osteoclasts(OC)in the bone resorption.5 The expression of OPG was group B >group C >group D>group A after afterburn 7 days and 14 days,and there was significant difference,but there was no significant difference at 21 days.The expression of OPG decreased gradually with the increase of afterburn time,and the expression of OPG was the highest at 7 days.Conclusions 1 The experimental results confirm that long term consumption of carbonated drinks can significantly reduced bone mineral density.2 In the orthodontic force value of drinking carbonated drinks rats,compared with 50 g and 80 g,the orthodontic force value of 30 g can be used to quickly and effectively move the orthodontic teeth,and could avoid root absorption,which is the most suitable force value.3 The experimental results confirm that the expression of OPG in the periodontal tissue of drinking carbonated beverages rats decreased with the increase of afterburn time.And the greater the orthodontic force in drinking carbonated rats,the less the corresponding OPG expression,suggesting that the more bone resorption in the periodontal tissue.