Curative Effect Analysis Of Maxillary Protraction With Bone Anchorage Before And After Treatment

Objective: Bone anchorage assisted maxillary protraction is adopted for all the patients with Skeletal Class Ⅲ malocclusion that met the treatment conditions.By comparing Cone-beam Computed Tomography(CBCT)before and after treatment,the changes of facial soft and hard tissues are analyzed to provide a non-operative treatment method for the patients with Skeletal Class Ⅲ Malocclusion.Methods: From October 2020 to June 2022,20 patients with Skeletal Class Ⅲmalocclusion who met the inclusion criteria,mainly with insufficient maxillary development,normal mandibular development or mild excessive mandibular development,were selected from the Orthodontic Department of Shenyang Stomatological Hospital and treated with maxillary protraction with bone anchorage,inclubing administered to 10 patients in the juvenile group and 10 patients in the adult group.Routine orthodonti-related examinations,including CBCT examination,routine photomicrography,and plaster casts,were performed prior to treatment.And comprehensive analysis of the examination data was conducted.Maxillary Skeletel Expander(MSE)with traction hooks which extend to the canines,was cemented and fixed on the maxillary dentition of all patients.All patients underwent maxillary protraction with face mask.The specific methods are as follows: local anesthesia was performed at corresponding locations of maxillary palatal and the skeletal expander was implanted with 4 micro-implants(1.45mm×11.1mm).In order to activate the suture,The patient was required to undergo maxillary bone expansion through MSE for one week prior to anterior maxillary traction with a face mask.At night,the mask and traction hook were worn for elastic traction through rubber bands.The traction force was 1000-2000g/ per side and the traction time was required to be 10-14 h at night every day.When the anterior teeth overjet covered 2-3 mm,the anterior traction treatment was completed.No obvious recurrence was observed for one month,and then traction was terminated,and the bracket was glued as soon as possible.CBCT and color photographs were taken at the beginning and end of traction.The CBCT data were imported into Dolphin image 11.95 measurement software to measure and analyze 51 soft and hard tissue measurements before and after treatment,and the changes in sagittal and vertical directions were compared.The measured data were imported into SPSS25.0 statistical software,so as to analyze the bone,dental and soft tissue changes in patients with skeletal class III malocclusion before and after treatment.And the paired sample T-test was performed on the measured results before and after treatment.The test criteria were as follows: the difference was statistically significant when P value < 0.05.The CBCT images and color facial photos of patients before and after treatment were imported into Dolphin image 11.95 for three-dimensional overlap to observe the therapeutic effect more directly.Results: 1.Changes of maxilla: In the juvenile group after treatment,SNA,A-Y,ANS-Y,Co-A,A-Nperp and SNO increased;A-X and ANS-X decreased,and the difference was statistically significant(P < 0.05).In the adult group after treatment,SNA,A-Y,Co-A and A-Nperp increased;A-X,ANS-X and SN-PP decreased,and the difference was statistically significant(P < 0.05).2.Changes of mandible: In the juvenile group after treatment,SNB,B-Y,Pog-Y and Pog-Nperp decreased;B-X and Pog-X increased,and the difference was statistically significant(P < 0.05).In the adult group after treatment,SNB,B-Y,Pog-Y and Pog-Nperp decreased;B-X,Pog-X,MP-FH and SN-Go Gn increased,and the difference was statistically significant(P < 0.05).3.Sagittal changes between mandible and mandible: ANB,Wits value,AB-MP and N-A-Pog were significantly increased after treatment in both juvenile and adult groups(P < 0.05).4.Changes of teeth: In the juvenile group after treatment,U1-PP,U1-NA Angle,U1-NA distance and U1-Ymx decreased;Overjet,U1-Xmx and U6-Ymx increased,and the difference was statistically significant(P < 0.05).In the adult group after treatment,U1-PP,U1-NA Angle,U1-NA distance and U1-Ymx decreased;Overjet,U1-Xmx,U6-Xmx,U6-Ymx and OP-SN increased,and the difference was statistically significant(P < 0.05).5.Changes of soft tissue and facial height: In the juvenile group after treatment,A ’-Y,Sn-Y,UL-Y,UL-Eline,N-Me and ANS-Me increased,and the difference was statistically significant(P < 0.05).In the adult group after treatment,A ’-Y,Sn-Y,UL-Y,UL-Eline,LL-Eline,N-Me and ANS-Me increased;LL-Y and Pog ’-Y decreased,and the difference was statistically significant(P < 0.05).Conclusions: 1.In the juvenile group after treatment,the maxilla shifted forward obviously,and the midfacial area of the infrorbital region also tended to grow forward.In the adult group after treatment,the maxilla tended to grow forward and upward.2.In both juvenile and adult groups after treatment,the mandible showed a backward and downward downward spiral trend.3.In both juvenile and adult groups after treatment,the sagittal relationship between maxilla and mandible was significantly improved and that facial protrusion was significantly increased.4.In both juvenile and adult groups after treatment,the overjet of the anterior teeth were significantly increased and the cross-bite relationship of the anterior teeth were all disengaged.In the juvenile group after treatment,maxillary anterior teeth leaned to the lingual side and maxillary molars are slightly forward.In the adult group after treatment,maxillary anterior teeth leaned to the lingual side,and maxillary molars are slightly forward and elongated,and the functional occlusal plane was supinated.5.In both juvenile and adult groups after treatment,the nasal base was plump,and the upper lip moved forward,and the side appearance was improved,and the anteriorly height and anteriorly below height increased.