Sweet soft drinks and lots of sugar increase the risk of both dental cavities and inflammation of the gums -- known as periodontal diseases, say researchers.

"Sugar hasn't traditionally been associated with the development of periodontal diseases," said study lead author from Aarhus University in Denmark. According to the researchers, back in the 1970s, two American researchers suggested that a diet, which was high in carbohydrates, could be a common risk factor for both dental diseases and inflammatory diseases such as diabetes, obesity and heart disease, but this knowledge was largely forgotten again.

The current study, published in the Journal of Oral Microbiology, suggests that a sugary diet can also promote periodontal diseases. "Today, there is general agreement that the above-mentioned diseases are associated with a high sugar intake. However, a hypothesis that could link and explain the two major dental diseases, caries and periodontitis, has been lacking," Nyvad said. In the new research project, the researchers have arrived at a common hypothesis for the development of the two major dental diseases.

The hypothesis is based on the biochemical processes that take place in the bacterial deposits on teeth when you add copious amounts of nutrients to the bacteria, particularly when you eat sugar. "In other words, we revive the 'forgotten' hypothesis that sugar can promote both dental cavities and periodontal diseases," said Nyvad. The research team emphasised the importance of continuing to brush teeth with fluoride toothpaste, even if you cut down on sugar.

The researchers assumption is that periodontal diseases caused by sugar belong to the group of inflammatory diseases in line with diabetes, obesity and heart disease. Healthy eating habits should be given much higher priority if the goal is to avoid expensive treatments in the healthcare system, the study said.