Perio
Reports Vol. 22 No. 3 |
Perio Reports provides easy-to-read research summaries on topics of specific interest to clinicians.
Perio Reports research summaries will be included in each issue to keep you on the cutting edge
of dental hygiene science.
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Bad breath might inhibit
bone regeneration
The two primary volatile sulphur compounds (VSCs) causing
bad breath are hydrogen sulfide and methyl mercaptan.
VSCs are toxic compounds that cause pathogenic changes in
periodontal tissues. VSCs strongly suppress the synthesis of gingival
collagen cells through several means, including apoptosis,
which is programmed cell death or cell suicide.
Using animal models, researchers have reported that hydrogen
sulfide passes through non-keratinized sublingual mucosa in
30 minutes, allowing it to reach the alveolar bone surface
quickly. Hydrogen sulfide also increases the permeability of the
sulcular epithelium and breaks down basement membrane cells.
With increased permeability, bacterial toxins including
lipopolysaccharide and prostaglandin can move through the
epithelium and into the connective tissue, triggering the periodontal
pathogenesis process. VSCs are also released with cell
death from subgingival pocket epithelium.
VSCs of bad breath are involved with both onset of periodontal
disease and chronic destruction of periodontal tissues.
VSCs initiate the periodontal pathogenesis process by enhancing
permeability of the junctional epithelium and VSCs are released
at the time of cell death during chronic periodontitis.
Researchers in Nippoin Dental University in Tokyo, Japan,
wanted to know if the impact of hydrogen sulfide on osteoblasts
would prevent bone repair and therefore indirectly lead to ongoing
bone loss.
Laboratory studies measured the effect of hydrogen sulfide
on osteoblast cells and found evidence in the cascade of reactions
that DNA synthesis was reduced, which inhibited osteoblast cell
proliferation. Changing the equilibrium between osteoblasts and
osteoclasts will allow proliferation of osteoclasts, potentially
leading to bone loss.
Clinical Implications: Bad breath is both the result and the
cause of tissue destruction in periodontal disease.
Imai, T., Ii, H., Yaegaki, K., Murata, T., Sato, T., Kamoda, T.:
Oral Malodorous Compound Inhibits Osteoblast Proliferation. J
Perio 80: 2028-2034, 2009. |
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Grape seed extract might protect
against collagen breakdown
Matrix metalloprotienases (MMPs) are released by
monocytes and macrophages in response to the bacterial
infection of periodontal disease, MMPs are also responsible
for connective tissue breakdown. MMPs 1, 3, 7, 8,
9 and 13 are associated with collagen destruction. MMP
1 is collagenase and MMP 9 is gelatinase. To block
MMP production, clinicians have used subantimicrobial
doses of doxycycline (SDD, Periostat), which controls
granulation tissue formation and connective tissue
breakdown. Researchers have demonstrated the capacity
of other natural substances to inhibit MMPs.
Proanthocyanidin from cranberries, green tea polyphenols
and flavonoids have all been shown to inhibit specific
MMP production or activities. Medical research
findings indicate that preventing MMP production can
prevent tumor growth.
Researchers at Laval University in Quebec City,
Canada and scientists from Tom’s of Maine evaluated the
potential of grape seed extract to inhibit MMP secretion
in laboratory studies. Macrophages were exposed to
varying concentrations of grape seed extract for two
hours. The cells were then stimulated with lipopolysaccharide
(LPS) from Aa bacteria for one hour and incubated
for 24 hours in an anaerobic chamber at 98.6
degrees Fahrenheit (37 degrees Celsius). Control cells
were exposed to the grape seed extract but not the LPS.
The grape seed extract inhibited the secretion of the
MMPs in the LPS stimulated macrophages. Cells treated
with higher concentrations of grape seed extract showed
a greater MMP inhibitory effect.
Clinical Implications: We might see grape seed
extract formulations used for host modulation treatment
of periodontal disease in the future.
La, V., Bergeron, C., Gafner, S., Grenier, D.: Grape Seed
Extract Suppresses Lipopolysaccharide-Induced Matrix
Metalloproteinase (MMP) Secretion by Macrophages and
Inhibits Human MMP-1 and -9 Activities. J Perio 80:
1875-1882, 2009. |
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Biofilm formation around implants
Peri-implantitis is triggered by the same bacteria that
cause periodontitis. Researchers have reported colonization of
periodontal pathogens on the inner threads of specific
implant designs. External hex implant designs are reported to
allow bacterial colonization. However, this bacterial leakage
doesn’t seem to affect implant survival rates, based on long
term studies. It might however lead to peri-implantitis. The
use of one percent chlorhexidine gel or 0.2 percent chlorhexidine
solution to disinfect the internal part of the fixture,
prior to abutment placement and screw tightening, effectively
reduced bacterial colonization for six months.
Researchers at the University of Florida in Gainesville
compared two implant designs in the laboratory to evaluate
microbial colonization in the microgap at the fixture-abutment
interface. One implant design had the Morse-taper connection
and the other had a tri-channel internal connection.
A third group was created by placing a vertical 0.5mm deep
groove on the abutment of the Morse-taper design prior to
fixture-abutment connection, to insure bacterial penetration.
Ten implants were included in each of the three groups.
Implants and abutments were assembled and incubated in
anaerobic conditions for five days in a bacterial solution of Aa
and Pg, early colonizers of periodontal biofilms.
Only one of 10 Morse-taper implants developed a single
colony forming unit of Aa and none of the 10 developed any
Pg colonies. All of the implants in the other two groups developed
numerous colonies of both bacterial species.
Clinical Implications: The geometry of implant-abutment
connections will influence the colonization of periodontal
pathogens. The Morse-taper design was less likely to allow
bacterial colonization.
Tesmer, M., Wallet, S., Koutouzis, T., Lundgren, T.: Bacterial
Colonization of the Dental Implant Fixture-Abutment Interface:
An In Vitro Study. J Perio 80: 1991-1997, 2009. |
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Does instrument choice matter on implants?
Dental implants are susceptible to peri-implantitis due to
bacterial biofilm accumulation. Studies have evaluated
instrument changes to implant surface with no consensus as
to the best choice for removing plaque and calculus.
Researchers at Guarulhos University in
Brazil performed laboratory tests to compare
surface changes and bacterial adhesions
to rough and smooth titanium discs treated
with one of four instruments plus a control:
Er:YAG laser, plastic curette, metal curette
and abrasive air polishing. Surface roughness
was measured and images were taken
with a scanning electron microscope.
To measure bacterial adhesions, the
discs were exposed to saliva for pelicle formation
and then S. sanguinis bacteria. Saliva was donated by
four healthy young men who collected saliva for one hour per
day for seven days. The saliva was pooled, frozen, and pasteurized
before use. Following incubation, some discs were viewed
microscopically and others were rinsed to dislodge free floating
bacteria and then placed in sterile tubes with water and shaken
vigorously for two minutes to dislodge the attached bacteria.
The liquid was then plated and grown to determine the number
of colony forming units for each disc.
No changes on the rough titanium surfaces were seen with
any of the test instruments compared to
control discs. On smooth discs, only metal
curettes increased surface roughness.
Bacterial adhesion was nearly the same for
all surfaces, including the control discs that
received no treatment.
Clinical
Implications: These laboratory
findings suggest very little difference
between instruments used on implant
surfaces. The real test is how the tissue
responds clinically, which depends on both instrumentation
and daily oral hygiene.
Duarte, P., Reis, A., de Freitas, P., Ota-Tsuzuki, C.: Bacterial
Adhesion on Smooth and Rough Titanium Surfaces After Treatment
with Different Instruments. J Perio 80: 1824-1832, 2009. |
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Sex hormones increase bleeding on probing
Hormonal fluctuations during puberty, pregnancy and
menopause impact the periodontal tissues. Very little research
has been reported about the impact of hormonal
changes during the menstrual cycle and even less
about the impact of these changes during premenstrual
syndrome (PMS). Estimates suggest that 80
percent of women experience PMS, which occurs
seven to 10 days before menstruation.
Researchers at Istanbul University in Turkey
monitored a group of 27 female dental students
to determine if changes in sex hormones
impacted clinical signs of gingivitis. Plaque
scores were recorded weekly for two months.
Probing, bleeding and gingival crevicular fluid
(GCF) samples were taken on the first day of the
period, the estimated day of ovulation and the
estimated day of highest progesterone secretion.
Blood samples were taken to determine these
days. Duration and regularity of menstrual cycles
were also reported. Oral hygiene instructions
were given at the start of the study to insure optimal
gingival health.
Plaque levels remained the same during the
study while bleeding scores, GCF levels and IL-1
scores were highest when progesterone levels were
at their peak.
Complaints of PMS were reported by 12 of the
women and six of these women also reported oral
complaints during this time. Menstrual cycles were
reported to be 20 to 32 days with duration of four
to six days.
Progesterone receptors are more evident following
ovulation, however little is know about receptor
levels in the gingiva. Complaints of gingival
tissue irritation during PMS and changes in the tissues
during the menstrual cycle might be due to
increased progesterone receptor expression in the
gingival tissues.
Clinical Implications: An unexpected increase in
bleeding on probing scores for a periodontally
healthy female patient might be due to hormonal
changes associated with menstruation.
Baser, U., Cekici, A., Tanrikulu-Kucuk, S., Kantarci,
A., Ademoglu, E., Yalcin, F.: Gingival Inflammation
and Interleukin 1-Beta and Tumor Necrosis Factor-
Alpha Levels In Gingival Crevicular Fluid During the Menstrual
Cycle. J Perio 80: 1983-1990. 2009. |
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Photodynamic therapy is useful adjunct
The goal of periodontal therapy is
to return the tissues to homeostasis,
where the tissues and the oral biofilm
are in balance. Mechanical instrumentation
is the standard treatment for
periodontal disease. Antibiotics are
used in some cases, in either local or
systemic form.
Another adjunct to scaling and root planing (SRP) is antimicrobial
photodynamic therapy. Following SRP, a photosensitizer formulation
made of 0.01 percent methylene blue in a phosphate buffered
system with viscosity enhancers, sweetener and a preservative agent
is applied subgingivally, followed by a 60 second non-thermal diode
laser application. The laser activates the methylene blue which has
attached to cell walls of subgingival bacteria, generating highly reactive
oxygen species, killing the bacteria and speeding periodontal
healing. This technology is currently available in Canada and
Europe from Ondine Biopharma as Periowave.
Researchers at the University of Washington in Seattle and a scientist
from Ondine Biopharma designed laboratory studies using 96 well
plates to test the effectiveness of the Periowave technology against Pg
bacteria, bacterial proteases and human host derived cytokines.
The Periowave was effective at killing the Pg bacteria and at the
same time inactivating the protease released by the bacteria. To test the
Periowave against the destructive host derived cytokines interleukin
and tumor necrosis factor, researchers used human umbilical vein
endothelial cells. The Periowave was effective in inactivating both of
these cytokines.
Clinical
Implications: Antimicrobial photodynamic therapy works
by killing the bacteria and inactivating bacterial virulence factors
and host cytokines that compromise periodontal healing. This
technology should soon be available in the U.S.
Braham, P., Herron, C., Street, C., Darveau, R.: Antimicrobial
Photodynamic Therapy May Promote Periodontal Healing Through
Multiple Mechanisms. J Perio 80: 1790-1798, 2009. |
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