I have been giving my girl teething biscuits when i suspected that she was teething and now with 4 teeth, she can bite the biscuits at a faster rate. However, dont't let your child finish up the biscuit cos it may cause choking. The moment the biscuit has become too short that it can be put right inside the mouth then you should take it away from yr child and throw it away.
You can get either Heinz or Bellamy's teething biscuits. I got Heinz from NTUC and Bellamy's organic teething biscuits online which is much cheaper.