title: MMP-2 assay within the hybrid layer created by a two-step etch-and-rinse adhesive: biochemical and immunohistochemical analysis.
abstract: OBJECTIVE
  Degradation of hybrid layers (HLs) within resin-infiltrated dentine results from multiple degradation factors, including collagenolytic activity of specific matrix metalloproteinases (MMPs). Inhibition of host-derived MMPs may, therefore, slow the degradation of HL. The null hypothesis tested is that the presence of MMP-2 is similar regardless of chlorhexidine (CHX) pre-treatment or the use of an adhesive.
  
  
  METHODS
  Powdered dentine prepared from extracted human teeth was divided into 4 groups: (G1) mineralised powder (control group); (G2) dentine powder treated with 1% phosphoric acid for 1 min; (G3) 1% phosphoric acid-etched dentine treated with Adper Scotchbond 1 XT (SB1XT; 3M ESPE); (G4) 1% phosphoric acid-etched dentine treated with 0.2% CHX followed by SB1XT. The concentration of detectable pro-MMP-2 and MMP-2 was assayed using a colorimetric assay system (QuantiSir). In addition, the presence of MMP-2 in the HL was assessed in 1 year-aged adhesive-dentine interfaces using an immunohistochemical approach under FEI-SEM/TEM.
  
  
  RESULTS
  In dentine powder treated with 1% phosphoric acid (G2), MMP-2 level decreased compared to controls (G1); the application of SB1XT (G3) resulted in an increase of MMP-2, whilst 0.2% CHX before SB1XT application (G4), reduced MMP-2. The FEI-SEM/TEM analysis revealed MMP-2 distribution within the HL of aged interfaces showing increase MMP-2 patterns in the control group and minor labelling in the CHX-pretreated specimens.
  
  
  CONCLUSIONS
  The results of this study support the use of non-toxic MMPs inhibitors, such as CHX, as an appropriate additional step in bonding procedures in order to increase the longevity of the adhesive restorations.
authors.affiliation: Department of SAU&FAL, University of Bologna, Bologna, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Mazzoni
authors.forename: Marcela
authors.initials: M
authors.lastname: Carrilho
authors.forename: Veronica
authors.initials: V
authors.lastname: Papa
authors.forename: Leo
authors.initials: L
authors.lastname: Tjäderhane
authors.forename: Pietro
authors.initials: P
authors.lastname: Gobbi
authors.forename: Cesare
authors.initials: C
authors.lastname: Nucci
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Lenarda
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mazzotti
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
mesh_terms: D000134:Acid Etching, Dental; D002710:Chlorhexidine / Q000494:pharmacology*; D003094:Collagen / Q000378:metabolism; D003188:Composite Resins; D001840:Dental Bonding / Q000379:methods*; D003799:Dental Stress Analysis; D003804:Dentin / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D017220:Dentin-Bonding Agents / Q000494:pharmacology*; D055785:Gene Knockdown Techniques; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D061965:Matrix Metalloproteinase Inhibitors; D008964:Molar, Third; D010756:Phosphoric Acids / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology*; D019279:Resin Cements / Q000494:pharmacology*; D013718:Tensile Strength
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D061965:Matrix Metalloproteinase Inhibitors; D010756:Phosphoric Acids; D011480:Protease Inhibitors; D019279:Resin Cements; D003094:Collagen; C030242:phosphoric acid; D020778:Matrix Metalloproteinase 2; D002710:Chlorhexidine