A critical appraisal of a scientific paper Analyzing the study’s methodology, data gathering, and statistical analysis.

1. A critical appraisal of a scientific paper
Vaccine against Dental Caries
: An Urgent Need
Presented by Ghada Elmasuri
14-Nov-2013

2. Contents of the paper
 Dental caries is still a major oral health problem.
 Affecting 60-90% of schoolchildren and the vast majority
of adults in most industrialized countries,.
 It is the most prevalent oral disease in several Asian and
Latin-American countries .
 More than 60% of the children aged 5 to 17 years in the US
have decayed, missing, or filled permanent teeth because of
dental caries and 91% of dentate adults have caries
experience.

3. Dental Caries Vaccine
Objective of this paper is supporting the development of
vaccine to prevent and eliminate dental caries.
Development of dental caries vaccine has been under
investigation since1968.
Three factors are assigned to the development of caries
over time
wide group of microorganisms can be isolated from carious
lesions
S. mutans is the main microorganism involved in the
initiation and development of carious lesions.

4. Antigenic components of S. mutans
Mutans streptococci
glucosyltransferases
(GTFs)
N-catalytic sucrose-
binding domain (CAT)
C- glucan-binding domain
(GLU)
cell- surface protein
PAc

5. Antigenic components of S. mutans targeted
by vaccine
GTF-B
GTF
1
GTF-C
GTF
-S-1
GTF-D
GTF
-S
Glucosyltransferase (GTF) is the proteins components “
enzyme” that have been associated with virulence and the
process of tooth surface colonization and adhesion.
In animal models, it was found; S. mutans that have lost
the ability to produce GTF are unable to produce disease.
There 3 forms of glucotransferases and respective genes
:

6. Vaccine hypothesis
Recent studies suggest that oral immunization with GTF,
has the potential to elicit a secretory IgA antibody
response to interfere with accumulation and permanent
colonization of S. mutans on tooth surfaces. This protein
thus can be utilized for vaccine preparation.
Forms of vaccine
highly purified GTF from S. mutans
Whole killed cell of s.Mutans
S. sobrinus cell

7. Vaccine hypothesis
Teeth
S.mutans
GTF
enzymes
GTF
Antigen
IgA
Antibody
Associated with adhesion
Utilized as vaccine
Inhibit to produce

8. Mechanism of Action of Dental Vaccine- 1st
mechanism
 Saliva contains various immune component “antibodies
,immunoglobulins” like IgA, IgG and IgM in which IgA is
the principal immune component.
The salivary IgA react with the bacterial surface
receptors It inactivate surface glucosyltransferase (GTF)
enzyme produced by streptococi resulting in preventing
binding function so inhibiting colonization and subsequent
caries formation.

9. Mechanism of Action of Dental Vaccine-
2nd mechanism
 The second important mechanism involves the migration
of antigen IgA from Gut-Associated Lymphoid Tissues
(GALT) “The digestive tract's immune system” to salivary
glands.
The GALT, has many lymphoid nodules and particularly
Peyer’s patches, are a rich source IgA that have the
potential to migrate and populate distant lymphoid
tissues and the salivary glands then inhibiting the activity
of GTF.

10. Mechanism of Action of Dental Vaccine-
3rd mechanism
 In addition to immunoglobulins” IgA, IgG and IgM ,
saliva also contains various cellular immune components
like;
lymphocytes, macrophages and neutrophils.
On the basis of sufficient evidence, it was found that
after a subcutaneous immunization with S. mutans, the
organism is phagocytosed “ antigenic processing” by
macrophages.

11. Experimental Studies- Animal trails
 Experiments have been conducted by utilizing rodents
and monkeys models.
 Rodents are inexpensive and easy to maintain but the
limitation is the short duration of the experiments
compared with caries development time in humans.
Therefore monkeys have been utilized for achieving the
same results as with the rodents.

12. Experimental Studies- Animal trails
 Immunization of monkeys utilizing a subcutaneous
injection of a highly purified GTF from S. mutans or
whole cells of S. mutans produced a reduction of about
70% in both smooth surface and fissure caries when
compared with controls.
 No increase in antibody titer was detected in saliva
from monkeys orally immunized with enterically coated
capsules containing viable S. mutans or uncoated capsules
containing killed cells of the same organism.

13. Different Routes to Immunization
Human trials
Few human trials in adults have shown that it is
possible to increase levels of salivary IgA antibodies
to interfere with mutans streptococcal colonization .

14. Different Routes to Immunization

15. Active immunization -1- Oral route
 by oral feeding “vaccine-containing capsules or liposomes”
 gastric intubation,
 Oral immunization of 14 subjects with a coated capsule
containing S. sobrinus resulted in an increase in salivary
IgA antibody response when combined with an aluminum
based adjuvant “aluminum phosphate capsule” .
 Oral immunization of 7 adult volunteers with a coated
capsule containing 500 micrograms of GTF from S.mutans
also resulted in elevating in elevating salivary IgA
antibodies.

16. Active immunization -1- Oral route
 Disadvantage: -
 Effects of stomach acidity on antigen
 Rapid breakdown “degredation” of antigenic proteins “ not
long sustained”
 Low absorption
 inductive sites were relatively distant.
 oral immunization with S. mutans is ineffective in
stimulating a secretory IgA response unless combined
with an adjuvant.

17. Adjuvant for the Vaccine
 Mucosal application of antigens by themselves rarely
results in sustained IgA responses.
 Considerable has been expended to develop
immunomodulators (adjuvants) that enhance mucosal
responses to dental caries vaccines.
 Adjuvant is defined as any substance that acts to
accelerate, prolong, or enhance antigen-specific immune
responses when used in combination with specific vaccine
antigens. “have been called the dirty little secret of
vaccines”

18. Types of Adjuvant
1. Synthetic peptides: subcutaneous immunization with a
synthetic peptide derived from the GTF “S. mutans”
enzyme, induced higher levels of serum IgG antibody.
2. Liposomes : as carriers of small drug molecule and
proteins.
 Used in delivery of several drugs particularly anticancer,
to target the cells where it should reach.
 Improve mucosal immune responses by facilitating delivery
of s. mutans antigen to lymphoid elements of inductive
tissue.
 Its efficacy has been found to increase two fold in a rat
model.
 An increase of IgA antibodies have been found in humans as
well .

19. Adjuvant for the Vaccine
3. Recombinant vaccines: oral immunization with the
recombinant Salmonella vaccine was effective in inducing
protection against S. sobrinus in rats.
4. Coupling with Cholera and E. coli toxin subunits: It has
been found that addition of small amounts of “nontoxin
unit” of the Cholera Toxin (CT) or E. coli toxin (LT) can
greatly enhance mucosal immune responses to
intragastrically or intranasally applied s. mutans antigens
and was effective in suppressing the its colonization.

20. Active immunization- 2- Intranasal route
 To induce protective immunity in mucosal inductive sites
that are in closer anatomical relationship to the oral
cavity.
 Targets the Nasal-Associated Lymphoid Tissue (NALT).
 When a formula containing 500 micrograms of GTF from
S.mutanswas administered intranasally to the tonsils,
either in soluble form or incorporated in liposomes,
salivary IgA antibodies were also increased.

21. Active immunization -3- Tonsillar route
 The palatine tonsils and especially the nasopharyngeal
tonsils, have been suggested as potent sites.
 Various trials have shown that topical application of
formalin-killed S. sobrinus cells in rabbits can can induce
the appearance of IgA antibody in both the major and
minor salivary glands and can significantly decrease the
consequences of infection with cariogenic S. sobrinus.

22. Active immunization- 4. Minor salivary gland
 Lips, cheeks and soft palate
 Experiments in which S.sobrinus GTF was topically
administered onto the lower lips of young adults showed
that those who received labial application of GTF had
significantly lower proportions mutans streptococci/total
streptococcal flora in their whole saliva during a six-week
period following a dental prophylaxis, compared with a
placebo group

23. Active immunization -5. Rectal
 Colo-rectal region has the highest concentration of
lymphoid follicles “lower intestinal tract” so this region is
an inductive location for mucosal immune responses in
humans.
 Preliminary studies indicated that rectal immunization with
bacterial antigens such as Helicobacter pylori or
Streptococcus pneumoniae have induced salivary IgA
responses.
 This route use can be an alternative for children who have
a respiratory disorder that prevent intranasal application
of vaccine.

24. Active immunization -6. Systemic route
Studies have shown that
IgG antibodies are well maintained at titre,
IgM progressively fall and
IgA antibodies increase slowly in titre.
Protection against caries was highly associated with
increased serum IgG antibodies.
After subcutaneous administration of S. mutans in monkeys;
IgA, IgG and IgM antibodies were produced, find their way
into the oral cavity via the gingival crevicular fluid and are
protective against dental caries.
The development of serum IgG antibodies takes place within
months of immunization.

25. Active gingivo-7. Salivary route
 To limit the potential side effects associated with the
other routes of vaccine administration, and to localize the
immune response, gingival crevicular fluid has been used as
the route of administration as follows:
 Injecting lysozyme into rabbit gingiva: elicited local
antibodies.
 Brushing live S. mutans onto monkey`s gingiva : failed to
induce antibody.
 Using smaller molecular weight Streptococci antigen
resulted in better performance probably due to better
penetration.

26. Passive Immunization “oral application”
 Is the transfer of active immunity in the form of ready-
made antibodies. “naturally acquired”
 Mouthrinses containing bovine milk or hen egg yolk, IgY
antibody to S. mutans cells led to short-term decreases in
mutans streptococci in saliva or dental plaque.
 British scientists at Guys Hospital in London working on
ways to inject a peptide that blocks S. mutans into fruits.
They have already isolated a gene and the peptide that
prevents the bacterium from sticking to the teeth. They
are trying to find ways to deliver the peptide into the
mouth through apples and strawberries.

27. Passive Immunization
 The latest research in the field of passive immunization is
developing a caries vaccine by generating a hybrid
immunoglobulin A-G heavy chain from four transgenic tree
Nicotiana tabacum.
 Itis colourless and tasteless, can be painted onto the
teeth rather than injected.
 Passive Immunization
 Advantage:
 Avoiding any risks that might arise from active
immunization.
 Cost and of acceptance.
 Disadvantage: The antibodies can persist in the mouth for
only a few hours at most or up to 3 days in plaque.

28. New Fusion Anti-caries DNA Vaccine
Mutans
streptococci
glucosyltransferases
(GTFs).
N-catalytic sucrose-
binding domain
(CAT)
C- glucan-binding
domain (GLU)
cell- surface protein
PAc
anti-caries DNA
vaccine,
pGJA-P/VAX
A fusion of antigenic domains, PAc & GLU
accelerated and increased antibody responses
in rabbits saliva compared with nonfusion DNA
vaccine.
its protective effect against S. sobrinus infection proved to be
weak.

29. Conclusion of the paper
 Dental caries is a major public health problems worldwide
that has a considerable impact on individuals and
communities as a result of the pain and suffering,
impairment of function and reduced quality of life.
 Animal studies suggest that a great promise in targeting key
elements in the molecular pathogenesis of S. mutans wither
through active or passive immunization strategies.
 Therefore, development of dental caries vaccine as
effective prevention measures to integrate any based public
health programs should be a main focus.

30. Paper Critique
General comments
1. Some information are represented in disarranged
and jumbled pattern.
2. Problem in linking and connection between
information.
3. Duplicating the information.

31. Paper Critique
scientific comments
 Author skewed toward caries vaccine
 Vaccine is not an urgent need. “ Title”
 Dental caries has been a problem for humans since
the beginning of time. The earliest recorded
reference to dental caries is from a Sumerian text
(5,000 B.C.)
 The author had over looked the following limitations
of dental caries vaccine :
1. The main target is infants & young children,
immunization should take place prior to infection “in
the second year of life”.
2. Most adults have already experienced dental caries
so good response may not be seen.

32. 3. Caries vaccine is mainly targeting S. Mutans.
 S. Mutans is not the only cariogenic
microorganism “Streptococcus sobrinus, Lactobacillus
acidophilus”
 Scardovia wiggsiae has been isolated in 2010 and
thought to be the main cause of early childhood
dental caries (Dewhirst et al.,2010)
Paper Critique
scientific comments
 This new pathogen, was
present in the mouths
of children with severe
early childhood caries
when other known
pathogens such as
Streptococcus mutans
were absent.

33. 4. Dental caries is multi factorial disease that is
highly related to living conditions, lifestyles and
environmental factors.
5. The issue of safety. Some patients with rheumatic
fever show cross reactivity between heart tissue
antigens and certain Streptococci antigens.
6. Debate similar to fluoride “about its effectiveness
and
number of vaccine received and ways of delivery
Funds to produce a
licensed products and
cost barrier for disadvantaged
children, FDA approval?.
Paper Critique
scientific comments

34. Paper Critique
scientific comments
 Objective of the paper is unrealistic “elimination of
caries”!?
 Its not mentioned number of papers reviewed
 The conclusion of the paper is not sound and doesn’t
answer the main objective and purpose of the paper .
 The author only considered recommendation of by a
‘Panel on Caries Vaccine’ constituted by ‘National
Institute of Dental and Craniofacial Research’ (NIDCR) in
2003.
Most of studies results cited in the paper to support
the paper objective are based on old studies. New
supporting evidences was neglected.

35. References
 History of Dentistry: Ancient Origins, hosted on the American Dental
Association website. Page accessed 9 January 2007.
 Dewhirst, F. E., Chen, T., Izard, J., Paster, B., Tanner, A. R., Yu, W., . . .
Wade, W. (2010 October). The Human Oral Microbiome. Journal of
Bacteriology, vol. 192 no. 19 5002-5017. doi: 10.1128/JB.00542-10
 Downes, J., Mantzourani , M., Beighton , D., Hooper, S., Wilson, M. J.,
Nicholson, A., & Wade, W. G. (2011). Scardovia wiggsiae sp. nov.,
isolated from the human oral cavity and clinical material, and emended
descriptions of the genus Scardovia and Scardovia inopinata.
International Journal of Systeatic and Evolutionary Microbiology, 61(Pt
1):25-9. doi: 10.1099/ijs.0.019752-0. Epub 2010 Feb 5.
 Gross, E. L., Beall, C. J., Kutsch, S. R., Firestone, N. D., Leys, E. J., &
Griffen, A. L. (2012). Beyond Streptococcus mutans: Dental Caries
Onset Linked to Multiple Species by 16S rRNA Community Analysis.
PLoS One, 7(10): e47722. doi: 10.1371/journal.pone.0047722.
 World Conference on Social Determinants of Health (2011). "Rio
Political Declaration on Social Determinants of Health" (PDF). World
Health Organization. Retrieved 2013-03-27.