DENTAL OUTLOOK
Vol. 115 No.6 2010-6

Verification

How much Extra-Oral Suction(EOS) can prevent dental aerosols?
Fluid dynamic analysis of aerosols with EOSTokyoMetropolitan
Nobuo
Motegi Cancer and Infectious Diseases Center
Komagome
Hospital・ Dentistry / Oral Surgery
Yumiko Ikegami

Nobuo
Midori Motegi
Chiba
YumikoIkegamiYoshi Asano
Midori Chiba
Yoshi Asano

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, JapanAbstract:
Intra-oral suction (IOS) works in big-volume andhigh-speed suctioning with the tube 10-20mm
diameter. The particle more than several 10μm in
diameter can be suctioned but smaller particles canbe distributed into to surroundings by the air
turbulence caused by IOS. Extra-oral suction (EOS)
has been used in order to reduce aerosols for the
purpose of infection control in dental treatment.
However, the effect of the apparatus to reduce theairborne contamination has never investigated in the
dynamic motion.
The present study was performed in fluid dynamic
analysis of aerosols particles with images taken by ahigh-speed camera using IOS alone and IOS with EOS.
In addition, the measurement of aerosol particle
number and aerosol bacterial colony count were also
performed and analyzed them comparing between
IOS alone and IOS with EOS.

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Materials and Methods
The present study was performed under thepermission of 57-year-old male patient who wastreated by scaling to the palatal periodontal pockets
in right upper incisors and canine. The aerosols
during the treatment were investigated.
Extra-oral suction (EOS) was performed by FreeArm Forte-S (Tokyo Giken Inc.). The working time ofthe equipment and scaling time were set in 3 min.
The suction cup of EOS was set at 5 cm high fromthe treating area angled at 45 degree.
The suctioning motion of aerosols contamination in
Intra-oral suction (IOS) and EOS was observed by
High-speed Camera Miro 4 Color Type (Phantom Inc.),
and the fluid dynamic motion of aerosols wasanalyzed by CFdesign V10 (CFdesign Japan K.K.).
The aerosol particle (0.5μ) number was measured
by a laser particle counter, and the aerosol bacterialcolony count was calculated by biological basic air.

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Materials and Methods
The present study was performed under thepermission of 57-year-old male patient who wastreated by scaling to the palatal periodontal pockets
in right upper incisors and canine. The aerosols
during the treatment were investigated.
Extra-oral suction (EOS) was performed by FreeArm Forte-S (Tokyo Giken Inc.). The working time ofthe equipment and scaling time were set in 3 min.
The suction cup of EOS was set at 5 cm high from thetreating area angled at 45 degree.
The suctioning motion of aerosols contamination in
Intra-oral suction (IOS) and EOS was observed by
High-speed Camera Miro 4 Color Type (Phantom Inc.),
and the fluid dynamic motion of aerosols wasanalyzed by CFdesign V10 (CFdesign Japan K.K.).
The aerosol particle (0.5μ) number was measured
by a laser particle counter, and the aerosol bacterialcolony count was calculated by biological basic air.

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Model of fluid dynamic analysis
Intra-oral suction (IOS) alone

Intra-oral suction (IOS) with Extra-oral suction (EOS)

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Condition of experimental circumstance• Suction flow rate in EOS tube

3 m3/min• Suction flow rate in IOS tube

0.18 m3/min

Atmospheric pressure inthe surrounding area

Suction flow ratein EOS tube

• Flow rate in aerosol creating area 50 L /min
• Atmospheric pressure in the surrounding area

Flow rate in aerosol
creating area

Condition of aerosol particles
All aerosol particles were made of water,
particle density : 1.0 g/cm3
particle diameter : ɸ1 μm ～ɸ10 μm(increase with 1 μm)
gravity : acceleration of gravity 9.807 m/s2
The trail of the particle movement wasinvestigatedSuction flow rate
in IOS tube

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Result 1
Imaging in dynamic motion of aerosol particles by high-speed camera using
IOS alone/ IOS with EOS

IOS alone
Aerosol particles wereseen distributing aroundthe face

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

IOS with EOS
Distributed aerosol
particles were being
suctioned by EOS

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Result 2

Model of fluid dynamic analysis,
The trail/distribution imaging of aerosol particles[The trail of aerosol particles (particle diameter ɸ5 μm) ]IOS alone

Aerosol particles went upward around the mouth then fall
down
Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, JapanIOS with EOS
Aerosol particles went up toward EOS
Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

[The distribution imaging of aerosol particles (particle diameter ɸ5 μm) ]IOS alone

Aerosol particles were distributed around the face
Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

IOS with EOS
Aerosol particles were not distributed around the face
Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Result 3

Distribution rate/ collection rate of aerosol particles[Distribution rate of aerosol particles]

Distribution rate (%)

IOS alone
IOS with EOS

12345678910particle diameter (μm)
Distribution rate of aerosol particles

Aerosol particles were distributed in 40-60% with IOS alone, but no distribution under IOS with EOS
Distribution rate = number of particles distributed without suctioning / total number of particles trail chased
Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

[Collection rate of aerosol particles]
9080
Collection rate (%)

7060504030IOS alone

20IOS with EOS

100123456particle diameter (μm)

78Collection rate of aerosol particles

910

Collection rates of aerosol particles were bigger in 40-60% under IOS with EOS than that of IOS alone
Collection rate = total number of particles collected with suctioning / total number of particles trail chased

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Result 4
Measurement of aerosol particle number5400
5300
5200
5100
5000
4900
4800
4700
4600
4500
4400
Before start suction

After start IOS alone

After start IOS with EOS

Aerosol particle (0.5 μm) number decreased under the IOS with EOS

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Calculation of aerosol bacterial colony countIOS alone

IOS with EOS

Aerosol bacterial colony count decreased under IOS with EOS

Summary: The fluid dynamic analysis of aerosol particles by a high-speed camera imaging proved
apparently smaller area of aerosol distribution when using IOS with EOS than IOS alone. The usageof EOS is necessary for the prevention of aerosols contamination during dental treatments.
Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan

Summary:
The fluid dynamic analysis of aerosol particles by a highspeed camera imaging proved apparently smaller area ofaerosol distribution when using IOS with EOS than IOS alone.
The usage of EOS is necessary for the prevention of aerosols
contamination during dental treatments.

Translation courtesy of Professor Takashi Fujibayashi, DDS, PhD of Tokyo, Japan