Comparative effects of two luting cements and different cement volumes on the post-cementation occlusal elevation and fit of zirconia crowns
摘要
This study investigated the effects of two luting cements and different cement volumes on occlusal elevation and fit of computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crowns, providing reference for clinical cementation.
Methods72 titanium dies models and zirconia crowns were fabricated, with laser-marked reference points on four axial surfaces. Specimens were randomly assigned to 6 groups and cemented using resin-modified glass ionomer cement (RMGIC) or self-adhesive resin cement (U200) at three volumes (full, 1/4, and 1/8). Occlusal elevation was recorded before and after cementation, while vertical marginal discrepancy (VMD), axial gap (AG), and occlusal gap (OG) were measured after cementation. Statistical analysis used one-way analysis of variance (ANOVA) with Bonferroni post hoc and independent-samples t tests (two-sided α = 0.05; P < 0.05 significant).
ResultsCementation increased occlusal elevation in all crowns. In both RMGIC and U200 groups, occlusal elevation decreased significantly with reduced cement volume (P < 0.001), with the smallest increase at 1/8 volume (RMGIC: 2.13 ± 0.38 μm; U200: 3.54 ± 0.47 μm). Sectioning further revealed that VMD, AG, and OG also decreased as cement volume was reduced. In RMGIC, significant reductions were observed for VMD at buccal (B), lingual (L), mesial (M), and distal (D) surfaces; AG at B, M, and D; and OG at the distal marginal ridge (P < 0.05). In U200, VMD decreased significantly at B, L, M, and D; AG at L and D; and OG at mesial and distal marginal ridges (P < 0.05). At the same cement volume, RMGIC showed significantly less occlusal elevation than U200 only at 1/8 volume (P < 0.001), while no significant differences were found between the two groups in VMD, IG, or OG at any measurement point (P > 0.05).
ConclusionIn zirconia crown cementation, using 1/8 of the full cement volume resulted in the smallest occlusal elevation and the best overall crown fit. However, at the same cement volume, RMGIC showed less occlusal elevation than U200 only at 1/8 volume, while no significant differences in crown fit were observed between the two materials.