Objective: to evaluate the effect of polymerisation time and curing unit-type on the curing quality of a nano-composite.
Materials and methods: A nano-composite (Filtek Supreme, 3M-ESPE) was polymerised for 5s, 10s and 20s by using three commercial available LED-units (Freelight2, 3M-ESPE; Smartlite, Dentsply and Demi, Kerr) and one LED-Prototype (Blue Dwarf, 3M-ESPE). To evaluate the degree of cure (DC), three consecutive increments, each 2-mm high, in a mold 6-mm high and with a diameter of 4-mm, cured by applying the curing unit after each increment at the top of the 6-mm high mold were prepared. Measurements were made in real time with an FTIR-spectrometer with an attenuated total reflectance (ATR) accessory (Nexus, Thermo Nicolet, Madison, USA) for 20 minutes, at the bottom of the 6-mm samples. Profiles of Hardness (HV), Modulus of elasticity (E), Creep (Cr) and elastic/plastic deformation work (We) were additionally measured through the middle of the 6-mm samples (FischerscopeH100C) starting at 0.1 mm under the surface, with 100-µm intervals between the measuring points.
Results: were compared using one and multiple-way ANOVA (general linear model) and Tukey HSD post hoc-test (α =0.05). The effects of the three main parameters — unit (Blue Dwarf, Demi, Freelight, Smartlite), polymerization time (5s, 10s, 20s), and depth are presented below.
Curing conditins | DC[%] | Parameters | Dependent Parameters | Partial Eta-squared |
Demi-5s | 45.8b,c(2.7) | unit | HV | 0.136 |
Demi-10s | 45.8b,c(2.0) | E | 0.181 | |
Demi-20s | 46.9c(2.9) | Cr | 0.069 | |
Bluedworf-5s | 45.5b.c(2.4) | We | 0.060 | |
Bluedworf-10s | 46.7c(2.2) | DC | 0.036 | |
Bluedworf-20s | 47.2c(3.9) | time | HV | 0.120 |
Freelight-5s | 41.1a(3.8) | E | 0.181 | |
Freelight-10s | 44.4a,b,c(2.6) | Cr | 0.090 | |
Freelight-20s | 47.3c(3.0) | We | 0.014 | |
Smartlite-5s | 42.4a,b(6.8) | DC | 0.070 | |
Smartlite-10s | 45.5b,c(3.1) | Depth | HV | 0.125 |
Smartlite-20s | 45.9b,c(2.4) | E | 0.142 | |
| Cr | 0.068 | ||
We | 0.129 | |||