Transcript Three Guys and a Girl

A New Front in War on Cavities
Aaron Madison
Takeaki Murakami
Alyssa Merrick
Anthony Meyer
 Cavities declined in the 70s and 80s and appeared to hit a low
around the mid 90s
 According to data from Centers for Disease Control and
Prevention, only 24% of children had cavities in mid 90s
 In more recent years, a survey has found that 28% of
children had cavities
 Reasons are unclear for the significant increase, but may be due
to children drinking more bottled water that doesn’t contain
fluoride, and to changes in dietary habits
 Scientists have found that not all mouth bacteria are harmful
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but they are currently trying to identify the worst pathogens
and stop them
Dennis Cvitkovitch, director of the Dental Research Institute
at the University of Toronto, has been probing deep into the
genetics of Streptococcus mutans, which has been
consistently implicated in causing cavities.
He identified S. mutans genome affects its ability to join
together with other bacteria
They found that it temporarily restrains the buildup of plaque
This discovery could someday lead to a decay fighting
additive for mouthwash and certain foods
So Many Places to Hide!!!
 Bacteria is hard to kill permanently because it contains so
many different species and crevices where they can hide.
 Within three to four hours of brushing or using mouthwash,
the microbes begin to multiply again.
 Bacteria works in groups communicating with each other
about where they have settled and ask other bacteria to join
them through direct contact by sharing nutrients and by
emitting small signaling molecules.
Preparing for Pathogens
 The first bacteria called colonizers do not cause harm alone
but they pave the way for other microbes, like S. mutans, that
promote tooth decay.
 When bacteria joins together with plaque they are more
difficult to remove with brushing and to kill with
mouthwash. There are some pathogens such as Lactobacillus
Casei, that accelerate tooth decay.
 Dr. Cvitkovitch’s goal is to interrupt communication among
bacteria.
 He hopes that will lead to a more targeted and effective way
of killing the pathogens or controlling the damage they cause.
His lab is working on “understanding intimate
communication between bacteria and finding ways to stop
plaque from binding so well.”
Virulent Characteristics
 S. mutans was chosen by scientists because its good at
converting sugars into lactic acid which eats away at tooth
minerals. It also makes a sticky substance that helps form the
glue that holds plaque together.
 The researchers identified a small sequence of amino acids on
the S. mutans DNA that encodes a peptide which appears
responsible for much of the bacteria’s communication ability.
Urging Microbes to Die!!!
 S. mutans cells begin to die off when the concentration of
CSP, the peptide that is responsible for the communication
ability, rises above a certain level.
 To test their thesis that CSP could be used to influence the
bacteria’s ability to form plaque, they constructed a
compound that closely relates to CSP.
 Although results remain unpublished, the analog appears to
temporarily reduce plaque by as much as 40%.
 Animal clinical trials of the CSP analog are expected to begin
in the spring.
 Other research efforts are focusing on other bacteria that
reside in the mouth.
 Some scientists are focusing on “good bacteria” and the
efforts are aimed at figuring out how to promote these
bacteria and prevent the environment from becoming
diseased.
 Some other scientists are focusing on the gum-diseasingcausing strains. They hope to learn how to jam their
communication signals, disrupt their feeding and prevent
their ability to attach to other bacteria.
TIPS FOR GOOD ORAL HYGIENE
 Tooth brushing
 Brush twice daily with fluoride toothpaste to remove plaque on tooth
surfaces
 Parents should help small children
 Flossing
 Floss daily to remove plaque and food between teeth and under gum
line
 It doesn’t matter if you brush or floss first
 Other tips
 Eat a balanced diet and limit snacks in between meals
 Get regular professional check ups and cleaning every 6 months to
reduce hard to reach plaque