title: Hydrofluoric acid on dentin should be avoided.
abstract: Hydrofluoric acid can be used for intra-oral repair of restorations. Contamination of tooth substrate with hydrofluoric acid cannot always be avoided.
  
  
  OBJECTIVE
  To investigate the bonding effectiveness to hydrofluoric acid contaminated dentin by, micro-tensile bond strength testing, SEM and TEM.
  
  
  METHODS
  For this study, 15 molar teeth were used of which dentin surfaces were subjected to five, different etching procedures. Group A, 37.5% phosphoric acid (Kerr Gel) (control group); group B, 37.5% phosphoric acid followed by 3% hydrofluoric acid (DenMat); group C, 37.5% phosphoric acid, followed by 9.6% hydrofluoric acid (Pulpdent); group D, 3% hydrofluoric acid followed by 37.5%, phosphoric acid; group E, 9.6% hydrofluoric acid followed by 37.5% phosphoric acid. After the bonding procedure (OptiBond FL, Kerr) a composite resin build-up (Clearfil AP-X, Kuraray), was made. After 1 week storage, specimens were prepared for micro-tensile bond testing, SEM- and, TEM-analysis. Data were analyzed using ANOVA and post hoc Tukey's HSD (p<0.05).
  
  
  RESULTS
  In the control group (solely phosphoric acid), the mean microTBS was 53.4+/-10.6 MPa, which was, significantly higher than any hydrofluoric acid prepared group (group A versus groups B-E, p<0.001). No, significant differences in microTBS were found between the 3% and 9.6% hydrofluoric acid groups: group B versus group C (13.5+/-5.5 MPa and 18.7+/-4.3 MPa, respectively) or group D versus group E (19.9+/-6.8 MPa and 20.3+/-4.1 MPa, respectively).
  
  
  CONCLUSIONS
  Due to its adverse effect on the bond strength of composite to dentin, contact of hydrofluoric acid to dentin should be avoided.
authors.affiliation: Department of Preventive and Restorative Dentistry, Radboud University Nijmegen Medical Centre, The Netherlands. b.loomans@dent.umcn.nl
authors.forename: B A C
authors.initials: BA
authors.lastname: Loomans
authors.forename: A
authors.initials: A
authors.lastname: Mine
authors.forename: F J M
authors.initials: FJ
authors.lastname: Roeters
authors.forename: N J M
authors.initials: NJ
authors.lastname: Opdam
authors.forename: J
authors.initials: J
authors.lastname: De Munck
authors.forename: M C D N J M
authors.initials: MC
authors.lastname: Huysmans
authors.forename: B
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D002124:Calcium Fluoride / Q000032:analysis; D003188:Composite Resins; D001840:Dental Bonding; D003799:Dental Stress Analysis; D003804:Dentin / Q000187:drug effects* / Q000648:ultrastructure; D003806:Dentin Permeability / Q000187:drug effects; D017220:Dentin-Bonding Agents; D006801:Humans; D006858:Hydrofluoric Acid / Q000009:adverse effects*; D008689:Methacrylates; D008854:Microscopy, Electron; D010756:Phosphoric Acids; D019279:Resin Cements; D013718:Tensile Strength
chemical_list: C112828:Clearfil AP-X; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C469607:OptiBond FL; D010756:Phosphoric Acids; D019279:Resin Cements; C030242:phosphoric acid; D002124:Calcium Fluoride; D006858:Hydrofluoric Acid