Plaque Control, Dental Hygiene, and the
Pioneering Work of Charles C. Bass
Adam Blatner, M.D.
"An ounce of prevention is worth a pound of
Most people past the age of 30 begin to have more obvious,
symptomatic gum disease.
Untreated plaque build-up leads to chronic inflammation (as shown
and/or to the right); which leads in turn to a susceptibility to
low-grade infection, breakdown of the tooth enamel leading to
infection and abcess formation, toothache, and tooth extraction.
of alignment that comes with tooth loss irritates the gums and
the other teeth more vulnerable to root decay and infection and
|Arrow points to dental plaque, associated
with swollen and reddened inflamed gums (gingivitis,
People born before around 1920 often began to suffer from
their middle years; they often had the offending teeth pulled and
was common that people sought a partial or full set of dentures
teeth) by the time they were in their 50s or 60s.
Not only was this pattern a source of chronic discomfort, acute
episodes of pain, the financial strain of dental fees, the
discomfort also of ill-fitting dentures, and so forth, but the
teeth or their tenderness led to dietary changes---a loss of
chewier, food---sometimes favorite foods!---, and an increasing
Nor whould we underestimate the subtle loss to the family and
that comes with a person who is in discomfort---grouchiness,
embarrassment at smiling with teeth missing, a tendency not to
bad breath, and so forth. This problem also perpetuated
a subtle stereotype of toothless elderhood as less attractive,
In other words, I used to think most dental problems are due to
cavities, a tooth problem; what's emerging is that most cavities
turn caused by gum problems, even more so in adulthood. There is
mounting evidence that chronic inflammation is associated with low
grade infection, and this in turn may be a factor in the formation
atherosclerosis, heart attacks, and other systemic medical
it is worthwhile to seek ways of understanding and countering gum
Only in the last fifty years have they elucidated the causes of
pervasive condition, and shown that reasonably easy techniques of
regular flossing and brushing can prevent this condition! While
tooth decay is probably inevitable, much of it can be prevented.
Plaque Build-up: The Real Cause of Tooth Decay and Loss in
The picture to the left is an enlarged side view of a tooth with
moderate gum disease. On the far left is a mild
brownish-grey stuff at the tooth edge being calculus, a calcium
build-up from the old secretions of plaque. You don't actually see
plaque in this picture. (It was drawn before scientists
dynamic nature of the bacterial overlay!) The pocket on the left
mild---on the right is moderate---note the depth of the pocket
the gum. Also notice that the top of the gum on the right is
away a bit---part of what they mean by a "receding gum-line."
spongy inflammation under it---why iwhen you begin to floss the
tend to bleed easily. (If you keep flossing and reducing the
irritation, the gums heal and the bleeding subsides---in about two
weeks of regular flossing.)
Also comparing the degeneration on the right as compared to the
you'll notice the bone has shrunken, as chronic inflammation of
will dissolve bone, so there is a tendency to loosenses. You can
that the calculus goes down below the gum-line. The pocket is much
deeper and the peridental membrane is vulnerable to infection and
cavity-producing processes. More, the whole tooth is more
because the gums are swollen. The old joke, "Your teeth are okay
your gums will have to come out" (a line I heard around 1950)
to be kind of true! Not come out, but your gums are what need to
What they discovered about fifty years ago about the nature of
plaque took about twenty
years to get to the dentists and another 20 years to become
with dental hygienists. Even so, it's not explained well: From my
informal research, less than ten per cent of people understand the
actual reasons one should floss! , and most folks today still
know about it.
Here is a cross-section, here’s the chronic inflammation, here’s
infection sets in and side-cavities, leading to deeper abcesses,
need for root canals, crowns, extractions.
It took a good deal of time for the theory which I’ll be
explaining to you
more in a minute or two to get disseminated into the population.
First, the biology of the condition needed to be explored. The
fellow who did this was not a dentist, but rather a physician.
dentist was a pioneer of anesthesia and surgery, so also can a
physician be a pioneer of dentistry.). Interestingly, this
Charles C. Bass, M.D. (1875-1975), is the same fellow who was also
minor pioneer in hookworm research and treatment in the Southern
as noted in that earlier part of this lecture (and on that related
webpage). Bass was on the faculty of the Tulane University Medical
School in New Orleans, where he: (1) isolated the hookworm
and published Hookworm Diseases
in 1909, with Dr. George Dock; (2) first identified beriberi and
pellagra in Louisiana; (3) simplified the method of diagnosing
fever; (4) discovered a method to cultivate the plasmodia
allowing malaria research as never before; (5) developed a
theory for tooth decay based on the idea of plaque control; and
devised a practical nylon-based dental floss and worked out how to
effectively use it. This work was revised and refined further by a
dentist, Dr. Sumter S. Arnim, DDS, and others.
Dr. Bass, shown at left at around age 74 and then closer to his
at 100, continued his professional career for over 70 years, and
the mid-later part of this work, sarting in the 1940s,
he sought to elucidate the causes of tooth decay and came up with
useful approaches. His focus was especiallyinvolved his campaign
treat tooth decay—especially the kind of tooth
decay that was made worse by a lack of plaque control.
Of course, tooth brushing has been around for literally thousands
years. But it doesn’t really do the job where it is needed, which
the gum line. For that you need dental floss: A brief summary
1815 a dentist named Levi Spear Parmly, also from New Orleans,
published a paper recommending flossing, at that time, with silk.
next advance was decades later, in 1892, when the Codman and
Company manufactured human-usable unwaxed silk floss; and not long
thereafter, in 1898, the Johnson & Johnson Corporation
first patent for dental floss.
The next development was in the 1940s when Dr. Bass developed
nylon floss, which was more resilient and stronger than silk.
Around that time, a Dr. D. M. Stephan noted that many types of
combine in dental plaque and their aggregate action excretes
gum-irritating substances---to be described below.
However, it wasn't until the late 1960s that the idea started
effectively disseminated: Plaque control via floss becoming more
prevalent in dentistry. The next challenge is then to sell it to
dental hygeinists and then through them and the dentists, to sell
the public. This is slow-going. Recently, survey shows only about
percent of Americans floss daily, 39 percent floss less than
49 percent do not floss at all.
To re-emphasize the theme of developing underlying technology:
What's needed is a floss that is thin enough to get in
between the teeth, but not so thin that it breaks easily, and
enough to slip and move. Floss wasn’t used much when it was cotton
silk. Technology again breaks through. Nylon not only makes
ladies’ stockings, it makes a stronger and smoother floss!
The Biology of Dental Plaque
As mentioned in the
that there is microscopic life in the scum around the gums is not
and here on the left is a picture drawn around 1600 by Leeuwenhoek
the kinds of germs he was able to vaguely see with his microscope.
67 Let’s look at the nature of dental plaque, to see why flossing
works.First of all, there are more germs in your mouth than there
people on the earth! (Leeuwenhoek made a similar claim, saying
there were more than all the men in the Netherlands! Big
underestimation!) To the right are two picutres that first
the general biofil, and then with a scanning electron microscope,
peculiar "corncob" formation of the way some of these germs
Bass and some others did careful research and discovered that
plaque is not just a layer of germs that can be brushed off. First
all, not just one kind of germ is involved, but over a hundred
different kinds! Here is a cross section (on the left,
electron microscope) of dental plaque against the trooth (again
This is explained more diagrammatically in the picture to the
First the germs lay down a layer of slime against the enamel on
left for stickiness, with these proteins (gold ovals) and other
substances to which they attach. The first layer are different
of dental streptococcus.
This is a very common germ. Hardly any of these are the type that
"strep throat" or rheumatic fever. And more, they alone don't make
much trouble. But they're sticky, and to them attach the other
sometimes other strains or species of streptococcus, forming that
aforementioned "corncob" formation, and often other types. This
process commences anew every time you brush your teeth, building
over twenty-four hours.
See the little strands they put out? They're no longer nice little
round germs minding their own business. You know how when nice
together they sometimes get pretty rowdy? And the lifeguard comes
and yells, "Okay, everybody out of the pool! and they all cool off
quiet down? Well, that's sort of what flossing does. The problem
aggregate, their ecology, because from this aggregate they
waste, just as we heard about with cholera or hookworm, only this
germ poop. It's acidic and it irritates the gums. If it's allowed
stick around, the gums react by becoming more and more inflamed.
The trouble with this aggregate is that the germs near the bottom
that need oxygen can't get enough; they die off; their rotting
are food for the other germ types that don't need oxygen---indeed,
can't stand the stuff!---they're called anerobicc bacteria,
without-air. This physiology is important, because if you can just
air into that pile of sticky germs that is dental plaque, you can
the cycle! That's where flossing comes in.
There are too many germs to get rid of them---you can use all the
mouthwash in the world. The good news, though, is that you don't
to brush and floss after every meal. On the other hand, you do
do it once every 24 hours---doesn't really matter whether it's
or evening. If you delay, that give the build-up of irritating
substances given off by the aggregate time to inflame the gums,
then leads to the other problems of gum and tooth breakdown.
How to Floss Correctly
Run the floss up and down along the gum line, especially
the teeth. The brush should also go up and down. A little
movement is okay, but not really needed, and too much cross-ways
movement then abrades and injures the teeth and gums at that
mainly try to go up and down or gently in a circle. The goal is to
remove some of the plaque, but mainly---this is the key---to break
it up, allow oxygen in the air to penetrate down deep, kill
the anerobes, and interrupt the ecological cycle that
produces gum-irritating acid waste!
(Most people have not had this
explained to them by their dentist or dental hygienist!)
Now if you haven't been flossing regularly, your gums may already
bit (or a lot) chronically inflamed. When you begin to floss, it
will hurt; and the gums will bleed!
Do not use this as an excuse to
Do not think, "Whoa! This must be bad for my gums!" You don't have
floss hard, but do it, break up that plaque, brush, let it bleed a
The irritating source is being removed! The gums will begin to
will take about two to three weeks if you keep at it! Keep at it,
day (or at bedtime. My wife and I read to each other---one read
the other flosses). Gradually the gums will become less tender,
bleeding will lessen, and finally pain and bleeding will stop.
The pockets behind the gums will become shallower. Your dentist or
dental hygienist will be pleased. (Tell them about this webpage!)
in there. Hold on to your teeth!
The healing is not from massaging the gums. And getting food
particles from out between the teeth is not the
therapeutic thing either, though it may help just a tiny bit.
Nor can you fully get rid of the plaque. The
key is to BREAK UP the plaque. If you don’t, the inflammation
continues, the pockets behind the gums
get deeper, there is bone loss, gum death and receding—so your
teeth will end up looking like the picture of later-stage
In the olden days occasionally they diagnosed "gingivitis" (gum
infection), but most folks just thought it was the fault of the
getting rotten. The point of Bass' research, though, is that
sense" is again mistaken. It's the gums that are the problem,
especially right at the gum line—the plaque! So this gave a big
to a new field, "periodontology," the study of the tissues around
(para) the teeth (odont)!
Another reason I particularly enjoy this idea is because it is an
example of how it takes time and patience to break an old habit,
as the habit of not brushing or flossing, and to build a new habit
its stead. Many of you know I'm a psychiatrist interested in
hygiene---prevention---and part of that is to build habits of more
positive and effective types of thinking that then supports the
development of habits of more positive feeling, too.
Acknowledgement: My wife, Allee Blatner, worked in a dental office
in the early 1970s and
taught me about Bass' work and how to floss correctly, stimulated
my reading and got me excited about the way
good dental hygiene can make a big difference in people's lives!)
Christen, A. (April, 1982). Charles C. Bass, M.D.--1875-1975: that
cantankerous genius of preventive dentistry. Bulletin of the History of
Dentistry, 30 (1).
Lott, Wayne (with Steve Brawner). (2004). Dr. Charles Bass
& the Bass Method: One man's crusade to end tooth decay and
gum disease. Lincoln, NE: xLibris. (www.xlibris.com)
O'Hara, J. W. (October, 1991). Prevention revisited: Dr. Bass
meets Dr. Robert F. Barkley. Bulletin
of the History of Dentistry, 39 (2).
Wilson, Michael. (2008). Chapter 8: The indigenous microbiota of
the oral cavity. In: Bacteriology of Humans: An ecological
perspective. Malden, MA (USA) and Oxford, UK:
Interesting photos and diagrams reinforcing points made above.