The Animal Experimental Study On The Effect Of Magnetic Force Combined With Microscrew Implant To Move Teeth On Alveolar Bone Remodeling

Objective:In order to study the effects and differences between the microscrew-retained magnetic orthodontic system and the traditional extension spring combined with microscrew implants on alveolar bone remodeling to provide a reference for understanding the mechanism and clinical application of magnetic orthodontic treatment.Methods:1.Design and produce the MTSCMThe MTSCM consists of a magnetic device and a miniscrew implant.The main part of the MTSCM magnetic device is stainless steel,the force source part is neodymium iron boron magnet and armature,and the anchorage part is micro screw implant.2.Animal experiment12 male Beagle dogs aged 18-24 months were adapted for feeding.The left lower jaw was used as the experimental site and the dogs were randomly divided into a microscrew-retained magnetic orthodontic system for moving teeth(hereinafter referred to as magnetic group)and a tension moving tooth group combined with miniscrew implants(hereinafter referred to as the tension spring group),and each group has six dogs.Using the self-control design,the right jaw of the beagle dog was used as a blank control group.Anesthesia was performed by intraperitoneal injection of 2% pentobarbital sodium solution,and the left and right mandibular first and second premolars and maxillary cuspids of 12 beagle dogs were removed immediately after the left mandibular canine in all beagle dogs.Microscrew implants were implanted,and then the right mandibular first and second premolars and maxillary cuspids were removed as the blank control group.After 2 weeks,the left mandibular third premolars were moved with MTSCM and tension springs respectively,and the time for exertion was 1 month.3.Obtain alveolar bone tissue specimenExcessive anesthetic was used to kill all Beagle dogs.The periodontal tissues of the left mandible and the third premolar in all Beagle dogs were removed,and the periodontal tissues of the third mandibular premolar in the Beagle canine were removed from the control group,and the soft tissues such as the surface mucosa and muscle were removed.Prune the bone tissue and cut the bone fragments.The tissue of each beagle dog was divided into two parts,one was stored in a liquid nitrogen tank and used as a RT-PCT test.One was stored in the refrigerator of-80℃ as a bone calcium phosphate test.4.Determine the relative gene expression levels in alveolar boneThe gene expression levels of bone BMP-2,Osterix,RANKL,OPG,and TRAF6 in alveolar bone were measured by RT-PCR.5.Determine the calcium and phosphorus content in alveolar boneThe calcium and phosphorus in the alveolar bone were extracted by concentrated acid digestion method.The content of calcium and phosphorus in the alveolar bone of the magnetic group,tension spring group and blank control group were measured and calculated.The degree of mineralization of the sulcus was measured.Results:1.The expression of BMP-2,RANKL,OPG,Osterix,and TRAF6 genes in the alveolar bone taken by beagle dogs in the magnetic group and the extension spring group was significantly higher than that in the blank control group,and there was significant difference(p<0.01).Compared with the tension spring group,the expression levels of BMP-2,RANKL,and OPG genes in the magnetic group were significantly higher than those in the tension spring group(p<0.05).The expression levels of Osterix and TRAF6 genes in the two groups were not statistically different.2.The content of bone calcium and bone phosphorus in the unit volume of the alveolar bone taken by Beagle dogs in the magnetic group and the tension spring group was significantly higher than that in the control group(p<0.01),while the magnetic group and the pull There was no statistical difference between the spring groups.Conclusion:1.Both magnetic force and spring tension can significantly enhance the expression of BMP-2,RANKL,OPG,Osterix,and TRAF6 in the alveolar bone around the moving tooth and the degree of bone mineralization.2.There was no difference in the contents of Osterix,TRAF6 and calcium and phosphorus in alveolar bone around the moving teeth.3.Compared with spring tension,the magnetic force significantly enhances the expression of BMP-2,RANKL,and OPG in the alveolar bone around the moving tooth,suggesting that magnetic force may promote osteogenic and osteoclastogenesis by affecting these three molecules.