Influence of simulated gastric acid on surface roughness and substance loss of different dental veneering porcelains and different surface finishing protocols: An in vitro study.

PURPOSE: Patients with bulimia nervosa or gastroesophageal reflux disease (GERD) are frequently exposed to gastric acid, which may cause tooth demineralization and degradation of dental ceramics. This in vitro study investigated the effect of simulated gastric acid on surface roughness and substance loss of two veneering porcelains subjected to different surface finishing protocols.

MATERIALS AND

METHODS

Eighty ceramic discs were fabricated from feldspathic porcelain (VITA VM13; VITA Zahnfabrik) and fluorapatite glass-ceramic (IPS Emax Ceram; Ivoclar Vivadent) (n = 40 each). Discs (10 mm × 2 mm) were prepared, fired, and subdivided according to surface finishing: polishing or glazing (n = 20). Each subgroup was immersed in simulated gastric acid or artificial saliva (control) for 24 h at 37°C (n = 10). Surface roughness (Ra) was measured before and after immersion using a mechanical profilometer, and surface morphology was examined by scanning electron microscopy (SEM) as two additional specimens per subgroup were prepared to avoid profilometer-contacted areas. Substance loss was determined by weighing specimens before and after immersion using a digital balance. Data were statistically analyzed with three-way ANOVA, followed by Tukey's HSD test (α = 0.05).

RESULTS

Both exposure medium and finishing protocol significantly affected surface roughness, with glazed specimens showing smoother surfaces than polished ones (p < 0.05). Finishing protocol also significantly affected substance loss after immersion in simulated gastric acid (p < 0.001). No significant difference was found between the two ceramic materials in terms of roughness or weight loss (p > 0.05).

CONCLUSION

Simulated gastric acid increases surface roughness and induces minor substance loss in veneering porcelains. Glazing provides more protection compared to polishing, maintaining smoother surfaces, and reducing degradation.