A ZnO-doped adhesive reduced collagen degradation favouring dentine remineralization.
OBJECTIVE
The objective of the study was to determine the efficacy of a ZnO-doped etch and rinse adhesive in decreasing MMPs-mediated collagen degradation at the resin-dentine hybrid layer, and increasing bonding stability.


METHODS
C-terminal telopeptide concentrations (ICTP) were determined after 24h, 1wk and 4wk in human dentine beams. Dentine was treated: (1) 37% phosphoric acid for 15s (PA), (2) PA-etched dentine infiltrated with Single Bond (SB), (3) PA-etched dentine infiltrated with ZnO doped SB (ZnO particles--10wt%--were added to the bonding resin) (ZnO-SB), and (4) Clearfil SE Bond primed-dentine was infiltrated with Clearfil SE bonding resin (CSE). Microtensile bond strength (MTBS) was assessed for the different groups at 24h and after 3months. Debonded dentine surfaces were studied by scanning electron microscopy.


RESULTS
MMPs-mediated collagen degradation occurred in demineralized dentine (PA). Resin infiltration decreased collagen degradation. The lowest collagen degradation was found for Zn-doped SB, followed by CSE. When these adhesives were applied, ICTP values did not change throughout the study period. At 24h, similar MTBS was attained for all adhesives. Only SB decreased MTBS after three months.


CONCLUSIONS
Addition of ZnO particles to SB produced a reduction in dentine collagen degradation and increased resin-dentine bonds durability. In Zn-doped adhesive interfaces, a calcium phosphate layer and tubular occlusion was encountered at the debonded interface.


CONCLUSIONS
ZnO particles addition into the bonding resin of SB makes a breakthrough to prevent the hybrid layer degradation and to preserve its bonding efficacy overtime.
Department of Dental Materials, School of Dentistry, Campus de Cartuja s/n, University of Granada, Granada, Spain. toledano@ugr.es
Manuel
M
Toledano
Monica
M
Yamauti
María Estrella
ME
Ruiz-Requena
Raquel
R
Osorio
D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry; D003094:Collagen / Q000378:metabolism*; D024042:Collagen Type I / Q000032:analysis; D001840:Dental Bonding / Q000379:methods*; D003738:Dental Cements / Q000737:chemistry*; D003804:Dentin / Q000378:metabolism* / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D020782:Matrix Metalloproteinases / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D010455:Peptides / Q000032:analysis; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors; D014089:Tooth Remineralization / Q000379:methods*; D015034:Zinc Oxide / Q000737:chemistry*
D002130:Calcium Phosphates; C438313:Clearfil SE Bond; D024042:Collagen Type I; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D010455:Peptides; D010756:Phosphoric Acids; D019279:Resin Cements; C511238:Single Bond Plus; C052929:collagen type I trimeric cross-linked peptide; D017438:Bisphenol A-Glycidyl Methacrylate; D003094:Collagen; C020243:calcium phosphate; C030242:phosphoric acid; D020782:Matrix Metalloproteinases; D015034:Zinc Oxide