Simulation of the Periodontal Ligament in Dental Materials Research: A CAD/CAM-Based Method for PDL Modeling

The periodontal ligament (PDL) is essential for the physiological mobility and load distribution of natural teeth, yet its simulation in mechanical testing remains inconsistent and insufficiently standardized. The absence of a resilient suspension system can alter force transmission, affect failure patterns, and reduce the clinical relevance of in vitro outcomes. This study aimed to develop a reproducible CAD/CAM-based model for PDL simulation that provides elastic suspension of a tooth replica under laboratory conditions. A digitally defined offset was applied around a tooth replica to create a controlled PDL space, which was filled with polyether. To ensure precise seating of the specimens, a 3D-printed positioning device was used. Functional calibration was performed using Periotest measurements to identify the offset that reproduced physiological tooth mobility. A digital offset of 0.85 mm produced a radiographically confirmed polyether layer of 0.86 ± 0.05 mm and yielded Periotest values comparable to natural teeth in the horizontal direction (mean PTV = 2.99 ± 0.92). Vertical measurements demonstrated higher damping (mean PTV = -4.02 ± 0.56), consistent with the anisotropic behavior of natural PDL. The model showed high fabrication accuracy and predictable mechanical behavior, providing a physiologically relevant method for incorporating PDL simulation into laboratory mechanical testing.