IADR Abstract Archives
Measurement of the Thickness of Paste Glaze Layers on E.max Crowns
Objectives: This study determined the average thickness of the glaze layer on e.max CAD/CAM crowns, after paste glaze treatments, using an optical 3-D measurement system.
Methods: Fifteen identical e.max crowns were fabricated using Planmecca CAD/CAM software and mill (Planmeca USA, Roselle, IL). An optical 3-D measurement system (InfiniteFocus-SL Microscope, Alicona Co., Itasca, IL) mapped each crown to generate a 3-D dataset where each point in the map held x. y and z data with respect to every other point in the map. These datasets became the unglazed crown models (UC) for further measurements. We made an impression of the crown, poured a stone cast, and mapped these casts. These became the unglazed crown cast datasets (UCC). The fifteen crowns were randomly divided into 3 three groups and three experienced practitioners placed clinically appropriate glaze layers on the crowns. Due to difficulty in optical scanning of the glazed crowns, we made an impression for each glazed crown, poured a cast for each, and optically mapped them. These data were the glazed crown cast datasets (GCC). Datasets for each crown were individually superimposed using the “Difference Measurement” mode in the Alicona software. This provided us with mapped height differences over the crown surface, corresponding to the thickness of the glaze.
Results: Differences between the UC and UCC maps averaged less than 5μm, and set the lower level for detection of differences. Comparing UCC with GCC and UC with GCC resulted in glaze thickness measurements in excess of 30-60 μm. The glaze layer was non-uniform and was thickest in the grooves of the crowns. A difference in thickness of the glaze was observed depending upon which practitioner placed the glaze.
Conclusions: The thickness of the paste glaze layer on crowns varied greatly and averaged 30-60 μm. Differences in observed glaze thickness depended upon the individual placing the glaze on the crown.
Methods: Fifteen identical e.max crowns were fabricated using Planmecca CAD/CAM software and mill (Planmeca USA, Roselle, IL). An optical 3-D measurement system (InfiniteFocus-SL Microscope, Alicona Co., Itasca, IL) mapped each crown to generate a 3-D dataset where each point in the map held x. y and z data with respect to every other point in the map. These datasets became the unglazed crown models (UC) for further measurements. We made an impression of the crown, poured a stone cast, and mapped these casts. These became the unglazed crown cast datasets (UCC). The fifteen crowns were randomly divided into 3 three groups and three experienced practitioners placed clinically appropriate glaze layers on the crowns. Due to difficulty in optical scanning of the glazed crowns, we made an impression for each glazed crown, poured a cast for each, and optically mapped them. These data were the glazed crown cast datasets (GCC). Datasets for each crown were individually superimposed using the “Difference Measurement” mode in the Alicona software. This provided us with mapped height differences over the crown surface, corresponding to the thickness of the glaze.
Results: Differences between the UC and UCC maps averaged less than 5μm, and set the lower level for detection of differences. Comparing UCC with GCC and UC with GCC resulted in glaze thickness measurements in excess of 30-60 μm. The glaze layer was non-uniform and was thickest in the grooves of the crowns. A difference in thickness of the glaze was observed depending upon which practitioner placed the glaze.
Conclusions: The thickness of the paste glaze layer on crowns varied greatly and averaged 30-60 μm. Differences in observed glaze thickness depended upon the individual placing the glaze on the crown.
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