OBJECTIVES The load-bearing capacity of ultra-thin occlusal veneers made of 3D-printed zirconia were compared to the ones obtained by fabricating these reconstructions by CAD/CAM milling zirconia or heat-pressing lithium-disilicate. METHODS On 60 extracted human molars, the occlusal enamel was removed and extended into dentin. Occlusal veneers of 0.5 mm thickness were digitally designed. The specimens were divided into 3 groups (n = 20 each) differing in the restorative material and the fabrication technique of the occlusal veneer. (1) 3DP: 3D-printed zirconia (Lithoz); (2): CAM: milled zirconia (Ceramill Zolid FX); (3) HPR: heat-pressed lithium disilicate (IPS e.max Press). After conditioning procedures, the restorations were adhesively bonded onto the conditioned tooth. Thereafter, all specimens were aged in a chewing simulator by exposure to cyclic fatigue and temperature variations. Subsequently the specimens were statically loaded and the load which was necessary to decrease the maximum load by 20% and initiate a crack (Finitial) and the load which was needed to fracture the specimen (Fmax) were measured. Differences between the groups were compared applying the Kruskal-Wallis (KW) test and the Wilcoxon-Mann-Whitney-Test (WMW: p < 0.05). RESULTS The median Finitial values for the groups 3DP, CAM and HPR were 1'650 N, 1'250 N and 500 N. The differences between all three groups were statistically significant (KW: p < 0.0001). The median Fmax values amounted to 2'026 N for the group 3DP, 1'500 N for the group CAM and 1'555 N for the group HPR. Significant differences were found between 3DP and CAM (WMW: p = 0.0238). SIGNIFICANCE Regarding their load-bearing capacity, 3D-printed or milled zirconia as well as heat-pressed lithium disilicate can be recommended as restorative material for ultra-thin occlusal veneers to prosthetically compensate for occlusal tooth wear. Despite statistically significant differences between the restoration materials, all load-bearing capacities exceeded the clinically expected normal bite forces.

中文翻译：

---

臼齿上的CAD / CAM 3D打印氧化锆，CAD / CAM研磨氧化锆和热压二硅酸锂超薄咬合贴面的承重能力。

目的将3D打印氧化锆制成的超薄咬合贴面的承重能力与通过CAD / CAM铣削氧化锆或热压二硅酸锂制造这些重建物而获得的承载面进行比较。方法在60颗提取的人类磨牙上，去除牙合釉并扩展到牙本质中。数字设计厚度为0.5毫米的牙合贴面。将标本分为3组（每组n = 20），它们的修复材料和牙贴面的制造技术不同。（1）3DP：3D打印的氧化锆（Lithoz）；（2）：CAM：磨碎的氧化锆（Ceramill Zolid FX）；（3）HPR：热压二硅酸锂（IPS e.max Press）。修整后，将修复体粘合到修整过的牙齿上。之后，通过暴露于周期性疲劳和温度变化，所有样品均在咀嚼模拟器中老化。随后，对样品进行静态加载，并测量将最大载荷降低20％并引发裂纹所需的载荷（Finitial）和使样品断裂所需的载荷（Fmax）。使用Kruskal-Wallis（KW）检验和Wilcoxon-Mann-Whitney-Test（WMW：p <0.05）比较两组之间的差异。结果3DP，CAM和HPR组的中位初始值分别为1'650 N，1'250 N和500N。三组之间的差异具有统计学意义（KW：p <0.0001）。3DP组的中值Fmax值为2'026 N，CAM组的中值为F'1,500 N，HPR组的为1'555N。发现3DP和CAM之间存在显着差异（WMW：p = 0.0238）。意义对于承重能力，可推荐使用3D打印或研磨的氧化锆以及热压二硅酸锂作为超薄咬合贴面的修复材料，以修复牙齿的咬合磨损。尽管修复材料之间存在统计学上的显着差异，但所有承重能力均超过了临床预期的正常咬合力。