Jacobus Marinus (Mark) van Nierop, 51, arrived in a police car, his head covered by a blanket, at a court in Nevers, central France, near the town of Chateau-Chinon where he began practising in 2008.
He faces charges of defrauding French social security and "wilful violence causing mutilation and permanent injury".
One former patient quoted by regional newspaper Le Journal du Centre described how van Nierop took out eight of her teeth in one sitting without permission. She said she bled for three days afterwards.
Another said her teeth were filed down when she was expecting them to be cleaned.
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His lawyer Delphine Morin-Meneghel was quoted in January as saying he "recognised that he did not do good work" but he was not the horrible person some people had described.
His flight to Canada after questioning by French police was part of a plan to commit suicide, she said, adding that he was in poor health.
Van Nierop was arrested in 2014 in New Brunswick, Canada and sent home. He said at the time he was suffering from psychological problems and confusion about his sexual identity.
