Cure kinetic behavior of light-cure dental composites

• Objective: To investigate differences in cure kinetic behaviours of different photo and co-initiator systems used in dental light-cure composites. Method: A resin system (50 wt.% of bisGMA and 50 wt.% of TEGDMA) was mixed with either campherquinone (CQ) or 1-phenyl-1,2-propanedione (PPD) as photo-initiator. N,N-dimethyl-p-aminobenzoic acid ethylester (DABE), N,N-cyanoethylmethylaniline (CEMA), N,N-diethanol-p-toluidine (DEPT) and 2-dimethylaminoethyl methacrylate (DMAEMA) were used as co-initiators respectively. Complex cure behaviour of 24 experimental mixtures made from 2 photoinitiators, 4 co-initiators, 3 curing light/time was studied with differential Scanning Calorimetery (DSC). Six specimens of each composition were cured either with 800 mW/cm2 for 40 s, soft start curing for 60 s or LED for 40 s. The DSC results were analysed using ANOVA and Duncan's multiple range test and regular t-test. Result: Rate of polymerisation was significantly (p<0.05) higher when materials were cured with 800 mW/cm2 compare to soft start and LED curing methods when the final degree of conversion values did not differ significantly (p>0.05). Compared to campherquinone, the photo-initiator PPD reduced the maximal DC% and rate of the polymerisation significantly (p<0.05). PPD was not a suitable photo-initiator when cured with LED since the blue spectra emitting from the used LED lamp does not cover the optimal activation wavelength for PPD properly. The highest DC% measured at the end of curing was for CQ & DABE 74%±1 cured with 800 mw/cm2 for 40s and the lowest was for PPD&DMAEMA 22%±1.1 when material was cured with LED for 40s. Use of DEPT resulted in significant decreases in degree of conversion (p<0.05). Conclusion: It was concluded that intrinsic slow cure might be obtained with certain compositions of photo & co-initiators and curing methods without impairing the final extent of degree polymerzation.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Tribologi (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Tribology (hsv//eng)

Keyword

Machine Elements

Maskinelement

Publication and Content Type

vet (subject category)

art (subject category)