Effect of oxygen inhibition on composite repair strength over time.
The study was aimed at examining whether an oxygen inhibition layer is required for bonding a repairing to a pre-existing composite, and to determine the time required for free radicals within a composite substrate to decay to the extent that the composite repair strength drops significantly. Ten slabs of Gradia Direct Anterior (GC Corp.) were divided into (1) control group: an interfacial oxygen inhibition layer was created by applying and light-curing two layers of bonding resin (D/E Resin, Bisco) to the slabs surface in atmospheric air; (2) experimental group: the absence of an interfacial oxygen inhibition layer was obtained by light-curing the second bonding resin layer in a nitrogen atmosphere. After 1 and 2 h, 1, 14, and 30 days of air storage, a composite repair was layered over the bonding resin. Microtensile bond strengths were measured and statistically analyzed. The curing atmosphere was not a significant factor for bond strength (p = 0.82), and time and curing atmosphere-time interaction were significant (p < 0.001). The 30 day-strengths were the lowest (p < 0.05). An oxygen-inhibited layer is not initially required for bonding to resin composite, and it takes more than 14 days before the bond strength between a pre-existing and a fresh composite drops.
Dall'Oca
Susanna
S
Department of Dental Materials, University of Siena, Policlinico Le Scotte, Viale Bracci, Siena 53100, Italy.
Papacchini
Federica
F
Goracci
Cecilia
C
Cury
Alvaro H
AH
Suh
Byoung I
BI
Tay
Franklin R
FR
Polimeni
Antonella
A
Ferrari
Marco
M
D001696:Biomechanical Phenomena; D003188:Composite Resins / Q000737:chemistry; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D009584:Nitrogen; D010100:Oxygen / Q000037:antagonists & inhibitors*; D013718:Tensile Strength; D013997:Time Factors
D003188:Composite Resins; D017220:Dentin-Bonding Agents; C470230:Gradia; D009584:Nitrogen; D010100:Oxygen