Comparison On Pre-post Leveling And Aligning Treatment In Angle Ⅱ~1Soft And Hard Tissue By Using Transmission And MBT Straight Wire Technology

BackgroundThe classical Angle classification of malocclusion initiated by dentist E.HAngle in1899is the most widely used one in the current word.Class II malocclusionis common in the clinic which usually show deep overbite,deep overjet,class II molarrelationship, discrepancy in upper and lower dental arch.Based on previous treatmentexperience,the dentists found deep overbite was a high incidence malocclusion typein AngleII1,and also the important question in process of treatment.Bite-opening,thatis adjusting vertical relationship has great importance of sagittal direction.So manyclinical dentists hold that bite-opening is not affiliated critical steps but was the keyone.Compared with edgewise technology,MBT straight wire technology was usedwidely in the clinic，which had greatly simplified the procedure of treatment anddecreased the chair-side operating time.MBT straight wire appliance has the tendencyof aggravating deep overbite in aliening and leveling process because of largeinclination of canine bracket. Transmission straight wire appliance technique wasinvited by professor Lin jiuxiang of Peking university in2006.It was an efficientappliance and had the advantage of Begg technique and Tip-Edge technique. Thedeep overbite was opened by the tip back bend on arch wire and little force class IIelastic in aliening and leveling process.This thesis is to compare the differences ofhard and soft tissue between transmission straight wire technology and MBT straightwire technology in opening AngleII1deep overbite process. ObjectiveThe patient of Angle II1malocclusion with deep overbite was treated bytransmission straight wire tech and MBT straight wire appliance. The change of hardand soft tissue and transform of teeth were contracted before treat and after alieningand leveling.MethodsSixteen patients has diagnosed for the Angle II1malocclusion, The maxillaryand mandibular anterior teeth with deep overbite II°or above, The relationship ofmolar is class II. In the treatment of extraction tooth design for maxillary firstpremolar, the mandibular second premolars.The experimental group (8cases) usedTransmission straight wire technology.The matched group (8cases) used MBTstraight wire technology. Have taken X-ray cephalometric analysis before and afteraliening and leveling. Compare the two groups before and after treatment the changesof skeletal and soft tissue and teeth. All X-ray cephalometric analysis for the oneperson to measured. Concentrate on fixed point and measurement analysis of X-ray.2times for the same project measurement and to find the average. Also requiredbetween two measurement error control in0.5mm, or is1.0°.If appear error, domeasurement again.Results1. It’s same to make deepbite opening for The experimental group and matchedgroup. The experimental group, the average time was4.0±0.5months; and in thematched group, the average time was7.0±0.5months.2. In the experimental group average U1-NA have reduced14.0°,the U1-NA(mm)have reduced4.8mm,U1-L1°have increased by17.0°was significantly(P<0.01). L1C-MP(mm) have reduced2.0mm.Anterior maxillary teeth protrusionwas decrease make patient have significantly improved after aliening and leveling. 3. In the experimental group UMC-PPV(mm) have increased by0.4mm withoutstatistical significance(P>0.05), maxillary molar just a little mesial movement.LMC-MPC(mm)have reduced2.8mm (P<0.01) mandibular molar moved wasstatistically significant.4. After aliening and leveling,in the experimental group the CmSnLs°increased1.3°have significant different (P<0.05).NsLs-FH°decreased1.1°was not statisticallysignificant.5. After finish,experimental group had more changed for anterior maxillary teethand upper lip.Conclusion1.Transmission straight wire technology can effectively open deep overbite in ashorter period of time.2.Transmission straight wire technology opens the deep bite and retracts theanterior tooth by the tip back bend on arch wire and class II elastic. The problem ofdeep overjet and the anterior maxillary teeth flared was solved.3.Facial profile have great improvement after the deep overbite opening. Itincreases the confidence of the patients for treatment.