| Objective:Evaluation study of the efficacy of invisible orthodontic treatment for adolescent skeletal II mandibular retrusion,In order to provide reference and basis for clinical correction of such patients Materials and methods:A total of 30 adolescent patients with skeletal II mandibular retraction were selected from our hospital from December 2017 to June 2021,including 15 males and 15 females.The initial diagnosis age was 10-13 years,with an average of 11.6±0.9 years,and the average duration of treatment was 13.5 months.The lateral radiographs of 30 patients were collected and imported into Dolphin Imaging software.The data were recorded as stage T0 before treatment and stage T1 after treatment.The changes of skeletal and tooth related items of MA patients were measured by linear measurement superimposed with lateral radiographs trajectory based on Pancherz technology.Establishment of Pancherz analysis: plane OL(through the line between the most convex edge of the upper central incisor and the distal buccal apical point of the maxillary first molar)was made on the lateral cephalic radiographs before treatment as the horizontal reference axis,and the sellar point S was used to make the vertical OLP to the OL plane as the vertical reference axis to establish the coordinate system between OL and OLP.Point S was used as the overlapping point,and the SN plane was used to transfer the pre-treatment coordinates to the post-treatment lateral cranial radiographs,and the changes of jaw and tooth related items were measured before and after MA correction.SPSS 23.0 software was used to complete statistical analysis,and the detection level was α=0.05.SPSS 23.0 software was used to complete statistical analysis,and the detection level was α=0.05.Results:1.Maxillary length and position changes before and after treatment: ss /OLP of maxillary position showed no statistically significant change,while Pg/OLP of mandible position increased by 3.13 ㎜,Pg/OLP+Co/OLP of mandibular length increased by 4.14㎜ on average,the Co-Go length of mandibular ramus increased by 4.09 ㎜,Go-Pg length of mandibular body increased by 4.25 ㎜,with statistically significant differences.2.Changes in sagittal relationship of skeletal before and after treatment: SNA slightly decreased,the difference was not statistically significant;SNB increased by 1.96°,ANB decreased by 2.03°,and Wits value decreased by 2.90 ㎜,with statistical significance(P < 0.05).3.The effect on TMJ before and after treatment: Co/OLP of condyle increased by1.03 ㎜ compared with before treatment,and the difference was statistically significant(P< 0.05).4.Changes in the vertical relationship of skeletal before and after treatment: SN-MP increased by about 1.65° on average,S-Go /N-Me decreased by 2.04%,and ANS-Me/ NME increased by 1.45% on average,with statistical significance(P<0.05).5.Changes of sagittal position and torque of upper and lower incisors before and after treatment: The position of the upper incisor point is/OLP was decreased by 1.33 ㎜on average,the difference was not statistically significant(P > 0.05),the upper and middle incisor inclination U1-NA was decreased by 3.44° on average,and the upper and middle incisor Angle U1/SN was decreased by 4.06° on average(P < 0.05).The position of lower incisor point ii/OLP increased by 2.98 ㎜ on average,the inclination of lower central incisor point L1-NB increased by 2.62° on average,and the Angle of lower central incisor point L1-MP increased by 1.23° on average,with statistical significance(P < 0.05).6.Before and after treatment,the change of overjet and molar relationship and the proportion of skeletal and dental: the total change of anterior tooth coverage is/ OLPii/OLP reduced 4.31 ㎜ on average(P < 0.05),of which,dental factors total 1.73 ㎜,accounting for 40.1%,skeletal factors accounted for 59.9%;molar relationship ms/OLPmi/OL improved 3.69 ㎜ on average(P < 0.05),among which,dental factors contributed1.34 ㎜,dental factors and skeletal factors accounted for 63.7% and 36.3%,respectively.Conclusions:For adolescent patients with skeletal retraction of the mandible,Invisalign MA mandibular advancement treatment:1.It can effectively promote the growth and development of mandible and improve the profile.2.There are both dental and skeletal effects,but the skeletal effect is the main one.3.It can promote the growth and reconstruction of condyle. |
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