Biomechanical force profiles and force decrease of direct printed versus thermoformed aligners with different trimlines: an in vitro analysis
摘要
This in-vitro study aimed to evaluate and compare the biomechanical force profiles of thermoformed and direct-printed aligners with different gingival trimlines during facial and palatal translation of a maxillary central incisor.
MethodsA 3D-printed model with a mounted central incisor was used to simulate 0.25 mm of bodily movement. Forces were recorded in three axes (Fx, Fy, Fz) using a multi-axis force sensor. Three aligner types (thermoformed with straight trimline: TFAS, and direct-printed with either straight: DPAS or garlanded trimline: DPAG) were tested (n = 10 each). Vertical, transverse, and sagittal force components and their decrease were analyzed. Forces were recorded over 60 min to characterize initial force delivery and early stress relaxation under standardized in vitro conditions.
ResultsThermoformed aligners exhibited the highest sagittal forces during facial movement (Fx − 0.70 N), while DPAG demonstrated significantly lower forces (Fx − 0.25 N; p < .001). During palatal translation, DPAS reached peak forces of 0.57 N, whereas DPAG showed lower, more controlled forces (p < .001). Vertical forces (Fz) were significantly higher in TFAS (− 0.10 N), while DPA remained near zero or slightly extrusive (p < .001).
ConclusionsIn this in vitro model, DPA, particularly DPAG, showed lower sagittal force values and smaller vertical force components. In the first 60 min, DPA showed a pronounced early force decrease. Longer observation periods are required to describe force behavior beyond the initial seating phase.