Comparing impression techniques in the prosthodontic treatment for edentulous patients: a 3D finite element analysis

The biomechanical advantage of selective pressure impressions over mucocompressive techniques remains unclear. This study aimed to determine whether selective pressure techniques offer substantial biomechanical advantage over mucocompressive impressions using clinical computer simulation.

Two models were analyzed: Model C, with mucocompressive impression tray, and Model S, with selective pressure impression tray with 10-mm diameter circular relief in the midline. Each model included the tray, polyvinyl siloxane (PVS), mucosa, cortical, and cancellous bone. Seven locations were designated, from which the results were analyzed. With a vertical load of 49 N on the palatal area, pressure, von Mises stress, and displacement were evaluated. Statistical analysis was performed using paired-samples t-test and effect size estimation (Cohen's d).

Both models generated mucosal displacement and stress transmission to the underlying structures upon load application. In Location 3, where the relief was placed, Model S exhibited lower pressure, stress, and displacement than Model C, indicating localized force reduction. Conversely, other locations exhibited higher values in Model S than in Model C. Low stress in bone for both trays suggested that tray design had minimal effect on bone. All variations demonstrated small effect sizes (d ≤ 0.2), despite statistical significance (P < .007).

Selective pressure trays modified tissue loading locally at the relief site; however, these did not seem to provide a substantial biomechanical advantage, particularly on bone. Their clinical relevance remains limited and needs further supporting evidence.