Load-bearing capacity of CAD/CAM 3D-printed zirconia, CAD/CAM milled zirconia, and heat-pressed lithium disilicate ultra-thin occlusal veneers on molars

Abstract

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 (F initial ) and the load which was needed to fracture the specimen (F max ) 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 F initial 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 F max 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.

Posterior minimally invasive full‐veneers: Effect of ceramic thicknesses, bonding substrate, and preparation designs on failure‐load and ‐mode after fatigue

“…Regarding LDS veneer restorations, several in vitro studies investigating occlusal veneers with different ceramic thicknesses and substrates, mainly in molars, have been published. [7][8][9] In one of the studies, the occlusal ceramic thickness was reduced to 0.3-0.6 mm and restorations still revealed load-bearing capacities that are comparable to healthy teeth. 7 An article reviewing preclinical studies concerning CAD/CAM occlusal veneers suggests 0.7-1.0 mm of thickness to be appropriate for LDS occlusal veneers.…”

“…4 Occlusal veneers and onlays aim to replace the lost occlusal tooth substance in the posterior region. [5][6][7][8][9][10][11][12] However, when defects additionally involve cervical areas, options are either to perform a full-crown preparation or to add a cervical Class V resin filling to occlusal restorations. Whereas crown preparation requires 63%-72% removal of coronal tooth structures, 13 Class V restorations reveal limited survival and impaired esthetics in the worn dentition.…”

Additive Manufacturing of Zirconia Ceramic and Its Application in Clinical Dentistry: A Review

“…Ioannidis et al [ 88 ] evaluated the load-bearing capacity of additively manufactured zirconia ultra-thin occlusal veneers on molars and compared to milled zirconia and heat-pressed lithium-disilicate. Occlusal veneers with 0.5 mm thickness on molars digitally were designed.…”

Relationship Between Internal Accuracy and Load-Bearing Capacity of Minimally Invasive Lithium Disilicate Occlusal Veneers

“…On the other hand, the high flexural strength and fracture toughness of reinforced glass ceramics or high strength ceramics could be in favour towards this application (3,4). Lithium disilicate (LS2) -as a representative of the reinforced glass ceramics -shows favourable mechanical and bonding properties and can be used for the fabrication of these occlusal veneers (5)(6)(7)(8). LS2 restorations can either be manufactured by heatpressing or by CAD/CAM procedures -namely milling (9).…”