Abstract
Background: This study compared the influence of three different radial spacers (60,90,120 microns) on the marginal gap adaptation by using computer-aided manufacturing (CAD-CAM) for producing monolithic zirconia reinforced lithium silicate (ZLS) ceramic crowns. Methods: A total of 45 abutment acrylic teeth were divided into three groups of different radial spacers (60, 90, and 120 microns). In each group 15 teeth were scanned by Omnicam intra oral scanner and ZLS crowns were ground. For each unit the marginal gap was evaluated at four regions of interest by scanning electronic microscope (SEM). To compare the marginal gap between the three groups a one-way ANOVA with post-hoc Bonferroni test was preformed (α = 0.05). Results: The marginal gap for a 60 microns (162.99 ± 16.25 µm) radial spacer was found significantly higher than 90 (41.85 ± 3.57 µm) and 120 (41.85 ± 5.3 µm) microns radial spacers (p < 0.05). Between 90- and 120-micron radial spacers no difference was obtained. (p < 0.05). Conclusions: A radial spacer of 60 microns showed a significantly higher marginal gap compared to 90 and 120 microns and was not clinically accepted (>120 microns). For both 90 and 120 microns the marginal gap was clinically accepted (<120 microns) with no difference between the groups. The radial spacer which should be optimum for CELTRA® DUO crowns is 90 microns.
Highlights
All-ceramic restorations are well accepted in recent years due to improved esthetic and mechanical characteristics [1,2]
Overall mean marginal gap (MMG) value and standard error were calculated for all three groups (Table 1)
The lowest measurement was obtained in the 120-micron group (17.85 microns) and the highest measurement was obtained in the 60-micron group
Summary
All-ceramic restorations are well accepted in recent years due to improved esthetic and mechanical characteristics [1,2] One of these materials is zirconia lithium silicate (ZLS), which is a metal-free material and can be used for several indications by CAD-CAM production [3]. This study compared the influence of three different radial spacers (60,90, 120 microns) on the marginal gap adaptation by using computer-aided manufacturing (CAD-CAM). Conclusions: A radial spacer of 60 microns showed a significantly higher marginal gap compared to 90 and 120 microns and was not clinically accepted (>120 microns). For both 90 and 120 microns the marginal gap was clinically accepted (
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