title: Host-derived loss of dentin matrix stiffness associated with solubilization of collagen.
abstract: Matrix metalloproteinases (MMPs) bound to dentin matrices are activated during adhesive bonding procedures and are thought to contribute to the progressive degradation of resin-dentin bonds over time. The purpose of this study was to evaluate the changes in mechanical, biochemical, and structural properties of demineralized dentin treated with or without chlorhexidine (CHX), a known MMP-inhibitor. After demineralizing dentin beams in EDTA or phosphoric acid (PA), the baseline modulus of elasticity (E) of each beam was measured by three-point flexure. Specimens were pretreated with water (control) or with 2% CHX (experimental) and then incubated in artificial saliva (AS) at 37 degrees C for 4 weeks. The E of each specimen was remeasured weekly and, the media was analyzed for solubilized dentin collagen at first and fourth week of incubation. Some specimens were processed for electron microscopy (TEM) immediately after demineralization and after 4 weeks of incubation. In EDTA and PA-demineralized specimens, the E of the control specimens fell (p < 0.05) after incubation in AS, whereas there were no changes in E of the CHX-pretreated specimens over time. More collagen was solubilized from PA-demineralized controls (p < 0.05) than from EDTA-demineralized matrices after 1 or 4 weeks. Less collagen (p < 0.05) was solubilized from CHX-pretreated specimens demineralized in EDTA compared with PA. TEM examination of control beams revealed that prolonged demineralization of dentin in 10% PA (12 h) did not denature the collagen fibrils.
authors.affiliation: Department of Oral Biology, School of Dentistry, Medical College of Georgia, Augusta, Georgia, USA.
authors.forename: Marcela R
authors.initials: MR
authors.lastname: Carrilho
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Adam M
authors.initials: AM
authors.lastname: Donnelly
authors.forename: Kelli A
authors.initials: KA
authors.lastname: Agee
authors.forename: Leo
authors.initials: L
authors.lastname: Tjäderhane
authors.forename: Annalisa
authors.initials: A
authors.lastname: Mazzoni
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
authors.forename: Stephen
authors.initials: S
authors.lastname: Foulger
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
mesh_terms: D002710:Chlorhexidine / Q000737:chemistry; D003094:Collagen / Q000737:chemistry*; D003804:Dentin; D006358:Hot Temperature; D006801:Humans; D020782:Matrix Metalloproteinases / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D010756:Phosphoric Acids / Q000737:chemistry; D012995:Solubility
chemical_list: D010756:Phosphoric Acids; D003094:Collagen; C030242:phosphoric acid; D020782:Matrix Metalloproteinases; D002710:Chlorhexidine