David C Watts1. 1. Biomaterials Research Group, School of Dentistry, The University of Manchester, Manchester M15 6FH, UK. david.watts@man.ac.uk
Abstract
OBJECTIVES: The aim of this paper is to address the relationship, existing in photo-cure composites, between the polymer-network forming reactions, along with their kinetics, and the resultant stress-transmitting micro-mechanical behavior. METHODS: Photon numbers and energies were calculated and compared for a simple model monomer-composite system. Expressions for light irradiance at depth within materials were computed and the consequences of steady-state assumptions in kinetic models of conversion and shrinkage-strain rate were considered. RESULTS: The resultant stress-transmitting properties are a complex function of photon-transport, absorption by photo-initiators, possibly non-steady-state free-radical cross-linking, collapse of free-volume and development of an elastic-network displaying non-homogenous structure, viscoelasticity and aging effects. SIGNIFICANCE: Researchers need to be aware of the complexity of these systems, so as to adequately control experimental variables and to develop more sophisticated models and hypotheses for experimental validation.
OBJECTIVES: The aim of this paper is to address the relationship, existing in photo-cure composites, between the polymer-network forming reactions, along with their kinetics, and the resultant stress-transmitting micro-mechanical behavior. METHODS: Photon numbers and energies were calculated and compared for a simple model monomer-composite system. Expressions for light irradiance at depth within materials were computed and the consequences of steady-state assumptions in kinetic models of conversion and shrinkage-strain rate were considered. RESULTS: The resultant stress-transmitting properties are a complex function of photon-transport, absorption by photo-initiators, possibly non-steady-state free-radical cross-linking, collapse of free-volume and development of an elastic-network displaying non-homogenous structure, viscoelasticity and aging effects. SIGNIFICANCE: Researchers need to be aware of the complexity of these systems, so as to adequately control experimental variables and to develop more sophisticated models and hypotheses for experimental validation.
Authors: William Cunha Brandt; Lais Regiane Silva-Concilio; Ana Christina Claro Neves; Eduardo Jose Carvalho de Souza-Junior; Mario Alexandre Coelho Sinhoreti Journal: Lasers Med Sci Date: 2012-09-13 Impact factor: 3.161