title: Pulpal heat changes with newly developed resin photopolymerisation systems.
abstract: Composite resin is a widely-used direct tooth coloured restorative material. Photoactivation of the polymerisation reaction can be achieved by visible blue light from a range of light sources, including halogen lamps, metal halide lamps, plasma arc lamps, and Light Emitting Diode (LED) lights. Concerns have been raised that curing lights may induce a temperature rise that could be detrimental to the vitality of the dental pulp during the act of photoactivation. The present study examined heat changes associated with standardised class V restorations on the buccal surface of extracted premolar teeth, using a curing time of 40 seconds. The independent effects of type of light source, resin shade, and remaining tooth thickness were assessed using a matrix experimental design. When a conventional halogen lamp, a metal halide lamp and two different LED lights were compared, it was found that both LED lamps elicited minimal thermal changes at the level of the dental pulp, whereas the halogen lamp induced greater changes, and the metal halide lamp caused the greatest thermal insult of all the light sources. These thermal changes were influenced by resin shade, with different patterns for LED versus halogen or halide sources. Thermal stress reduced as the remaining thickness of tooth structure between the pulp and the cavity floor increased. From these results, it is concluded that LED lights produce the least thermal insult during photopolymerisation of composite resins.
authors.affiliation: School of Dentistry, University of Queensland, 200 Turbot Street, Brisbane, Queensland, 4000.
authors.forename: A T
authors.initials: AT
authors.lastname: Weerakoon
authors.forename: I A
authors.initials: IA
authors.lastname: Meyers
authors.forename: A L
authors.initials: AL
authors.lastname: Symons
authors.forename: L J
authors.initials: LJ
authors.lastname: Walsh
mesh_terms: D000134:Acid Etching, Dental; D000704:Analysis of Variance; D001641:Bicuspid; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001831:Body Temperature / Q000502:physiology*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000145:classification; D003782:Dental Pulp / Q000503:physiopathology* / Q000648:ultrastructure; D003793:Dental Restoration, Permanent; D003804:Dentin / Q000503:physiopathology / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004867:Equipment Design; D006801:Humans; D008029:Lighting / Q000295:instrumentation; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013814:Thermal Conductivity; D013821:Thermometers; D013997:Time Factors
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D011108:Polymers; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate