Bruce Willis appears to be missing tooth in birthday video shared by Demi Moore

Demi Moore shared a video of her family singing happy birthday to her ex-husband Bruce Willis on Sunday.

To mark the Die Hard actor's 68th birthday, the actress posted footage showing his family, including his new wife Emma Heming Willis and his daughters, singing him a rendition of happy birthday in a kitchen.

Bruce seemed in good spirits as he smiled and sang along to the tune before joining in with their whoops and cheers. He then blew out the candles on his dessert as his loved ones sang "hip-hip, hooray!"

However, eagle-eyed viewers noticed that one of his front teeth seemed to be missing.

In the caption, Demi wrote, "Happy birthday, BW! So glad we could celebrate you today. Love you and love our family. Thank you to everyone for the love and warm wishes — we all feel them."

The video marks the first new footage the family has posted of Bruce since they shared his frontotemporal dementia diagnosis (FTD) last month.

The Pulp Fiction star retired from Hollywood early last year after he was diagnosed with aphasia, or an inability to comprehend or formulate language. In February this year, they revealed his condition had progressed to FTD.

Bruce was married to Demi from 1987 until 2000, with the former couple sharing daughters Rumer, 34, Scout, 31, and Tallulah, 29.

The Armageddon star wed Emma in 2009 and they share daughters Mabel, 10, and Evelyn, eight.