Biomechanical impact of attachment design on canine retraction and stress patterns following first premolar extraction: An in silico study
Prakash C, Praveen Kumar Varma, Padma Priya C.V, Pradeep Kandikatla, Nagisetti Haribabu, Nachu Lakshmi ManojnaObjectives:
The objective of the study is to evaluate the characteristics of tooth movement during canine retraction in a first premolar extraction case using clear aligners with vertical rectangular attachment and semi-elliptical attachment.
Material and Methods:
The canine retraction using a clear aligner is simulated using finite element analysis. A geometric model of the maxillary arch was constructed using CBCT data, which includes teeth, alveolar bone, and periodontal ligament, using SolidWorks 2021. The two types of attachments used in this study are vertical rectangular attachment and semi-elliptical attachment, while a model without attachment is used as a control. The first premolar was extracted, and an aligner thickness of 0.5 mm was used in this study. A mesh model was created using Hypermesh 14.0, which is incorporated into Abaqus 6.14 for finite element analysis. A force of 2N is applied on the canine in the distal direction and evaluated for stress distribution and initial displacement of the canine.
Results:
The model with vertical rectangular attachment (0.0315 mm) showed more crown movement than the model without attachment (0.0308 mm) and semi-elliptical attachment (0.0309). The model with vertical rectangular attachment (0.00970 mm) showed more root movement than the model without attachment (0.00947 mm) and semi-elliptical attachment (0.00951 mm). The least von Mises stress is seen in the model with vertical rectangular attachment (0.496 MPa) when compared with semi-elliptical (0.759 MPa) and without attachment (0.835 MPa).
Conclusion:
Within the limitations of an initial displacement of Finite Element (FE) analysis, the vertical rectangular attachment demonstrated slightly more efficient force transmission during canine retraction. Thus, the vertical rectangular attachment can be preferred for canine retraction in first premolar extraction cases rather than the semi-elliptical attachment. However, the magnitude of differences was minimal; therefore, clinical extrapolation should be made with caution.