Jeremy Corbyn joked about Andrew Marr's teeth as he outlined Labour's election policy of making NHS dental checks free.
One in five adults puts off seeing a dentist because of the £22.70 charge for a visit.
But under the fist stage of Labour ’s plans teeth checks, oral cancer examinations, X rays, clinical scaling and polishing and emergency treatment will not cost a penny.
And Mr Corbyn explained scrapping the cost of a checkup would make dental care less expensive in the long run.
"If you or I had a dental check...and maybe you do, or maybe you don't...I don't want to know about your teeth, actually. So I won't ask."
He added: "But if we don't have a dental check, and somewhere down the line we have a catastrophe, a disaster, massive pain, we have to go to A&E - and that is very expensive.
"So a dental check - a free dental check is actually an investment for the future.
"And also helps people have some education about dental hygiene."
Earlier, Shadow Health Secretary Jon Ashworth raised concerns about "DIY dentistry" being performed by people who can't afford NHS treatment.
Mr Ashworth said: "It's shocking that so called 'DIY dentistry' is becoming so common with people resorting to doing their own fillings and seriously risking their teeth deteriorating further.
"With 135,000 patients presenting at A&E with dental problems every year, it's time we put prevention at the heart of our approach to dental health.
"People should not be risking their teeth because they can't afford the care. With Labour, dental check-up fees will be scrapped as we help people live healthier lives."
Dental care was free at the point of use when the NHS was launched in 1948, but due to overwhelming demand, charges for dentures, the first charges of any kind for NHS treatment, were introduced in 1951.
Charging for dental procedures proved to be controversial and led to the resignation of Aneurin Bevan, the Labour minister who played a pivotal role in bringing the NHS into existence.
Other charges for treatment soon followed and today, a band one NHS dental check-up costs a patient £22.70.
