Researchers have linked the use of cannabis to an increase in the risk of gum disease.

A new study from Columbia University shows that the frequent use of marijuana, hashish and hash oil has significant long-term impacts on dental health.

“It is well known that frequent tobacco use can increase the risk of periodontal disease but it was surprising to see that recreational cannabis users may also be at risk,” Dr. Jaffer Shariff, a postdoctoral resident in periodontology at Columbia University School of Dental Medicine and lead author, said in a statement. “The recent spate of new recreational and medical marijuana laws could spell the beginning of a growing oral public health problem.”

The researchers analyzed the data of 1,938 adults who participated in the Centers for Disease Control and Prevention’s 2011-2012 National Health and Nutrition Examination Survey, administered in collaboration with the American Academy of Periodontology, where about 27 percent of the participants admitted to using cannabis at least once in the previous year.

Periodontal gum disease is an inflammatory reaction to a bacterial infection below the gum line and if left untreated could lead to receding gums and tooth loss, as well as a number of non-oral health issues including preterm labor during pregnancy and heart disease.

Periodontists look for plaque, inflammation, bleeding and gum recession and use a probe to measure the space between the teeth and their surrounding gum tissue during periodontal exams.

Healthy gums have no more than one to three mm of space between the tooth and surrounding gum tissue and deeper pockets indicate the presence of periodontitis.

The study showed that those who frequently used cannabis had more sites with pocket depths indicating moderate to severe periodontal disease than the less frequent users of cannabis.

“Even controlling for other factors linked to gum disease, such as cigarette smoking, frequent recreational cannabis smokers are twice as likely as non-frequent users to have signs of periodontal disease,” Shariff said. “While more research is needed to determine if medical marijuana has a similar impact on oral health, our study findings suggest that dental care providers should ask their patients about cannabis habits.”

The study was published in the Journal of Periodontology.