iDentistry The Journal Volume 14 No.1 | Page 10

The Journal The accuracy of most tooth movements was lower than 50%, except for the labial expansion of mandibular lateral incisors, the lingual constriction of maxillary central incisors, mandibular lateral incisors, mandibular canines, the rotation of maxillary central incisors, mandibular lateral incisors9. When analyzing the accuracy of each tooth movement, rotation was the only tooth movement that showed significant difference between the teeth. It was thought that the attachments would increase the undercut and geometrical retention of the teeth and make the tooth rotaton better 8. The use of vertical- shaped ellisoid attachments placed in the middle of the tooth crown, showed little clinical improvement compared to the rotation of teeth without attachments 8. However clinician should be cautious when using Invisalign to treat patients with the discrepancies of crowding and spacing of more than 5mm, anterioposterior discrepancies of more than 2mm, tooth rotation of more than 20 degrees, anterior, posterior openbite, extrusion, tooth tipping of more than 45 degrees, short crown teeth; and severe missing teeth . Factors affecting treatment outcomes by clear aligners:- One of the important reasons that makes Invisalign less effective than fixed appliances seems to be the patient‟s compliance. Invisalign patients are recommended to remove aligners when eating, but clinicians find it hard to control the patient‟s wear time and this causes biomechanical disadvantages 10. Recommended activation time is two- weeks, but if the aligners are not entirely passive, because the teeth have not yet moved to the programmed position, the patient can take longer time, for example 3 weeks. According to the study by Bollen (et al), a two-weeks activation time had better completed results 3. Since the effectiveness of clear aligners is still limited in some tooth movements, especially in the vertical movements, there is a need to use auxilarries as well as new treatment methods in order to increase the effectiveness of clear 9 aligners . Due to the current lack of scientific evidence, clinicians should be careful when choosing the appropriate cases to combine with auxillaries to complete treatment goals. Although the clear