EXPERIMENTAL SUBSTANTIATION OF THE CHOICE OF BASE MATERIALS FOR REMOVABLE DENTURES IN PATIENTS WITH GASTROESOPHAGEAL REFLUX DISEASE

Subject. Resistance of five classes of dental materials (self curing acrylic Villacryl S, heat curing acrylic Urakril, nylon Evidsan Dent, 3D printed photopolymer HARZ Labs Dental Denture Base Soft, cobalt chromium alloy Co Cr) to long term exposure to media simulating gastroesophageal reflux disease (GERD). Objective. Based on a comprehensive experimental study of chemical stability, structural integrity and microbiological safety, to develop scientifically justified criteria for selecting the optimal material for removable denture bases in patients with GERD. Methodology. Four series of in vitro tests were performed: microbiological assessment after 30 day incubation in saliva (pH 5.2–5.5); spectrophotometric determination of leachate color (GOST 31868 2012) after 90 days in simulated gastric juice (pH 1.5–2.0); light microscopy (×200) after 3 month exposure; mass spectrometric analysis of metal ion release and gel permeation chromatography for polymer degradation evaluation. Results. All materials were microbiologically safe (TMC < 1 CFU/cm²). The lowest color migration was recorded for Co Cr (32.5 °) and photopolymer (32.4 °), the highest — for Urakril acrylic (68.9 °) and natural teeth (65.5 °). Microscopy revealed complete destruction of self curing acrylic, surface deposits on nylon, and no changes in Co Cr and photopolymer. Nickel (382.3 µg/L), chromium (157.2 µg/L) and molybdenum (286.7 µg/L) ion release was detected from CoCr alloy; GPC showed absence of high molecular fragments in acrylic leachates, confirming hydrolytic degradation. Conclusions. Cobalt chromium alloy and 3D printed photopolymer proved most resistant (integral index S = 5.0). Acrylic plastics (S ≤ 2.75) are not recommended for long term use in uncontrolled GERD. Nylon (S = 3.9) is acceptable in compensated GERD with regular polishing. A material selection algorithm is proposed.