title: Hybrid layer thickness and resin tag length of a self-etching adhesive bonded to sound dentin.
abstract: OBJECTIVE
  the purpose of this study is to employ optical microscopy to measure the thickness of the hybrid layer and the penetration (tags) of an aggressive self-etching adhesive system into sound dentin.
  
  
  METHODS
  occlusal cavities were prepared in 40 extracted human posterior teeth. The prepared teeth were randomly assigned to four experimental groups with 10 specimens each. The self-etching adhesive system Adper Prompt L-Pop was applied to the dentin surface as follows: Group 1: cavosurface enamel was etched for 60 s and dentin for 20 s with 35% phosphoric acid gel, immediately followed by application of the self-etching adhesive with a brush to the entire cavity for 15 s; Groups 2, 3, and 4: no pre-etching was performed, and the self-etching adhesive was applied to both enamel and dentin for 15, 30 and 45 s, respectively. After curing, the cavities were filled with composite resin Filtek Z250. Afterwards, the teeth were decalcified and the restorations were carefully removed for later embedding in paraffin. The specimens were serially sectioned at 6 microm of thickness and sequentially mounted in glass slides. These sections were stained with Brown and Brenn staining for posterior analysis and measurement of the hybrid layer and resin tags on a light microscope with a micrometric ocular 40/075. The results were submitted to analysis of variance at the 5% level.
  
  
  RESULTS
  whenever there was significance, the Tukey test was applied at the 5% level. The specimens receiving application of acid etching before the self-etching adhesive displayed a larger thickness of the hybrid layer; on the other hand, specimens receiving only application of the self-etching adhesive on dentin for 15, 30 and 45 s exhibited similar thickness of the hybrid layer. As regards the resin tags, no statistically significant differences could be found between the study groups.
  
  
  CONCLUSIONS
  it could be concluded that the increase in the time of application of the self-etching adhesive Adper Prompt L-Pop did not significantly influence the formation and thickness of hybrid layer, as well as its penetration into the sound dentin surface.
authors.affiliation: Discipline of Restorative Dentistry, Araçatuba Dental School, UNESP, Brazil, Rua José Bonifácio 1193, CEP 16015-050 Araçatuba, São Paulo, Brazil. sundfeld@terra.com.br
authors.forename: Renato Herman
authors.initials: RH
authors.lastname: Sundfeld
authors.forename: Thiago Assunção
authors.initials: TA
authors.lastname: Valentino
authors.forename: Rodrigo Sversut
authors.initials: RS
authors.lastname: de Alexandre
authors.forename: André Luiz Fraga
authors.initials: AL
authors.lastname: Briso
authors.forename: Maria Lúcia Marçal Mazza
authors.initials: ML
authors.lastname: Sundefeld
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000293:Adolescent; D000328:Adult; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003737:Dental Cavity Preparation; D003743:Dental Enamel / Q000648:ultrastructure; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008853:Microscopy; D016612:Paraffin Embedding; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors
chemical_list: D004396:Coloring Agents; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D010756:Phosphoric Acids; C408584:Prompt L-Pop; D019279:Resin Cements