ABSTRACT
Objective: To evaluate the degree of conversion [DC] and depth [extent] of cure of four resin cements [Variolink E, Calibra, NX3 and Variolink N] using Fourier transform infrared [FTIR] and Vickers Micro hardness [MH]
Methods: Ten disks [1mmx2mm] of each resin cement were light cured through a ceramic disk for 40 seconds prior to assessment. The ATR spectra of the uncured resin were collected in absorbance mode from 16 scans at 4 wave number resolutions. Degree of conversion was calculated by estimating the changes in peak height ratio of the absorbance intensities of aliphatic C=C peak at 1638 cm-1 and that of an internal standard peak of aromatic C=C at 1608 cm-1 during polymerization. For Vickers microhardness testing 10 disks of each cement specimen was exposed to 100 grams of load for 15 seconds. Three indentations were made 0.5mm apart and an average Vickers micro-hardness [MH] for each specimen. Two way ANOVA and multiple comparison tests were performed to assess data
Results: The highest degree of conversion by peak area was shown by Variolink-Esthetic [light-cure [87.18+/-2.90%]]; however the lowest was observed in samples of Variolink-N [Dual cure [44.55+/-4.33%]]. Similarly, Variolink-Esthetic and NX3 cement showed significantly higher MH as compared to other groups
Conclusion: Ivocerin containing Variolink-E cement showed high degree of conversion and extent of polymerization when compared to conventional light and dual cure luting cements
ABSTRACT
Objectives: To assess compressive strength and effect of duration after photoactivation on the compressive strength of different dual cure bulk fill composites
Methods:Seventy-two disc shaped [4x10mm] specimens were prepared from three dual cure bulk fill materials, ZirconCore [ZC] [n=24], MulticCore Flow [MC] [n=24] and Luxacore Dual [LC] [n=24]. Half of the specimens in each material were tested for failure loads after one hour [MC1 [n=12], LC1 [n=12] and ZC1 [n=12]] and the other half in 7 days [MC7 [n=12], LC7 [n=12], ZC7 [n=12]] from photo-polymerization using the universal testing machine at a cross-head speed of 0.5 cm/minutes. Compressive strength was calculated using the formula UCS=4f/[Pi]d[2]. Compressive strengths among different groups were compared using analysis of variance [ANOVA] and Tukey's multiple comparisons test
Results:Maximum and minimum compressive strengths were observed in ZC7 [344.14+/-19.22] and LC1 [202.80+/-15.52] groups. Specimens in LC1 [202.80 [15.52]] showed significantly lower compressive strength as compared to MC1 [287.06 [15.03]] [p<0.01] and ZC1 [276.82 [11.51]] [p<0.01]. ZC7 [344.14 [19.22]] specimens showed significantly higher [p<0.01] compressive strengths compared to LC7 [324.56 [19.47]] and MC7 [315.26 [12.36]]. Compressive strengths among all three materials were significantly higher [p<0.01] at 7 days as compared to one hour
Conclusions:Bulk fill material with Zr nano-hybrid filler [ZC] showed high compressive strength compared to MC and LC. Increasing the post photo-activation duration [from one hour to 7 days] significantly improves the compressive strengths of dual cure bulk fill material