title: Synergistic degradation of dentin by cyclic stress and buffer agitation.
abstract: Secondary caries and non-carious lesions develop in regions of stress concentrations and oral fluid movement. The objective of this study was to evaluate the influence of cyclic stress and fluid movement on material loss and subsurface degradation of dentin within an acidic environment. Rectangular specimens of radicular dentin were prepared from caries-free unrestored 3rd molars. Two groups were subjected to cyclic cantilever loading within a lactic acid solution (pH = 5) to achieve compressive stresses on the inner (pulpal) or outer sides of the specimens. Two additional groups were evaluated in the same solution, one subjected to movement only (no stress) and the second held stagnant (control: no stress or movement). Exterior material loss profiles and subsurface degradation were quantified on the two sides of the specimens. Results showed that under cyclic stress material loss was significantly greater (p ≤ 0.0005) on the pulpal side than on the outer side and significantly greater (p ≤ 0.05) under compression than tension. However, movement only caused significantly greater material loss (p ≤ 0.0005) than cyclic stress. Subsurface degradation was greatest at the location of highest stress, but was not influenced by stress state or movement.
authors: Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD, USA.
authors: Santiago
authors: S
authors: Orrego
authors: Department of Endodontics, Prosthodontics, and Operative Dentistry, Dental School, University of Maryland, Baltimore, MD, USA.
authors: Elaine
authors: E
authors: Romberg
authors: Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA; Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA, USA. Electronic address: darola@u.washington.edu.
authors: Dwayne
authors: D
authors: Arola
mesh_terms: D000293:Adolescent; D000328:Adult; D002021:Buffers; D003804:Dentin / Q000166:cytology / Q000378:metabolism; D006801:Humans; D057446:Hydrodynamics; D008422:Materials Testing; D008903:Minerals / Q000378:metabolism; D008963:Molar; D013314:Stress, Mechanical; D013499:Surface Properties; D055815:Young Adult
chemical_list: D002021:Buffers; D008903:Minerals
keywords: Acid; Demineralization; Dentin; Fatigue; Microstructure; Non-carious cervical lesions; Secondary caries
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