Warming Composite increases the flow of composites up to 68%.
The reason this is so important is that it makes the composite so much easier to work with.
Now a heavily filled material can be used on posterior teeth with no compromise to the strength of the restoration.
By warming composite, the properties change in a positive way. Once the composite has been warmed to 130°F or 140°F, and the composite is cured immediately after placement, a greater depth of cure is experienced in the same amount of curing time, hence a much stronger restoration.
When the composite is warmed, it becomes more flowable. By becoming more flowable, the composite has much better adaptation to the tooth structure, which decreases microleakage significantly.