Frequently Asked Questions

Filtek One Bulk Fill Restorative contains two novel methacrylate monomers that, in combination, act to lower polymerisation stress.

One monomer, a high-molecular-weight aromatic dimethacrylate (AUDMA) decreases the number of reactive groups in the resin. This helpsto moderate the volumetric shrinkage as well as the stiffness of the developing and final polymer matrix—both of which contribute to the development of polymerisation stress.

The second unique methacrylate represents a class of compounds called addition fragmentation monomers (AFM). During polymerisation, AFM reacts into the developing polymer, forming cross-links between adjacent polymer chains. AFM contains a third reactive site that may cleave through a fragmentation process during polymerisation. This process provides a mechanism for the relaxation of the developing network and subsequent stress relief. The fragments still retain the capability to react with each other or with other reactive sites of the developing polymer, making stress relief possible while maintaining the physical properties of the polymer.

Polymerisation shrinkage is simply the decrease in volume of the composite as it shrinks due to the curing process.

Polymerisation stress is a measurement of the impact on the interface of the composite, adhesive and tooth as a result of the composite shrinking upon curing. It is determined via a cusp deflection methodology and is more indicative of the actual clinical placement concerns.

Polymerisation shrinkage stress can contribute to adhesive failure between the tooth and composite, resulting in post-operative sensitivity, marginal leakage and marginal discolouration.

If the bond does not fail, polymerisation stress may cause fracture of the enamel adjacent to the cavosurface, which may contribute to marginal ditching over time. Polymerisation stress may also cause an in-ward deflection of the cusps in Class II restorations.