Evaluation of the physiological wear of the applied characterization layer on dental ceramics

Author(s)

Jefferson David Melo de Matos

• Document type: Master's Dissertation
• Press: São José dos Campos. 2020-03-09.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Ciência e Tecnologia. São José dos Campos
• Defense date: 2020-02-03
• Advisor: Marco Antonio Bottino

Abstract

The present study aimed to evaluate the behavior of the characterization layer on high translucency zirconia (YZHT, Vita YZ HT), feldspar ceramic (FD / VMII, Vita Mark II) and zirconia reinforced lithium silicate (ZLS, Vita Suprinity) compared to the simulation of physiological wear, varying the antagonists in YZHT, steatite and hybrid ceramic with polymer (Vita Enamic). 120 ceramic discs (ø 12 mm, 1.2 mm thick) were obtained, 30 from YZHT and FD, and 60 from ZLS, by cutting blocks for CAD / CAM. The YZHT samples were sintered, and in the sequence the groups YZHT and FD received the characterization layer. The characterization of the ZLS samples was carried out in the same act of crystallization (ZLS1, single step) or in burning after crystallization (ZLS2, two steps). The characterization was carried out according to the manufacturer's recommendations and all samples received application of glaze and consequent burning. The specimens were divided into subgroups (n = 10) according to the antagonists: steatite, hybrid ceramic or zirconia; then, they were submitted to the simulation of physiological wear. The parameters of average roughness (Ra) and average width of the elements of the roughness profile (Rsm) were analyzed at different moments of the simulation of physiological wear from the beginning to the end of the cycle. After 15,000 cycles, the mass loss of the ceramic discs and antagonistic pistons was calculated. The results were analyzed statistically by Anova 2 factors and Tukey (p <0.05). Before wear, the ceramics showed no differences for the roughness parameters, Ra (p = 0.3348), Rz (p = 0.5590) and Rsm (p = 0.5330). The antagonists showed no differences for the parameters, Ra (p = 0.0541) and Rsm (p = 0.0613), while the parameter Rz (p = 0.000) showed a difference, since steatite (18.98 ± 2) , 98 μm) presented a higher average roughness when the maximum profile height was analyzed when compared with the antagonists in enamic (12.35 ± 0.91 μm) and zirconia (11.47 ± 0.89 μm). After wear, the ceramics continued to show no statistical differences for the roughness parameters, Ra (p = 0.488), Rz (p = 0.681) and Rsm (p = 0.256). The antagonists showed no difference for the Ra parameter (p = 0.124), however, they showed a difference for the Rz parameter (p = 0.000), since steatite (57.98 ± 4.11 μm) showed a higher average for such parameter when compared with antagonists in enamic (44.86 ± 2.34 μm) and zirconia (37.81 ± 1.40 μm); and for the parameter Rsm (p = 0.000), since the averages of steatite (502.72 ± 72.20 μm), enamic (385.67 ± 24.84 μm) and zirconia (268.94 ± 27.99 μm ) showed differences between them. The type of ceramic (p <0.0001) influenced the loss of mass of the samples and the interaction between ceramic and antagonist (p = 0.0098), thereby influencing the loss of mass of the antagonist pistons. The ZLS 2 group showed the greatest loss of mass among the tested groups. All tested antagonists showed similar mass loss against FD, while steatite showed greater mass loss when tested with YHZT, ZLS 1 and ZLS 2 samples. All ceramics showed similar roughness before and after wear simulation. The ceramic samples showed a similar mass loss. However, the additional burning of the characterization of the zirconia-reinforced lithium silicate ceramic favored a greater loss of mass, without altering its strength. (AU)

• FAPESP's process: 18/04454-0 - Evaluation of the physiological wear of the characterization layer applied on dental ceramics
• Grantee: Jefferson David Melo de Matos
• Support Opportunities: Scholarships in Brazil - Master