Scientists found that when the oil was treated with digestive enzymes it became a powerful killer of mouth bugs.
The bacteria it attacked included Streptococcus mutans, an acid-producing microbe that is a major cause of tooth decay.
Researchers were following work which showed that partially digested milk made S. mutans less likely to stick to tooth enamel.
Studies will look at how coconut oil interacts with the bacteria at the molecular level.
Tests also suggest that enzyme-treated coconut oil is harmful to the yeast Candida albicans, the cause of thrush.
The findings were presented at the autumn meeting of the Society for General Microbiology at the University of Warwick.
Lead researcher Dr Damien Brady, from the Athlone Institute of Technology in Ireland, said: “Incorporating enzyme-modified coconut oil into dental hygiene products would be an attractive alternative to chemical additives.”