As tooth-colored restorative materials, CAD/CAM composites are an alternative to dental ceramics. They are offered as industrially manufactured, fully polymerized blocks and can be processed quickly and cost-effectively in the CAD/CAM process. The range of indications extends beyond that of dental ceramics. For example, minimally invasive chewing surfaces and veneers with thin preparation edges can be made. The materials science team at the Polyclinic for Dental Prosthetics at the LMU Munich compared five different CAD/CAM composites in a study.
Aim of the investigation
The mechanical and optical properties of five CAD/CAM composites (LAVA Ultimate, Cerasmart, Shofu Block and two experimental materials from Coltene Whaledent and Ivoclar Vivadent), a hybrid material (VITA Enamic), a leucite ceramic (IPS Empress CAD) were determined and compared. and a lithium disilicate ceramic (IPS e.max CAD).
Materials and methods
The three-point bending strength was examined according to ISO 6872: 2008. A chewing simulator (1.200000 cycles, 50 N, 5 °C/55 °C) with human teeth as antagonists was used to analyze abrasion resistance. The quantitative analysis of the material loss was carried out using a 3D scanner and appropriate software.
The examined materials
In addition, the translucency and discoloration of the CAD/CAM materials were measured with a spectrophotometer (14-400 nm wavelength) after 700 days of storage in cress, curry, red wine and distilled water. The data collected were evaluated using two-factor analysis of variance, Kruskal-Wallis H test and linear mixed models (p < 0,05).
Results of the investigation
IPS e.max CAD showed the highest bending strength (p < 0,001), followed by LAVA Ultimate. However, the strengths of Lava Ultimate were not significantly higher than those of the other CAD/CAM composites (exception: Shofu block). VITA Enamic and IPS Empress CAD showed the lowest strength values in this study (p < 0,001).
IPS Empress CAD, VITA Enamic, experimental CAD/CAM composite (Coltene Whaledent) and IPS e.max CAD showed higher abrasion resistance than the other tested materials (p < 0,001). The highest antagonist wear was observed for the glass ceramics and the hybrid material (p < 0,001).
Storage medium had the greatest influence on discoloration rates (p < 0,001). The highest discoloration rates were observed in test specimens stored in red wine, followed by those stored in curry. Distilled water had the least influence on the discoloration rates and was only used as a control. The glass ceramics showed lower discoloration rates than the CAD/CAM composites (p < 0,001).
Conclusions: Based on this study, it can be claimed that CAD/CAM composites have moderate strength, high translucency and good antagonistic behavior in terms of abrasion resistance. In the study, glass ceramics showed the lowest discoloration rates and the highest abrasion resistance, but caused the most damage to the enamel of the antagonists.
Author: A. Kieschnick (www.annettkieschnick.de)
Note: The experimental CAD/CAM composite from Coltene Whaledent is now available with the product name Brilliant Crios.
Left: Grinding restorations made from a CAD/CAM composite in the milling machine. Right: Partial crowns ground out of blanks before being separated from the blank holder (Images: C. Fischer)
Right: Color customization of the occlusal surface with a special light-curing varnish. Left: Finished implant crowns made from a CAD/CAM composite (cerasmart) (Images: C. Fischer)
FURTHER INFORMATION ON THE PRESENTED INVESTIGATION
Full article: Stawarczyk B, Liebermann A, Eichberger M, Güth JF. Evaluation of mechanical and optical behavior of current esthetic dental restorative CAD/CAM composites. J Mech Behav Biomed Mater. 2015;55:1-11. doi: 10.1016/j.jmbbm.2015.10.004.