A Randomized Controlled Trial on the Effectiveness ofProtractionTherapy for Early Permanent Dentition Skeletal Anterior Crossbite

INTERVENTION: Traditional expansion set:Traditional bow expansion;Alt‐RAMEC Set:Bone expansion+Alt‐RAMEC; CONDITION: Skeletal Class III malocclusion PRIMARY OUTCOME: Treatment Efficacy Rate; SECONDARY OUTCOME: Rate of orthodontic appliance loosening and falling off; INCLUSION CRITERIA: 1 Age: Female: 10 years old <= age <= 14 years old; Male: 11 years old <= age <= 15 years old; 2 Early permanent teeth, anterior anticuspension; 3 Imaging criteria: ‐4° < ANB <= ‐1°, Wits < ‐2mm, Pog‐Np < 2mm, CVS staging III‐V (cervical spine maturity assessment); 4 Not having received orthodontic treatment; 5 Informed consent signed by the patient and his/her guardian.