Assessment of Invisalign treatment outcome by model analysis using the ABO objective grading system

InvisalignRTM is a new orthodontic treatment modality of treating malocclusion with an advanced esthetic approach. It provides an esthetic and hygienic alternative for patients who want to undergo orthodontic treatment without affecting their facial appearance. However, few studies have been published to evaluate the effectiveness of this appliance. Purpose of the study. The purpose of this study is to evaluate the Invisalign treatment outcome of mild to moderate malocclusions by using the Model grading system (MGS) of the American board of orthodontics (ABO). Materials and Methods. A total of 425 InvisalignRTM cases were identified from an orthodontic private practice in buffalo, New York State. Of 425 cases, 119 met the inclusion criteria of having full permanent dentition with (DI) score between 10 and 20, and treated completely with Invisalign without extraction. From those 119 cases, only 31 cases had a complete set of records before and after treatment. The pre-and post-treatment models were assessed using the ABO Model Grading System (MGS) .Wilcoxon signed rank test was used to compare the pre-and post-treatment MGS scores in all categories. Results. The mean scores of all MGS categories (except occlusal contacts score and occlusal relationship score) were improved after treatment. Significant improvements were found in OGS Score (45.03+/-7.47 vs. 35.87+/-9.36, p<0.0001), alignment score (15.16+/-5.00 vs. 6.00+/-3.78, p<0.0001).and in B-L inclination Score (7.00+/-3.14 vs. 6.26+/-3.58, p=0.0243). However a negative change was found in occlusal contacts and occlusal relationship score. Conclusion. Results of the OGS show that InvisalignRTM treatment for mild to moderate cases are effective in tooth alignment and buccolingual inclination, however it has a negative effect on posterior occlusal contacts and occlusal relationships.