Integration of milled components in a fully digital workflow for removable partial dentures using a novel box-joint mechanism.

PURPOSE: This report presents a proof-of-concept, fully digital workflow for fabricating removable partial dentures by integrating milled resin and titanium components via a box-joint interlocking mechanism.

METHODS

A bilateral free-end mandibular model was scanned and imported into computer-aided design (CAD) software. After arranging the artificial teeth, the denture outline was designed using non-uniform rational basis-spline curves while considering tooth position, denture contour, and undercut areas. The CAD surface model was exported in STL format and refined using mesh-modeling software to create a more organic morphology. It was then re-imported into the CAD environment, divided into multiple components, and equipped with box-joint mechanisms comprising sockets and socket mates to facilitate component assembly. These components were milled from prefabricated PMMA and Ti6Al4V discs, thereby eliminating the need for conventional resin polymerization or metal casting. The denture was designed to be assembled without a plaster working model because the box-joint mechanisms guided each component toward its predetermined position during assembly.

CONCLUSIONS

In this technical demonstration, the box-joint mechanism enabled a model-free assembly process and simplified fabrication by eliminating the need for conventional curing and casting procedures. The components were designed to be guided into place unidirectionally and disassembled for adjustment, which may facilitate intraoral try-ins. The combination of CAD-based design and mesh modeling may provide a flexible workflow for removable partial denture fabrication. This report presents a proof-of-concept technical procedure; however, further investigation is required to evaluate the mechanical accuracy, durability, retention, and clinical performance of the proposed system.