iDentistry The Journal Volume 14 No.1 | Page 9

The Journal Invisalign was also successful with straightening teeth by rotation, and the alignment by Invisalign had the same OGS points with fixed braces 4. According to Nguyen and Chang, the mean accuracy of the incisor rotation was 60%, the molar rotation was 50%, the premolar rotation was 47% and the rounded teeth (canine and premolar) was 39% 5. G. Translation Although the translational movement is programmed, the results still showed the uncontrolled tipping that created some clinical implications 12. Because translational movements with aligners are difficult with aligners. The translational movement used to close extraction spaces is poorly predicted 1. None of the patients completed the initial treatment with two or more extractions of premolars because of the excessive tooth tipping in the locations of extractions 3.Although the gap caused by tooth extraction may be closed completely, achieving the parallelism of the roots is still a major challenge, especially in the lower jaw 3. 3] Efficacy of clear aligners depends upon; A] Patient Compliance Patients are advised to wear aligners for at least 20 hours per day . The compliance of patient is critical factor to the treatment of Invisalign. To control for the patient's compliance, a compliance indicator can be used . However, there is currently no clinical studies on this issue. B] Activation time Currently, the majority of patients are recommended to change aligners every two weeks ever though there is not enough evidence for this. There were no significant differences between the change of aligners every week or two weeks. Orthodontic teeth movement during the first week is more than 4.4 times the second week for two- weeks prescribed wear time 12. 8 Successful rate of completing the initial set of aligners is higher at two-weeks activation time (37%) than one-week activation time (21%) 3. C]Materials There were no significant differences between hard and soft materials in the completion of series of aligners (2, 3) . However, in four different groups of treatment protocols, the combination of hard materials and two-weeks activation times had the best results in all the measurements of occlusal improvement and alignment 2. Although, the aligner degradation has not been fully studied, it seems that the aligner‟s ability of force magnitude is reducing over time. Research on material fatigue did not detect any difference in tooth movement between the two- weeks activation time group and the group who wore a new aligner after one week of two weeks prescribed activation time 12. Discussion So which tooth movements are possible using clear aligners? The study of Vlaskalic (et al) was concluded that although Invisalign can be an alternative for removable or fixed orthodontic appliances in select cases, by comparing the results and the effectiveness of Invisalign treatment with traditional orthodontic treatments, it is clear that more studies are needed that have further clinical prospective, controlled studies with appropriate sample sizes and the use of assessment objective methods to evaluate the results 1. There are three studies about the accuracy of tooth movements (5,8, 9). The study by Nguyen and Cheng concluded that clinicians should use overcorrection and refinement to complete treatment goals. In this study, the mean accuracy of anterior tooth movement was 56%5. On the other hand, in the study of Kravitz, the mean accuracy of anterior tooth movement was lower at 41%. Vol. 14 No. 1 Jan-Apr 2018