Abstract

BABIOLAKIS, GP  and  OWEN, CP. The effect of off-axis seating on the marginal adaptation of full coverage all ceramic crowns. S. Afr. dent. j. [online]. 2020, vol.75, n.6, pp.303-310. ISSN 0375-1562.  http://dx.doi.org/10.17159/2519-0105/2020/v75no6a3.

INTRODUCTION: No studies on the marginal gap or internal fit of crowns have reported the effect of non-axial seating which may often occur inadvertently clinically. AIM: Therefore this in vitro study sought to investigate the off-axis seating of CAD/CAM crowns and its effect on the marginal gap and internal fit. METHOD: A standardised crown preparation on a typodont tooth was used to design and mill 30 crowns with a flat occlusal surface. Ten Zirconia (Dentsply Sirona, Germany), 10 Enamic (Vita, Austria), and 10 Brilliant Crios (Coltene, Switzerland) crowns were milled, Ave of each milled with a luting space of 100µm, and Ave of 200µm. The marginal gap was measured in two and three dimensions after luting with silicone on a 3D-printed metal replica. Seating occurred axially, at 5° buccally and 5° lingually. The silicone was used to calculate the internal fit RESULTS: Axial seating with a 100 µm luting space obtained the smallest marginal gap, irrespective of material or luting space. 3D measurements were larger than 2D measurements, but not significantly. The maximum off-axis gap was 117µm, on the opposite side to which pressure was applied. CONCLUSIONS: Care must be taken clinically to ensure that luting takes place in an axial direction only.

Keywords : Marginal gap; Internal fit; Luting Space; full crown.

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