1) Lasers can effectively kill bacteria through photothermal and photochemical mechanisms of action. Different laser wavelengths like Nd:YAG, Er:YAG, and CO2 lasers have been shown to reduce bacterial counts significantly. 2) Photodynamic therapy using photosensitizers and laser or light sources can inactivate bacteria and detoxify lipopolysaccharides. Methylene blue and toluidine blue are effective photosensitizers. 3) Low-level laser therapy and nanoparticles also exhibit antibacterial effects and can disrupt biofilms formed by pathogens.

1. P R E S E N T E D B Y
DR .HESHAM ADEL EL-NOUBY
U N D E R S U P E R V I S I O N O F
PROF. DR. LATIFA ABD EL GAWAD
Antibacterial effects of laser

8. bacteria are often found forming multilayers
of dense aggregates known as biofilms.
which are matrix-enclosed communities of
microorganisms that tightly interact and colonize
surfaces in aqueous environment

9. Microorganisms Involved in the Formation
of Biofilm
Gram-negative
anaerobic rods
lactobacillus
Gram-positive
anaerobic cocci,
Gram-positive
facultative
Streptococcus species.
Gram-positive
anaerobic and
facultative rods
Polymicrobial
anaerobic bact. In inf
root canal

10. facultative bacteria such as
nonmutans Streptococci
Enterococci
Lactobacilli
Bact. survive
chemical-mechanical
instrumentation

11. Enterococcus faecalis
yeasts eg. Candida albicans
in failed root
canal treatments

12. Traditional irrigation
NaOCl
EDTA
Cholorohexidine

13. NaOCl 0.5 2.5%
Disrupting microbial
metabolism
By oxidation of sulphdryl
gp. Within bact. Enz. By
hydrochlorous acid HOCL

14. EDTA
ethyle-nediamine tetraacetic acid
remove
the smear layer and enhance adhesion of
resin-based endodontic sealers
17%

15. Chlorhexidine
Binding bact.
Cytoplasmic membrane
Cause disruption of
osmotic balance
Leakage of intercellular
component

16. Chlorhexidine
Activity at PH 5.5 -7
Broad spectrum
antibiotic gram +,_

17. HIGH-POWER NEARIR LASER
BACTERIAL KILLING IS
THE MOST IMPORTANT
PARAMETER IS THE MAXIMUM
TEMPERATURE. LASER
IRRADIATION OF BACTERIA AT
LOW TEMPERATURES DOES NOT
RESULT IN KILLING.
Laser action

18. A laser is a photo-thermal
device.
1 .It acts directly on cellular
structures.
2 .Destroying cell walls.
3. Altering DNA.
4 .Modifying metabolic
processes.
5.Ungluing the polysaccharide
structure of the biofilm.

19. Nd:YAG and Diode lasers have an
antibacterial but not sterilizing capability,
substantiating that laser irradiation is a
possible supplement for disinfection but
not an alternative

20. ND:YAG Bactericidal effect
To evaluate the bactericidal effects of Nd:YAG laser 3-
W laser beam for 10 sec on biofilm of Enterococcus
faecalis.
Based on the results of the present study, the effect of
Nd:YAG laser beam on E .
faecalisbiofilm is less than that of sodium
hypochlorite solution. A combination of laser and
sodium hypochlorite results in complete
elimination of E. faecalis biofilm.

21. Bactericidal activity of pulsed Nd-YAG
laser radiation
At 1994 in vitro for oral bacteria using several pulse
energies and exposure duration
120-mJ laser pulses proved more efficient with 99.9%
kills .
90% in 80-mJ pulses kills after exposure to 1800
pulses

22. Antimicrobial effects of 2.94 μm
Er:YAG laser
After application of 75 laserpulses
1.E. coli was reduced by the Er:YAG laser radiation
after exposure to 105 laser pulses to 5.5% of the
initial count
2.In the Staph. aureus group to 15.1%.
3.The number of bacteria in case of A.
actinomytemcomitans was reduced to 8.3%,
4.In E. corrodens to 3.0%
5.In case of Peptostreptococcus micros to 22%

23. Besides the selective
removal of plaque and
calculus, the 2.94 μm
Er:YAG laser radiation
causes reduction in
bacteria on root surfaces.

24. AT 1.5 W, THE BEST RESULTS
WERE OBTAINED BY THE ER:YAG
LASER ACHIEVING A MEAN
BACTERIAL ELIMINATION OF
99.64%,
FOLLOWED BY THE ND:YAG
LASER (99.16%)
THE HO:YAG LASER(99.05%.)
The Bactericidal Effect of Nd:YAG, Ho:YAG,
and Er:YAG Laser Irradiation in the Root
Canal: An in Vitro Comparison 1999.

25. Diode effects on Streptococcus sanguis
in biofilm J. Antimicrob. Chemother
BiofUms were grown on hydroxyapatite, irradiated
with up to 12.2 J of light from a gallium aluminium
arsenide laser in the presence of aluminium
disulphonated phthalocyanine
(AlPcS2) and survivors enumerated.
No significant decrease in the viable count was found
when either the AlPcS2 or the laser light was used
alone.
No viable streptococci were detectable following
irradiation with 12.2 J of laser light

26. Co2 bactericidal effect
The energy density required to kill
greater than 99.5% of the bacteria
is less than 200 J/cm2

27. The effects of super pulsed CO2 laser
irradiation on periodontopathic bacteria
The effects of super pulsed CO2 laser irradiation on
1 . periodontopathic bacteria .
2 .lipopolysaccharide (LPS).
The irradiation at low energy densities of 7.5 and 12.5
J/cm2 killed more than 99.9 and 99.999% of
Porphyromonas gingivalis .
More than 99% of Actinobacillus
actinomycetemcomitans was sterilized by the
irradiation at 7.5 J/cm2.

28. Super pulsed CO2 on LPS
LPS biological activity was
significantly decreased by laser
irradiation at energy densities of
more than 7.5 J/cm2 , and the
components of LPS analyzed by
SDS-PAGE was diminished non-
specifically.

29. CO2
The results indicate that CO2 laser irradiation at low
power is capable of bactericidal effect on
periodontopathic bacteria and decreasing LPS
activity.
CO2 laser
(1.064nm, 1.5W, 100mJ, 15Hz
sec) showed a higher antibacterial efficacy against E.
faecalis as compared to the Nd:YAG laser

30. Comparative evaluation of antimicrobial
effects of laser on staphylococcus aureus
J oral
Maxillofac Surg
2012
Co2
Diode 320 mm
fiber optic
Diode R24 B
handpeice with
focal spot 6 mm
Er:YAG with
superpulse
Er:YAG with
very super
pulse

31. This study examined carbon dioxide (CO2;
10,600 nm), diode (808 nm), and erbium

 The CO2 laser eliminated 100% of the bacteria at
6 W, 20 Hz, and a 10-ms exposure time/pulse
 Diode laser eliminated 97% with a 10-second application
period (0.8-mm spot size),continuous-wave.
 The Er:YAG laser eliminated 100% of the bacteria at 90
mJ and 10 Hz using a 10-second application in a
superpulse mode
(300-ms exposure time/pulse).
The Er: YAG laser also eliminated 99% to 100% of the
bacteria in VSP mode
at 90 mJ and 10 Hz with a 10-second application.










33. Application of photodynamic therapy
in dentistry
Antimicrobial PDT (aPDT) non thermal light
induced inactivation of cells,microorganism .
Can be considered as an adjunctive to conventional
mechanical therapy.
Antimicrobial PDT not only kills the bacteria, but
may also lead to the detoxification of endotoxins
such as lipopolysaccharide. These
lipopolysaccharides treated by PDT do not
stimulate the production of pro-inflammatory
cytokines by mononuclear cells.

34. light source
helium – neon lasers (633 nm) visible
red
gallium – aluminum – arsenide diode
lasers (630-690, 830 or 906 nm) IR
argon laser (488-514 nm)Visible
blue

35. PS
Methylene blue and toluidine
blue O .
very effective photosensitizing
agents for the inactivation of both
gram-positive and gram-negative

36. PDT
P. intermedia, P.gingivalis
Enterococcus
faecalis
Fusobacterium
PDT could reduce the
bacterial count of

37. PDT
It has been demonstrated that bacteria associated with
periodontal disease can be killed through
photosensitization with toulidine blue O
By irradiating with helium – neon soft laser.
Data from an in vitro study indicated that PDT could
kill bacteria organized in a biofilm.
In an animal study, bleeding on probing, and
porphyromonas gingivalis levels.

38. PDT
The optimal concentration of toluidine
blue O to kill P. gingivalis was 12.5
μg/ml with helium-neon laser
irradiations.
This was caused by the disruption of
outer membrane proteins of these
bacteria

39. PDT
 Methylene blue at the wavelength of 632.8
nm & helium-neon laser 665 & 830 nm
(diode laser) has a high bactericidal effect.
 Methylene blue served as the
photosensitizer and was used as a mouth
rinse

40. PDT
PDT on endodontic pathogens in planktonic phase as well
as on Enterococcus faecalis biofilms in experimentally
infected root canals of extracted teeth. Strains of
microorganisms were sensitized with methylene blue (25
μg/ml) for five minutes followed by exposure to red light
of 665 nm with an energy florescence of 30 J/cm2.
 Methylene blue fully eliminated all bacterial species with
the exception of E. faecalis (53% killed). The same
concentration of methylene blue in combination with red
light (222 J/cm2) was able to eliminate 97% of E.
faecalis biofilm bacteria in root canals using an optical
fiber with multiple cylindrical diffusers that uniformly
distributed light at 360

41. PDT
Recently, non laser light source, such as light –
emitting diodes (LED), has been used as new light
activators in PDT.
LED devices are more
1 compact
2 portable
3 cost effective compared to
traditional lasers.

42. Effect of Low-Level Laser Therapy on
Typical Oral Microbial Biofilms
LLLT had an inhibitory effect on typical oral
microbialbiofilms, and this capacity can be altered
according to the interactions between different
species Streptococcus mutans, Candida albicans or
an
association of both species. Single and dual-species
biofilms - SSB and DSB – were exposed to laser
doses of 5, 10 or 20 J/cm2 from a near infrared
InGaAsP diode laser prototype 780 ± 3 nm, 0.04 W

43. LLLT
Figure 1 illustrates the effects of LLLT on S mutans
The irradiation promoted a decrease in the number
of microorganisms, though without significant
difference among the laser doses or the types of
biofilm.

44. LLLT
Figure 1. SEM micrograph showing the morphology
and structure of SSB of S. mutans (Original
magnification ×5000). A= Control,
B-D= Biofilm after irradiation with laser dose of 5, 10
and 20 J/cm2.

45. Antibacterial effect of nanoparticles
on Staphylococcu
Previous studies have reported
significant antibacterial effect of
1. Chitosan nanoparticles (CS-Np).
2. Zinc oxide nanoparticles (ZnO-Np) against
planktonic Enterococcus faecalis.the CS-Np and
ZnO-Np reduce and disrupt the biofilm structure.
3. Silver nanoparticles (AgNPs).

46. Thank You
‫د‬.‫أسنان‬ ‫طب‬ ‫ماجستير‬ ‫النوبي‬ ‫عادل‬ ‫هشام‬-‫ليزر‬2015
N.I.L.E 2015