Pablo Lirio-del Saz
AUTHORS
Lirio-del Saz, P. Tello-Pareja, C. Martínez-González, A.
TITLE
Dentoalveolar expansion with Invisalign System ®: Is it as predictable as it seems?
ABSTRACT
Objectives
The aim of this study is to evaluate the efficiency of the Invisalign System ® in arch dentoalveloar expansion treatments. Four aspects are analyzed: initial digital treatment plan (ClinCheck ®) predictability; one-by-one tooth expansion; predictability of the expansion according to the size and lenght of the teeth; and differences in expansion predictability depending on the complexity of the case.
Material and methods
167 ClinChecks ®, 377 teeth, 192 teeth from the upper arch and 185 from the lower arch were included in this study.
Three different stages of the treatment were recorded and compared: initial .STL digital model file (T0), final .STL file of the first Clincheck ® (T1-planned final position) and patient’s actual final .STL file after that first Clincheck ® (T2-clinical result achieved).
A total of ten parameters were measured, five of them for the transversal expansion análisis and five about the teeth height.
Results and discussion
Regarding the transversal measurements, the higher predictability was in the upper arch in first permanent molars (1MP), with 102.73% and in canines (C) of 91.51% in the lower arch.
In the upper arch, in the most complexity cases (expansion greater than 4mm) a greater predictability was found at the second premolars (2PM) with 78.93%. In the lower arch, the first premolars (1PM) were the most predictable teeth with a % of 90.01%.
According to the height of the teeth, it was observed that in the upper premolars, the greater the tooth height, the greater the predictability (till 98.69% in 2PM). In the lower arch, the highest percentage was found at the second molars associated with greater height (140%).
Finally, it was found that the highest percentage of movement prediction (116.26%) was at the lower canines when there was no expansion planned at the second molars or they were even compressed during treatment.
In the literature it seems that the predictability percentages are similar at the level of C and 1PM y 2PM, differing at the level of first and second molars with the results obtained in the present study.
Conclusions
Aligners are effective for dentoalveolar expansion. It is less predictable at the level of second molars and when the cases have a higher degree of difficulty. It is not always true that the greater the height of the teeth the greater the plastic fits on the clinical crowns, and the greater the predictability of the expansion. Overcorrection of some teeth should be taken into account when digitally planning to obtain the expected results.
Key Words: invisalign AND expansion, invisalign AND smartforce e invisalign AND movements.