Therapeutic Effect Of Miniscrew Assisted Maxillary Skeletal Expansion In Adults

Objective:The aim of this study was to evaluate the skeletal and dentoalveolar changes after miniscrew assisted maxillary skeletal expansion with maxillary skeletal expander(MSE)in adults with transverse maxillary deficiencies,using high-resolution cone-beam computed tomography.Specific aims were to evaluate the influence of gender,screw opening and age on the efficiency of skeletal expansion.Methods:In this study,52 consecutive adults(19 males,29 females,22.6±3.5 years old)who were treated with MSE were obtained in Stomatology Hospital of Shandong University.CBCT scans of all subjects were taken before expansion and 3 months after completion and were imported into Dolphin Imagine 3D software at DICOM format.All measurements were performed using Dolphin Imaging 3D software,which included transverse width of maxilla,nasal bone,lateral pterygoid plate,zygomatic bone and temporal bone and dentoalveolar measurements.Paired sample t-test,independent sample t-test and correlation analysis were utilized using SPSS.Results:1.The failure rate of MSE was 7.7%in this study.After the screw was opened 6.3±1.1mm in average in 48 patients,the transverse width of maxillary base increased significantly(P<0.05).The amount of split at HP-PM was 96.7%of that at HP-M;The amount of split at NF-5 was 63.6%of that at HP-5.The efficiency of skeletal expansion at HP was 64.3%±16.5%.No significant differences were found in the efficiency of skeletal expansion at HP-M between males and females(P>0.05).Correlation between screw opening,age and efficiency of skeletal expansion was negligible(P>0.05).2.The transverse width of nasal cavity,lateral pterygoid plate,zygomatic bone and temporal bone increased significantly(P<0.05)3.There were less buccal inclination(1.8±2.8° left,2.0±2.6°right)and intrusion of anchorage teeth(P<0.05).And slight buccal inclination of alveolar bone(0.9±1.1°left,1.1±1.0° right)and loss of vertical alveolar bone were observed(P<0.05).Conclusion:1.Miniscrew assisted maxillary skeletal expansion is an effective therapeutic strategy to correct transverse maxillary deficiencies for young adults,which increases the transverse width of maxillary base,nasal cavity,zygomatic bone et al,produces anterior-posterior parallel expansion of maxilla and results in less unwanted dentoalveolar effects2.The efficiency of skeletal expansion varies greatly among individuals,which has no relevance to gender,age and screw opening,the failure rate of MSE is low.