The effects of light curing units (LCU) and energy doses on the chemical and physical properties of a dental composite were investigated.
Methods
The effects on the chemical and physical properties of a bisphenol A diglycidylether methacrylate (Bis-GMA) based dental restorative material were evaluated through photospectrometry, differential scanning calorimetry, and mechanical measurements.
Results
The light curing conditions associated with direct and indirect restorations were replicated in vitro using optical investigation techniques. A slight attenuation resulted independently of the LCU and a strong attenuation was measured for the cement luting a thick inlay, as well as for the deepest layer of a composite filling increment. Calorimetric measurements indicated that the curing degree is very sensitive to the light energy dose rather than to the LCU. Mechanical testing showed a transient phase during which properties increased. The delay of the composite in reaching adequate properties is strongly dependent on the energy dose.
Conclusions
It is recommended that composites subject to unfavorable light curing conditions undergo a prolonged light curing process.
De SantisR., SarracinoF., MollicaF., NettiP.A., AmbrosioL., NicolaisL.Continuous fibre reinforced polymers as connective tissue replacement. Comp Sci Tech2004; 64: 861–71.
2.
IkedaT., SidhuS.K., OmataY., FujitaM., SanoH.Colour and translucency of opaque-shades and body-shades of resin composites. Eur J Oral Sci2005; 113: 170–3.
van DijkenJ.W.V., Direct resin composite inlays/onlays: an 11 year follow-up. J Dent2000; 28299–306.
9.
BottB., HannigM.Effect of different luting materials on the marginal adaptation of Class I ceramic inlay restorations in vitro. Dent Mater2003; 19: 264–9.
10.
StrubJ.R., PontiusO., KoutayasS.Survival rate and fracture strength of incisors restored with different post and core systems after exposure in the artificial mouth. J Oral Rehab2001; 28: 120–4.
11.
PriscoD., De SantisR., MollicaF., AmbrosioL., RengoS., NicolaisL.Fiber post adhesion to resin luting cements in the restoration of endodontically-treated teeth. Oper Dent2003; 28: 515–21.
12.
Truffier-BoutryD., GallezX.A., Demoustier-ChampagneS.. Identification of free radicals trapped in solid methacrylated resins. J Polym Sci Part A-Polym Chem2003; 41: 1691–9.
PavlinecJ., MosznerN.Dark reactions of free radicals crosslinked polymer networks trapped in densely after photopolymerization. J App Polym Sci2003; 89: 579–88.
15.
FerracaneJ.L., GreenerE.H.The effect of resin formulation on the degree of conversion and mechanical properties of dental restorative resins. J Biomed Mater Res1986; 20: 121–31.
DebS., SehmiH.A comparative study of the properties of dental resin composites polymerized with plasma and halogen light. Dent Mater2003; 19: 517–22.
18.
SpagnuoloG., GallerK., SchmalzG., CosentinoC., RengoS., SchweiklH.Inhibition of phosphatidylinositol 3-kinase amplifies TEGDMA-induced apoptosis in primary human pulp cells. J Dent Res2004; 83: 703–7.
19.
TheiligC., TegtmeierY., LeyhausenG., GeurtsenW.Effects of BisGMA and TEGDMA on proliferation, migration, and tenascin expression of human fibroblasts and keratinocytes. J Biomed Mater Res2000; 53: 632–9.
20.
NodaM., WatahaJ.C., LockwoodP.E., VolkmannK.R., KagaM., SanoH.Sublethal, 2-week exposures of dental material components alter TNF-alpha secretion of THP-1 monocytes. Dent Mater2003; 19: 101–5.
21.
LovellL.G., BerchtoldK.A., ElliottJ.E., LuH., BowmanC.N.Understanding the kinetics and network formation of dimethacrylate dental resins. Polym Adv Tech2001; 12: 335–45.
22.
JakubiakJ., NieJ., LindenL.A., RabekJ.F.Crosslinking photocopolymerization of acrylic acid (and N-vinylpyrrolidone) with triethyleneglycol dimethacrylate initiated by camphorquinone/ethyl-4-dimethylaminobenzoate. J Polym Sci Part A-Polym Chem2000; 38: 876–86.
23.
PavlinecJ., MosznerN.Dark reactions of free radicals crosslinked polymer networks trapped in densely after photopolymerization. J App Polym Sci2003; 89: 579–88.
24.
ShimuraR., NikaidoT., YamautiM., IkedaM., TagamiJ.Influence of curing method and storage condition on microhardness of dual-cure resin cements. Dent Mater J2005; 24: 70–5.
25.
LeeJ.K., ChoiJ.Y., LimB.S., LeeY.K., SakaguchiR.L.Change of properties during storage of a UDMA/TEGDMA dental resin. J Biomed Mater Res Part B: App Biomater2004; 68B: 216–21.
26.
De SantisR., MollicaF., AmbrosioL., NicolaisL., RoncaD.Dynamic mechanical behavior of PMMA based bone cements in wet environment. J Mater Sci: Mater in Med2003; 14: 583–94.
27.
TanoueN., AtsutaM., KitazawaS., KoizumiH., MatsumuraH.A new laboratory polymerizing apparatus equipped with halogen and metal halide light sources. Dent Mater J2005; 24: 43–8.
28.
DunnW.J., BushA.C.A comparison of polymerization by light-emitting diode and halogen-based light-curing units. J Am Dent Ass2002; 133: 335–41.
29.
VenhovenB.A., De GeeA.J., DavidsonC.L.Light initiation of dental resins: dynamics of the polymerization. Biomater1996; 17: 2313–8.
30.
PriceR.B.T., FelixC.A., AndreouP.Effects of resin composite composition and irradiation distance on the performance of curing lights. Biomater2004; 25: 4465–77.
31.
KimJ.W., JangK.T., LeeS.H., KimC.C., HahnS.H., Garcìa-GodoyF.Effect of curing method and curing time on the microhardness and wear of pit and fissure sealants. Dent Mater2002; 18: 120–7.
MaffezzoliA., Della PietraA., RengoS., NicolaisL., VallettaG.Photopolymerization of dental composite matrices. Biomater1994; 15: 1221–8.
34.
BorzacchielloA., AmbrosioL., NicolaisL., HarperE.J., TannerK.E., BonfieldW.Isothermal and non-isothermal polymerization of a new bone cement. J Mater Sci: Mater in Med1998; 9: 317–24.
35.
SohM.S., YapA.U.J.Influence of curing modes on crosslink density in polymer structures. J Dent2004; 32: 321–6.
36.
MicelliF., MaffezzoliA., TerziR., LupranoV.A.Characterization of the kinetic behavior of resin modified glass-ionomer cements by DSC, TMA and ultrasonic wave propagation. J Mater Sci: Mater in Med2001; 12: 151–6.
37.
ImazatoS., McCabeJ.F., TarumiH., EharaA., EbisuS.Degree of conversion of composites measured by DTA and FTIR. Dent Mater2001; 17: 178–83.
38.
FerrettiA.M., CostanteG., PontiA.Conformational disorder in the propagating radical of dimethacrylate polymers. Res Chem Interm2002; 28: 159–74.
39.
SakaguchiR.L., BergeH.X.Reduced light energy density decreases post-gel contraction while maintaining degree of conversion in composites. J Dent1998; 26: 695–700.
40.
HofmannN., RennerJ., HugoB., KlaiberB.Elution of leachable components from resin composites after plasma arc vs. standard or soft-start halogen light irradiation. J Dent2002; 30: 223–32.
ChungS.M., YapA.U.J., TsaiK.T., YapF.L.Elastic modulus of resin-based dental restorative materials: A microindentation approach. J Biomed Mater Res Part B-App Biomater2005; 72B: 246–53.
43.
VersluisA., TantbirojnD., DouglasW.H.Distribution of transient properties during polymerization of a light-initiated restorative composite. Dent Mater2004; 20: 543–53.
