Tooth decay may result from immune response, not just bacterial plaque

U of T researchers find evidence for maverick theory first published in 1970

Tooth decay may result from immune response, not just bacterial plaque

Cavities in teeth may result from an immune system response, not just bacteria, according to a recent U of T study. This counters decades of established thinking in dental research.

In 1970, Dr. John Gabrovsek of the Cleveland Clinic published research in the Journal of Dental Research that found that our immune system may contribute to dental cavities. But during the almost 50 years since it was published, most dental researchers have not taken Gabrovsek’s theory seriously — until U of T’s findings were published in April.

The research was spearheaded by Dr. Yoav Finer and Dr. Michael Glogauer, both professors at the U of T Faculty of Dentistry.

“Glogauer approached me a few years ago, [and] told me that these immune system cells have the same enzymes and more enzymes than bacteria have, so why not check them?” Finer explained to The Varsity.

The research team began by examining immune cells called neutrophils. Neutrophils are a type of white blood cell routinely found in the mouth, and they act as the first line of defense against harmful bacteria.

However, as these immune cells fight against harmful pathogens that can damage teeth, they can also cause collateral damage to what they are originally trying to protect — our teeth.

While bacteria still cause most of the damage that results in tooth decay, Finer explained that the research team has found evidence that these immune cells also contribute to cavity formation.

How the research team arrived at the discovery

Through years of study, the team created samples from extracted teeth and then used acid to remove minerals from them.

The application of acid mimicked the effect that harmful bacteria have on teeth, as the acid they release causes tooth decay.

The researchers then isolated neutrophils from human volunteers and kept them at a warm temperature with the extracted teeth.

“That was a daily procedure because you can’t culture these cells — neutrophils — unlike bacteria,” said Finer. “You need to get these cells isolated from the blood donors on a daily basis or every other day.”

The team found that while these immune cells help protect teeth from damage caused by bacteria, they can also remove minerals from tooth dentin, as well as break down white-coloured tooth fillings.

A possible explanation for why neutrophils can degrade teeth, according to Finer, is their enzymes — biological molecules that speed up chemical reactions. However, it remains unclear which type of enzyme could be responsible for contributing to dental decay.

Applications of the research findings

Protecting our teeth is important, as dental diseases can affect not just our mouths, but our overall health. For example, bacteria that cause gum disease can lead to infections of our lungs and increased risk of blockage in arteries that can damage our hearts.

Glogauer’s research team has been developing a mouth rinse that could prevent some of the degradation caused by these immune cells to apply the findings to clinical dentistry.

Finer’s research team has also been developing a dental varnish that contains anti-degradative factors to help counteract the effect of both bacteria and neutrophils on teeth.

However, preventing tooth decay ultimately comes down to maintaining good oral hygiene.

“With a recommended toothpaste and toothbrush, keeping good oral hygiene is the key,” explained Finer. “It’s our first line of defense and can eliminate a lot of problems… the immediate thing is making sure you keep your sugar consumption under control.”

Academizing the anti-#MeToo movement

The baseless fear of false accusations and avoidance of women in academia helps no one and hurts everyone

Academizing the anti-#MeToo movement

Content warning: references to sexual violence.

A few weeks ago, the swearing-in of Judge Brett Kavanaugh as a Supreme Court Justice not only filled the court’s ninth seat, but introduced a worrisome shift in American culture: a legitimization of the fear of false sexual allegations.

The #ProtectOurBoys movement is a testament to this troubling phenomenon: mothers, sisters, daughters, cousins, and friends alike are banding together to resist, in their perception, the threat of false accusers waiting to attack their male family members or friends. Even the President of the United States attests that “it’s a very scary time for young men.”

This is a dangerous ideology, as it portrays survivors in a warped light — that the ones who experience and come forward about sexual violence despite their own fears are the real threats. Unfortunately, this perverse phenomenon is spreading into academia.

In a recent piece for The New England Journal of Medicine, U of T-affiliated researchers, including Deborah Gillis, Sophie Soklaridis, and Catherine Zahn, wrote that men in academic medicine are shying away from mentoring women for fear of being falsely accused of sexual harassment. The #MeToo movement is sadly being used to justify the unjustified fear of lying women.

Indeed, these fears are completely baseless because false accusations are statistically rare. The National Sexual Violence Resource Center found that false accusations account for between two and ten percent of reports. Moreover, the reports themselves are labelled as “inconsistent definitions and protocols” by the Center.

In Pacific Standard, Emily Moon wrote that “researchers relying on federal data often conflate ‘unfounded’ reports — when law enforcement labels an accusation false or ‘baseless’ — with entirely false ones.” This means that there are ‘false allegations’ that aren’t really false at all, but instead just don’t meet legal criteria.

It can be concluded from this, then, that the wide statistical range of two to 10 per cent leans, in fact, toward the lower end. The point is that survivors who come forward are almost certainly telling the truth about their assailant. A man who has behaved professionally his entire life has nothing to worry about. Therefore, men who are fearful feel this way because of a culture and system that supports their victim status — not because there is any empirical backing or rationale behind their fear.

One possibility is that men who refuse to mentor women are not scared of the prospect of false accusers, but rather because their own behaviour is no longer acceptable. As psychiatrist Prudy Gourguechon wrote in Forbes, “The essence of maturity is to be able to control and moderate sexual and power-related impulses in a context where they are not warranted. Like at work.” She explained how most men do not have to actively think about this control, because it’s subconscious. By default, they view the people they work with as respected co-workers or friends.

However, some men do worry — implying that they have heretofore viewed their female colleagues in a non-professional, non-friendly way, and that this outlook might now have consequences. Rather than professionally adjust their interactions and behaviours with women in an era where women are more likely to come forward, they choose to avoid them.

This response is detrimental to women. Currently, men dominate leadership roles in academia. According to University Affairs, in Canada, only 36 per cent of associate professors and around 22 per cent of full professors are women. For many women hoping to advance and develop within their academic fields, mentorship is a crucial asset.

The refusal of mentorship based on unfounded fears, then, hinders women’s chances in career advancement. Furthermore, they cannot close the disproportionate gender gap in leadership positions if they aren’t given the tools and assistance to do so.

Evading women in academia is also the least constructive solution for men who fear false allegations. It judges and reacts to the #MeToo movement by its false cover: a supposed male witch hunt. These men will never learn the important lessons that the movement is trying to teach — namely, how to treat women properly, especially in professional contexts.

Listening to, instead of avoiding, the movement would also make it clear that women are not the only people who are sexually assaulted. Men, too, can be victims of sexual violence. Consider the fact that, according to the Sexual Assault Centre Hamilton Area, one in six men will experience some form of sexual violence in their lifetime. Secluding yourself to only interacting with men is not protecting yourself — it is making a deluded assumption about how sexual assault works.

Fear and avoidance are also problematic because they put the onus of sexual assault on women in academia to not accuse others of sexual assault — instead of on the assailant to not assault women in the first place. It is not the woman’s fault if she is assaulted, and bringing her story forward is not an attack on the assailant but a call for justice and a change in culture.

Avoiding women also makes it difficult for women who have been assaulted within academic contexts to come forward, when the consequences for their fellow female academics is not only a more tense environment, but also fewer career opportunities. The act presents itself as a punishment for being a woman within the workplace and for being a woman who is assaulted within the workplace.

The final truth is that false accusations are rare, precisely because they rarely benefit the accuser in any way. Telling the world that you were assaulted isn’t a trophy to put on the shelf. For Christine Blasey Ford, her alleged assailant is a Supreme Court justice. She has had to deal with death threats, insults, and a life that has been uprooted with no result.

Men must learn that the #MeToo movement is not about living in fear; it is about changing the way that people are treated, and about making every environment safe for everyone. It is ultimately asking that they see everybody, especially women, as human beings — not as sexual objects, and certainly not as monsters lurking around the corner, waiting to attack you.

Nadine Waiganjo is a first-year Social Sciences student at University College.