Ambient light working times of visible light-cured restorative materials. Does the ISO standard reflect clinical reality?

D. Andrew Lane, David C. Watts, Nairn H F Wilson

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Objectives. The aim of this study was to determine whether a custom-built light box could reliably reproduce clinical conditions and whether the current ISO standard test for the working time of visible light cured (VLC) materials (ISO. Dental Resin-based Restorative Materials. 180:4049, 1991) reflected clinical reality. Method. The ISO test requires a VLC material to remain homogenous after exposure to an 8 kLux light source for 60 s. The relationship between the intensity of ambient lighting and the working times of visible light-cured (VLC) restorative materials was investigated by exposing 23 different VLC composite resin materials to a range of light intensities and measuring the working time in seconds: (a) under clinical operating conditions; (b) in a custom light box at 24 kLux; and (c) at 8 kLux in the light box. Working times were determined by placing 0.06 g samples between two glass plates and gently rotating until clefts or voids appeared. Results. Clinical lighting conditions (24 kLux) gave a mean working time of 54 s (s.d. 14s). In the light box at 24 kLux the mean working time was 54s (s.d. 11s). At 8 kLux (under otherwise identical conditions) the mean working time was 162 s (s.d. 49 s). Significance. A 24 kLux illuminance in the laboratory gives an optimal correspondence to operative lighting conditions. This is three times the lighting level required for ISO purposes, and gives more realistic working times. © 1999 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.
    Original languageEnglish
    Pages (from-to)353-357
    Number of pages4
    JournalDental Materials
    Volume14
    Issue number5
    Publication statusPublished - Sep 1998

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