Abstract
The aim of the study was to determine the depth of cure of a new nanocomposite when exposed to different curing times and also when different shades were polymerized. The nanocomposite, Filtek Supreme (3M ESPE), was packed into 96 plastic cylindrical moulds measuring 4 mm in internal diameter and 8 mm in length and then polymerized using a conventional quartz-tungsten-halogen light curing unit. The first part of the study involved curing 16 samples each of A2 shade of the nanocomposite at exposure times of 20s, 40s, 60s and 120s. For the second part, a similar number of samples of the dentinal opacity shades of A2, B3 and A4 of the nanocomposite were polymerized at a constant exposure time of 40s. The depth of polymerization of the nanocomposite in each sample was measured using a digimatic indicator. Curing depths were found to increase significantly (P < 0.05) with longer exposure time (20s < 40s < 60s < 120s) and decrease significantly with darker shades (A2 > B3 > A4).
Highlights
Visible light-curing composite resins are one of the most popular dental materials nowadays and they are being extensively used in dentistry for various restorative and preventive procedures
The results showed that it was possible to achieve greater depths of polymerization by increasing the exposure time
The results revealed that the depth of polymerization was reduced in the darker shade nanocomposite
Summary
Visible light-curing composite resins are one of the most popular dental materials nowadays and they are being extensively used in dentistry for various restorative and preventive procedures. Recent developments include the argon-ion laser, plasma arc curing device, high intensity QTH light and blue light-emitting diode which have been demonstrated to reduce the exposure time whilst providing a cure similar to the conventional QTH device[1] Since their introduction, there has been concern about the depth of cure of visible light-activated. The intensity of light decreases greatly as light passes through the bulk of the restorative material; reducing the potential for curing This decrement in cure from the top surface inward is known as ‘limited depth of cure’ and it has certain clinical implications on the physical and biological properties of the restoration. Loss of the restoration may occur [3,4,5]
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