ABUJA, Nigeria — A group of chimpanzees that were once used for hepatitis B vaccine experiments in laboratories have received health checks at their new home in Liberia, in hopes of giving them a second chance at a normal life.

The West African chimpanzees received checks ranging from teeth cleaning to X-rays and pedicure at the Humane World for Animals’ Second Chance Chimpanzee Refuge in central Liberia, Liliana Pacheco Ricote, director of the sanctuary, told The Associated Press.

More than 400 of the chimpanzees had been used by American researchers in Liberia in the hepatitis B vaccine experiments from the 1970s until early 2000s, Ricote said, many of them captured in the wild as infants.

Liberia has the second-highest number of chimpanzees in West Africa, after Guinea. The West African chimpanzees are classified as critically endangered species because of their rapidly declining numbers.

“They were used in very invasive research … (and) went through a lot of experiments and pain,” Ricote said.

Humane World for Animals said that in 2015, it assumed permanent responsibility for 60 of the chimpanzees that were remaining at the end of the research program. The chimps now mostly live at the sanctuary on a series of mangrove forest-covered islands.

The checks carried out under anesthetic gave the chimpanzees head-to-toe exams to assess their long-term health, detect any early signs of disease and tailor care plans for individuals as they age, Humane World for Animals said in a statement to the AP.

The tests included dental examination, the heart, lungs and nervous system as well as blood. They get booster vaccinations and fingernail trims, it said, adding that plans are in place to carry out the checks on the remaining ones.

“The health checks are a vital part of caring for these chimpanzees who have been through so much,” said Belen Perez Hernando, the sanctuary’s veterinarian.

The extent of the impact of the experiments on the chimps, whose average age is 30 to 35, is unclear, as findings from the assessments are yet to be concluded. However, “for those who were under experiments, you could still feel the hurt and the pain that they went through,” Ricote said.

“Seeing how much they hurt about what we’ve done, it gives me a lot of pleasure … to give them this second chance to live with dignity the life that they deserve,” she added.