Pan Yu, Lin Honglei, Wang Yinghui, Jiang Lei, Cheng Yiling, Yu Hao, Cheng Hui
Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key Lab of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, 88 Jiaotong Road, Fuzhou, 350004, Fujian, China.
Institute of Stomatology & Research Center of Dental Esthetics and Biomechanics, School and Hospital of S tomatology, Fujian Medical University, 246 Yangqiao Zhong Road, Fuzhou, 350002, Fujian, China.
Clin Oral Investig. 2023 Mar;27(3):1301-1310. doi: 10.1007/s00784-022-04764-8. Epub 2022 Nov 5.
The purpose of this self-controlled clinical study was to evaluate the trueness of occlusal contacts of chairside CAD/CAM crowns fabricated using different ceramic materials.
Ten volunteers (8 females, 2 males, average aged 20-30) were recruited in this study registered in the Clinical Trials Registry (#NCT05346744). After tooth preparation on tooth 36 or 46, an optical scan unit (CEREC Omnicam, Sirona Dental Systems, Germany) was utilized to perform the intraoral scanning. For each volunteer, 6 crowns were fabricated via the chairside CAD/CAM process (CEREC, Sirona Dental Systems, Germany) using the following materials: InCoris TZI (ZIR), Celtra Duo (CD), e.max CAD (EMA), UP.CAD (UP), Enamic (ENA) and Hyramic (HY). The microhardness of the milled surfaces was measured through a Vickers hardness Tester (HVS-50Z, Trojan, China). Together with the amount of occlusal adjustment, the occlusal contact trueness at both milling and postprocessing stages were quantitatively analyzed by using a high-precision scanner (ATOS, GOM Technologies, USA) and a reverse engineering software (Geomagic Control, 3D Systems, Rock Hill, SC). The times of chairside occlusal adjustment were also recorded. Data were analyzed by one-way analysis of variance (ANOVA) and ANOVA with randomized block design followed by Bonferroni test (p = 0.05).
Significant differences were found in surface microhardness of the materials tested (CD > EMA ~ UP > ENA > HY > ZIR, p < 0.05). Regarding the occlusal contact trueness at milling stage, ZIR showed the lowest (p < 0.05), while no significant difference was found among others (p > 0.05). At postprocessing stage, except for ENA, the occlusal contact trueness of ZIR was significantly lower than that of others (p < 0.05). As for occlusal adjustment amount, ZIR was lower than CD and ENA (p < 0.05). In addition, ENA, HY and ZIR required fewer times of occlusal adjustment than EMA, UP and CD.
The type of chairside CAD/CAM ceramic materials affected the occlusal contact trueness throughout the process of manufacturing and the amount of clinical occlusal adjustment as well. Zirconia exhibited the worst occlusal contact trueness at both milling and postprocessing stages, while the amount of occlusal adjustment was the least, which recommended the least occlusal compensation.
For better trueness, different negative occlusal offsets are suggested to be applied in the design process, so as to suit the material of the restoration.
本自身对照临床研究的目的是评估使用不同陶瓷材料制作的椅旁CAD/CAM全冠的咬合接触准确性。
本研究招募了10名志愿者（8名女性，2名男性，平均年龄20 - 30岁），该研究已在临床试验注册中心注册（#NCT05346744）。在对36或46号牙进行牙体预备后，使用光学扫描单元（CEREC Omnicam，德国西诺德牙科系统公司）进行口内扫描。对于每位志愿者，通过椅旁CAD/CAM工艺（德国西诺德牙科系统公司的CEREC）使用以下材料制作6个全冠：InCoris TZI（ZIR）、Celtra Duo（CD）、e.max CAD（EMA）、UP.CAD（UP）、Enamic（ENA）和Hyramic（HY）。通过维氏硬度计（HVS - 50Z，中国特洛伊）测量研磨表面的显微硬度。结合咬合调整量，使用高精度扫描仪（美国GOM技术公司的ATOS）和逆向工程软件（3D Systems公司的Geomagic Control，南卡罗来纳州罗克希尔）对研磨和后处理阶段的咬合接触准确性进行定量分析。还记录了椅旁咬合调整的次数。数据采用单因素方差分析（ANOVA）和随机区组设计的ANOVA，随后进行Bonferroni检验（p = 0.05）。
在所测试材料 的表面显微硬度方面发现了显著差异（CD＞EMA～UP＞ENA＞HY＞ZIR，p＜0.05）。关于研磨阶段的咬合接触准确性，ZIR表现最低（p＜0.05），而其他材料之间未发现显著差异（p＞0.05）。在后处理阶段，除ENA外，ZIR的咬合接触准确性显著低于其他材料（p＜0.05）。至于咬合调整量方面，ZIR低于CD和ENA（p＜0.05）。此外，ENA、HY和ZIR所需的咬合调整次数比EMA、UP和CD少。
椅旁CAD/CAM陶瓷材料的类型在整个制造过程中影响咬合接触准确性以及临床咬合调整量。氧化锆在研磨和后处理阶段的咬合接触准确性最差，而咬合调整量最少，这表明所需的咬合补偿最少。
为了获得更好的准确性，建议在设计过程中应用不同的负向咬合偏移量，以适应修复材料。
