| Objective:The aim of this study was to evaluate the effect of rapid maxillary expansion(RME)and face mask(FM)therapy on the skeletal,dental,and soft tissue of the prepubertal patients with normodivergent skeletal Class III malocclusion using a three-dimensional facial scanner and lateral cephalometric radiographs.Methods:A total of 32 patients with skeletal class III malocclusion,aged 8 to 10 years(9.15±1.43 years on average),who were treated in the Orthodontics Department of the Stomatological Hospital of Jilin University from May 2021 to May 2022,were selected as the study subjects according to the inclusion criteria.All patients were treated with maxillary rapid expansion for two weeks,the expander was turned up0.25mm/day in the first six days of each week and closed 0.25 mm in the seventh day of the week and repeated expansion in the second week.Forward traction was performed during the expansion treatment.The average correction time was6.28±0.55 months,which significantly improved the patient’s anterior crossbite(occlusion)and soft tissue profile.Before treatment(T0)and after treatment(T1),the head positioning lateral films(LCRs)and 3D photographs were taken,and the LCRs were imported into Dolphin software to measure and analyze the dental and maxillofacial structural indicators.3D photographs were scanned by a hand-held color3 D scanner(Space Spider of Luxembourg Artec 3D Group)to perform face scanning before treatment(T0),three months later(T ’)and after treatment(T1).The data is saved in Standard Template Library(STL).Import STL format digital model data into Geomagic Control X software for fixed point,measurement and data collection.The model was overlapped through the forehead before,during and after the treatment to analyze the movement of the marker point in the three-dimensional direction.After three months of treatment(T ’),additional three-dimensional facial scans were taken to record the mid-term soft tissue changes.The measured data were statistically analyzed with SPSS 26.0.Using paired sample t-test to compare the changes of soft and skeletal tissues of maxillofacial region before and after treatment.Results:1.Analysis of lateral radiographs before and after treatment showed that the measured items representing maxillary growth and development increased significantly.SNA,ANB,NA-AP and Wits increased by 3.41 °(P<0.01),3.47 °(P<0.01),6.89 °(P<0.01)and 3.89 mm(P<0.01)respectively;Point A moves forward and down,with sagittal moving forward 3.72 mm(P<0.01)and vertical moving downward 1.19 mm(P<0.01)Coben analysis showed that the length and depth of the maxillary were significantly increased(P<0.05),while the changes of mandibular was not obvious(P>0.05).2.After correction,the facial height of the patients increased,and S-Go,N-Me,Sn ’-Me’ increased(P<0.05),but the length of Go-Po(mandibular body)and Ar-Go(mandibular branch)did not change significantly,and the changes of FMA,S-Go/N-Me were not statistically significant(P > 0.05),indicating that the treatment had no effect on the growth direction of the mandible;The labial inclination of maxillary incisors increased by 3.61°(P<0.05),and the lingual inclination of mandibular incisors decreased by 2.77°(P<0.01).At the same time,the relationship between the upper and lower lips and the E-line was significantly improved after the correction.The upper lip position moved 1.31 mm forward due to the sagittal growth of the maxilla and the lip inclination of the upper anterior teeth(P<0.01).3.The soft tissue analysis showed that the change of the width of the maxillofacial region caused by rapid maxillary expansion was mainly manifested in the increase of 0.78 mm(P < 0.01);The bilateral nostrils were basically symmetrically widened,with 0.24 mm increase on the left side(P < 0.01)and0.25 mm increase on the right side(P<0.01);.The improvement of soft tissue profile was mainly attributed to the reduction of facial convex angle(P<0.01)and the increase of upper and lower lip angles(P<0.01);The soft tissue analysis after three months of treatment showed that the change of convex angle of face and upper and lower lip angles accounted for about 70% of the change before and after treatment.4.Three-dimensional analysis of the marker points showed that only the soft tissue marker points of the nose changed in width,indicating that the expansion of the arch could cause the nasal width to increase;The marker points at the base of the nose and upper lip move significantly forward in the sagittal direction due to the growth and development of the upper jaw,while the marker points of the soft tissue of the lower jaw move backward and downward due to the increase of the face height and the treatment of the cross bite.Conclusions:1.The treatment of rapid maxillary expansion combined with anterior traction has a significant therapeutic effect on skeletal class III patients with maxillary hypoplasia.2.The lateral radiograph analysis showed that the maxilla moved forward and down after treatment,while the mandible and mandibular plane did not change significantly.3.Three-dimensional soft tissue is characterized by an increase in the upper and lower lip angles and a decrease in the convex angle of the face.Significant effects can be observed in the middle stage of treatment. |
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