Wytrzymałość połączenia żywicy kompozytowej z MTA w różnych przedziałach czasowych i po odmiennym sposobie użycia systemu wiążącego

Abstract

Background. MTA cannot be used as a single restorative material due to poor esthetics and mechanical properties. Resin-based composite is often placed on top of MTA. Optimal time of doing that and the most effective bonding strategy have not been clearly determined.Objectives. The aim of the study was to evaluate the bond strength of a composite to MTA at various time intervals and with different adhesive strategies.Material and Methods. Composite material was bonded to MTA after different time intervals: directly after the placement of MTA (group I), after 24 h (group II), after 72 h (group III). Each group was divided into 2 subgroups (n = 15) in which a universal bonding system was used respectively: in subgroups A as a total-etch adhesive (TE), in subgroups B as a self-etch (SE). The specimens were subjected to shear bond strength test in a universal testing machine.Results. Statistically significant differences were observed at all time intervals for both bonding protocols TE/SE. In all groups shear bond strength values were higher when the bonding agent was used as a TE vs SE (statistically significant differences in groups I and III). Group II demonstrated the highest bond strength (TE 6.89 MPa; SE 3.82 MPa), followed by group III (TE 5.19 MPa; SE 2.74 MPa) and group I (TE 1.52 MPa; SE 0.74 MPa) where the bond strength was the lowest.Conclusion. The shear bond strength of composite to MTA depends on both – time interval between MTA placement and the application of an adhesive system and on the bonding strategy. The highest bond strength was obtained when the adhesive was used after 24 h in a total-etch technique.