Slađana Milardović Ortolan

Analysis of Translucency Parameter of Glass-Ceramics Fabricated by Different Techniques

THE PURPOSE 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. MATERIALS AND 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.

Comparison of time consumption and color matching results of different dental occupational groups.

PURPOSE A study was conducted to compare the accuracy and time consumption of shade matching tasks performed by students, clinicians, and dental technicians. MATERIALS AND METHODS A total of 126 participants were asked to pair shade tabs and to choose the best shade match for three natural teeth using the Chromascop shade guide. Time consumption was recorded. The frequency of correct answers and time consumption results were compared across occupational groups and by levels of clinical experience. RESULTS No significant difference was found between occupational groups in shade tab pairing or natural tooth color matching. Experience did not affect the shade tab pairing, but experienced participants were better in natural tooth color matching. Clinicians performed the shade tab matching task faster than preclinical and clinical students, while technicians were faster than preclinical students. In the natural tooth color matching task, clinicians and technicians were faster than students. Regarding experience, novice observers were slower than experienced individuals. A significant negative correlation was observed between time consumption for visual shade matching and the frequency of correct matches for both shade tabs and natural teeth. CONCLUSION The level of professional experience improved color matching of natural teeth. Overall, clinicians and dental technicians performed faster than students, while lower time consumption for shade matching was associated with better scores.