On January 7, the day after she was allegedly hit by then-beau Mel Gibson, Oksana Grigorieva paid a visit to the dentist.

And that dentist now says that Grigorieva was hit in the mouth and head– causing the damaged front teeth depicted in the shocking photo that went online Friday.

A rep for Dr. Ross Sheldon told TMZ Monday: "Based on Dr. Shelden's observations and his experience, Oksana sustained injuries from being struck twice, once in the side of the head and once in the mouth."

On Sunday, a rep for Grigorieva slammed claims that Radaronline's shocking photo was doctored. "The photo released by RadarOnline.com is 'true and accurate' and real," the rep told Entertainment Tonight.

TMZ reported over the weekend that authorities were "investigating [whether] the damage to the veneers could have been self-inflicted."

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And a source close to Gibson, 54, says that he and Grigorieva did have a heated argument on Jan. 6 — but the spat never got physical.

Says the source, "They got into it, but he absolutely did not injure her," the rep says.

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