Abstract
The purpose of this study was to demonstrate the time-efficiency and the clinical effectiveness of chairside-fabricated lithium disilicate single crowns by digital impressions compared to the conventional method. Thirteen patients requiring a single crown on the maxillary or mandibular premolar or first molar were assigned as study subjects. The impressions were obtained using the conventional method and two digital methods with intraoral scanners: AEGIS.PO (Digital Dentistry Solution, Seoul, Korea) and CEREC Omnicam (Sirona, Bensheim, Germany). Two types of lithium disilicate single crowns were obtained; a reference crown (by conventional workflow) and a chairside crown (by digital workflow). The total time taken for fabricating the chairside crown was recorded. The replica technique was performed to compare the marginal and internal fit of the two types of crowns. In addition, accuracy of the intraoral scanners was evaluated by the best-fit alignment method. The difference between the groups was analyzed using the two-tailed paired t-test or one-way ANOVA, followed by the Student–Newman–Keuls test for multiple comparisons. Statistical significance was accepted at p < 0.05 for all statistical tests. The time required to obtain the impressions by the AEGIS (7:16 ± 1:50 min:s) and CEREC (7:29 ± 2:03 min:s) intraoral scans was significantly lower than the conventional method (12:41 ± 1:16 min:s; p < 0.001). There was no significant difference between the intraoral scanners. The total working time to fabricate the chairside crown averaged 30:58 ± 4:40 min:s. The average marginal gap was not significantly different between the reference (107.86 ± 42.45 µm) and chairside (115.52 ± 38.22 µm) crowns (p > 0.05), based on results of replica measurement. The average internal gaps were not significantly different. The average value of the root mean square between the AEGIS (31.7 ± 12.3 µm) and CEREC (32.4 ± 9.7 µm) scans was not significantly different (p > 0.05). Intraoral scans required a significantly shorter impression time than the conventional method, and it was possible to fabricate a lithium disilicate crown in a single visit. There were no statistically significant differences in the fit of the restorations and accuracy of the intraoral scanners compared to the conventional workflow.
Highlights
Chairside CAD/CAM (Computer Aided Design/Computer Aided Manufacturing)procedures are more advantageous than the conventional methods in terms of fabrication efficiency of the prostheses [1,2].Digital workflow does not require time-consuming laboratory procedures and transportation, and improvesMaterials 2020, 13, 5467; doi:10.3390/ma13235467 www.mdpi.com/journal/materialsMaterials 2020, 13, 5467 patient comfort [3,4]
There were no statistically significant differences in the fit of the restorations and accuracy of the intraoral scanners compared to the conventional workflow
With the exception of zirconia, which takes 6–8 h for the post-milling process, feldspathic, leucite-reinforced, lithium disilicate ceramics, and composite resin are considered for chairside CAD/CAM restorations [5]
Summary
Chairside CAD/CAM (Computer Aided Design/Computer Aided Manufacturing)procedures are more advantageous than the conventional methods in terms of fabrication efficiency of the prostheses [1,2].Digital workflow does not require time-consuming laboratory procedures and transportation, and improvesMaterials 2020, 13, 5467; doi:10.3390/ma13235467 www.mdpi.com/journal/materialsMaterials 2020, 13, 5467 patient comfort [3,4]. Chairside CAD/CAM (Computer Aided Design/Computer Aided Manufacturing)procedures are more advantageous than the conventional methods in terms of fabrication efficiency of the prostheses [1,2]. Digital workflow does not require time-consuming laboratory procedures and transportation, and improves. The restorative materials used in the chairside CAD/CAM systems need to be milled immediately, usually within 30 min, to be delivered on the same day of tooth preparation. Manufacturers have adopted a wet grinding process on preformed blocks to minimize damage to the materials during milling and to achieve efficient post-milling time. With the exception of zirconia, which takes 6–8 h for the post-milling process, feldspathic, leucite-reinforced, lithium disilicate ceramics, and composite resin are considered for chairside CAD/CAM restorations [5]. In 2006, Ivoclar introduced IPS e.max CAD as a lithium disilicate CAD/CAM material, which has
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