A pan-European study, featuring research from nine different countries, suggested bad dental care could lead to a greater risk of cancers in the mouth, larynx, pharynx and the oesophagus.
But excessive use of mouthwash — defined as more than three times a day — has also been named as a contributory risk factor.
One of the report's authors, Professor Wolfgang Ahrens, admitted that further research would have to be carried out to confirm this claim because people who use mouthwash very regularly may be masking the smell of smoking and alcohol - which are also risk factors for cancer.
Dr David Conway, clinical senior lecturer at Glasgow University's Dental School, said: "There are occasions and conditions for which a dentist could prescribe a mouthwash - it could be that a patient has a low salivary flow because of a particular condition or medicine they are taking.
"I would not advise routine use of mouthwash; all that's necessary in general is good regular brushing with a fluoride toothpaste and flossing combined with regular check-ups by a dentist."
A total of 1962 patients with mouth and throat cancers, and a further 1,993 people with no such illness, took part in the study.
Smoking and heavy alcohol consumption have long been linked with risk of mouth and throat cancer. Low socio-economic status has also been highlighted.
However, when looking at poor dental care, the research was able to strip out these factors and found a connection between bad oral health and an increased risk of these types of cancers.
Prof Ahrens said: "Up until now, it was not really known if these dental risk factors were independent of the well known risks for mouth and throat cancers - smoking, alcohol and low socio-economic status."
Dr Conway warned everyone to attend regular dental check-ups.