Influence of Chemical Disinfection on the Flexural Strength of PETG and PMMA Materials Used in Occlusal Splints

Background: Occlusal splints are commonly used for the management of temporomandibular disorders (TMDs), bruxism, and occlusal imbalance. Polymethyl methacrylate (PMMA) and polyethylene terephthalate glycol-modified (PETG) are frequently employed materials for their fabrication. Regular disinfection of these appliances is critical for infection control; however, prolonged exposure to chemical disinfectants may compromise their mechanical properties, particularly flexural strength, which is vital for clinical longevity. Aim: To evaluate and compare the effects of three chemical disinfectants—chlorhexidine gluconate (CHX), glutaraldehyde (GA), and sodium hypochlorite (NaOCl)—on the flexural strength of PMMA and PETG materials used in occlusal splints. Materials and Methods: An in vitro experimental study was carried out using 120 standardized samples, equally divided between PMMA and PETG (n=60 each). Each material group was further subdivided into four subgroups (n=15): three experimental groups based on disinfectant type (4% CHX, 2.45% GA, 5% NaOCl) and one control group. Samples in the test groups were immersed daily in the assigned disinfectant for 15 minutes over 60 days. Flexural strength was measured using a Universal Testing Machine. Statistical analysis was performed using ANOVA and post-hoc tests. Results: All disinfectants caused a reduction in flexural strength for both materials. Sodium hypochlorite (5%) led to the most significant decrease, followed by glutaraldehyde (2.45%). Chlorhexidine gluconate (4%) caused the least reduction. PMMA consistently demonstrated higher flexural strength than PETG across all groups. Conclusion: Chemical disinfection impacts the mechanical integrity of PMMA and PETG. Chlorhexidine gluconate caused the least degradation and is recommended for routine disinfection. Sodium hypochlorite significantly compromised flexural strength and should be used cautiously. These results highlight the importance of selecting disinfectants that maintain the structural performance of occlusal splint materials.