More than a third of British five-year-olds have some form of tooth decay while one in 10 has at least one filling.
However, dentists say that there is no scientific evidence that giving children fillings reduces the number of infections they develop or the number of extractions which have to be carried out.
Now the first study of its kind is launched into treating baby teeth. Researchers at the University of Dundee plan to assess which of three treatments is best for baby teeth.
These are fillings, no fillings or a paint-on tooth enamel that can seal the tooth and even help prevent further decay.
In 2003 a University of Manchester study suggested that filling baby teeth made no difference to the number of extractions or infections children suffered.
Kamini Shah, honorary secretary of the British Association for the Study of Community Dentistry, said: "There are two schools of thought, one being that baby teeth can cause pain and sleepless nights and so dentists should fill.
"The other is that actually the evidence around filling baby teeth is questionable."
Dr Gail Topping, from the University of Dundee, who will lead the new study, said: "Treatment for decay in baby teeth varies widely across the UK and there is, as yet, no conclusive evidence for the most effective approach to its management.