Depth of light-initiated polymerization of glass fiber-reinforced composite in a simulated root canal.
OBJECTIVE
The possibility of polymerizing glass fiber-reinforced composite (FRC) material into the root canal was preliminarily evaluated by determining the depth of light-initiated polymerization of FRC.


METHODS
The material used was polymer-preimpregnated E-glass fiber reinforcement, which was further impregnated with light-polymerizable dimethacrylate monomer resin. The same resin without fiber reinforcement was used as a control. Six different lengths (range 4 to 24 mm) of light-protected cylinders filled with the test materials were light polymerized from one end. The degree of monomer conversion was determined from the other end by FT-IR spectrometry. Infrared spectra were recorded at six time points from the beginning of polymerization. The microhardness of the test materials was measured from the light-exposure surface toward the other end of the cylinder.


RESULTS
Both groups showed a reduction in the degree of conversion with increased lengths of the cylinder. The FRC group showed a higher degree of conversion in the longest sample group compared to the resin group. Microhardness measurement confirmed the constant reduction of the degree of conversion by the reduced Vickers hardness values with increased cylinder length of the FRC.


CONCLUSIONS
Generally, the glass FRC showed an almost equal degree of conversion after light curing as monomer resin without fibers. However, in the longest cylinders, FRC showed a slightly higher degree of conversion compared to resin only; this might be due to the fibers' ability to conduct light.
Le Bell
Anna-Maria
AM
Department of Prosthetic Dentistry and Biomaterials Research, Institute of Dentistry, University of Turku, Finland. ami.lebell@utu.fi
Tanner
Johanna
J
Lassila
Lippo V J
LV
Kangasniemi
Ilkka
I
Vallittu
Pekka K
PK
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D005898:Glass / Q000737:chemistry / Q000528:radiation effects*; D006244:Hardness; D006801:Humans; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry / Q000528:radiation effects; D011092:Polyethylene Glycols / Q000737:chemistry / Q000528:radiation effects; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D011109:Polymethacrylic Acids / Q000737:chemistry / Q000528:radiation effects; D019904:Polymethyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013997:Time Factors
D003188:Composite Resins; D008689:Methacrylates; D011108:Polymers; D011109:Polymethacrylic Acids; C009753:fiberglass; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D019904:Polymethyl Methacrylate