Analysis of Translucency Parameter of Glass-Ceramics Fabricated by Different Techniques.
OBJECTIVE
of the study was to analyse translucency parameter (TP values) of glass-ceramics fabricated by different techniques and investigate the effect of the corrosive medium on TP values.


METHODS
Three specimens of each type of IPS e.max ceramics (Ivoclar Vivadent, Schaan, Liechtenstein) were made in three colours (A2, C2 and B3) by three fabrication techniques (layering - e.max Ceram Dentin; heat-pressing - e.max Press; CAD/CAM - e.max CAD). Specimens were made in the form of plates (10 mm x 12 mm x 0.8 mm). CIE L*a*b* values were measured by a spectrophotometer (X-Rite DTP 20 Pulse, Neu Isenburg, Germany) before and after exposure to 4% acetic acid at 80 °C for 16 hours (ISO 6872) to calculate translucency parameter (TP values). Statistical data were analysed using the IBM SPSS 22 software.


RESULTS
IPS e.max Ceram Dentin had significantly the lowest TP values, and IPS e.max Press the highest TP values of all colours (A2, C2, B3), both prior and after exposure to acid (p<0.001). The difference in TP values among colours was evident in the IPS e.max Ceram Dentin material, both before and after exposure to acid with a great effect size (p<0.001; η2 = 0.702 and 0.741), and in the IPS e.max Press material (p<0.001, effect size 0.547 and 0.576). CAD/CAD specimens showed uniform TP values between three colours. Further, exposure to a corrosive medium did not result in a statistically significant change of TP values in any of the materials tested.


CONCLUSIONS
Different types of glass-ceramics showed significant difference in TP values both with respect to the fabrication technique and colour. Exposure to a corrosive medium did not result in a statistically significant change of TP values.
Polyvalent Dental Office, Health Centre Zagreb - Centar, Zagreb, Croatia.
Karla
K
Ledić
Faculty of Graphic Arts, University of Zagreb, Zagreb, Croatia.
Igor
I
Majnarić
Polyvalent Dental Office, Health Centre Zagreb - Centar, Zagreb, Croatia.
Slađana
S
Milardović
School of Dental Medicine, University of Zagreb, Zagreb, Croatia.
Ortolan
School of Dental Medicine, University of Rijeka, Rijeka, Croatia.
Stipe
S
Špalj
Dental Polyclinic Zagreb, Zagreb, Croatia.
Sanja
S
Štefančić
School of Dental Medicine, University of Zagreb, Zagreb, Croatia; Dental Clinic, University Hospital Centre Zagreb, Zagreb, Croatia.
Ketij
K
Mehulić
corrosion; glass-ceramics; spectrophotometer; translucency
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