A dentist has been charged in the death of a patient who became unresponsive while having 20 teeth pulled and several implants installed last year.

Rashmi Patel, 45, of Suffield, turned himself in Tuesday at the Enfield Police Department and was charged with a misdemeanor count of criminally negligent homicide and a felony count of tampering with evidence, police said. Patel has offices in Enfield and Torrington.

The charges came exactly a year after Patel's patient, 64-year-old Judith Gan of Ellington, died at a hospital Feb. 17, 2014. State dental regulators concluded that Patel failed to adequately respond when Gan's oxygen levels dropped dangerously low when she was consciously sedated in the middle of the tooth extraction and implant procedures in Patel's Enfield office the same day.

Patel, who posted $25,000 bail, has denied any wrongdoing in his treatment of Gan. He and his attorney didn't return messages Wednesday.

Gan's death and other incidents prompted the State Dental Commission in December to suspend Patel's license pending a monthslong review of his practice and permanently ban him from performing conscious sedation.

The commission said in a report that Patel "ignored" signs that Gan was in distress, including the drop in her oxygen saturation, changes in the color of her face and hands, and wheezing and gurgling sounds. The commission said Patel also ignored warnings from his dental assistants that Gan was in danger and continued on with the procedures.

When one of Patel's assistants yelled that Gan was "flat lining," Patel tried to revive Gan while the assistant called 911, according to the Dental Commission's report. Gan was rushed to a hospital, where she was pronounced dead.

The commission also found that Patel should not have attempted to perform so many procedures on Gan in one office visit, given that her medical history included a heart attack six months before the visit, two strokes within the last two years and medication that could have affected her response to the sedation.

Patel also violated care standards in December 2013 when another patient under conscious sedation to have teeth extracted inhaled a piece of gauze called a throat pack, which was designed to protect him from swallowing foreign objects, the commission found. The patient began flailing, his blood pressure spiked and he was rushed to a hospital but recovered.

A lawyer for Gan's husband has said a lawsuit against Patel is planned.