Polymerization Stress of Dental Resin Composite Continues to Develop 12 Hours after Irradiation

Abstract

Since the elastic modulus is a measure of stiffness and resistance to load, clinicians might consider advising their patients to avoid heavy occlusal function until the elastic modulus has reached a plateau, which would be 60 minutes for Venus Diamond, 12 hours for Kalore, and 24 hours for Revolution Formula 2.

Changes in polymerization stress and elastic modulus of bulk-fill resin composites for 24 hours after irradiation

“…The disks had an inner and outer diameter of 3.0 and 12.0 mm, respectively, and were 2.0 mm thick. The elastic modulus (E) and fracture toughness (K c) of the glass were 70 GPa and 0.63 MPa-m 0.5 , respectively 13) . The toughness was measured in a preliminary study by the indentation method (9.8-N load for 15 s) and using the following equation 10) :…”

“…Filtek and Venus generated similar magnitudes of stresses, but were significantly higher than the stresses in SDR at p<0.01. Formula 2, Kerr, Orange, CA, USA) is also drawn in the graph, which was obtained by the same crack analysis used in our previous study 13) .…”

“…This analysis is very sensitive to small changes in stress and can reveal the changes in stress on the same specimen. Using this analysis, Yamamoto et al 13) recorded the increases in polymerization stress of lowshrinkage dental resin composites filled in soda-lime glass cavity up to 12 h after irradiation.…”

“…The elastic modulus, which is an indicator of stiffness, is one of the dominant factors determining the polymerization stress 2) , and significant relationships between the modulus and stress have been reported by numerous researchers [13][14][15][16] . Some flowable and packable resin composites have reportedly demonstrated increasing of the elastic modulus for longer than 12 h after irradiation due to post-irradiation polymerization 13,17) . If bulk-fill resin composites exhibit similar behavior in stiffness, the polymerization stress may develop for several hours after irradiation.…”

Polymerization stress – Is it clinically meaningful?

“…Thus, these stresses are transferred to the bonded interfaces with the tooth structure creating delamination or tooth fracture whenever and wherever the localized stress exceeds the adhesion strength or the strength of the adjacent residual tooth structure [32][33][34]. Furthermore, these stresses may increase with time, causing delayed damage to cavity margins [35].…”