Cleaning of rotary ni ti endodontic instruments / dental implant courses

CLEANING OF
ROTARY Ni-Ti
ENDODONTIC
INSTRUMENTS
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

SOURCE
LIBRARY

INTRODUCTION
CROSS INFECTION IS A MAJOR
ISSUE IN THE DENTAL CARE
SETTING BECAUSE OF CONCERNS
ABOUT TRANSMISSION OF DISEASE
via THE ORAL CAVITY.

Indian Dental academy
• www.indiandentalacademy.com
• Leader continuing dental education
• Offer both online and offline dental
courses

AIM
TO DEVELOP AND EVALUATE AN
EFFECTIVE CLEANING PROCEDURE FOR
ROTARY NICKEL-TITANIUM (Ni-Ti)
ENDODONTIC INSTRUMENTS

Sterilization:
The process that destroys all types and
forms of microorganisms including
viruses, bacteria, fungi and bacterial
endospores.

Disinfection:
A less lethal process than sterilization it
eliminates virtually all pathogenic
vegetative microorganisms, but not
necessarily all microbial forms (spores).
Disinfection is usually reserved for large
surfaces that cannot be sterilized.
Disinfection locks the margin of safety
afforded by sterilization procedures.

Objectives of infection
control
 Decrease the number of pathogenic
microbes to the level where normal body
resistance mechanisms can prevent
infection.
 Break the cycle of infection from dentist,
assistant and patient and eliminate cross-
contamination.
 Treat all patients and instruments as though
they could transmit an infectious disease.
 Protect patients and personnel from infection.

Route of transmission of
microorganisms in the dental
field
 Patient to dental team
 Dental team to patient
 Patient to patient
 Dental office to the community

Methods of sterilization
 The four methods of sterilization that are
generally accepted in dentistry include
steam under pressure, chemical vapor,
dry heat sterilization and glutaraldehyde
solutions.

Steam under pressure –
autoclaving
 A temperature of 121°C, a pressure of 15lb is
used for 15 to 20 minutes. Denaturation and
Coagulation of microbial protein occurs during
exposure to high temperature of steam under
pressure. Advances in this method called
“flash” sterilization technique uses shorter time
with higher temperatures. There is however
greater chances for sterilization errors to occur
in this technique.

Dry heat sterilization
 They use hot air to kill microorganisms. The
technique requires a temperature of 160°C
for 2 hours.
 Recently a rapid heat transfer sterilizer was
introduced operated at 190°C it will by rapid
airflow sterilize unpacked instruments in
6mins and packaged instruments in 12
minutes.

Chemical vapour
sterilization
 This method is based on the factors of heat,
water and chemical synergism. The chemicals
include alcohol, acetone, ketones and
formaldehydes.
 The water content is below the 15% level, above
which rust, corrosion and dullness of metal occur.
 The temperature requirements are 132°C for 20
minutes. The composition of heat and chemicals
is much kinder to metal surfaces than the other
techniques.

Portable unit for
premises disinfection
and
sterilization with
formaldehyde and
ammonia neutralization.

Formalin Chamber :
For dry sterilization
of instruments.

Glutaraldehyde as
immersion chemical
steriliant :
 For endodontic instruments sterilization by
heat is the method of choice, however the
use of glutaraldehyde preparations for the
chemical sterilization of heat sensitive
equipment has become a widespread
practice.
 Glutaraldehyde kills microorganisms by
altering essential protein components.

A 2.5% glutaraldehyde based
high-level disinfectant and cold
chemical steriliant. After activation
the solution has a 28 day activity
and can be reused during that
time.
Metricide 28 has a broad
spectrum activity against viruses,
bacteria, molds, fungi and other
vegetative organisms.

Ethylene Oxide Gas (E.T.O.)
 Ethylene oxide was first used as a sterilizing
agent in the late 1940’s. Since then ETO has
become an increasingly popular means of
sterilization especially in hospitals. It has high
penetration capacity. Temperature required
is low i.e. 25°C.
 This makes it ideal for sterilizing heat
sensitive instruments. Time period required
for proper sterilization varies from 10 to 16
hours.

Glass bead sterilizers
 Chair side sterilization of endodontic files,
reamers and broaches can be accomplished
by using a glass bead sterilizer.
 The transfer medium heats the endodontic
instrument through heat connection and kills
any adherent microorganisms.
 At a temperature of 220°C contaminated
endodontic instruments require 15 seconds
to be sterilized.

Glass Bead Sterilizer :
Used for sterilization of
instruments.
In few seconds you can
sterilize the instruments.

Ultraviolet sterilization cabinet

Chemical Disinfectants
 Alcohols
 Chlorine compounds
 Glutaraldehyde
 Iodophores
 Phenolic compounds

Ultrasonic Baths

KEYWORDS
 CLEANING
 CLEANING OF Ni-Ti INSTRUMENTS
 CROSS-INFECTION
 ENDODONTIC INSTRUMENT
 NICKEL-TITANIUM.

MATERIAL AND METHODS
 New rotary NiTi instruments
ProFile
Flexmaster
K3
Quantec
 Instruments were stored in covered Petri
dishes excepts during the cleaning and
scoring procedures

 Before the cleaning procedures,
instruments were used under simulated
clinical conditions to prepare canals of
extracted teeth
 Scoring system
1. The entire surface of the flutes of each
instrument was examined at 45×

1. All instruments were immersed in Van
Gieson’s solution for 3 mins to stain any
biological debris
2. The instruments were rinsed using
distilled water and air-dried on an
endodontic stand
3. The category and extent of debris were
recorded using the criteria shown in the
table

Scoring system for debris on instruments
Categories of debris
SD (stained particulate debris) : particulate matter stained red or orange
F ( organic film ) : a thin unstructured layer covering part of the
instrument surface and generally stained red
UD ( unstained particulate debris) : fine particles that did not exhibit any
red/orange coloration after staining
C : clean
Extent of stained debris
0 (none)
1 (film only)
2 (slight) : scattered particles spaced widely apart on the flute sufaces
3 (moderate) : numerous particles with areas of continuous coverage of
surfaces
4 (heavy) : areas of the instruments where the flutes were packed with
debris to there entire depth.

Evaluation of different cleaning
procedures
 Baseline levels of contamination
1. 40 new instruments were stained immediately after removal from
their packages
2. 20 instruments were contaminated by using them to prepare
canals of extracted and then stained after dry storage overnight
without any cleaning procedure
3. 20 instruments were contaminated by the same procedure , then
inserted into a sponge saturated with 0.1% Cholorhexidine
gluconate sol. For 2 hrs and stained in the same manner as the
dry storage group

Experimental groups
 80 instruments were used to instruments
canals of extracted teeth.
 All instruments were inserted into a sponge
soaked in 0.1% chlorhexidine gluconate for 30
mins.
 The instruments were then randomly assigned
into 4 equal groups representing four different
cleaning procedures

Experimental groups
Group 1 : the instruments were placed in a
stand and the flues were brushed for 20
strokes per row with a nylon bristle brush
under running distilled water.
Group 2 : instruments were brushed as in grp 1
and then laced in a beaker containing 1%
NaOCl , soaked for 10 mins and rinsed under
running distilled water.

Experimental groups
Group 3 : without brushing the instruments
were directly placed in a beaker containing
1% NaOCl for10 mins and the beaker was
placed into an ultrasonic bath.
Group 4 : instruments were brushed ,
immersed for 10 mins in 1% NaOCl , placed in
the ultrasonic bath for 5 mins and rinsed

Experimental groups
 After the cleaning procedures,
instruments were air dried and immersed
in Van Gieson’s solution for 3 mins,
rinsed under running distilled water and
air-dried on the endodontic stand.
 Instruments were then scored for debris
at 45× magnification.

Effect of storage conditions or
autoclave sterilization on cleaning
effectiveness
 100 instruments from previous
experiments were cleaned using the
complete cycle
 They were reused to instrument canals
of extracted teeth
 They were divided into five equal groups

effectiveness
 Group 1(dry-storage) : the instruments
were bench-dried overnight
 Group 2(moist-storage): the instruments
were kept moist by placing them
overnight in a sponge soaked in
0.1%aqueous chlorhexidine gluconate.
With no additional cleaning

effectiveness
 Group 3(dry storage, complete cleaning
sequence) : the instruments were bench-
dried overnight and were then transferred to
the brushing stand and subjected to the
complete cleaning sequence
 Group 4(moist storage, complete cleaning
sequence) : the instruments were inserted
into a sponge soaked in 0.1% chlorhexidine
gluconate solution

effectiveness
 Group 5(autoclave sterilization group) :
instruments were brushed on the
instrument stand and passed through
autoclave sterilization at 134ºc , 220kPa
for 3 min. the instrument were then
cleaned with the full cleaning protocol.
All instruments were stained and scored in
the same manner as before

Biological risk analysis
 Considering each instrument as one unit, the
instrument was classified as either positive
(stained debris or film present) or negative
(unstained debris only or clean) ‘biological
risk’
 The presence of stained material in any
location of the instrument was considered to
constitute a biological risk.

Results

n number mean % SE
clean of MBC
New instruments (N) 40 38 0.6 0.1
Dry storage (D) 20 0 52 0.9
Moist storage (M) 20 0 31 0.4
Baseline extent of biological contamination

n no. Mean % SE
clean of MBC
Baseline (moist sponge) 20 0 31.0 0.4
Brushing only (B) 20 0 15.0 0.4
Brushing plus NaOCl
Soak (BN) 20 15 4.2 0.4
NaOCl soak + ultrasonic (NU) 20 16 3.0 0.3
Brushing, NaOCl + ultrasonic
(BNU) 20 20 0.0 0.0
Effect of cleaning procedures on the extent of
biological contamination of instruments

n number mean%
SE
clean of MBC
Autoclaving (A) 20 0 17.0 0.5
Dry storage (D) 20 11 6.2 0.4
Moist sponge (M) 20 20 0.0 0.0
Effect of storage on the effectiveness of cleaning

Review of literature
 Miller C. et. al. 2002
conducted a study on preparing instruments for sterilization
and concluded that moist storage after clinical use is
essential for a proper sterilization
 Martins et. al. 2002
conducted a study on surface analysis of ProFile
instruments by SEM and reported that adherent deposits
containing carbon and sulphur, which originate from
lubricating oils used during manufacture serve as sites for
subsequent accumulation of debris during clinical use.

Review of literature
 Moorer & Wesselink 1982
conducted a study on the factors promoting the
tissue dissolving capability of sodium hypochlorite
and concluded that it’s tissue dissolving ability
does not depend only on it’s concentration but also
increased with mechanical agitation.
 Tanomaru Filho et. al. 2001
recommended the use of the ultrasonic bath as
the most effective method to remove foreign
particles from the surface of the instruments.

Conclusions
 All new instruments should be cleaned and
sterilized before clinical use.
 Instruments should be kept in moist storage
while waiting the cleaning process.
 And that, no one method of cleaning is efficient
in complete removal of debris and that
methods are to be used in conjunct with others
for achieving proper sterilization

Cleaning of rotary ni ti endodontic instruments / dental implant courses

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