Bruce Willis celebrated his 68th birthday with his family
Ex-wife Demi Moore shared a video of the celebration
Willis has been diagnosed with frontotemporal dementia (FTD)
FTD is an incurable disorder that causes degeneration in the frontal and temporal lobes of the brain
Willis' missing front tooth raised concerns among fans, but it is unclear what happened to it
Bruce Willis retired from acting in April 2020
He was diagnosed with aphasia, a language and cognition disorder.