title: Dynamic mechanical thermal analysis of composite resins with CQ and PPD as photo-initiators photoactivated by QTH and LED units.
abstract: OBJECTIVE
  The aim of this study was to evaluate the thermal and mechanical properties of the composite resins containing the photo-initiators camphorquinone (CQ) and/or phenyl-propanodione (PPD) when photoactivated with halogen lamp (XL2500/3M-ESPE), monowave (UltraBlueIS/DMC) and polywave (UltraLume5/Ultradent) LED units.
  
  
  METHODS
  A blend of BisGMA, UDMA, BisEMA and TEGDMA was prepared with the same wt% of photo-initiators CQ and/or PPD and 65wt% of silaneted filler particles. Compression strength (CS), diametral tensile strength (DTS) and diametral modulus (DM) were tested. Thermogravimetric analysis (TGA) was made and the lost residual monomer were verified. Dynamic mechanical thermal analysis (DMTA) was used for to analyze the glass transition temperature (Tg) and the storage modulus in 37°C. Degree of conversion (DC) was accomplished in the same samples of DMA using middle-infrared spectroscopy (mid-IR).
  
  
  RESULTS
  CQ, CQ/PPD and PPD obtained the same results for all mechanical properties (CS, DTS and DM), lost residual monomer and storage modulus in 37°C, regardless LCU used. The results of Tg showed that the combination PPD-UltraLume5 produced the highest values. DC showed that the combination CQ-UltraLume5 resulted in the highest values and PPD-XL2500 in the lowest DC values.
  
  
  CONCLUSIONS
  The study shows that PPD is not only effective photosensitizers, but also photocrosslinking agents for dental composite resins with a similar efficiency to CQ.
authors.affiliation: School of Dentistry, University of Santo Amaro-UNISA, Prof. Eneas de Siqueira Neto, 340 São Paulo, SP, Brazil. williamcbrandt@yahoo.com.br
authors.forename: William Cunha
authors.initials: WC
authors.lastname: Brandt
authors.forename: Cristina Gomes
authors.initials: CG
authors.lastname: Silva
authors.forename: Elisabete
authors.initials: E
authors.lastname: Frollini
authors.forename: Eduardo Jose Carvalho
authors.initials: EJ
authors.lastname: Souza-Junior
authors.forename: Mário Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
mesh_terms: D002164:Camphor / Q000031:analogs & derivatives* / Q000737:chemistry; D047188:Chalcones / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D006219:Halogens; D008027:Light; D055595:Mechanical Phenomena; D011791:Quartz; D044366:Transition Temperature; D014414:Tungsten
chemical_list: D047188:Chalcones; D003188:Composite Resins; D006219:Halogens; D011791:Quartz; D002164:Camphor; C553149:camphorquinone; D014414:Tungsten; C100349:1-phenyl-1,2-propanedione