The Influence of Three Different Digital Cement Spacers on the Marginal Gap Adaptation of Zirconia-Reinforced Lithium Silicate Crowns Fabricated by CAD-CAM System

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.

Zirconia-Reinforced Lithium Silicate Marginal Gap Evaluation Using Various Self-Adhesive Resin Cements by SEM

“…In this research we used a previous method which we already used before and was published in our previous research [12]. Forty-ve machine-made identical plastic teeth (FLUX 8634; Columbia Dentoform, upper right rst molars) were used, Occlusal clearance 2mm, axial convergence angle of 6 degree and shoulder nish line at the width of 1.2mm all around.…”

“…,9 years of experience) marked the nish and a virtual single x partial denture design (CEREC SW 5.2.4; Dentsply Sirona) was created with the following digital parameters: radial spacer: 90 µm, occlusal spacer 120 µm, proximal contacts strength:25 µm, occlusal contacts strength:25 µm, radial minimal thickness:1000 µm, occlusal minimal thickness:1500 µm, margin thickness:100 µm, margin ramp width:100 µm, margin ramp angle:60º. It is important to mention that due to the results of our previous research [12] we used a 90 µm radial spacer for all ZLS crowns.…”

“…Measurements were obtained in four regions by scanning electronic microscope (SEM). The study concluded that the preferable radial spacer for CELTRA® DUO (CELTRA® DUO, Sirona Dentsply, Milford, DE, USA) crowns is 90 µm [12].…”

Effect of Digital Blocking of Reversed Tapered Preparations in Comparison to Conventional Wax Blocking on Fracture Resistance of Monolithic Zirconia Crowns .

“…Twist Hackles 77 ns on the CAD software. 23 The current study employed airborne particle abrasion with alumina particles (sandblasting) to raise the zirconia crown's surface energy, wettability, and roughness.…”

Three Self-Adhesive Resin Cements and Their Influence on the Marginal Adaptation of Zirconia-Reinforced Lithium Silicate Single Crowns: An In Vitro Scanning Electron Microscope Evaluation

“…It has been shown that crowns with reduced cement spacers lead to an increased marginal discrepancy due to a reduction in the passive fit on the abutment. A study that evaluated the marginal gap adaption of CELTRA ® DUO (CELTRA ® DUO, Sirona Dentsply, Milford, DE, USA) with different digital radial spacers set at 60, 90, and 120 µm and measured the marginal gap in four regions by scanning electron microscope (SEM) concluded that the preferable radial spacer for CELTRA ® DUO (CELTRA ® DUO, Sirona Dentsply, Milford, DE, USA) crowns is 90 µm [ 12 ].…”