Effect of access‐opening closure materials on fluid‐related mass gain and volumetric change in three‐dimensionally printed closed‐hollow obturator specimens

PURPOSE: To investigate how denture base resin and access-opening closure material affect fluid-related mass gain and micro-computed tomography-derived volumetric changes in three-dimensionally printed closed-hollow obturator specimens. MATERIALS AND METHODS: Specimens were printed from NextDent Denture 3D+ or Apex Base resin. Access-opening specimens had two 3-mm openings sealed with self-cure acrylic, material-matched printed resin (3D), PermaFlo Pink (PF), or CHAIRSIDE composite (ZC) (8 subgroups, n = 10; 80 specimens), plus 2 nonaccess-opening controls. After 24 h of conditioning, specimens underwent thermocycling (5°C-55°C; 2500-10,000 cycles) with gravimetric and micro-computed tomography measurements at baseline and after cycling. Net fluid-related mass gain (dW), relative fluid-related mass gain (rW), net micro-computed tomography-derived volumetric change (dV), and relative micro-computed tomography-derived volumetric change (rV) were analyzed. RESULTS: The thermocycling interval and closure material affected all outcomes, whereas the parent resin affected only dW. Gravimetric change was lowest with ZC and highest with self-cure acrylic; dV was lowest with 3D and highest with PF. Both outcome families were moderately correlated at all intervals (r = 0.39-0.56). dV/rV reached approximately 22%, 53%, and 80% of the 10,000-cycle values after 2500, 5000, and 7500 cycles, respectively. The controls exhibited the highest dW/rW and rV; net dV was highest in the PF access-opening groups. CONCLUSION: ZC minimized gravimetric change, whereas 3D minimized volumetric change. The preferred closure material depended on the prioritized outcome. Eliminating the access-opening interface did not prevent mass gain or cavity air-volume replacement.