Nevers – A Dutch man dubbed by French media the "dentist of horror" went on trial on Tuesday after allegedly causing horrific injuries to the mouths of more than 100 patients in France.Jacobus van Nierop, 51, ripped out healthy teeth and left dozens of patients in a remote French village with broken jaws, recurrent abscesses and septicaemia.He is charged with aggravated assault, as well as fraud over claims that he tried to rip off patients and insurance companies, and faces up to 10 years in prison and a $165 000 fine if found guilty.Although he is not required to offer a plea under French law, Van Nierop has previously sought to deflect responsibility, saying he suffers from "psychological problems" including gender identity issues and suicidal tendencies.He hid his face under a blanket as he arrived at the court in Nevers in central France, near the rural area of Chateau-Chinon where he came to work in 2008. He has already been detained for 18 months in the case.Van Nierop, who went by the first name of Mark, was hired by a head-hunter and was initially welcomed by locals who were sorely lacking in medical services.A neighbour recalled the arrival of a smiley, larger-than-life character, with a "big 4x4, a big dog, a big cigar".But by 2011, the authorities were starting to question some of his accounting, and patients were starting to compare notes on his dentistry.Sylviane Boulesteix, 65, visited the dentist in March 2012 to have braces fitted."He gave me seven or eight injections, and pulled out eight teeth in one go. I was gushing blood for three days," she said.An 80-year-old, Bernard Hugon, said the dentist left "pieces of flesh hanging everywhere" after tearing out a tooth."Every time, he would give us what he called 'a little prick' and we were asleep, knocked out," said Nicole Martin, a retired teacher who lost several teeth to abscesses caused by the horrific operations."When it was over, we would find a Post-it note saying to come back for an appointment the next day or the day after," she added.Fled to CanadaWith the help of one of Van Nierop's assistants, Martin set up a victims' group in early 2013 to press charges, and it soon swelled to 120 members.In June of that year, police arrested Van Nierop but left him free pending trial, and he fled the country the following December.He was eventually tracked down to a small Canadian town in New Brunswick and arrested under an international warrant in September 2014.Local media reported that he tried to slit his throat when police came for him.Van Nierop tried to block his extradition first to the Netherlands and then France on psychological grounds, but was eventually placed in a prison psychiatric unit in the Loiret department, south of Paris."He claimed to have killed his first wife, he played crazy, he said he was trans-sexual. He tried everything" to avoid extradition, Martin said.According to Dutch media, Van Nierop had already come under investigation at home over his working practices before coming to France.