PSI - Issue 28

Vesela Hristova et al. / Procedia Structural Integrity 28 (2020) 1002–1009 Vesela Hristova, Tsanka Dikova, Vladimir Panov / Structural Integrity Procedia 00 (2019) 000–000

1005

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cavity, and photopolymerized for 20 s. The cavity was then filled with FPC, pressed with celluloid tape and irradiated for 10 s. Table 1. Data about the materials used in the study (Objelean et al. (2016), GC Fuji VIII GP (2020), Scientific Documentation Adhese® Universal (2020), Technical Report, Estelite® Flow Quick (2020), Safety data sheet, Evetric (2015), Cefaly et al. (2005), Spajic et al. (2019). Materials Composition P/L or M/F ratio* Shrinkage Component Amount, %

Liquid:

2-HEMA (hydroxyethyl methacrylate)

25-50 % 5-10 %

P/L 3.4/1.0 g/g (77/23%)

Tartaric acid

3 %

GIC: FUJI VIII GP

7,7,9(or 7,9,9)-trimethyl-4,13-dioxo-3,14-dioxa-5,12 diazahexadecane-1,16-diyl Bismethacrylate

1-5%

2-Hydroxy-1,3 dimethacryloxypropane Powder: Fluoro-Alumino-Silicate glass, pigment

1-5%

BisGMA, HEMA, ethanol, 1,10-decandiol dimethacrylate, methacrylated phosphoric acid ester, CQ, DMAEMA,

67 %

Adhesive: Adhese Universal

Water, ethanol

25 %

Highly dispersed silicon dioxide Initiators and Stabilizers

4 % 4 %

Matrix:

FPC: Estelite Flow Quick - High Flow

BIS-GMA (Bisphenol A glycydil dimethacrylate) TEGDMA (Triethylene glycol dimethacrylate) UDMA (Urethane dimethacrylate)

0-30%

3 %

M/F 32/68 wt %

5-20%

Filler: Si-Zr supra-nano spherical particles ( 70 nm and 0.4 μm)

Matrix:

BIS-GMA (Bisphenol A glycydil dimethacrylate)

3-10%; 10-25%; 3-10%

1.5 %

M/F 19-20/80-81 wt %

UPC: Evetric

UDMA (Urethane dimethacrylate)

Bis-EMA (Bisphenol A polyethethylene glycol dimethacrylate) Filler: Ba glass particles, ytterbium trifluoride, mixed oxides and pre polymers (40nm-3μm)

*Note: P/L (Powder/Liquid), M/F (Matrix/Filler). Universal photo-cured nanohybrid composite Evetric (Ivoclar Vivadent AG, Liechtenstein ) was used for restoration of the cavities in Group 3. The same protocol was used as the previous one, except the deposition of the composite. The incremental technique was used and the UPC was applied with reverse spatula in two layers with successive 20 s photopolymerization of each layer. All samples were subjected to 500 thermal cycles in temperature 5-50 °C and holding time 15 s (Dikova et al. (2020), Anastasova et al. (2019). After that the teeth were isolated with contrast lacquer except the cavities (Fig.1). They were placed in a colorant - a 2% solution of methylene blue for 8 h, after which they were washed and cut vertically through the crown and the root with a diamond separator. 2.2. Samples characterization The restored V-shape defects were observed at magnifications x8, x15 and x25 using Olympos SZ51 optical microscope, digital camera Zuzi Ucmos № TP6080000B with ToupView software. 2.3. Microleakage evaluation The degree of microleakage was evaluated by measuring the penetration depth of the dye between the tooth wall and the cavity, cervical and occlusal of the tooth. The relative microleakage (%) in the occlusal and cervical regions of the cavity as well as the mean relative microleakage (%) in each group was calculated.