Treatment Effects Of Reverse-Headgear In Correction Of Severe Skeletal Anterior Cross-Bite In Mixed Dentition

Objective:The purpose of this study is to analyze the treatment effects of maxillary protraction treatment on severe skeletal anterior cross-bite in mixed dentition, to analyze the skeletal changes and dental changes on severe skeletal anterior cross-bite group, to provide experimental results to help orthodontic clinic diagnosis and treatment.Methods:According to inclusion criteria of the study,40 patients(20 boys and 20 girls, aged 7-12 years, average 8.7±1.4 years) with severe(-6°<ANB<-4°) and mild-moderate (-4°<ANB<0°) skeletal anterior cross-bite in mixed dentition were selected and treated with maxillary protraction. Each group was homogenous as to age and sex distribution. All of the patients comply with the standards:concave facial profile, anterior cross-bite, reverse overjet 2-6mm, skeletal classⅢrelatianship, no mandibular overgrowth, with no obviously asymmetric in width of upper and lower dental arch, with no orthodontic history. For each patient, maxillary protraction was taken without maxillary expansion. The lateral cephalogram was taken before and after treatment. Hard and soft tissue changes were analyzed by both traditional and Pancherz analysis to evaluate the effects of maxillary protraction(21 hard tissue parameters and 6 soft tissue parameters). All datas were analyzed by SPSS13.0 software.Results:After 4-6 months(average 5.3±1.3 months) maxillary protraction treatment, anterior cross-bite of all subjects were removed, and all were established shallow overjet and overbite. Patients and their parents are satisfied with their facial profile. The course of treatment was 4-6 months, average 5.3±1.3 months.1. Several hard tissue parameters were found to be significant, including SNA,ANB,ANS-Me,N-Me,U1-SN,U1-NA(°),L1-MP,SN-MP,Wits appraisal. In severe group, there were significant changes in U1-NA(mm),L1-NB (°),L1-NB(mm),U1-L1.2. Comparing the difference value, severe group changed more remarkably than mild-to-moderate, including ANS-Me,U1-SN, U1-NA(°),U1-NA(mm),L1-MP,L1-NB (°),L1-NB(mm),SN-MP,Wits appraisal. Several soft tissue parameters were also changed significantly, including ULP,FCA,UL-E,LL-E.Conclusion:1. After the maxillary protraction treatment on severe skeletal anterior cross-bite patients in mixed dentition, maxillar moved forward, mandibular clockwise rotation downward, and the intermaxillary relationship(ANB) changed obviously. The treatment effects were changed significantly, but there were no significant differences compared with mild-to-moderate anterior cross-bite patients.2. There were significant differences in dentoalveolar parameters:maxillary incisors labial tipping, mandibular incisors retroclination. And there were significant differences compared with mild-to-moderate group.3. After the maxillary protraction treatment on severe skeletal anterior cross-bite patients in mixed dentition, the skeletal changes(26%) were obviously less than that of mild-to-moderate anterior cross-bite patients(42%).4. After the maxillary protraction on the severe skeletal anterior cross-bite patients in mixed dentition, significant dentoskeletal and soft tissue changes and improvements were obtained. Early treatment effects were remarkable.