Comparative Evaluation of Robotic and Manual Bending of Clasps for Removable Partial Dentures

Conventional removable partial denture (RPD) clasp fabrication with wrought wire depends on operator skill, limiting efficiency and reproducibility. This study compared robotically and manually bent clasps for fabrication efficiency, adaptation, reproducibility, and initial retentive force.

Two groups of clasps (n = 10 per group) were bent using either a robotic clasp-bending machine or an experienced technician. Bending time was recorded. Clasp adaptation and reproducibility were evaluated using scanning and 3D registration software. Initial retentive force was measured using a specialized clasp retention testing system for (1) dentures incorporating robot-bent clasps with 3D-printed bases and (2) dentures incorporating manually bent clasps with conventionally processed acrylic resin bases. Data were analysed using independent-samples t tests or Mann-Whitney U tests, as appropriate, with α = 0.05.

Robotic clasp fabrication was significantly faster (median, 69.9 seconds) than manual bending (median, 336.9 seconds; P < .001). Robotically bent clasps demonstrated superior adaptation, with smaller clasp-abutment gaps at the clasp body (83.1 µm vs 121.5 µm; P < .001) and reduced variability. At the mid-clasp arm, disto-axial angle of the clasp body, and the middle and lingual aspects of the proximal groove, robotically bent clasps also showed closer adaptation than manually bent clasps (P < .05). Initial retentive force did not differ significantly between groups.

Robot-assisted clasp bending significantly improved efficiency, clasp adaptation, and reproducibility compared with manual bending, while preserving comparable initial retentive force between groups.

This digital approach offers a practical option for routine RPD fabrication, facilitating more consistent clasp quality and potentially reducing clinical and laboratory workload.