Investigation of dentinal tubule occlusion using FIB-SEM milling and EDX.
OBJECTIVE
The aim of this study was to evaluate in vitro the dentin tubule occluding effect of an 8% strontium acetate dentifrice (Sensodyne Rapid Relief) compared to patent dentin tubules using modern sample preparation, imaging, and analysis techniques.


METHODS
Etched dentin discs, either untreated or treated with the dentifrice, were analyzed by preparing cross-sections using focused ion beam scanning electron microscopy (FIB-SEM) milling, and the strontium presence mapped using energy dispersive X-ray spectroscopy (EDX).


RESULTS
Surface imaging showed the dentifrice had coated the treated sample. Sub-surface information gained by preparing longitudinal cross-sections of the treated samples showed the tubule openings to be plugged, and EDX mapping of the cross-section confirmed enhanced strontium levels within the tubules several microns below the treatment surface.


CONCLUSIONS
The combination of modern sample preparation, imaging, and analysis techniques employed in this study has shown that the 8% strontium acetate dentifrice occludes dentin tubules. EDX analysis has shown the presence of strontium within the dentin tubules, with elemental maps illustrating how the strontium has been incorporated into the dentin.
Earl
J S
JS
GlaxoSmithKline Consumer Healthcare, Weybridge, Surrey, UK. jonathan.s.earl@gsk.com
Ward
M B
MB
Langford
R M
RM
D000085:Acetates / Q000032:analysis / Q000627:therapeutic use*; D000134:Acid Etching, Dental / Q000379:methods; D019343:Citric Acid / Q000008:administration & dosage; D003461:Crystallography; D003802:Dentifrices / Q000627:therapeutic use*; D003804:Dentin / Q000737:chemistry / Q000187:drug effects / Q000648:ultrastructure*; D057133:Dentin Desensitizing Agents / Q000627:therapeutic use*; D017886:Durapatite / Q000032:analysis; D006801:Humans; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D046529:Microscopy, Electron, Transmission; D012969:Sodium Fluoride / Q000032:analysis / Q000627:therapeutic use; D013052:Spectrometry, X-Ray Emission / Q000379:methods*; D013324:Strontium / Q000032:analysis / Q000627:therapeutic use*
D000085:Acetates; D003802:Dentifrices; D057133:Dentin Desensitizing Agents; D019343:Citric Acid; C106741:strontium acetate; D012969:Sodium Fluoride; D017886:Durapatite; D013324:Strontium