UW School of Dentistry

Important notice to unvaccinated patients

No COVID testing will be required

On Jan. 6, we announced a change in our treatment policy for unvaccinated patients. These patients would now have to submit a negative COVID-19 test from a medical testing facility – not a rapid at-home test – no more than 48 hours before an appointment. Otherwise, their treatment would be delayed.

However, we also recognize that Seattle-area testing facilities have been pushed to their limit. Getting a test result within this 48-hour window is more difficult than ever.

In addition, we also know that the omicron variant of COVID-19 produces infections faster than any previous variant. Even a negative test cannot guarantee that a patient has not developed an infection between the time of the test and the dental appointment. On top of that, omicron can infect people regardless of their vaccination status.

Therefore, we are dropping the testing requirement for unvaccinated patients. You are welcome to schedule an appointment for any treatment regardless of your vaccination status.

However, we still urge unvaccinated people to get their COVID-19 shots, including a booster if possible. While the vaccines may not prevent a COVID-19 infection, they drastically reduce your chance of death or the need for hospitalization.

We understand how confusing and frustrating this may be. We are operating in a rapidly changing pandemic environment, and we are responding as best we can. Our biggest concern remains your health, and we also want to protect the health of our own dental students, faculty, and staff.

Thank you again for your patience as we continue to deal with the challenges of the pandemic.

Ultra-small, parasitic bacteria found in groundwater, moose – and you

Inside your mouth lives a group of bacteria whose closest relatives can also be found in the belly of a moose, in dogs, cats, and dolphins, and in groundwater deep under the Earth’s surface. In a noteworthy discovery, scientists led by a UW School of Dentistry researcher have found that these organisms have adapted to these incredibly diverse environments without radically changing their genetic makeup, or genomes.

Saccharibacteria are found in humans, a range of other mammals, and in groundwater. The nano-sized parasitic bacteria (stained red) can be seen in the upper right.
Saccharibacteria are found in humans, a range of other mammals, and in groundwater. The nano-sized parasitic bacteria (stained red) can be seen in the upper right.

The organisms are members of the TM7 family, also known as Saccharibacteria. These are ultra-small parasitic bacteria with small genomes that belong to a larger group called the Candidate Phyla Radiation (CPR). These CPR bacteria are referred to as “microbial dark matter” that represent more than 25 percent of all bacterial diversity, yet we know very little about them since the vast majority have defied attempts to culture them in the lab.

In research first published as a pre-print in 2018, and now formally in the journal Cell Reports, scientists describe their findings that Saccharibacteria within a mammalian host are more diverse than ever anticipated. The researchers also discovered that certain members of the bacteria are found in the oral cavity of humans, the guts of other mammals, and in groundwater. While these environments are all very different, the bacteria’s tiny genomes remain minimally changed between humans and groundwater. This indicates that humans acquired the bacteria more recently, on an evolutionary timescale.

“It’s the only bacteria we know that has hardly changed when they adapted to humans,” said Dr. Jeffrey McLean, a microbiologist and associate professor of periodontics at the School of Dentistry, and lead author of the paper.

The TM7 bacteria were a complete mystery to scientists until Dr. Xuesong He first isolated the bacterium TM7x, a member of CPR, in 2014. Dr. He is co-author of the paper and associate staff member at the Forsyth Institute of Cambridge, Mass., a leading center of dental and craniofacial research. Since then, researchers have learned that CPR includes a huge number of different bacteria, all with tiny genomes. These bacteria need a host to survive and are unique in that they can’t make their own amino acids and nucleotides, which are essential building blocks for life.

“I see this as a huge discovery,” said Wenyuan Shi, CEO and chief scientific officer at the Forsyth Institute and also co-author of the paper. “This creature survives in both humans and groundwater, which indicates there are similarities that allow these bacteria to adapt to humans.”

Previous research by another co-author, Dr. Batbileg Bor of the Forsyth Institute, showed that TM7 can easily jump from one bacterial host to another. This could explain how they ended up in mammals, since mammals drink groundwater.

“The most likely reason we see a large diversity of these bacteria in humans, yet one group of bacteria remains nearly identical to those in groundwater, is that some groups were acquired in ancient mammal relatives and they expanded over time across mammals, whereas this one highly similar group more recently jumped directly into humans,” Dr. McLean said.

TM7 and other ultra-small, parasitic bacteria within CPR may play important roles in health and disease that we have yet to discover. Since they act as parasites – living with and killing other bacteria – TM7 could change the overall microbiome by modulating the abundance of bacteria, Dr. McLean said. Scientists are just scratching the surface of understanding how much our microbiome, which is the human body’s full microbial population, impacts our overall health. TM7, for one, thrives under the conditions found in oral diseases such as gingivitis and periodontitis.

Another major contribution of this research has been developing a systematic way to name these newly discovered bacteria, setting the foundation for classifying other isolated strains.

The discovery that humans acquired TM7 recently has broader implications for understanding our co-evolutionary pathways with the microbes that live on and within us.

“There are only a couple hundred genes that are different in these ultra-small bacteria between what lives deep in the subsurface environment and those that have become common bacteria in our mouths,” Dr. McLean said. “That is a remarkable feat for bacteria missing so many genes and has to make a living by feeding off other bacteria.”

UW researchers learning how to fine-tune immune response

A pair of studies led by University of Washington researchers has cast important new light on the body’s response to viral or bacterial invaders. In particular, they are learning how that immune response might be controlled to target the response more tightly and limit the collateral damage on this biological battleground.

When a microorganism or toxin enters the body, the immune system swings into action, sending white blood cells known as lymphocytes to fight the invaders. T-cells and B-cells, which are specialized forms of these lymphocytes, attack the source of infection. But in the course of this fight, the T-cells also spur inflammation, which can severely damage tissue. Some of these T-cells are also critical for tissue repair and resolving inflammation, but it has remained unclear if the balance can be tipped to favor tissue repair over inflammation.

The CCR5 protein, which is stained green in this slide, acts like a GPS device for the cells of the immune system, steering them around tissues.
The CCR5 protein, which is stained green in this slide, acts like a GPS device for the cells of the immune system, steering them around tissues.

Now, Dr. Douglas Dixon, Dr. Martin Prlic, and their research colleagues are advancing our knowledge of how to possibly tip the balance of these T-cells to limit the collateral tissue damage. Dr. Dixon is a clinical associate professor of periodontics at the School of Dentistry, and Dr. Prlic holds faculty appointments in the Molecular and Cellular Biology Program at the UW and at Seattle’s Fred Hutch Cancer Research Center.

“We’re gaining a better understanding of chronic inflammation,” Dr. Dixon said. “The possibilities include localized treatment to block inflammation or turn up the immune response, depending on the need. You can design a molecule to bind to a receptor and turn it on or off as needed.”

A key finding has been that while the body rushes reinforcements to the site of an attack, they may not be needed – the defenders already residing at the site may be able to handle the job. Most importantly, these defenders also have the ability to rebuild tissue. That’s what the researchers discovered in a study published in the Science Translational Medicine journal. They investigated a protein called CCR5, which acts as a GPS for cells of the immune system and guides them around tissues but can also be a “back door” for HIV to enter and spread throughout the body.

Anti-HIV drugs that work on blocking CCR5 to prevent infection also block that GPS function. However, the researchers found that the T-cells already residing in the tissue aren’t affected.

“So if you block new T-cells from entering the site of the infection, you may be able to prevent damaging inflammation while the resident T-cells handle the infection and carry out repair functions,” Dr. Dixon said.

A second study, published in the ImmunoHorizons journal of the American Association of Immunologists, focused on the MAIT cell, an unusual type of T-cell that can sense the presence of bacteria.

MAIT stands for mucosal associated invariant T-cell. When one of these cells are exposed to inflammation, they quickly generate-the protein CTLA-4, which the researchers say is basically an “off” switch for the immune response.

“Now we’re working on identifying ways to turn these cells on and off for therapeutic purposes,” Dr. Dixon said.

Drs. Dixon and Prlic are studying how inflammation is regulated in oral tissues, but the implications are wide-ranging. Chronic inflammation has been implicated in many illnesses ranging from gingivitis to heart disease. However, Dr. Dixon said, inflammation is not necessarily a bad thing at a sufficiently low level. “There’s always a background level of inflammation in the mouth and the gut,” he said, adding that it’s actually a protective “sentinel state.”

“But some patients’ immune system just can’t resolve or respond appropriately during an infection, and we’re trying to figure that out,” he said. “You can’t have an unbridled immune response – there would be massive tissue destruction. The challenge is to know how to turn immune cell functions off and on as necessary.”

Using their discoveries, Drs. Dixon and Prlic recently applied for additional National Institutes of Health funding to support the development of therapies to halt chronic inflammation and induce tissue repair.

“I am excited to keep working with Doug on trying to figure out how we can best tweak the immune response to resolve inflammation and enhance tissue repair,” Dr. Prlic said.

Honorary society recognizes outstanding students, faculty

The School of Dentistry’s chapter of Omicron Kappa Upsilon (OKU), which is the dental equivalent of Phi Beta Kappa, inducted seven new student members and two faculty members on May 22.

2019 Inductees
Flanked by Dr. John Evans (far left) and Dr. Greg Huang and Dr. Natasha Flake (at right) of the School of Dentistry faculty, the inductees from the Class of 2019 are (from left) Kerry Streiff, Anoop Gill, Anmol Gill, Lauren Blanchard, Mari-Alina Timoshchuk, Stephen Siew, and Elizabeth Floodeen.

At the Sigma Sigma chapter’s annual dinner at the UW Club, scholarships also were awarded to six students, while another student received OKU’s annual award of excellence.

Faculty member Amy Kim inducted
Dr. Amy Kim (center) is inducted by Dr. Flake and Sandy Phillips of the School of Dentistry faculty.
Dr. Richard Presland (center) is inducted by Dr. Daniel Chan and Dr. Flake of the faculty.
Dr. Richard Presland (center) is inducted by Dr. Daniel Chan and Dr. Flake of the faculty.

Robert Rosenthal receives the Dr. William S. Kramer Award of Excellence from Dr. Flake and Dr. Randy Maebo of the faculty.

The student inductees, all from the graduating Class of 2019, were Lauren Blanchard, Elizabeth Floodeen, Anmol Gill, Anoop Gill, Stephen Siew, Kerry Streiff, and Mari-Alina Timoshchuk. Dr. Amy Kim of the Department of Pediatric Dentistry, who also holds an appointment in the Department of Periodontics and is associate director of the Regional Initiatives in Dental Education (RIDE) program, was inducted as a faculty member. Dr. Richard Presland, graduate program director of the Department of Oral Health Sciences, was inducted as an honorary member.

Robert Rosenthal, a RIDE student in the Class of 2021, received the Dr. William S. Kramer Award of Excellence. The award recognizes a rising third-year student who has demonstrated scholarship, character, and the potential promise for advancement of dentistry and service to humanity.

Standing with Dr. Flake and Dr. Andy Marashi (far right) of the faculty are the OKU scholarship recipients (from left): Asher Chiu and Samuel Snipes of the Class of 2021, Calvin Panah and Fang Sun of the Class of 2022, and Nadia Grishin and Kayla Casebier of the Class of 2020.
Standing with Dr. Flake and Dr. Andy Marashi (far right) of the faculty are the OKU scholarship recipients (from left): Asher Chiu and Samuel Snipes of the Class of 2021, Calvin Panah and Fang Sun of the Class of 2022, and Nadia Grishin and Kayla Casebier of the Class of 2020.

Dr. Jon Suzuki of Philadelphia’s Temple University, professor of microbiology and immunology in Temple’s School of Medicine and professor of periodontology and oral implantology in its School of Dentistry, presented the keynote speech, relating lessons he had learned over the course of his career.

Dr. Jon Suzuki
Dr. Jon Suzuki
Interim Dean Gary Chiodo, who is an OKU member, welcomes guests at the dinner.
Interim Dean Gary Chiodo, who is an OKU member, welcomes guests at the dinner.

OKU scholarships went to Kayla Casebier and Nadia Grishin of the Class of 2020, Asher Chiu and Samuel Snipes of the Class of 2021, and Calvin Panah and Fang Sun of the Class of 2022.

Dr. Gary Chiodo named interim dean

Dr. Gary Chiodo of Oregon Health & Science University has been appointed interim dean of the University of Washington School of Dentistry, effective Aug. 1, UW President Ana Mari Cauce and Provost Mark Richards announced Monday.

Dr. Gary ChiodoDr. Chiodo is assistant director of the Center for Ethics in Health Care and professor emeritus in the Department of Community Dentistry at OHSU. He succeeds Dr. James Johnson, who stepped down as interim dean in April and resumed his earlier duties as chair of the Department of Endodontics.

“Dr. Chiodo is a highly respected and capable dental education leader who will provide the focused, knowledgeable, dedicated and collaborative leadership needed by the School of Dentistry at this time,” Cauce said. “We are confident that he will engage faculty, staff, and students in transforming the School into an organization that is committed to excellence, accountability and sustainability.”

From 2012 to 2014, Dr. Chiodo served as interim dean at the OHSU School of Dentistry, where he worked to solve financial challenges. He is expected to serve as interim dean for at least two years before the university conducts a search for a new permanent dean.

From 2014 to 2017, Dr. Chiodo served as vice president and system compliance officer/organizational integrity with PeaceHealth, a non-profit chain of hospitals, medical clinics and laboratories located in Alaska, Washington, and Oregon. At OHSU, he has been a longtime faculty member in the Department of Public Health Dentistry, earning promotion to full professor in 1992.

Dr. Chiodo served as OHSU’s Chief Integrity Officer from 2000 through 2011, overseeing health care compliance, human and animal subject research, environmental health and radiation safety, institutional biosafety, conflict of interest, audit and advisory services, information privacy and security, and compliance education.

Dr. Chiodo received his bachelor’s degree in biology from Portland State University in 1974 and his DMD from the University of Oregon Health Sciences Center in 1978. He earned a Certificate in Health Care  Ethics from the UW School of Medicine in 1992.

For two decades at the start of his career, he practiced at a Portland public health dental clinic that treated the majority of identified HIV-positive persons in Oregon and southwest Washington. He has served on state and national committees related to public health, ethics, and infectious diseases. He has lectured internationally on these issues and has published more than 100 related peer-reviewed articles. In 2002, he was elected as a Fellow of the American College of Dentists.

He has also served on committees with the Oregon Health Division, the Oregon Health Authority, and on the board of the Oregon Public Health Association, and has held membership in the American Dental Association, Academy of General Dentistry, and Oregon Dental Association. He has received OHSU’s Distinguished Faculty Award for Leadership and the Ecumenical Ministries of Oregon HIV Honor Award.

“I am sincerely honored to be joining the University of Washington School of Dentistry leadership team at a critical time of transformation,” Dr. Chiodo said. “The school has consistently been rated as one of the very best, nationally and internationally.  It is my intent to firmly secure that rating and continue to drive us forward.  We certainly have challenges to address as we resolve operational issues and improve our infrastructure.  After meeting with department chairs, faculty, staff, students, and UW executive leadership, I am confident that we are well prepared to meet these challenges.  I will be an enthusiastic partner in this effort.”

In recent years, the School of Dentistry has won national attention for its innovative new curriculum. The school’s last two graduating classes have recorded composite scores on the clinical proficiency portion of the national dental board examinations that placed them among the nation’s top two or three classes. This year, the school was ranked No. 14 in the world and moved up one spot to No. 4 in the United States in Britain’s Quacquarelli Symonds World University Rankings.

UW dental volunteers to boost Special Olympics screening program

Special athletes deserve special care, and the University of Washington School of Dentistry will help make sure that happens at the upcoming Special Olympics Summer Games around and near Seattle.

Faculty, staff and students volunteers from the school will be out in force July 1-6 to support the Special Smiles dental screening program at the landmark 50th-anniversary games.

2 runners on track
More than 4,000 athletes, coaches, and families are expected for the 50th-anniversary Special Olympics in Seattle.

Part of the Special Olympics Healthy Athletes program, Special Smiles screenings can include oral hygiene instructions and goodie bags, mouth guard fabrication, fluoride application, and a dental  evaluation. Athletes will be told if they have an urgent or emergency dental need, and the screeners will try to connect them with care. The screenings will also be used to collect information that may help attract funding for treatment and research.

With more than 4,000 athletes, coaches, and families expected for the games, it will be a massive undertaking. It will also help focus attention on the importance of oral health for people with special needs, says Dr. Kimberly Espinoza, who is leading the School of Dentistry’s volunteer effort.

“Oral health is important for everyone, but unfortunately, people with developmental disabilities have difficulty accessing oral health care and have higher rates of untreated dental decay and gum disease,” says Dr. Espinoza, a member of the Department of Oral Medicine faculty and director of the school’s Dental Education in Care of People with Disabilities (DECOD) program.

Dr. Travis Nelson, a faculty colleague in the Department of Pediatric Dentistry who is also helping the volunteer effort, adds: “The lives of children and adults with disabilities are complicated by a wide variety of physical and behavioral conditions. This can make receiving dental care and maintaining good oral health a challenge.”

The Special Smiles program has been a major asset to researchers, Dr. Espinoza says, since it has the largest database on the oral health of people with developmental disabilities. And it clearly shows that dental issues are a widespread problem.

“Special Olympics data show high rates of oral pain among athletes in addition to untreated dental decay,” she says. The Special Smiles screenings have found that a large number of the athletes are unaware of the condition of their oral health:

  • 46 percent have periodontal conditions.
  • 36 percent have untreated tooth decay.
  • 14 percent need urgent care.
  • 12 percent have dental pain.


Improving oral health and access to dental care for people with special needs requires the support of the entire dental community, she adds, but that’s more easily said than done, according to Dr. Nelson.

“Children and adults with disabilities make up a significant portion of our population, yet dental providers are often anxious about providing care to these patients, and caregivers often face difficulty finding providers to care for their child’s oral health,” he says.

Reiterating the prevailing thought among dentists, Dr. Nelson says that all patients should have access to a dental home, which is a steady and continuing source of oral health care. “The Special Smiles program focuses on screening patients for dental disease and facilitating connections with providers who can provide comprehensive dental care,” he says.

“While disability may impact health, it isn’t necessarily synonymous with poor oral health,” he adds. “Special Olympics and the Special Smiles program are a great way to help athletes access oral health services. In turn, this can improve the individual’s overall quality of life.”

The dental volunteer organizing efforts have received a boost from the American Academy of Developmental Medicine and Dentistry (AADMD), Dr. Espinoza says. The AADMD’s Special Olympics Coordinator, Stephanie Clark, “has been doing an amazing job of recruiting students to participate in the 2018 USA National Games here in Seattle,” she says. In addition, Dr. Espinoza says, the UW’s AADMD student chapter has been especially active this year, already having completed two other Special Olympics Special Smiles events.

A greener smile is a good thing

Thanks to an enterprising UW undergraduate, School of Dentistry clinics will help make the world a little greener while making patients’ smiles brighter.

Bamboo ToothbrushIsabelle de Mozenette, who graduated on Saturday in the College of Built Environments, approached the school early this year with a plan to replace some of the plastic toothbrushes handed out to patients with ones that have bamboo handles. She quickly gained the approval of Dr. Ricardo Schwedhelm, Associate Dean of Clinics, and then worked with Dr. Diane Daubert of the Department of Periodontics faculty to implement the plan.

De Mozenette majored in Community, Environment, and Planning, with a focus on environmentally sustainable business. Her idea, she said, originated last winter in a class called Attaining a Sustainable Society.

“My teammates and I thought that dentists handing out free bamboo toothbrushes to their patients instead of plastic ones would be a really good example of businesses using the power and the impact that they have for good,” she said, “and for setting a norm by communicating to their patients that they value patient safety as well as environmental sustainability.” The idea soon evolved into her senior project.

De Mozenette secured grants to purchase the toothbrushes, which she obtained from the Seattle company SenzaBamboo. The company uses wild bamboo grown with no pesticides or fertilizer, and says  the variety is one that pandas do not eat, and thus are not deprived of a food source. While other companies make bamboo toothbrushes, SenzaBamboo stood out not only because of its local nature  but because it donates part of its profits to the Mary’s Place women’s shelter in Seattle.

The bamboo handle holds up well beyond the three months’ maximum that dentists recommend patients use a toothbrush before discarding, but then biodegrades in a natural environment or in a commercial composting facility, de Mozenette said.

The brushes were given to Dentistry faculty and staff as part of a “goodie bag” that also included sample-size toothpaste and compostable dental floss. Although the pilot project was set up for spring quarter, de Mozenette recently purchased another $900 worth of toothbrushes that will allow patients to receive them during the summer as well.

She also offered a parting plug for the green initiative, directed at School of Dentistry alumni and other dentists: “If they want to be more sustainable in their own personal practices, then they can order from SenzaBamboo and get the same wholesale price of 70 cents per toothbrush.”

Student competition winners announced at Research Day

At the School of Dentistry’s annual Research Day on Tuesday, Kristie Cheng was announced as the winner of the Summer Research Fellowship (SURF) Student Clinician Competition. Cheng, a second-year dental student, presented a study of factors affecting citation rates in oral and maxillofacial surgery.

Kristie Cheng
Second-year dental student Kristie Cheng won the Summer Research Fellowship Student Clinician Competition.

Runners-up in the SURF competition were second-year dental students Taylor Wilkins and Mark Van Duker. Wilkins presented a study of genotype-dependent T2R38 regulation of epigenetic markers and antimicrobial peptides, while Van Duker studied the effect of silver diamine fluoride and potassium iodide on bonding to caries-affected dentin.

Dr. Jevin West of the UW School of Information delivered the Research Day keynote talk, titled “Sorting Evidence from BS in the Age of Evidence-Based Dentistry,” at the start of the day’s activities in the UW’s South Campus Center.

He told students that even when they don’t know how an algorithm or a statistical test works, they can spot research flaws by looking carefully at what goes in and what comes out of a study.

Jevin West
Dr. Jevin West of UW’s Information School delivered the Research Day keynote talk.

He focused closely on the issue of causality and warned of the dangers of confusing a simple common cause with cause and effect. He also noted that correlations may not be prescriptive in research, but they turn out that way as a research proceeds from an original paper to the news and public awareness. As an example, he cited findings that moderate wine consumption may be associated with a reduced risk of heart disease, which somehow became a popular prescription to drink a glass with dinner to reduce the chance of heart disease.

He also discussed “post hoc ergo propter hoc,” the logical fallacy stating that since one event follows another, the second event must have been caused by the first. This fallacy is especially prevalent in medicine, he said, citing the contention that vaccines caused autism – a widely discredited assertion that nevertheless has caused thousands of preventable deaths.

He cautioned students to guard against this fallacy and said that the best way to determine true causality was through manipulative experimentation – changing variables and studying carefully how they affect outcomes. A key question, he said, would be to ask whether causality was direct or mediated by a common cause.

He also called on students to support efforts to spread public awareness. “Science works, but given the amount pseudoscience out there, we need to engage with the public,” he said.

Other presentations were given by Dr. Greg Huang, Chair of the Department of Orthodontics; Dr. Brian Leroux of the Departments of Oral Health Sciences and Biostatistics; and Dr. Philippe Hujoel of the Department of Oral Health Sciences.

After the morning’s talks, student research poster presentations followed in the UW’s Health Sciences Center lobby.