Effect of simulated gastric acid exposure on the hardness, topographic, and colorimetric properties of machinable and pressable zirconia-reinforced lithium silicate glass-ceramics.

STATEMENT OF PROBLEM

The effects of gastric acid on the hardness, topographic, and colorimetric properties of zirconia-reinforced lithium silicate glass-ceramics (ZLSs) for dental restorations remain unknown.

PURPOSE

The purpose of this in vitro study was to investigate the effect of simulated gastric acid exposure on the microhardness, surface roughness, color stability, and relative translucency of ZLSs.

MATERIAL AND METHODS

Two pressable ZLSs (VITA AMBRIA, VA and Celtra Press, CP) and 2 machinable ZLSs (VITA Suprinity, VS and Celtra Duo, CD)(n=64) were randomly allocated to artificial saliva (control) or gastric juice immersion groups simulating 10 and 20 years of clinical exposure. Microhardness (Hv) was measured with a Vickers hardness device, and surface roughness (Sa) was recorded with an optical profilometer. The color stability (ΔE) and relative translucency parameter (RTP) were measured with a spectrophotometer. Data for Hv, Sa, and RTP were analyzed by repeated 2-way ANOVA, and data for ΔE were analyzed by 2-way ANOVA. Post hoc comparisons were obtained from Tukey HSD and Student t tests (α=.05).

RESULTS

Machinable ZLSs exhibited greater Hv after the simulated gastric acid challenge than pressable ZLSs. Sa was significantly impacted by material type (P=.001), storage media (P=.050), and their interaction (P<.001). ΔE was significantly affected by the type of simulated aging media (P<.001). After 20 years of simulated gastric acid aging, all ZLS materials surpassed the ΔE perceptibility threshold but did not exceed the ΔE acceptability threshold. VS displayed significantly lower RTP than other ZLS materials at all time points (P<.001).

CONCLUSIONS

The topographic and colorimetric characteristics of ZLS were significantly altered by exposure to simulated gastric acid.