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