11. Composition and preparation of light-cured composite material
Covers the composition of light-cured composite, including its resin matrix, filler particles, coupling agent and camphorquinone photoinitiator, set out in a component table. Walks through the preparation steps of etching, bonding, layering and curing, then tabulates the factors that affect curing depth, such as thickness, shade and light intensity. Ends with a short note on eye safety when working with curing lights.
Topic 11 of 52 in the MU Sofia syllabus for Dental Materials (Dental Medicine, Year 1). The free AceMed note covers it in 5 sections, about 160 words (2 min of reading), with 14 flashcards.
In this note
Introduction
Composition
Preparation
What affects curing
Eye safety
Introduction
A light-cured composite, or photopolymer, is a single-paste filling material that stays soft until it is exposed to blue light. This gives the dentist plenty of time to shape it.
Composition
The paste comes in light-tight syringes or compules, which fit a compule gun. Close the cap straight after use, because light hardens the material.
Preparation
Etch: apply 37% phosphoric acid gel to the enamel for 30 seconds. Rinse for 30 seconds and dry for 15 seconds. Correctly etched enamel looks frosted.
Bond: apply the adhesive system and polymerize it. It leaves an oxygen-inhibited surface layer, which bonds to the composite.
Layer: place small increments of no more than 2 to 3 mm.
Cure: shine the light on each layer for 20 to 40 seconds, or as the manufacturer recommends, with the tip almost touching the material.
Finish: shape and polish the restoration.
Eye safety
Blue light can damage the retina. Curing lights have orange shields, and the work should be watched through them.
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