Evaluation of the cement layer thickness on the glass fiber posts retention: thin-slice push-out tests and SEM observations

• Grant number: 06/03759-4
• Support Opportunities: Regular Research Grants
• Start date: December 01, 2006
• End date: June 30, 2008
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Gerson Bonfante
• Grantee: Gerson Bonfante
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

The objective of this investigation was to evaluate the influence of the cement layer thickness on the thin-slice push-out resistance of resin cements used for bonding glass fiber posts. The fiber posts will be luted to post spaces using a dual-cured resin cement Duolink (Bisco) or a self-curing resin cement C & B Cement (Bisco). For each cement, the specimens will be randomly assigned to one of three groups (n=5) according to the cement layer thickness. Three drills with different diameters will be used for preparation of the post space in the root canal (Ø1,00 mm; Ø 1,25 mm; Ø 1,50 mm), and fiber posts with the same diameter will be used in all groups (Ø 1,00 mm), resulting in 6 groups: (1) Duolink / Ø 1,00 mm / Ø 1,00 mm (control); (2) Duolink / Ø 1,25 mm / Ø 1,00 mm; (3) Duolink / Ø 1,50 mm / Ø 1,00 mm; (4) C & B Cement / Ø 1,00 mm / Ø 1,00 mm (control); (5) C & B Cement / Ø 1,25 mm / Ø 1,00 mm; (6) C & B Cement / Ø 1,50 mm/ Ø 1,00 mm. The roots containing the fiber post will be transversally cut into five to eight 1-mm thick slices with a water-cooled diamond saw on an Isomet machine. The specimens will be stored for 1 week in physiological saline at 37oC before taking the tests. Duplications of the sections will be obtained for scanning electron microscopy observations (SEM). The measurement of the layer cement thickness and the interfacial gaps will be taken. Thereafter, the specimens will be submitted to the thin-slice push-out test in a universal testing machine. (AU)