7��4.0%a), selleck chemicals llc MH (70.1��4.9%ab) and MF (68.9��6.7%ab, P<.01). However, GC (67.4��6.8%b) and LD (68.2��6.9%b) presented lower DC than the control. Table 3. Mean and standard deviation of degree of conversion, Knoop microhardness and flexural strength values as a function of curing unit, cement activation mode and restorative material interaction. Columns with same letters indicate absence of statistical ... Knoop microhardness Table 3 shows Knoop microhardness means and standard deviations as a function of curing unit, resin cement activation mode, and restorative material interaction. The triple-order interaction was statistically significant (P<.001). The control groups were not affected by any curing unit/resin cement activation mode combinations.
Dual-cure mode specimens presented higher Knoop microhardness than light-cure for all curing unit/restorative material combinations. In general, hardness values obtained by the dual-cured cement were similar to the control, except for LD-QTH. When the cement was light-cured, none of the restorative material/curing unit combinations reached hardness similar to the control. The curing units did not influence the Knoop microhardness values of the light-cured cement. The Knoop microhardness values for the dual-cured cement were not affected by the curing unit, except for LD (LED>QTH). Flexural strength The statistical analysis for the flexural strength test detected significant differences only for the main factors (P<.001). Table 3 shows the flexural strength means and standard deviations as a function of curing unit, cement activation mode, and restorative material interaction.
When tested in dual-cure mode, the flexural strength mean was higher than in the light-cure mode (199.4��36.5 MPa and 152.9��45.3 MPa, respectively, P<.001). Furthermore, the use of the QTH resulted in higher strength than the LED unit (194.5��45.2 MPa and 164.9��48.4 MPa, respectively, P<.001). Regarding the restorative materials, MH (198.7��33.8 MPaab) allowed a flexural strength similar to the control (215.0��37.5 MPaa). There was no statistical difference between MH and MF (186.7��37.6 MPabc) or between the latter and LD (171.2��42.2 MPac). Specimens photoactivated through GC (126.8��44.0 MPad) showed the lowest flexural strength value for the resin cement (P<.001).
DISCUSSION The first hypothesis Dacomitinib of this study, which stated that the light attenuation caused by the indirect restorative materials impairs the evaluated properties of the resin cement in light-cure mode but not in dual-cure mode, was partially proven. For DC, in spite of the fact that the light-cure mode showed lower values than the dual-cure mode, the interaction between the cement activation mode and the restorative material was not statistically significant. Therefore, it is not possible to affirm that the attenuation caused by the restorative materials was the sole factor responsible for the lower DC of the resin cement in light-cure mode.