Clinical Application Research Of Miniscrew Implant Anchorage In Maxillary Protraction

Objective:We aimed to investigate the clinical effectiveness of maxillary protraction with miniscrew implant anchorage for skeletal Class III malocclusion with maxillary deficiency in growing children,and to explore the indications,advantages and disadvantages of maxillary protraction anchored with miniscrew implants.Methods:Pick out 41 cases of patients of skeletal Class III malocclusion with maxillary deficiency in growing period coming to Orthodontic Department of Stomatology Hospital of Lanzhou University from the year 2015 to 2017.Patients who have no apparent maladjustment of arch width in the early permanent dentition were included into the group of maxillary protraction with skeletal anchorage,and miniscrew implants were implanted into maxillary zygomatic alveolar ridge?MA-Z group?or alveolar septum of maxillary premolar region?MA-P group?according to the shape of zygomatic alveolar ridge.Patients who have apparent maladjustment of arch width in the late mixed dentition and early permanent dentition were included into the group of maxillary protraction with dental anchorage,and then they were divided into two groups?TA-RME group and TA group?according to whether it is necessary to expand the maxillary arch at the same time.All the four groups were treated with maxillary protraction with facemask for orthopedic therapy.Lateral cephalograms were taken before?T₀?and after?T₁?treatment,34 indexes of soft tissue,jaw and teeth were measured,and the comparison of cephalometric analysis were carried out.Mann-Whitney U test and Wilcoxon rank test were used for statistical analysis.Results:1.After treatment,statistically significant increases in SNA,Nperp-A,A-VR,Co-A,ANB,Wits and NA-PA were observed in group of maxillary protraction with skeletal anchorage?MA-P,MA-Z?and group of maxillary protraction with teeth anchorage?TA-RME,TA?,which indicates the point of A moved forward.The SNB,Pg-VR decreased significantly,and HR-GoMe,SN-Go Gn increased significantly,which indicates that point of B rotated backward and the mandibular plane angle increased.There was no statistical difference of X-ray cephalometric changes before and after treatment between the group of maxillary protraction with skeletal anchorage and the group of TA.2.There was no statistical difference of X-ray cephalometric changes before and after treatment between the group of TA-RME and the group of TA.There was no significant change of U1-PP in TA-RME group after treatment,U1-PP in TA group increased by 4.83°after treatment?P>0.05?;U1-PP in TA group decreased by 6.50°after treatment?P<0.05?,there was no significant change of U1-PP in MA-Z group after treatment.3.ANS-Me in TA-RME group and TA group increased by 1.86mm?P<0.05?and2.33mm?P<0.05?after treatment,respectively,which indicates that there is an increasing trend of the front anterior face height;but there was no statistical difference in changes before and after treatment between the two groups.ANS-Me in MA-Z group and MA-P group increased by2.75mm?P<0.05?and 1.75mm?P>0.05?after treatment,respectively,which indicates that there is an increasing trend of the front and lower height height;but there was no statistical difference in changes before and after treatment between the two groups.4.HR-PP in TA-RME group and TA group decreased by 1.00°?P>0.05?and 1.25°?P>0.05?after treatment,respectively,but there was no statistical difference in changes before and after treatment between the two groups.HR-PP in MA-Z group increased by 1.25°?P<0.05?,HR-PP in MA-P group decreased by 0.75°?P<0.05?after treatment,but there was no statistical difference in changes before and after treatment between the two groups.Conclusions:1.Miniscrew implants implanted into the maxillary zygomatic alveolar ridge and the alveolar septum in maxillary premolar region,combined with extraoral facemask for maxilary protraction,which can be successfully used for orthopaedic therapy for skeletal Class?malocclusion caused by maxillary deficiency in early permanent dentition,which can significantly reduce or even eliminate the compensation of upper and lower anterior teeth,which is often found in maxillary protraction with teeth anchorage.2.Maxillary protraction with miniscrew implants anchorage are suitable for patients who have no apparent maladjustment of arch width in the early permanent dentition with a decreased or normal vertical pattern,furthermore,rapid maxillary expansion does not promote the effect of maxillary protraction.