Qiman Gao, Anna Henley and Zixin He are collaborating on a aerosol management project that aims to make dental procedures safer for both patients and dentists during the COVID-19 outbreak


Making your trip to the dentist safer

COVID-19 has made many things trickier – a trip to the dentist, for instance. Students from dentistry and engineering are carefully assessing aerosol spread and they've devised a new system for dental procedures that is safe, affordable and easy to use.

Story by Brenda Branswell

August 2020

Three enterprising McGill students embarked on a timely research project last spring that may prove to be quite valuable as dentists and their patients adjust to the pandemic reality.

The trio are doctoral student Qiman Gao, master’s student Anna Henley, and undergraduate Zixin He.

Drawing on their complementary skills in dentistry and engineering, the three friends developed a low-cost aerosol management system aimed at lowering or preventing the spread of the coronavirus during aerosol-generating dental procedures.

The students are running the project as a team, “but we also have a lot of mentors and supervisors behind us to support us,” says Gao, a PhD candidate in the Faculty of Dentistry and an oral maxillofacial surgeon in China.

In fact, it was her PhD supervisor, Faleh Tamimi Marino, the Faculty of Dentistry’s associate dean of research and graduate dental education, who suggested looking for a solution to manage aerosols to increase safety in dental clinics. He has offered research guidance on the project.

Gao’s co-supervisor, mechanical engineering professor Luc Mongeau, arranged for the team to have access to research facilities during the COVID shutdown so they could work on the project. Dr. Michael Wiseman, a clinical dentist and faculty lecturer in the Faculty of Dentistry, also provided a lot of support for finding space for experiments, says Gao.

The students held their first meeting in mid-April.

“We went through quite a bit of back and forth in terms of designs and more meetings to figure out the needs of dentists,” says He, who is in his final year of mechanical engineering studies.

By mid-May they had a prototype and moved to the testing phase.

The students are trying to raise money for their research on McGill’s Seeds of Change crowdfunding platform. They hope to raise $3,000 to optimize their system, rent better equipment such as an air particle counter, and do more research and testing to validate their system’s efficiency. They also intend to donate their aerosol management system units to charity dental clinics in Montreal.

But there’s more to their work than the physical unit. “The research part is also very meaningful and valuable,” says Gao.

“The plan is to really get accurate data, first about the height and amount of aerosols that are being generated by the aerosol-generating tools that dentists use,” she explains. “And then once we have good data on that, we’ll also try to test our system to really make sure it’s foolproof.”

Their two-part system features a transparent shelf-like shield, which is placed above the patient’s face, and surrounded by an impenetrable material – both designed to limit the spread of aerosols. The shield can adapt to any patient position and any type of dental chair.

The shield has also been designed to be as easy to use as possible for dentists. The assembly process requires no tools and it can be converted for use by both right-handed and left-handed dentists.

The second part of their solution aims to extract aerosols from underneath the shield while a dentist conducts procedures. Using a 3D printer, Henley produced an aerodynamic nozzle, which attaches to the aerosol shield, and fits onto the hose of their suction vacuum system to extract aerosols.

“I have a lot of experience [with] 3D printing,” says Henley, BEng’19, a master’s student in biomedical engineering. As an undergrad in mechanical engineering, she co-founded The Cube, a student-run 3D printing lab in the Faculty of Engineering.

While the students are using a vacuum cleaner with their system for testing purposes, the idea is that their shield and aerodynamic nozzle could hook up to any effective air suction system.

In their initial tests, the students found their system can reduce the aerosol count at the dentist’s position by up to 83 per cent. When used with an additional indoor air filtration system, it can be reduced by up to 96 per cent. (The students will need to repeat tests to confirm their results.)

Wendy Somerville, the Faculty of Dentistry’s infection control specialist, and Dr. Zovinar der Khatchadourian, a clinical dentist and assistant professor of dentistry, both provided input for the project.

Der Khatchadourian praises the students for showing initiative. “They’re really taking the time to measure how much aerosols we produce with regards to hand pieces [drilling] versus scaling, ultrasonic instruments. I think it’s going to be a nice project for us to show what the impact of aerosol is in the dental field. I don’t think there are any precise studies like this.”

Aerosols are created during drilling and teeth cleaning and that’s normal, notes der Khatchadourian. “That’s why we dentists have different infection control guidelines. We wear masks, we wear eyewear, special glasses.” They also use high and low-speed suction and protective rubber dams for drilling, for instance.

The pandemic has necessitated more advanced guidelines for infection control, says der Khatchadourian, who adds it’s not easy for dentists to operate wearing visors and surgical gowns and “all that stuff that comes with it.

“And by the same time token, there’s no real data out there showing us how aerosol is really created in a dental environment and how we can manage that properly. So that’s why I believe there’s going to be several papers published through this project because one of the things we’re looking at is the way aerosols are produced in terms of the quantity and [the] projectile…and how it can have an impact on the dentist and their staff.”

Preliminary data from the students’ research suggests that the ultrasonic scaler, used by hygienists in teeth cleaning, produces mainly droplets from the patient’s mouth, which are heavy and fall much more quickly, rather than aerosols, which float in the air. “Which is very reassuring,” says der Khatchadouri.

She calls the project encouraging on two levels: For shedding more light on aerosols and the fabrication of a device to help dentists contain them, especially during this pandemic, “that is feasible, easy to maintain, not too expensive” and which could possibly be produced on a large scale.

Cost was an important design consideration, according to He, the designer on the team. “It could be easily mass produced,” says He. They used PVC piping, metal conduits and, polycarbonate for the shield. “The parts are ready-made and also if we decide to, say, post blueprints of our system, anyone can go out to their local hardware store and build it.” The cost would be in the $250 range, separate from the air purification system.

For Henley, perhaps the most challenging part of this project was trying to manage expectations from the many stakeholders and clinicians they spoke to who had lots of ideas about what would work best.

“It’s a pretty classic engineering example where you have to hear people and kind of argue for why maybe we don’t need a $5,000 solution.”

Gao is hopeful that their aerosol management system will be embraced.

“I think so, because we designed it according to the dentists’ needs,” she says.

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