Dentists in India removed a shocking 526 teeth from a seven-year-old boy’s mouth in what they’re calling the first-ever documented case of its kind.

The young boy, who hails from the town of Tiruvallur in southeast India, first visited a hospital in the city of Chennai when he was only three years old because his parents were concerned about “small swelling” in his right lower jaw.

According to the Saveetha Dental College, the boy refused to undergo investigative procedures and he left the hospital undiagnosed.

Four years later, the swelling had increased in the same area of of the child’s jaw and he was referred to Saveetha Dental College in Chennai.

“He was brought to our institution at the age of seven years as the swelling was slowly increasing in size,” the college wrote in an online blog about the case. “The parents were very apprehensive as they had thought it could be a cancer of the jaw.”

While they didn’t find cancer, surgeons did discover a “large lesion with multiple hard structures at a single site within the lower jaw.”

The operating surgeon noticed a “bag-like mass” in the right lower jaw and removed it during a 90-minute procedure.

Following the surgery, X-ray and CT scans revealed the tissue mass, which weighed 200 grams, contained “multiple tiny radiopaque structures.”

Upon further investigation, the dentists said they were surprised to discover the structures inside the mass were actually “rudimentary” teeth, and there were 526 of them in all.

“It was reminiscent of pearls in an oyster,” Dr. Prathibha Ramani, the head of the college, said.

The surgeons said they spent the next five hours carefully removing each tooth from the opened tissue.

“The tooth sizes varied from 1 mm to 15 mm and each resembled a tooth with crown covered by enamel and a root like structure,” the college wrote.

Although the mass prevented the boy’s permanent molar teeth from growing, the college said he will be able to get implants for those later in life.

The boy’s rare condition is called “compound odontome,” according to the dentists. The college also said this is the first documented case where so many minute teeth were found in a single individual.

Dentists said it’s unclear what caused the extreme growth in the boy’s mouth, but they suggested that genetics or environmental hazards may have played a role.