title: Does tin pre-treatment enhance the bond strength of adhesive systems to enamel?
abstract: OBJECTIVE
  The study investigated the modification of composite-to-enamel bond strength by pre-treatment of enamel with a concentrated, acidic SnCl2-solution.
  
  
  METHODS
  Six groups of flat human enamel specimens (n=44 per group) were treated as follows: OB-H: H3PO4 etching, Optibond FL application (primer+adhesive; manufacturer's instructions); OB-S: SnCl2 pre-treatment, Optibond FL application (primer+adhesive); OB-HS: H3PO4 etching+SnCl2 pre-treatment, Optibond FL application (primer+adhesive); CF-N: Clearfil SE application (primer+bond; manufacturer's instructions); CF-H: H3PO4 etching, Clearfil SE application (primer+bond); CF-S: SnCl2 pre-treatment, Clearfil SE application (primer+bond). Enamel specimens were then built up with resin composite (Clearfil Majesty Esthetic) and stored (100% humidity, 37 °C, 1 week). μTBS-measurement and failure mode analysis of one-half of the specimens were performed immediately after storage, while the other half was analysed after a thermocycling procedure (8500 cycles; 5 °C and 55 °C; dwell time 30s). Additional specimens were prepared for SEM- and EDX-analysis.
  
  
  RESULTS
  Highest values were measured for OB-H before and after thermocycling, lowest values for CF-N. Compared to OB-H treatment, OB-S treatment reduced μTBS before/after thermocycling by 23%/28% and OB-HS treatment by 8%/24% (except for OB-SH before (n.s.), all p≤0.001 compared to OB-H). In the Clearfil SE treated groups pre-treatment increased μTBS significantly compared to CF-N (before/after: CF-H: +46%/+70%; CF-S: +51%/42%; all p≤0.001).
  
  
  CONCLUSIONS
  Pre-treatment with H3PO4 or SnCl2 markedly increased the μTBS of Clearfil SE to enamel. However, thermocycling partly reduced the gain in μTBS obtained by SnCl2 pre-treatment.
  
  
  CONCLUSIONS
  The application of an acidic and highly concentrated SnCl2 solution is a good option to increase the μTBS between enamel and a resin composite mediated by an adhesive system containing the multifunctional monomer MDP.
authors.affiliation: Department of Preventive, Restorative and Pediatric Dentistry, University of Bern, Switzerland. nadine.schlueter@dentist.med.uni-giessen.de
authors.forename: Nadine
authors.initials: N
authors.lastname: Schlueter
authors.forename: Anne
authors.initials: A
authors.lastname: Peutzfeldt
authors.forename: Carolina
authors.initials: C
authors.lastname: Ganss
authors.forename: Adrian
authors.initials: A
authors.lastname: Lussi
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel / Q000187:drug effects / Q000648:ultrastructure*; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D006813:Humidity; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D017971:Tin Compounds / Q000737:chemistry* / Q000494:pharmacology
chemical_list: C438313:Clearfil SE Bond; D003188:Composite Resins; C469607:OptiBond FL; D010756:Phosphoric Acids; D019279:Resin Cements; D017971:Tin Compounds; C541508:clearfil majesty; C023599:stannous chloride; C030242:phosphoric acid