title: Influence of surface conditioning on ceramic microstructure and bracket adhesion.
abstract: The objective of this study was to investigate the influence of different conditioning procedures on various ceramic microstructures and bracket adhesion. Ceramic specimens (feldspathic, leucite, leucite-free, and fluorapatite) were mechanically conditioned (n = 20 per ceramic type) with conventional hydrofluoric acid (5 per cent HF; 60/30 seconds), buffered hydrofluoric acid (9.6 per cent BHF; 60/30 seconds), or sandblasting (Al(2)O(3)/SiO(2) particles). Silane coupling agents were added for chemical conditioning before bracket bonding. Bracket adhesion was calculated with a shear test in a universal testing machine. The bracket-composite-ceramic interface was further evaluated using the adhesive remnant index (ARI). One specimen of each ceramic/conditioning combination was subjected to qualitative electron microscopy investigation. One-way analysis of variance followed by Tukey's honestly significant difference test were applied for inferential statistics. Conditioning with conventional 5 per cent HF or sandblasting resulted in significantly (P < 0.001) higher bond strengths (mean values: 34.11 and 32.86 MPa, respectively) than with 9.6 per cent BHF (mean value: 12.49 MPa). Etching time or sandblasting particles had no statistical (P > 0.001) influence on bond strength. Higher ARI scores were found in the conventional 5 per cent HF and sandblasted groups, when compared with the 9.6 per cent BHF group. Microscopic examination of the conditioned ceramic surfaces showed that leucite and leucite-free ceramics differed most with respect to their surface roughness, though without an influence on shear bond strength (SBS; P < 0.001). Bracket adhesion was mostly influenced by the conditioning procedure itself. Sandblasted ceramic surfaces showed sufficient conditioning and bracket adhesion; however, the increased bracket adhesion was associated with a risk of ceramic surface damage.
authors.affiliation: Department of Orthodontics, Bernhard Gottlieb University Dental Clinic, Medical University of Vienna, Austria. frank.falkensammer@meduniwien.ac.at
authors.forename: Frank
authors.initials: F
authors.lastname: Falkensammer
authors.forename: Josef
authors.initials: J
authors.lastname: Freudenthaler
authors.forename: Bernhard
authors.initials: B
authors.lastname: Pseiner
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Bantleon
mesh_terms: D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D045662:Dental Etching / Q000379:methods*; D008854:Microscopy, Electron; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D012821:Silanes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D019279:Resin Cements; D012821:Silanes