OBJECTIVE: To investigate the effect of various energy sources on the upper and lower surface hardness of a setting glass ionomer with various thicknesses. METHOD: Cylindrical specimens (4 mm diameter by 1, 2 or 4 mm thickness) of a glass-ionomer cement were prepared with no applied energy source (control), by preheating GIC capsules in a waterbath prior to mixing, application of light with high irradiance or ultrasonic excitation with a scaler tip. The upper and lower surface hardness was measured 0.5 h, 4 h and 1 week following material mixing. The increase in temperature towards the lower surface of each specimen was monitored throughout the first 5 min of setting. RESULTS: No significant differences in hardness between upper and lower surfaces or varying thicknesses were identified for control and preheated samples at any post-mix time (p>0.05). At 0.5 h post-mix, the upper surface hardness of preheated, light and ultrasonic treatments was significantly increased compared with that of the control groups. Following 4 h post-mix, the overall hardness of preheated samples was significantly greater (p<0.001) than other sample groups, which were not statistically different (p=0.684). No significant differences in hardness between test groups were identified following 1 week (p>0.05). CONCLUSIONS: Preheating GIC capsules prior to mixing resulted in superior hardness values through depth up to and including 4 h post-mix compared with specimen surfaces treated with light irradiation or with an ultrasonic scaler tip. Copyright 2010 Elsevier Ltd. All rights reserved.
OBJECTIVE: To investigate the effect of various energy sources on the upper and lower surface hardness of a setting glass ionomer with various thicknesses. METHOD: Cylindrical specimens (4 mm diameter by 1, 2 or 4 mm thickness) of a glass-ionomer cement were prepared with no applied energy source (control), by preheating GIC capsules in a waterbath prior to mixing, application of light with high irradiance or ultrasonic excitation with a scaler tip. The upper and lower surface hardness was measured 0.5 h, 4 h and 1 week following material mixing. The increase in temperature towards the lower surface of each specimen was monitored throughout the first 5 min of setting. RESULTS: No significant differences in hardness between upper and lower surfaces or varying thicknesses were identified for control and preheated samples at any post-mix time (p>0.05). At 0.5 h post-mix, the upper surface hardness of preheated, light and ultrasonic treatments was significantly increased compared with that of the control groups. Following 4 h post-mix, the overall hardness of preheated samples was significantly greater (p<0.001) than other sample groups, which were not statistically different (p=0.684). No significant differences in hardness between test groups were identified following 1 week (p>0.05). CONCLUSIONS: Preheating GIC capsules prior to mixing resulted in superior hardness values through depth up to and including 4 h post-mix compared with specimen surfaces treated with light irradiation or with an ultrasonic scaler tip. Copyright 2010 Elsevier Ltd. All rights reserved.
Authors: Lidia Gavic; Kristina Gorseta; Domagoj Glavina; Beata Czarnecka; John W Nicholson Journal: J Mater Sci Mater Med Date: 2015-09-28 Impact factor: 3.896
Authors: Gustavo Fabián Molina; Ricardo Juan Cabral; Ignacio Mazzola; Laura Brain Lascano; Jo E Frencken Journal: Biomed Res Int Date: 2013-06-12 Impact factor: 3.411