title: Effect of Gamma Radiation and Endodontic Treatment on Mechanical Properties of Human and Bovine Root Dentin.
abstract: This study evaluated the effect of gamma radiation and endodontic treatment on the microhardness and flexural strength of human and bovine root dentin. Forty single-rooted human teeth and forty bovine incisor teeth were collected, cleaned and stored in distilled water at 4 °C. The human and bovine teeth were divided into 4 groups (n=10) resulting from the combination of two study factors: first, regarding the endodontic treatment in 2 levels: with or without endodontic treatment; and second, radiotherapy in two levels: with or without radiotherapy by 60 Gy of Co-60 gamma radiation fractioned into 2 Gy daily doses five days per week. Each tooth was longitudinally sectioned in two parts; one-half was used for the three-point bending test and the other for the Knoop hardness test (KHN). Data were analyzed by 3-way ANOVA and Tukey HSD test (α=0.05). No significant difference was found for flexural strength values. The human dentin had significantly higher KHN than the bovine. The endodontic treatment and radiotherapy resulted in significantly lower KHN irrespective of tooth origin. The results indicated that the radiotherapy had deleterious effects on the microhardness of human and bovine dentin and this effect is increased by the interaction with endodontic therapy. The endodontic treatment adds additional negative effect on the mechanical properties of radiated tooth dentin; the restorative protocols should be designed taking into account this effect.
authors.affiliation: Department of Operative Dentistry and Dental Materials, Biomechanics Research Group, Dental School, UFU - Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Veridiana Resende
authors.initials: VR
authors.lastname: Novais
authors.affiliation: Department of Periodontology and Implantology, Biomechanics Research Group, Department of Operative Dentistry and Dental Materials, Dental School, UFU - Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Priscilla Barbosa Ferreira
authors.initials: PB
authors.lastname: Soares
authors.affiliation: Department of Operative Dentistry and Dental Materials, Biomechanics Research Group, Dental School, UFU - Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Carlla Martins
authors.initials: CM
authors.lastname: Guimarães
authors.affiliation: Department of Operative Dentistry and Dental Materials, Biomechanics Research Group, Dental School, UFU - Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Laís Rani Sales Oliveira
authors.initials: LR
authors.lastname: Schliebe
authors.affiliation: Department of Operative Dentistry and Dental Materials, Biomechanics Research Group, Dental School, UFU - Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Stella Sueli Lourenço
authors.initials: SS
authors.lastname: Braga
authors.affiliation: Department of Operative Dentistry and Dental Materials, Biomechanics Research Group, Dental School, UFU - Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Carlos José
authors.initials: CJ
authors.lastname: Soares
mesh_terms: D000818:Animals; D002417:Cattle; D003804:Dentin / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006245:Hardness Tests; D006801:Humans; D066298:In Vitro Techniques; D014092:Tooth Root / Q000528:radiation effects*