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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Can phenyl-propanedione influence Knoop hardness, rate of polymerization and bond strength of resin composite restorations?

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Author(s):
Brandt, William Cunha [1] ; Tomaselli, Lucas de Oliveira [2] ; Correr-Sobrinho, Lourenco [2] ; Coelho Sinhoreti, Mario Alexandre [2]
Total Authors: 4
Affiliation:
[1] Univ Taubate, UNITAU, Sch Dent, Dept Prosthodont, BR-12020330 Taubate, SP - Brazil
[2] Univ Estadual Campinas, Dept Restorat Dent, Dent Mat Div, Piracicaba Dent Sch, BR-13414903 Piracicaba, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Journal of Dentistry; v. 39, n. 6, p. 438-447, JUN 2011.
Web of Science Citations: 11
Abstract

Objectives: The aim of this study was to evaluate the degree of conversion (DC), rate of polymerization (R(p)(max)), Knoop hardness (KHN) and bond strength between tooth/restoration of composite resins containing different photo-initiators photo-activated by different light-curing units (LCUs). Materials and methods: A mixture of BisGMA, UDMA, BisEMA and TEGDMA was prepared along with the following photo-initiators: camphorquinone (CQ), phenyl-propanedione (PPD) or the association (CQ/PPD) and 65 wt% of silanated filler particles. The LCUs included a halogen lamp XL 2500 and two LEDs: UltraBlueIS and UltraLume5. The conversion profiles during photo-polymerization were investigated using middle-infrared spectroscopy (mid-IR). Bond strength was evaluated using push-out test in ninety teeth with prepared cavities. Before the push-out test, Knoop hardness (KH) was verified in the top and at the base of the restorations. Results: PPD obtained lower R(p)(max) values, regardless of the LCU used. It also provided a greater bond strength than CQ when the LEDs LCUs were used. The degree of conversion after 40 s of irradiation was the same for all composite resins, except PPD photo-activated for XL 2500, which showed lower DC values than CQ and CQ/PPD. In the top and at the base of the restorations, PPD showed the lowest KH values when photo-activated with XL 2500. XL 2500 produced higher KH values than UltraBlueIS when used with CQ or CQ/PPD photo-initiators. Conclusion: Because it increased the bond strength without compromising the properties of composite resins when photo-activated by an LED, PPD can be used as an alternative photo-initiator. (C) 2011 Elsevier Ltd. All rights reserved. (AU)