Skeletal ClassⅡ Combine Congenitally Missing Mandible Incisor In Dual-phase Continuous Treatment

Object:This study designed to observe and evaluate the clinic effect of thedual-phase treatment in skeletal ClassⅡmalocclusion.Methods:A female case with skeletal Class Ⅱ malocclusion was selected fromDalian ortho clinic in2011,who was13-year-old2months,the skeletal age of cervicalvertebra is12.54ages（Use the WinCeph Version8.0software）.normal maxilla andmandibular retrusion relative to the SN plant, deep overbite of Ⅱdegree and overjet Ⅲdegree, labial inclination of the upper incisor, lingual inclination of the lower anteriors,moderately crowded upper dentition, congenital absence of bilateral mandibular centralincisor, gap under the denture with scattered, perfect the uppermiddle line. The patient istreated by the Twin-block functional appliance in combination with Roth straight wireappliance of the dual-phase continuous treatment. And compare cephalometricradiograph measurements of the pre-post orthodontic treatment.Results: The course of orthodontical treatment needs23months.Compare thechanges between pre-treatment and pro-treatment:(1)Maxilla is essentially thesame,mandible in the sagittal and vertical directions has changed significantly.Mandible length from104mm to108mm; the high of ANS-Me from63mm to65.5mm.SNA did not significantly change, SNB increased3°,ANB decreased2°.(2)Theanterior teeth of upper and lower jaw are close to normal. The U1-SN angle decreasedfrom109°to100°, and increased to106°at the end of the second phase; The L1-MPangle increased from93°to100°, the L1-NB angle increased17°to31°.(3)Coordination of facial height ratio. ANS-Me/N-Me(%) essentially unchanged.(4)Thevalues of soft tissue are close to normal. A’UL’-FH angle and B’LL’-FH angle increasedsignificantly. A’UL’-FH increased from57.5°to61°;B’LL’-FH increased from41°to45°;Merrifield’s Z angle increase from71°to73°;Nasal-labial angle increased from 70°to78°.Mandibular soft tissue profile improved, the patient and her parents weresatisfied with the result of orthotherapy after treatment.Conclusions: Using the dual-phase continuous treatment to the patient who is thepeak in the growth and development of skeletal ClassⅡ can improve bone, soft tissueprofile and have satisfactory occluding relation effects, but also shorten the course oftreatment.