Evaluation of fracture resistance of acrylic denture teeth immersed in simulated gastric acid: an in vitro study

Aim To evaluate the effect of simulated gastric acid exposure on the fracture resistance of acrylic denture teeth of different brands. Method Acrylic denture tooth specimens from five different brands were used. A total of 100 specimens were included, with 20 teeth from each brand. Each brand was divided into two subgroups: simulated gastric acid exposure and control, with 10 specimens per subgroup. The teeth were immersed in simulated gastric acid or artificial saliva as the control medium for 96 h. Fracture resistance was measured using a universal testing machine. Data were analyzed using two-way ANOVA and Tukey HSD post hoc test. Results A statistically significant difference was found in the mean fracture resistance among the acrylic denture tooth groups ( p = 0.001; p < 0.05). A significant difference was also observed between the acid-exposed and control groups ( p = 0.001; p < 0.05). However, the combined effect of acrylic tooth type and acid exposure on fracture resistance was not statistically significant ( p = 0.953; p > 0.05). In the artificial saliva control group, the Vita group showed significantly lower mean fracture resistance than the Eray and Acrylux groups (p < 0.05), while no significant difference was found among the other groups (p > 0.05). In the simulated gastric acid group, the Vita group exhibited significantly lower fracture resistance than the Eray, Yamahachi, and Acrylux groups, whereas the Ivoclar group had significantly lower fracture resistance than the Acrylux group (p < 0.05). For all groups, teeth not exposed to acid demonstrated significantly higher fracture resistance than those exposed to acid (p < 0.05). This result was consistent across the Eray, Yamahachi, Ivoclar, Acrylux, and Vita groups. Conclusion Within the limitations of this in vitro study, simulated gastric acid exposure significantly reduced the fracture resistance of acrylic denture teeth. Both acrylic tooth brand and acid exposure had statistically significant main effects on fracture resistance (p < 0.05). However, the interaction between acrylic tooth brand and acid exposure was not statistically significant (p > 0.05), indicating that the effect of acid exposure did not significantly differ among brands under the present laboratory conditions. Clinical significance The findings provide preliminary laboratory evidence that simulated gastric acid exposure may reduce the fracture resistance of acrylic denture teeth. Because the study used a continuous 96-hour in vitro immersion protocol, the results should not be interpreted as direct evidence for clinical material selection. Further studies incorporating intermittent acid exposure, thermocycling, fatigue loading, and clinically relevant aging protocols are required.