Effect of Arch Form and Water Sorption on the Palatal Base Adaptation of ProBase Hot Versus the Conventional Heat Cured Acrylic Resin

Background: The greater the curvature of the tissue at the posterior palatal region, the greater the distortion of the denture base. Purpose: This study was carried out to evaluate the effect of the arch form and water sorption on the posterior palatal base adaptation of ProBase Hot dentures compared to those processed by conventional heat cure acrylic resin. Materials and Methods: Forty waxed denture bases were prepared for U-shaped and V-shaped palatine arch forms from both ProBase Hot and Acrostone materials. Waxed denture bases were flasked, packed and processed according to the manufacturer’s instructions. Immediately after decasting, the dentures were repositioned on their corresponding casts to measure the amount of gap formed between denture base and cast at 5 points along the posterior border of denture base using a measurescope. Denture bases were stored in tap water for 4 weeks then the same test was repeated. Results: Both palatine arch forms exhibited a significant amount of posterior palatine base discrepancy particularly at the center of the palate. The V-shaped arch form showed a greater amount of discrepancy than that with the U-shaped vault. ProBase Hot denture bases showed better palatal adaptation than that of the Acrostone denture bases. The posterior palatal base adaptation was significantly improved after immersion in water for 4 weeks at all points of measurements. Conclusions: ProBase Hot denture bases showed better palatal adaptation than conventionally cured acrylic denture bases. All the tested groups demonstrated improved dimensional accuracy when stored in tap water for 4 weeks.