A Study On Treatment Design Of Upper Arch Expansion And Its Clinical Therapeutic Efficacy Of Non-extraction Treatment With Clear Aligners

Objective:Preliminary study on treatment design of the amounts of upper arch expansion with Clear Aligners and assessment of its non-extraction therapeutic efficacy and to provide a reference for clinical treatment.Method:From September 2016 to December 2021,66 patients who received nonextracted treatment of upper arch expansion with Invisalign in the First Affiliated Hospital of Zhengzhou University were selected to be part of this study.There were 32 male patients and 34 female patients,aged 24.66±6.7 years.Their three-dimensional models were respectively collected before treatment(T0),after expansion(T2)and after treatment.The 3D models designed by computer software were also collected(T1).Besides,the lateral cephalometric X-rays,panoramic tomography and smiling images were needed.Clinicians used Geomagic Wrap.2017 software to measure the linear values of upper arch widths for canines,premolars,first and second molars at cusp tips and for canines,premolars and first molars at lingual gingival margins.The efficiency of upper arch expansion and bodily expansion were both calculated.Also,scatterplots were drawn and We analyzed the correlation between planned expansion and final expansion using linear regression analysis.So did the correlation between planned bodily expansion and posttreatment bodily expansion.The initial treatment difficulty of 66 patients were evaluated by CAT-CAT through assessing their lateral cephalometric X-ray films,panoramic tomography,full-faced smiling photos and 3D dental models.Non-extraction therapeutic efficacy with Invisalign was assessed by ABO-OGS through measuring their panoramic tomography and 3D dental models.The scatterplot was drawn between ABO-OGS scores and CAT-CAT scores.To investigate whether the therapeutic effect of non-extraction treatment with Invisalign was influenced by treatment difficulty through linear regression analysis,and to verify whether the therapeutic effect of non-extraction treatment with Invisalign was reliable and valid.Results:1.There was a statistically significant increase in upper arch width after arch expansion using Invisalign.(P<0.05).However,the final outcomes didn’t reach the amounts that Clincheck software anticipated(P<0.05).The efficiency of upper arch expansion from canines to molars were[(64.51 ±8.08)%]、[(68.62±6.48%]、[(64.34±5.51)%]、[(44.08±8.77)%]、[(28.99±10.36)%]respectively.The efficiency of upper arch bodily expansion from canines to molars were[(56.70±6.97)%]、[(60.05±5.19)%]、[(55.33±5,56)%]、[(33.64±1 0.75)%].2.The scatterplot showed there was a linear correlation between planned expansion and final expansion.Linear regression equations had been worked out between planned expansion and posttreatment expansion,as well as the linear regression equations of bodily expansion.And linear regression equations were depicted as follows from canines to molars y=-0.181+1.79x(r=0.96,P<0.05),y=-0.299+1.72x(r=0.98,P<0.05),y=-0.285+1.79x(r=0.96,P<0.05),y=-0.626+3.26x(r=0.90,P<0.05),y=-0.442+5.04x(r=0.89,P<0.05).And the linear regression equations of bodily movement from canines to molars were respectively depicted as follows.y0=-0.306+2.24x0(r=0.98,P<0.05),y0=-0.359+2.04x0(r=0.97,P<0.05),y0=-0.337+2.18x0(r=0.96,P<0.05),y0=-0.18+4.14x0(r=0.72,P<0.05).3.The CAT-CAT average scores were 34.90±11.30.The maximum and minimum values were 64 and 14.The ABO-OGS average scores were 19.89±5.59.The maximum and minimum values were 29 and 10.The alignment,the height of posterior margin ridge,the buccal and lingual inclination of posterior teeth and occlusion got higher marks than the rest.And the interproximal contacts scored the lowest,which average value was 0.38±0.83.4.In the scatterplot,points distributed well.There was not significant correlation between ABO-OGS scores and CAT-CAT scores.R value was 0.461 and R2 value was 0.213(P<0.05).5.According to ABO-OGS,39 patients reached the criterion of excellent curative effect and the rate was 59.09%.66 patients reached the criterion of standard curative effect and its rate was 100%.And none of these were below standard.Conclusion:1.There is an acceptable efficacy of upper arch expansion which is higher than efficacy of upper arch bodily expansion using Invisalign.2.The posttreatment expansion does not go that much as planned.Linear regression equations could help clinicians better predict upper arch expansion.And if tipping movement is not needed,linear regression equations of bodily buccal movement would be better to be used as a reference.3.Through linear regression analysis,the clinical therapeutic effect of non-extraction treatment with clear aligners is not affected by treatment difficulty.4.It has been proved that the clinical therapeutic efficacy of non-extraction treatments for mild crowded cases at all levels of difficulty with clear aligners was desirable.And it is necessary to control the occlusal contact and torque of posterior teeth and to get rotated teeth better corrected.