Effect of Firing on the Marginal Fit of Heat-Pressed Lithium Disilicate Veneers: An in-vitro study
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The purpose of this in vitro study was to evaluate and compare the marginal fit of heat-pressed lithium disilicate veneers fabricated with the “staining”, or “cut-back” technique, using 3D analysis. Two groups of ten specimens were fabricated and each group differed in core thickness and the fabrication process. Group S was a full contour veneer, with one glaze firing. Group CB had a “cut-buck” core of 0.6mm on the cervical and middle third and 0.5mm on the incisal areas, with three firings (wash, incisal and glaze firing). Marginal fit was evaluated at two stages; first after the copings were pressed (baseline) and second after the fabrication of the veneers. The wax copings were processed and pressed with IPS e.max lithium disilicate LT, and the overall marginal fit, along with measurements from the cervical, mesial, distal and incisal areas were obtained using the virtual replica technique. The Shapiro-Wilk test was used to evaluate normality. A student T-test (α=.05) was used to evaluate differences between and within the groups in the four locations; cervical, mesial, distal and incisal. A statistically significant difference was found for the incisal area of the CB group (p=0.04). In all other areas of measurements, no statistically significant differences were found. The overall marginal fit of group S and CB was 61.5 µm (8.4) and 67.5 µm (9.7) respectively. The increase of marginal discrepancy on the incisal of CB group was attributed to the porcelain application. The results suggest that heat-pressed lithium disilicate veneers fabricated either with the “staining” or with the “cut-back” technique produce marginal discrepancies within the clinical acceptable standard.
Gakis, Panagiotis (2018). Effect of Firing on the Marginal Fit of Heat-Pressed Lithium Disilicate Veneers: An in-vitro study. Master's thesis, Texas A & M University. Available electronically from