Charlie Sheen, erratic Taco Bell enthusiast and former television Man, is being investigated for assault after allegedly threatening his dentist with a knife Thursday. A dental technician told police Sheen was high on cocaine and flipped out while she was trying to administer nitrous oxide.

She says the actor, who now stars in something called Anger Management (I don't know what it is, but it sounds ironic!) punched her in the face. After she left the room, Sheen allegedly pulled a knife on his dentist.

The technician claims Sheen's bodyguard told her the actor was "high on rock cocaine," according to TMZ.

TMZ reports the LAPD is actively investigating the incident, and considering charging Sheen with battery for the alleged punch and assault with a deadly weapon for the alleged knife incident. The status of Sheen's abscess, for which he was reportedly seeking treatment that day, is unknown.

Gossip Cop points out that Sheen has a history with knives, having pleaded guilty to a 2009 assault on his then-wife, Brooke Mueller, that allegedly involved a knife. He served his 30-day sentence in rehab.

Production on Anger Management was recently halted after Sheen turned up with a facial injury that required stitches. A rep said he accidentally dove into the shallow end of his swimming pool.

Uhh, #winning!

Update: Sheen says he had a bad reaction to the combination of prescription of pain meds and the nitrous oxide, and accidentally knocked over a tray of dental instruments while flailing his arms.

He says the rest of the story is bogus, and the technician is just mad that she was fired for violating HIPAA by telling her son that Sheen was in the office.

Law enforcement sources told TMZ that the dentist also refuted the dental tech's story, and charges will likely not be filed.

[h/t Gossip Cop, Photo: Getty Images]