Thiol-ene-methacrylate composites as dental restorative materials.
OBJECTIVE
The objective of this study was to evaluate composite methacrylate-thiol-ene formulations with varying thiol:ene stoichiometry relative to composite dimethacrylate control formulations. It was hypothesized that the methacrylate-thiol-ene systems would exhibit superior properties relative to the dimethacrylate control resins and that excess thiol relative to ene would further enhance shrinkage and conversion associated properties.


METHODS
Polymerization kinetics and functional group conversions were determined by Fourier transform infrared spectroscopy (FTIR). Volume shrinkage was measured with a linometer and shrinkage stress was measured with a tensometer. Flexural modulus and strength, depth of cure, water sorption and solubility tests were all performed according to ISO 4049.


RESULTS
All of the methacrylate-thiol-ene systems exhibited improvements in methacrylate conversion, flexural strength, shrinkage stress, depth of cure, and water solubility, while maintaining equivalent flexural modulus and water sorption relative to the dimethacrylate control systems. Increasing the thiol to ene stoichiometry resulted in further increased methacrylate functional group conversion and decreased volume shrinkage. Flexural modulus and strength, shrinkage stress, depth of cure, water sorption and solubility did not exhibit statistically significant changes with excess thiol.


CONCLUSIONS
Due to their improved overall functional group conversion and reduced water sorption, the methacrylate-thiol-ene formulations are expected to exhibit improved biocompatibility relative to the dimethacrylate control systems. Improvements in flexural strength and reduced shrinkage stress may be expected to result in composite restorations with superior longevity and performance.
Septodont, Confi-Dental Division, Louisville, CO 80027, United States.
Jordan E
JE
Boulden
Neil B
NB
Cramer
Kathleen M
KM
Schreck
Charles L
CL
Couch
Cora
C
Bracho-Troconis
Jeffrey W
JW
Stansbury
Christopher N
CN
Bowman
D000042:Absorption; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D004987:Ethers / Q000737:chemistry*; D007700:Kinetics; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D018583:Pliability; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D017550:Spectroscopy, Fourier Transform Infrared; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014867:Water
D003188:Composite Resins; D004987:Ethers; D008689:Methacrylates; D013438:Sulfhydryl Compounds; D014867:Water; D011092:Polyethylene Glycols