A group of some 150 dental patients across Japan is seeking compensation from a clinic and a firm for botched teeth alignment procedures.

The patients filed their lawsuit with the Tokyo District Court on Tuesday. They had been treated at a dental clinic that operates outlets in Tokyo, Fukuoka and other areas.

The plaintiffs' lawyers say they signed a contract with a Tokyo-based company from 2020 through last year for teeth alignment using orthodontic trainers at the clinic.

They were reportedly told that if they become test cases for the clinic, they would be paid fees that would effectively offset the cost of the procedure.

But the payment of fees from the firm stopped, and the patients were left with huge loans they had taken out to have their teeth fixed.

Then the clinic closed most of its outlets. The plaintiffs say they were left halfway through the procedure. They claim this resulted in bad teeth and other health problems.

The group is seeking more than 260 million yen, or over 1.8 million dollars, from the clinic and the firm.

Teeth alignment using orthodontic trainers became popular mostly among young women during the coronavirus pandemic, as their faces were covered with masks.

Another group of patients filed a similar lawsuit with the Tokyo District Court in January of this year, bringing the total number of plaintiffs to more than 300.

One of the plaintiffs, a woman in her 20s, claimed her teeth still ache from the drilling, and she is worried about the future.

She said she was suffering alone until she learned there were many others like her, and so she decided to join the lawsuit.