Teeth wanted: How S’pore’s first Tooth Tissue Bank is advancing dental research

To add another layer of complexity, a researcher must also navigate ethical and legal requirements, obtaining approvals from institutional review boards or ethics committees.

Associate Professor Vinicius Rosa (below) of the Faculty of Dentistry at NUS says: “It would take months before we start collecting any teeth, and maybe years before we actually start on the project. It would be a time-consuming and tedious process, even before we begin the study.”

Singapore’s first Tooth Tissue Bank speeds up this process by keeping a ready supply of teeth donated by patients after extraction. The teeth are available to researchers at the NUS Faculty of Dentistry and National University Centre for Oral Health Singapore (NUCOHS) for their projects.

The Tooth Tissue Bank, which is located in NUCOHS in Lower Kent Ridge Road, was established in 2021 by the centre, with the support of the NUS Faculty of Dentistry.

On days that an extraction is scheduled at NUCOHS, the faculty’s Clinical Research Unit reaches out to the dentist in charge of the procedure.

The dentist then invites the patient to donate the extracted tooth and, if the patient agrees, it is collected for the NUCOHS Tooth Tissue Bank.

“About 40 per cent of patients are willing to donate their extracted tooth and the rest either prefer to take it home or discard it,” says Prof Rosa.

On the day of the photo shoot, The Straits Times speaks to X, who was scheduled to have a third molar – also known as the wisdom tooth – extracted, to find out why the patient agreed to the donation.

“I see no purpose in keeping or discarding my extracted tooth. Donating it helps with important dental research and contributes to advancements in dental science,” says the patient.

Two research coordinators from the Clinical Research Unit are tasked to collect the extracted teeth at the end of the day.

Their responsibilities involve decontaminating the teeth by soaking them in a solution containing alcohol before transferring them into a test tube.

The test tube is then placed in a box and transported to a fridge in the Tooth Tissue Bank.

“The fridge temperature is set at 4 deg C – a good temperature to prevent the growth of bacteria,” says Ms Nur Ashira Abdul Rahman (below), a research laboratory technologist at the faculty.

The fridge houses jars of teeth sorted according to their types: incisors, canines, premolars and molars.

Ms Ashira is responsible for cleaning and sorting the teeth, and replacing the water in the jars weekly.

Cleaning is a manually intensive process that starts with rinsing the teeth in highly purified water. She then uses tweezers to remove blood, tartar, plaque and other debris. This can take up to 15 minutes per tooth.

The teeth are sorted into two main categories after cleaning: restored teeth and those that are perfect or close to perfect and untarnished by decay or filling.

The tooth samples have to be further processed to meet the requirements and exact measurements needed for different research projects, says Prof Rosa.

The first step in processing a tooth is to cut it into thin slices using a machine with a mechanised circular blade that is sharp and fragile.

“The tooth enamel is the hardest tissue in the body, even harder than bone,” says Prof Rosa.

It takes a lot of training to slice a tooth down to a few millimetres, says Prof Rosa.

The edges are then trimmed so that each tooth slice becomes a small rectangle, which is ideal for some projects. Depending on the project requirements, a slice might be trimmed into an oval or square shape. Each slice can take up to two hours to perfect, he notes.

With a ready supply of extracted teeth, researchers are ready for work.

One of the projects that Prof Rosa has been working on is the use of stem cells from extracted teeth to regenerate tooth pulp – the soft, innermost part of the tooth containing nerves, blood vessels and connective tissues.

While root canal treatments are effective at stopping infection and saving the tooth structure, they remove the pulp and replace it with mostly synthetic materials, leaving the tooth essentially “dead”.

“Dental pulp tissue engineering aims to change that by using natural biological materials to keep the tooth alive and healthy by rebuilding the dental pulp,” says Prof Rosa.

By using stem cells harvested from the pulp of extracted teeth, researchers hope to fill the empty pulp chamber with living tissues that can repair themselves, respond to damage and maintain the tooth’s health.

“This could keep the tooth alive and healthy and capable of fighting off future infections or injuries, unlike current root canal treatments that leave the tooth lifeless,” says Prof Rosa.

He adds that the concept of pulp regeneration is currently being tested in clinical trials across the world, but it will take several years before the procedure is introduced in dental clinics.

Researchers at the NUS Faculty of Dentistry are also working to improve the strength of the bonding materials for dental restorations, like fillings and crowns.

“New materials are constantly being developed and these need to be tested to ensure they adhere well, are durable and safe,” says Prof Rosa.

In five to 10 years, he hopes that the bank will expand its collection to include tissues from biopsies, stem cells and saliva.

“As dental science continues to evolve, the contributions of the Tooth Tissue Bank will remain pivotal in shaping the future of oral healthcare,” says Prof Rosa.