Accelerated fatigue of dentin with exposure to lactic acid.
Composite restorations accumulate more biofilm than other dental materials. This increases the likelihood for the hard tissues supporting a restoration (i.e. dentin and enamel) to be exposed to acidic conditions beyond that resulting from dietary variations. In this investigation the fatigue strength and fatigue crack growth resistance of human coronal dentin were characterized within a lactic acid solution (with pH = 5) and compared to that of controls evaluated in neutral conditions (pH = 7). A comparison of the fatigue life distributions showed that the lactic acid exposure resulted in a significant reduction in the fatigue strength (p ≤ 0.001), and nearly 30% reduction in the apparent endurance limit (from 44 MPa to 32 MPa). The reduction in pH also caused a significant decrease (p ≤ 0.05) in the threshold stress intensity range required for the initiation of cyclic crack growth, and significant increase in the incremental rate of crack extension. Exposure of tooth structure to lactic acid may cause demineralization, but it also increases the likelihood of restored tooth failures via fatigue, and after short time periods.
Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD USA.
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Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD USA.
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Orrego
Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD USA.
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Majd
Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD USA.
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Ryou
Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD USA.|Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, Turku, Finland.
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Mutluay
Department of Endodontics, Prosthodontics, and Operative Dentistry, Dental School, University of Maryland, Baltimore, MD 21201.
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Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD USA.|Department of Endodontics, Prosthodontics, and Operative Dentistry, Dental School, University of Maryland, Baltimore, MD 21201.
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Arola
D000293:Adolescent; D000328:Adult; D003743:Dental Enamel / Q000737:chemistry; D003804:Dentin / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000009:adverse effects*; D008855:Microscopy, Electron, Scanning; D013314:Stress, Mechanical; D013499:Surface Properties; D017001:Tooth Demineralization / Q000139:chemically induced* / Q000473:pathology; D055815:Young Adult
D019344:Lactic Acid
Cyclic crack growth; Demineralization; Dentin tubules; Fatigue; Fracture toughness