Joint Skeletal Class â…¡ Of Twin-block Appliance In Dual-phase Continuous Treatment

Objective:To evaluate the efficacy of the dual-phase continuous tre-atment on the growth and development of skeletal Class II malocclusionMethods:A male case with skeletal Class II malocclusion was selected from Dalian Ortho clinic in 2009, who was 11-yeas-old 7 months, normal maxilla and mandibular retrusion relative to the SN plane, bilateral rela-tions between molar neutral and nearly, deep overbite of incisorⅢdegree and overjet II degree, lingual inclination of incisor, moderately crowded upper dentition,congenital absence of bilateral mandibular lateral incisor, gap under the denture with scattered, the left side under the middle 1.5mm. The patient is treated by the Twin-block functional appliance in combin-ation with Roth straight wire appliance of the dual-phase continuous treat-ment.And compare cephalometric radiograph measurements of the pre-post orthodontic treatmentResults:The course of orthodontical treatment needs 16 month-s.Compare the changes between pre-treatment and protreatment:(1)Maxilla is essentially the same,mandible in the sagittal and vertical directions has changed significantly.Mandible length from 121mm to 125mm;Po-NaPerp. increased from-6 mm to 0;the hight of ANS-Me from the 71.5mm to 73.5mm.SNA did not significantly change,SNB increased 3.5°,ANB decrea-sed 3.0°.(2)The U1/SN angle decreased from 102°to 98.2°,and increased to 110°at the end of the second phase.The Ll/MP angle increased from 92°to 98°,the L1/NB angle increased from 27°to 31.2°.(3)Coordination of facial height ratio.ANS-Me/N-Me(%) essentially unchanged,S-Go/N-Me(%) increased from 68.7 to 70.1.(4)The lower lip protru-sion.chin groove angle and facial angle increased significantly.LLP incre- ased from 2.0mm to 4.0mm,Pg'B'-FH increased from 74°to 84°,FH-Ns-Pg increased to 95.5°,the values are close to normal.Mandibular soft tissue profile improved, the patient and his parents were satisfied with the result of orthotherapy after treatment.Conclusions:Using the dual-phase continuous treatment to the patient who is the peak in the growth and development of skeletal ClassⅡcan improve bone,soft tissue profile and have satisfactory therapeutie effec ts,but also shorten the course of treatment.