Occlusal Adjustment in Free‐End Implant‐Supported Restorations: Digital Scans Versus Conventional Impressions With Full‐ and Half‐Arch Techniques

Abstract

ABSTRACT Objectives To quantify the occlusal adjustment required for two‐unit, implant‐supported polymethyl‐methacrylate (PMMA) crowns with either digital or conventional impression techniques, using full‐arch and half‐arch workflows. Material and Methods An acrylic maxillary–mandibular model carrying two bone‐level implant analogs (sites 46–47) was mounted on a semi‐adjustable articulator. Twenty impressions were made (n = 5 per group): digital full‐arch, digital half‐arch, conventional full‐arch, and conventional half‐arch. PMMA crowns were designed using computer‐aided design (CAD) software, milled, and surface‐scanned before adjustment. Occlusal contacts were refined on the articulator with 21 µm film while recording adjustment time. Pre‐ and post‐adjustment scans were superimposed and analyzed using three‐dimensional surface analysis software to quantify mean material reduction (µm). Data were analyzed with one‐way ANOVA and independent‐samples t‐tests (α = 0.05). Results Digital workflows required significantly less occlusal reduction (146 ± 35 µm vs. 226 ± 35 µm; p = 0.035) and shorter adjustment times (144 ± 36 s vs. 385 ± 36 s; p < 0.001) than conventional, with no effect of arch span (full vs. half; p > 0.05). Within protocols, the digital half‐arch group showed the smallest adjustment (127 ± 37 µm) and fastest finishing (98 ± 33 s), whereas the conventional half‐arch group required the longest time (456 ± 21 s). Conclusion Fully digital impressions reduce both the amount of occlusal adjustment and the chairside time needed to seat implant‐supported crowns compared with conventional silicone impressions. Reducing the scan to a half‐arch does not compromise occlusal precision, making the digital half‐arch workflow an efficient alternative for posterior, free‐end implant restorations. Clinical Relevance In implant posterior PMMA crowns, the impact of impression/workflow choice on occlusal adjustment is unclear. This in‐vitro study measured occlusal reduction and chairside time across digital versus conventional and full‐ versus half‐arch workflows. Digital, especially half‐arch, required less adjustment and shorter time. Clinically, a digital half‐arch approach may streamline delivery and reduce unnecessary material removal, pending confirmation in patient‐based settings.