Impact of cleaning protocols on surface integrity and biofilm formation of heat-polymerized and 3D-printed denture base resins after gastric acid exposure.

OBJECTIVES

To investigate the effects of commonly used cleaning protocols on the surface, physical, chemical, optical, and microbiological properties of heat-polymerized and 3D-printed denture base resins after gastric acid exposure.

METHODS

Disc-shaped specimens (10 × 3 mm) were fabricated from one heat-polymerized resin (HT) and two 3D-printed resins (Yller® [YL] and Monile® [M]). After erosive cycling with gastric acid, specimens were allocated to four cleaning protocols (n = 20): brushing with denture paste, effervescent tablet combined with brushing, immersion in mouthwash, and rinsing with tap water. Surface roughness, wettability, Vickers hardness, water sorption and solubility, Fourier transform infrared spectrophotometer (FTIR), color stability (CIEDE2000), and microbiological behavior were assessed at baseline and after cleaning. Data were analyzed using repeated-measures ANOVA and Tukey's post hoc test (α = 0.05).

RESULTS

Erosive cycling followed by cleaning increased surface roughness (p = 0.03) and hydrophilicity (p < 0.01) in all resins. Hardness was influenced by both resin type and cleaning protocol (p < 0.05), with the greatest reduction observed in YL. Water sorption and solubility remained low and unchanged (p > 0.05), and FTIR analysis revealed no chemical degradation. However, all resins exhibited clinically perceptible color changes (p < 0.01) and increased Candida albicans colonization (p < 0.05).

CONCLUSIONS

Despite stable chemical structure and bulk properties, gastric acid exposure combined with routine cleaning impaired surface integrity, color stability, and resistance to microbial colonization of denture base resins.

CLINICAL SIGNIFICANCE: Gastric acid erosion associated with daily hygiene procedures may accelerate denture degradation and microbial colonization, potentially reducing prosthesis longevity and reinforcing the need for closer monitoring of patients with gastroesophageal reflux.