IADR Abstract Archives
Scanning Electrochemical Microscopy: a new tool to characterize dental materials
Objectives: Bioactive glass (BAG) has been suggested as an additive to dental composites because it is known to neutralize local acidic environments produced by oral bacteria and release calcium ions which might react with phosphate in solution to precipitate as amorphous calcium phosphate for tooth remineralization. To understand this process, it is necessary to characterize the local chemical environment influenced by BAG materials.
The main objective of this study is to quantitatively characterize the local chemical environment above the surface of BAG particles using a new electrochemical technique, scanning electrochemical microscopy (SECM).
Methods: BAG (65% mol% Si, 31% Ca, 4% P) was prepared by a sol-gel process and ground and micronized into micro-particulates. The particles were pressed at 41.3 MPa into 12.5 mm diameter disks, around which a resin composite holder was cured.
We developed new solid-state ion-selective microelectrodes (25 μm diameter) capable of detecting and mapping Ca2+ release into solutions of various pH. The Ca2+-sensor was precisely positioned within 20 μm of the surface and scanned in the x-y direction at different heights above the BAG while measuring potential to produce a 3-D map of [Ca2+]. Our newly developed pH ultramicrosensor was also used to map the local DpH and the zone at which acidic pH was neutralized.
Results: BAG released calcium ions in acidic conditions (pH = 4.5) and maintained a concentration of 1.4 mM at 20 μm above the surface. In addition, the solution up to 500 μm above the surface of the BAG was neutralized from pH 4.5 to 6.2. A 3-D chemical mapping of pH is shown in the figure. Further studies will focus on similar experiments with BAG-containing resin composites.
Conclusions: SECM is capable of precisely monitoring calcium release from bioactive glass in an acidic environment, and identifying the zone within which the acidic environment can be neutralized.
The main objective of this study is to quantitatively characterize the local chemical environment above the surface of BAG particles using a new electrochemical technique, scanning electrochemical microscopy (SECM).
Methods: BAG (65% mol% Si, 31% Ca, 4% P) was prepared by a sol-gel process and ground and micronized into micro-particulates. The particles were pressed at 41.3 MPa into 12.5 mm diameter disks, around which a resin composite holder was cured.
We developed new solid-state ion-selective microelectrodes (25 μm diameter) capable of detecting and mapping Ca2+ release into solutions of various pH. The Ca2+-sensor was precisely positioned within 20 μm of the surface and scanned in the x-y direction at different heights above the BAG while measuring potential to produce a 3-D map of [Ca2+]. Our newly developed pH ultramicrosensor was also used to map the local DpH and the zone at which acidic pH was neutralized.
Results: BAG released calcium ions in acidic conditions (pH = 4.5) and maintained a concentration of 1.4 mM at 20 μm above the surface. In addition, the solution up to 500 μm above the surface of the BAG was neutralized from pH 4.5 to 6.2. A 3-D chemical mapping of pH is shown in the figure. Further studies will focus on similar experiments with BAG-containing resin composites.
Conclusions: SECM is capable of precisely monitoring calcium release from bioactive glass in an acidic environment, and identifying the zone within which the acidic environment can be neutralized.
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