Maxillary molar distalization with invisalign in adult patients: a preliminary study using iTero-created digital models.

Abstract

Background: Studies have assessed the impact of Invisalign on maxillary molar distalization; however, varying results were reported.

Methods: By using the iTero intraoral laser scanner to obtain three-dimensional (3D) digital models and using the palatal area for the registration of models, the position and angulations of the maxillary first molar (U6) and second molar (U7) were determined before treatment (T0), after U7 distalization (T1) and after U6 distalization (T2). In addition, the rotation angle and vertical changes of U6 and U7, and the sagittal and torque changes of the maxillary central incisor (U1) were determined from T0 to T2.

Results: The U6 was moved distally from T0 to T1, T1 to T2, and T0 to T2, by 0.91 ± 0.80 mm, 0.80 ± 0.49 mm, and 1.71 ± 0.89 mm, respectively. Similarly, the U7 was moved by 2.25 ± 1.30 mm, -0.21 ± 0.78 mm, and 2.04 ± 1.16 mm, respectively. From T0 to T2, the U6 and U7 molars were distally tipped by angles of -5.20 ± 2.62° and - 5.35 ± 4.19°, respectively. Molar intrusion and loss of anterior anchorage were also observed.

Conclusions: Invisalign can achieve maxillary molar distalization primarily through tipping movement, often accompanied by decreased angulation control and anterior anchorage loss, which requires additional auxiliaries to strengthen anchorage.