Calcitonin's Effect On Reconstruction Of Suture During Early Maxillary Expansion:An Animal Experiment

Objective:Maxillary Expansion is a effective method to correct horizontal dissonance in arch.But many factors make the healing effect failing,there is a certain recurrence rate.Calcitonin is a kind of polypeptide hormone comes from thyroid parafollicular cell,which can regulate whole calcium current.Calcitonin may be able to accelerate mineralization and reconstruction in median palatine sutures of patients under maxillary expansion.The study aims to observe whether calcitonin can acceleate mineralization and reconstruction in mid sutures of rats under maxillary expansion,and to make references of the application of calcitonin in orthodontics.Methods:Part I:The establish of animal model,putting the appliance(bending two-helix spring expansion appliance with 0.016 inch Australian wire)into rats' mouth after anesthesia(pentobarbital intraperitoneal injection),then bending two free ends outward and insert into space between the first and second molars.Fixing the appliance with light-cured resin at the lingual of first molars.Besides,implanting two micro implants at two sides of the suture.At the beginning of experiment,surving the distances between buccal cusp of 1st molars,and measuring the distances between two implants.After 7 days,Measuring the same items,survey whether appliance can establish the animal experimental model.Part II:Calcitonin's effect on maxillary expansion,establishing experimental animal models like part I.24 SD rats(4 month)divide into two groups at random.During experimental session(7days),experimental group(12 rats),lumbar injecting with calcitonin(15 IU/kg)every day.Control group with physiological saline.Measuring the distance between buccal cusp of 1st molars and between two implants at the beginning and termination of the experiment,survey whether calcitonin can accelerate the expansion of maxillary.Part?:executing all rats and making tissue slice at the area between 1st molars,survey the histological changes in surure area.Results:1.In part I,the difference was statistically significantin(P<0.05)distance between buccal cusp of 1st molars,also in distances between two implants.The difference was statistically significant(P<0.05)in weight of rats.2.In Part ?,the difference was statistically significant in distance between buccal cusp of 1st molars,also in distances between two implants.3.There is a increase in numbers of osteoclast and osteoblast,and median palatine suture cartilage became wider,compared with control group.Conclusions:1.Two-helix spring expansion appliance can establish the experimental animal model successfully.2.Implanting two micro implants at two sides of the suture is a effective convenient and reliable way to measure the amount of expansion.3.Calcitonin can accelerate the amount of maxillary expansion.4.Calcitonin can accelerate mineralization and reconstruction in mid sutures during early maxillary expansion.