Orange County public health officials on Tuesday lifted a ban on water use for dental procedures at Children’s Dental Group of Anaheim after the clinic replaced the contaminated water system that sickened more than 50 young patients.

The county Health Care Agency ordered the clinic to stop using water on Sept. 15 after samples tested positive for mycobacterium. Since then, at least 57 children have been hospitalized for lab-confirmed or probable mycobacterial infections, which are very difficult to treat.

“The on-site water system has been completely removed, replaced with new equipment, and the water from the new system has been tested to ensure it meets the standards established by the American Dental Association,” Dr. Eric Handler, county health officer, said in a statement.

The children, ages 2 to 9, received pulpotomies, also known as baby tooth root canals, between March 1 and Aug. 11. In addition to surgery to remove the infection, many children have needed long-term intravenous antibiotics.

On Friday, Claremont attorney Catherine Lombardo filed a lawsuit against Children’s Dental Group alleging that a 6-year-old boy with autism received two unnecessary pulpotomies at the Anaheim clinic in May.

According to the suit, Leonel Sanchez has undergone follow-up appointments at Children’s Dental Group’s Carson clinic to determine if he has mycobacterial infection. But the suit says his parents were never told if he does and they believe the clinic’s dentists “are concealing the fact that Leo is indeed infected with the mycobacteria, which is causing them extreme anxiety.”

Lombardo said in an interview Tuesday that the boy’s parents have not yet taken him to Children’s Hospital of Orange County for evaluation but that he “has all of the symptoms” of infection.

Sam Gruenbaum, CEO of Children’s Dental Group, said in an email that the clinic hopes to begin seeing patients again Nov. 21. He said the new water system has been designed to protect the health and safety of patients.

As for the lawsuit, Gruenbaum said he had not been served, but “we deeply regret that any patient had complications following treatment here.”

The county said safeguards in place to prevent future contamination at the dental office include use of a treatment designed to prevent bacteria from adhering to equipment and installation of purification cartridges at every dental chair connected to the on-site water system.

Mycobacteria is a naturally occurring germ found in water that can cause illness in high levels, or if a strain is particularly virulent. Last month, the county awarded $150,000 to CHOC to help the hospital manage the complex treatment of patients, some of whom must take an antibiotic used to treat leprosy which must be special-ordered from the Food and Drug Administration.

Jessica Gomez, whose 4-year-old daughter contracted an infection after two March pulpotomies, said she was upset that the clinic will be able to treat patients again.

“I would never go there again and I would never refer anyone there,” Gomez said. “I feel like a lot of the parents whose children were affected are probably shocked to hear they’re still going to be up and running when our children didn’t get a second chance; some of them lost their teeth and their jaw bones.”

Gomez, 25, of Corona, said her daughter Janell was hospitalized at CHOC last month. Surgeons scraped infection from her jaw bone and extracted five baby teeth, including her four molars. Janell is recovering but is struggling with eating meat and vegetables, Gomez said.

Gomez said it’s important for parents to take their children to be checked if they received the baby tooth root canals at the Anaheim clinic, even if they don’t have swelling, redness or pain, which can develop weeks or months after the procedure.

“That’s my concern is just that people should be aware,” she said.

Contact the writer: cperkes@scng.com 714-796-3686