title: Degree of conversion and permeability of dental adhesives.
abstract: The aim of this study was to analyse the extent of polymerization of different adhesive films in relation to their permeability. One adhesive of each class was investigated: OptiBond FL; One-Step; Clearfil Protect Bond; and Xeno III. Adhesive films were prepared and cured with XL-2500 (3M ESPE) for 20, 40 or 60 s. Polymerization kinetic curves of the adhesives tested were obtained with differential scanning calorimetry (DSC) and data were correlated with microhardness. The permeability of the adhesives under the same experimental conditions was evaluated on human extracted teeth connected to a permeability device and analysed statistically. The results showed that the extent of polymerization obtained from DSC exotherms was directly correlated with microhardness. An increased level of polymerization after prolonged light-curing was confirmed for all adhesives. Simplified adhesives exhibited a lower extent of polymerization and showed incomplete polymerization, even after 60 s. An inverse correlation was found between the degree of cure and the permeability. This study supports the hypothesis that the permeability of simplified adhesives is correlated with incomplete polymerization of resin monomers and the extent of light exposure. These adhesives may be rendered less permeable by using longer curing times than those recommended by the respective manufacturer.
authors.affiliation: Department of Dental Sciences, Biomaterials and Bioimplants, University of Trieste, Trieste, Italy.
authors.forename: Milena
authors.initials: M
authors.lastname: Cadenaro
authors.forename: Francesca
authors.initials: F
authors.lastname: Antoniolli
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sauro
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Lenarda
authors.forename: Carlo
authors.initials: C
authors.lastname: Prati
authors.forename: Matteo
authors.initials: M
authors.lastname: Biasotto
authors.forename: Luca
authors.initials: L
authors.lastname: Contardo
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
mesh_terms: D000269:Adhesives / Q000737:chemistry* / Q000528:radiation effects; D000328:Adult; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry* / Q000145:classification / Q000528:radiation effects; D001840:Dental Bonding / Q000379:methods*; D003763:Dental Leakage / Q000517:prevention & control*; D006801:Humans; D066298:In Vitro Techniques; D008027:Light; D008422:Materials Testing; D008875:Middle Aged; D008964:Molar, Third; D010539:Permeability / Q000528:radiation effects; D019279:Resin Cements / Q000737:chemistry* / Q000145:classification / Q000528:radiation effects; D018709:Statistics, Nonparametric
chemical_list: D000269:Adhesives; D003188:Composite Resins; D019279:Resin Cements