(CNN) Dr. Given Kachepa strides confidently into his practice, greeting a 17-year-old patient who's come in to have her braces tightened.
"Hello. How are you?"
Life in the United States is quite different now for the 29-year-old Kachepa, compared to how it started as an 11-year-old orphan.
From his office, filled with fading family photos and handicrafts from his native Zambia, he reflects on how he first bought in to the allure of the American Dream.
"I came to the United States without a dollar in my pocket," says Dr. Kachepa. "The only thing I had was hope."
Born in a little village called Kalingalinga, Zambia, Kachepa met a man named Keith Grimes in 1998.
Grimes, a pastor from Whitesboro, TX, just outside Dallas, ran a high-profile, faith-based endeavor called TTT: Partners in Education.
He offered Kachepa and 11 other boys, an amazing opportunity. Come to the United States and sing in front of audiences, as part of an a cappella boy's choir.
In exchange, the young singers would earn money for themselves, and more to send back to their families. They would also receive a U.S. education and help raise funds to build a school back in their village.
The boys stayed on Grimes' ranch in Texas, performing at shopping malls, schools and churches across the South.
One budget statement from TTT: Partners in Education, obtained by CNN, showed the organization took in more than $1 million from the performances, sponsorships, and donations, in just one year.
But the boys weren't going to school, and they weren't getting paid what was promised. When some of the older boys complained, Kachepa says the organization responded angrily.
"They said if you're not going to sing, we're either not going to feed you or we're going to send you back home to Zambia," Kachepa says, claiming they were performing as many as three to seven concerts a day, every single day.
Sandy Shepherd, a former TTT volunteer, grew concerned about what she was witnessing.
"They'd do an elementary school and then they'd have to move to another school they had to do all their set up and all their take down up," says Shepherd. "They'd been promised they'd get an education and that obviously wasn't true. They'd been promised some sort of compensation, which they didn't get any of that, until the labor department got involved."
Federal investigators, acting on tips from concerned host families and interviews with choir members, eventually raided the ranch and removed the children.
Keith Grimes became the subject of a criminal investigation. But the investigation ended when he died of natural causes in 1999. Two years later, the U.S. Department of Labor ruled TTT: Partners in Education was liable for $966,422.00 in back wages and civil money penalties for the members of the choir.
To date, no choir member has received a penny.
A statement from the Department of Labor to CNN in 2010 said: "The U.S. Treasury was unsuccessful in securing back wages for these employees because the employer had died and his company was bankrupt."
For her part, Shepherd tried to help many of the boys find foster families, including Kachepa. But when his previous arrangement fell through, she brought him into her family, where he's been ever since.
The kindness has made a lasting impression on the young Zambian.
"To have a wonderful family take me in and say we're willing to see you as our son. You make look different, but we're willing to see you as a son and provide you with all the things you're going to need to be a success, that was inspiring to me," says Kachepa. "The only way I could pay them back was by working hard and trying to be the best person I could be, so that when I reach my goal I could provide the same opportunity to someone else."
One of Kachepa's goals, was to become a dentist. After graduating high school and college, CNN followed Kachepa, the day he enrolled at the dental school, back in 2010.
"Dental school was by far the hardest thing I've ever done," says Kachepa. "It really just gives me chills to know I could be a dentist today. Where I grew up in Kalingalinga, there has never been a single dentist. I remember when I was a little boy my aunt had a toothache and the pain was so excruciating, she just kept pacing up and down up. But there was nothing anybody could do to help her. The only thing she could do was just wait until the pain went away."
On May 27, 2016, Kachepa received his Doctor of Dental Surgery degree from Texas A&M University Baylor College of Dentistry in Dallas.
Dr. Robert Baker became not just a professor, but a mentor, to Kachepa.
"He'd been through a lot and I didn't know any of that at first," says Dr. Baker. "He had a lot of walls. He wouldn't let people get close to him."
But that changed as Kachepa grew closer to graduating. Those closest to him say they've seen a remarkable blossoming in his personality.
"Now that he's graduated, his self-confidence has just soared and it's been so much fun to see," says Shepherd. "I wake up in the morning and I will text him and say 'good morning, doc. Am I'm really calling you doc?'"
Dr. Kachepa is now starting his own practice in Dallas, with plans to eventually return home to build dental practices in Zambia.
"That's the way I can give back to the disadvantaged people of the world," says Kachepa. "God brought me this far, not to let me fail at the end of it."