title: Degree of conversion and contraction stress development of a resin composite irradiated using halogen and LED at two C-factor levels.
abstract: This study verified the influence of curing methods and light sources on contraction stress, stress rate and degree of conversion (DC) of a restorative composite at two C-factor (CF) levels. For the stress test, composite (0.84 mm thick) was applied between two glass rods 5-mm in diameter mounted in a servohydraulic testing machine. Stress rates were calculated as the change in stress vs time at each second. DC was measured by micro-FTIR. Five curing methods were tested at two C-factor levels (1.5 and 3.0): High Intensity LED (LED HI), Continuous Light (QTH CL), Medium Intensity LED (LED MI), Low Intensity LED (LED LI) and Pulse Delay (QTH PD). The results were analyzed by ANOVA and Tukey's test (alpha = 0.05). For the stress test at CF 1.5, QTH PD presented lower values than LED HI, QTH CL and LED LI. At CF 3.0, no difference was observed among the curing methods. For all curing methods, stress values at CF 3.0 were statistically higher than those at CF 1.5. LED HI presented the highest maximum stress rate, followed by QTH CL, LED MI, LED LI and QTH PD for both C-factors. In the DC test, no difference was observed among the methods and between the C-factor levels.
authors.affiliation: University of Taubate-UNITAU, Department of Dentistry, Prosthodontics Area, Taubate, SP, Brazil. leonardogcunha@yahoo.com
authors.forename: Leonardo Gonçalves
authors.initials: LG
authors.lastname: Cunha
authors.forename: Roberta Caroline Bruschi
authors.initials: RC
authors.lastname: Alonso
authors.forename: Ana Christina Claro
authors.initials: AC
authors.lastname: Neves
authors.forename: Mario Fernando
authors.initials: MF
authors.lastname: de Goes
authors.forename: Jack Liborio
authors.initials: JL
authors.lastname: Ferracane
authors.forename: Mário Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
mesh_terms: D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D055117:Curing Lights, Dental / Q000145:classification; D003764:Dental Materials / Q000737:chemistry / Q000528:radiation effects*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D006801:Humans; D008027:Light; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D011829:Radiation Dosage; D019279:Resin Cements / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D011108:Polymers; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; D012821:Silanes