title: Resin bonding to root dentin: influence of the alveolar bone level and thickness of the cement layer.
abstract: OBJECTIVE
  Aim of the present study was to evaluate the influence of the alveolar bone level and thickness of the cement layer on the push-out bond strength of fiber posts luted to root dentin.
  
  
  METHODS
  We prepared post spaces in 60 bovine roots (16 mm), embedded in acrylic resin to simulate different scenarios of alveolar bone resorption. They were divided into six groups (N.=10), according to the factors "alveolar bone level" (14, 10, and 7 mm) and "cement thickness" (post no. 3/control and post no. 1/ thicker cement layer): G14P3 - 14-mm root + post n. 3; G10P3 - 10-mm root + post n. 3; G7P3 - 7-mm root + post n. 3; G14P1 - 14-mm root + post n. 1; G10P1 - 10-mm root + post n. 1; and G7P1 - 7-mm root + post n. 1. The fiber posts (White Post DC, FGM) were luted, and composite cores were made. Each specimen was subjected to mechanical cycling, and four slices were obtained from each root specimen and subjected to push-out testing in a universal testing machine. The data (MPa) were analyzed by ANOVA (two way) and Tukey's test (5%).
  
  
  RESULTS
  The factor "cement thickness" (P=0.0057) significantly influenced bond strength, but the factor "alveolar bone level" (P=0.0605) did not. The thicker cement layer/post n. 3 presented bond strength values higher than those with cement layer/post n. 1.
  
  
  CONCLUSIONS
  Bond strength was not influenced by different scenarios of alveolar bone resorption, although higher bond strength values were found for thinner cement layers.
authors.affiliation: Dentistry, Federal University of Rio Grande do Norte (UFRN), Natral/RN, Brazil - rodrigoothavio@gmail.com.
authors.forename: R O
authors.initials: RO
authors.lastname: Souza
authors.forename: M L Lima
authors.initials: ML
authors.lastname: Alves
authors.forename: R Santiago
authors.initials: RS
authors.lastname: De Sousa
authors.forename: A M De Oliveira
authors.initials: AM
authors.lastname: Dal Piva
authors.forename: L D
authors.initials: LD
authors.lastname: Gondim
authors.forename: I Lima Arrais
authors.initials: IL
authors.lastname: Ribeiro
authors.forename: J Magalhães Da Costa
authors.initials: JM
authors.lastname: Lima
mesh_terms: D000539:Alveolar Process / Q000648:ultrastructure*; D000818:Animals; D001862:Bone Resorption; D002417:Cattle; D002484:Cementation; D019232:Dental Restoration Failure; D003804:Dentin / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D011176:Post and Core Technique; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013718:Tensile Strength; D014082:Tooth Fractures / Q000517:prevention & control; D014092:Tooth Root / Q000293:injuries / Q000648:ultrastructure*
chemical_list: D019279:Resin Cements