If you have visited a dentist to get a tooth-coloured filling done, the blue light that the dentist shone in your mouth must have certainly caught your attention.

What is this blue light?

The device which emits the blue light is called a dental curing light. It is used to set composite (tooth-coloured fillings). Most dentists today use the LED curing light. Previously halogen curing lights were used which had the disadvantage of producing significant heat.

How is the tooth-coloured filling done?

The dentist removes the decay, shapes and prepares the tooth to receive a filling. The tooth-coloured filling is made up of a material called composite resin. The composite resin filling material is available in syringes with different tooth shades. They are available in soft dough-like and flowable consistencies. The composite resin is used to fill up the cavity in increments, sometimes with multiple shades, so that it matches the natural tooth colour. The soft composite resin is shaped to resemble the original tooth and then ‘cured’.

What does ‘curing’ do to the filling?

After the soft composite resin is filled in the cavity and shaped, the curing light is shone on to the filling for approximately 20 seconds(can vary according to size of filling and manufacturer’s instructions). This makes the material to set hard.

How does it make the soft filling hard?

When the curing light is shone on the filling, the composite resin starts undergoing a process called polymerization. The soft composite filling is made up of many small parts called monomers. For the material to set hard, these monomers should link up together to form chains called polymers. Shining the blue curing light activates the material to form polymer chains and harden.

Is the light harmful?

There are no harmful effects of this light on the teeth or gums. But, the light is very bright and can put strain on your eyes. Hence it is not advisable to look at it for a long time.

What procedures is it used in?

Dental curing light is used in procedures like - 

- Tooth coloured (composite) fillings

- Pit and fissure sealant application in children

- Placing braces on the teeth