title: The effect of pre-warming and delayed irradiation on marginal integrity of a resin-modified glass-ionomer.
abstract: Recent studies have indicated that the acid-base reactions and polymerization of resin-modified glass-ionomers (RMGIs) compete with and inhibit each other; however, external energy can also influence the properties of RMGIs. This in vitro study evaluated the effect of pre-warming and/or delayed light irradiation on marginal integrity of RMGIs in cervical restorations. Standard Class V cavities were prepared on the buccal aspects of 60 human maxillary premolars. Each cavity was treated with a cavity conditioner for 10 seconds, rinsed, and gently air-dried. An RMGI was applied to the prepared cavities as dictated by the study protocol. Group 1 samples were treated per manufacturers' instructions. Group 2 samples were photocured after a delay of 2 minutes. For samples in Group 3, the encapsulated material was pre-warmed (at 40° C) for 90 seconds; for Group 4 samples, capsules were pre-warmed and photocuring was delayed for 2.4 minutes. Microleakage scores were determined using dye penetration technique; Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis (α  = 0.05).  The enamel groups exhibited statistically significant differences (P = 0.036), while the dentin groups did not (P = 0.122); however, in both cases, Group 2 demonstrated the highest marginal integrity. Based on the results of this study, pre-warming could jeopardize the marginal integrity of RMGIs in cervical restorations, while delaying the curing process might improve it (particularly for enamel).
authors.affiliation: Dental Materials Research Center, Department of Operative Dentistry, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Khoroushi
authors.forename: Tayebeh
authors.initials: T
authors.lastname: Mansoori-Karvandi
authors.forename: Saeed
authors.initials: S
authors.lastname: Hadi
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D001641:Bicuspid / Q000033:anatomy & histology; D004396:Coloring Agents; D003737:Dental Cavity Preparation / Q000145:classification; D003743:Dental Enamel / Q000033:anatomy & histology; D003763:Dental Leakage / Q000145:classification; D018772:Dental Marginal Adaptation; D003804:Dentin / Q000033:anatomy & histology; D005899:Glass Ionomer Cements / Q000737:chemistry* / Q000528:radiation effects; D006358:Hot Temperature; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D058105:Polymerization; D019279:Resin Cements / Q000737:chemistry* / Q000528:radiation effects; D012117:Resins, Synthetic / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D019237:Tooth Cervix / Q000033:anatomy & histology
chemical_list: D000180:Acrylic Resins; D004396:Coloring Agents; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D019279:Resin Cements; D012117:Resins, Synthetic; C006903:carbopol 940