Banca de DEFESA: LARISSA MENDONÇA DE MIRANDA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LARISSA MENDONÇA DE MIRANDA
DATE: 01/10/2020
TIME: 08:00
LOCAL: PLATAFORMA REMOTA
TITLE:

Reuse of lithium disilicate ceramics for CAD / CAM: effect of surface treatment and thermocycling  on the durability of bonding to resin cement

KEY WORDS:

shear strength, CAD-CAM, ceramic

PAGES: 42
BIG AREA: Ciências da Saúde
AREA: Odontologia
SUBÁREA: Materiais Odontológicos
SUMMARY:

Objective: To investigate the effect of reusing CAD / CAM blocks of lithium disilicate (DL) ceramics, surface treatment (hydrofluoric acid-HF or Monobond Etch & Prime -MEP) and thermocycling on the bond strength to resin cement. Materials and methods: 48 blocks of lithium disilicate (LD) (E.max CAD, Ivoclar Vivadent) were made and sintered according to the experimental group. Thus, for the groups that used conventional LD ceramics (C), twenty-four blocks were obtained from the section of LD / CAM blocks of LD in the dimensions of 14x12x2mm, which were sanded (# 600) and then sintered . For the groups that used LD ceramic after reuse (R), 24 blocks waxed in the dimensions of 10x10x3mm, were included in coating and then residues of non-sintered LD ceramic blocks were pressed by the lost wax technique. Afterwards, the blocks were included in chemically activated acrylic resin and divided into 12 groups (4 blocks per group) according to the factors: “Reuse cycles” (C and R) “surface treatment” (HF20s and HF120s and Monobond etch & prime / MEP) and “thermocycling” (with and without). After treatment, on each treated block surface, four cylinders (Ø2mm) of dual resin cement (Allcem Dual, FGM) were made and photopolymerized for 60s (N = 180 / n = 15). Half of the samples from each group were subjected to thermocycling (10,000 cycles, 5-55 ° C, 30s) and then subjected to the shear bond strength test (SBS- 100KgF, 1mm / min). Failure, wettability, roughness analyzes will also be performed. The SBS (MPa) data were analyzed using 2-factor ANOVA for each group and 1-factor ANOVA for the treatment surface. Tukey's test (5%) and Weibull's analysis were also performed. Results: ANOVA revealed that for conventional ceramics, thermocycling and surface treatment were significant (P=0.0000) but the interaction between them was not significant (P=0.6799). For reused ceramics, thermocycling (P=0.0000), surface treatment (P=0.0000) and interaction (P=0.0117) were significant. Higher SBS values were found in the HF120s and MEP group, both for conventional and reused ceramics. However, in the TC condition, the reuse reduced the adhesive strength significantly when the ceramic was conditioned with HF for 20 or 120s. When the MEP was used, the bond strength was not affected by the reuse (C = 22.30 MPa; R = 20.39MPa). The Weibull module (m) was not significant (P=0.547), but the characteristic resistance (σ0) varied between the experimental groups (P = 0.000). Conclusion: The reuse of the lithium disilicate ceramic reduces the durability of the bond to the resin cement, except when the ceramic surface treatment is carried out with self-conditioning silane.

BANKING MEMBERS:
Presidente - 1640419 - RODRIGO OTHAVIO DE ASSUNCAO E SOUZA
Externa ao Programa - 2492886 - SAMIRA ALBUQUERQUE DE SOUSA
Externo à Instituição - FABÍOLA PESSÔA PEREIRA LEITE - UFJF