Oper Dent. 2020 Nov 1;45(6):608-617. doi: 10.2341/18-315-L.
Using the deep margin elevation technique in preparations extending beyond the cemento-enamel junction appears to be beneficial in maintaining structural integrity of CAD/CAM-fabricated feldspathic ceramic inlays.
Objective: To evaluate the effect of deep margin elevation on structural and marginal integrity of ceramic inlays.Methods and Materials: Forty extracted human third molars were collected and randomly separated into four groups (n=10/group). In group 1 (enamel margin group), the gingival margin was placed 1 mm supragingival to the cemento-enamel junction (CEJ). In group 2 (cementum margin group), the gingival margin was placed 2 mm below the CEJ. In group 3 (glass ionomer [GI] margin group), the gingival margin was placed 2 mm below the CEJ, and then the margin elevated with GI to the CEJ. In group 4 (resin-modified glass ionomer [RMGI] margin group), the gingival margin was placed 2 mm below the CEJ, and then the margin elevated with RMGI to the CEJ. Standardized ceramic class II inlays were fabricated with computer-aided design/computer-aided manufacturing and bonded to all teeth, and ceramic proximal box heights were measured. All teeth were subjected to 10,000 cycles of thermocycling (5°C/55°C) and then underwent 1,200,000 cycles of vertical chewing simulation at 50 N of force. Ceramic restorations and marginal integrity were assessed with a Hirox digital microscope. The Fisher exact test (two-tailed) with adjusted p-values (α=0.05) and logistic regression were used for statistical analysis.Results: The cementum margin group had a significantly higher ceramic fracture rate (90%) compared to other groups (10% in enamel margin and GI margin groups, p=0.007; 0% in RMGI group, p<0.001). Logistic regression showed that with increased ceramic proximal box heights, the probability of ceramic fracture increased dramatically.Conclusion: Deep marginal elevation resulted in decreased ceramic fracture when preparation margins were located below the CEJ. There was no difference found between margin elevation with GI or RMGI. Increased heights of ceramic proximal box may lead to an increased probability of ceramic fracture.
在延伸至釉牙骨质界的预备中使用深边缘抬高技术，似乎有利于维持 CAD/CAM 制作的长石质陶瓷嵌体的结构完整性。
目的：评估深边缘抬高对陶瓷嵌体的结构和边缘完整性的影响。
收集 40 颗离体人第三磨牙，随机分为四组（每组 10 颗）。在第 1 组（釉质边缘组）中，牙龈边缘置于釉牙骨质界（CEJ）上方 1mm 处。在第 2 组（牙骨质边缘组）中，牙龈边缘置于 CEJ 下方 2mm 处。在第 3 组（玻璃离子[GI]边缘组）中，牙龈边缘置于 CEJ 下方 2mm 处，然后用 GI 将边缘抬高至 CEJ。在第 4 组（树脂改性玻璃离子[RMGI]边缘组）中，牙龈边缘置于 CEJ 下方 2mm 处，然后用 RMGI 将边缘抬高至 CEJ。用计算机辅助设计/计算机辅助制造制作标准化的 II 类陶瓷嵌体，并将其粘结到所有牙齿上，测量陶瓷近中盒高度。所有牙齿均经受 10,000 次热循环（5°C/55°C），然后在 50N 的力下进行 1,200,000 次垂直咀嚼模拟。用 Hirox 数字显微镜评估陶瓷修复体和边缘完整性。采用调整后的双侧 Fisher 确切检验（α=0.05）和逻辑回归进行统计分析。
与其他组（釉质边缘和 GI 边缘组为 10%，p=0.007；RMGI 组为 0%，p<0.001）相比，牙骨质边缘组的陶瓷破裂率（90%）显著更高。逻辑回归显示，随着陶瓷近中盒高度的增加，陶瓷破裂的概率显著增加。
当预备边缘位于 CEJ 下方时，深边缘抬高导致陶瓷破裂减少。用 GI 或 RMGI 进行边缘抬高没有区别。陶瓷近中盒高度的增加可能会导致陶瓷破裂的概率增加。
