Oksana Grigorieva`s dentist insists she sustained injuries to her teeth by being "struck twice". The Russian singer split from her partner Mel Gibson, with who she has eight-month-old daughter Lucia, in April. The separation initially seemed to be amicable, but has become increasingly acrimonious in recent weeks. Oksana filed for a restraining order against Mel, claiming he had been violent towards her. She alleges he hit her in the face during an argument in Malibu on January 6, breaking her teeth. Her claims have caused Los Angeles police to start investigating Mel for possible domestic violence. In turn, Mel has filed for custody of Lucia. A number of recordings of a man purported to be Mel using racist and degrading language during arguments with a woman said to be Oksana have also been released. They were reportedly used during a court hearing about the custody of Lucia last week, where Mel retained visitation rights. On Friday, a picture of Oksana showing her broken front teeth was leaked to website Radar Online. After claims the image was doctored, Oksana publicly confirmed it was her in the photo. Her dentist Dr. Ross Shelden has now spoken out in her defence, confirming she came to see him on January 7. "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," his representative told website TMZ. The dentist had previously stated the injuries were a "chain reaction" from being hit on the temple, and weren`t linked to a punch in the mouth. His representative has now said Shelden will go on record with his comments about the injury. Mel has denied hurting Oksana, with sources close to him stating that although they argued it did not get physical. "They got into it, but he absolutely did not injure her," the source stated. Meanwhile, it has been reported Oksana signed an agreement which would have netted her $15 million of Mel’s fortune in May, but ended up not taking it. The deal was worked out during a child custody meeting, and saw Oksana getting child support, a house and other assets worth the staggering sum. Under the terms of the agreement, Oksana allegedly promised "all evidence" would remain confidential. The evidence is said to be the tapes, some of which were played to Mel’s lawyers. "The tapes loomed large in the mediation. The word `tapes` was never used in the agreement, but it was central to the deal," a source told TMZ. Oksana and Mel both signed a "short for agreement", which included the vague terms of the deal. However, she didn`t sign the resulting long form as she said she felt pushed into it.