title: Fiber-matrix integrity, micromorphology and flexural strength of glass fiber posts: Evaluation of the impact of rotary instruments.
abstract: Several rotary instruments have been daily employed on clinic to promote cut aiming to adjust the length of fiber posts to the radicular conduct, but there is no information on the literature about the effects of the different rotary instruments and its impact on the micromorphology of surface and mechanical properties of the glass fiber post. This study aimed the impact of rotary instruments upon fiber-matrix integrity, micromorphology and flexural-strength of glass-fiber posts (GFP). GFP (N=110) were divided into 5 groups: Ctrl: as-received posts, DBc: coarse diamond-bur, DBff: extra-fine diamond-bur, CB: carbide-bur, DD: diamond-disc. Cutting procedures were performed under abundant irrigation. Posts exposed to rotary instruments were then subjected to 2-point inclined loading test (compression 45°) (n=10/group) and 3-point flexural-strength test (n=10/group). Fiber-matrix integrity and micromorphology at the cut surface were analyzed using a SEM (n=2/group). Cutting procedures did not significantly affect the 2-point (51.7±4.3-56.7±5.1 MPa) (p=0.0233) and 3-point flexural-strength (671.5±35.3-709.1±33.1 MPa) (p=0.0968) of the posts (One-way ANOVA and Tukey׳s test). Fiber detachment was observed only at the end point of the cut at the margins of the post. Cut surfaces of the CB group were smoother than those of the other groups. After 3-point flexural strength test, fiber-matrix separation was evident at the tensile side of the post. Rotary instruments tested with simultaneous water-cooling did not affect the resistance of the tested fiber posts but caused disintegration of the fibers from the matrix at the end of the cut, located at the margins.
authors.affiliation: PhD-MSci, Graduate Program in Oral Science, Prosthetic Dentistry Unit, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil.
authors.forename: Gabriel Kalil Rocha
authors.initials: GKR
authors.lastname: Pereira
authors.affiliation: Faculty of Odontology, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil.
authors.forename: Mateus
authors.initials: M
authors.lastname: Lançanova
authors.affiliation: PhD-MSci, Graduate Program in Oral Science, Prosthetic Dentistry Unit, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil.
authors.forename: Vinicius Felipe
authors.initials: VF
authors.lastname: Wandscher
authors.affiliation: PhD-MSci, Graduate Program in Oral Science, Prosthetic Dentistry Unit, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil.
authors.forename: Osvaldo Bazzan
authors.initials: OB
authors.lastname: Kaizer
authors.affiliation: Department of Mechanical Engineering, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil.
authors.forename: Inácio
authors.initials: I
authors.lastname: Limberger
authors.affiliation: Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, University of Zürich, Plattenstrasse 11, CH-8032 Zürich, Switzerland.
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
authors.affiliation: PhD-MSci, Graduate Program in Oral Science, Prosthetic Dentistry Unit, Federal University of Santa Maria - UFSM, Santa Maria, RS, Brazil. Electronic address: lfvalandro@hotmail.com.
authors.forename: Luiz Felipe
authors.initials: LF
authors.lastname: Valandro
mesh_terms: D019245:Compressive Strength / Q000502:physiology*; D015921:Dental Implants; D017267:Dental Prosthesis Design / Q000295:instrumentation*; D003799:Dental Stress Analysis; D004548:Elasticity; D005898:Glass / Q000737:chemistry*; D008422:Materials Testing; D013499:Surface Properties
chemical_list: D015921:Dental Implants; C009753:fiberglass
keywords: Fiber post; Flexural strength; Micromorphology; Root post; Rotary instruments