University College Cork
Ireland Should Follow U.K. Practice By
Insisting On The Single Use Of
Endodontic Files. Discuss.
David William McGibney
108882932
david.mcgibney@gmail.com
1
Ireland Should Follow U.K. Practice By Insisting On The
Single Use Of Endodontic Files. Discuss.
Introduction
A policy of single use endodontic instruments is controversial. The British and German dental
associations, along with the Centre for Disease Control and World Health Organisation regard such
a policy as justifiable considering the risks posed by file reuse. The U.S. and Canada do not
consider the risk to be great enough to justify the cost implications of such a policy, whilst the
Australian association perceive reuse as posing no cross infection risk as long as sterilisation
protocols are followed (Azarpazhooh et al., 2008).
As part of the duty of care owed to every patient by their dentist, the clinician should cause no harm
to those people by their acts or omissions. If a clinician fails in the standard of care owed, they will
be liable for their acts or omissions on the grounds of negligence ( Hinds et al., 2006 ) ''Standard of
care is defined as that reasonable care and diligence ordinarily exercised by similar members of the
profession in similar cases in like conditions given due regard for the state of the art'' (Ingle et al.,
2008). In Irish Tort Law, during endodontic treatment as well as every other treatment that a dental
professional provides, they owe their patient a standard of care. In order to satisfy this professional
requirement the clinician may be required to clean, disinfect and sterilise their instruments both
before and after use and to dispose of instruments in certain situations. They must also ensure all of
their instruments are in optimum condition at all times.
Cross infection is a risk that comes with almost any dental procedure, and this is especially true of
endodontics due to the intimate contact that files and reamers have with neural and vascular tissues.
The clinician must always strive to prevent or minimize the risk of cross infection by using the most
up to date sterilization techniques and disposal protocols. The understanding that the specialist has
of the strengths and limitations of his or her endodontic instruments is also an integral part of
achieving successful endodontic treatment. During and after root canal therapy the endodontic files
and reamers are subjected to a range of forces which can alter their clinical efficacy. Clinical
instrumentation, cleaning, disinfection and sterilization can all impact upon the ability of these
instruments to perform to their optimum level. (Haikel et al., 1996).
The decision to adopt a single use policy for endodontic instruments is based
on the belief that it is the only effective way to guarantee that the profession can meet the
obligations laid out above. In order to determine whether or not such a policy is necessary in Ireland
we must examine all of the relevant literature focussing on the following key points :
1. The ability of cleaning, disinfection and sterilization to achieve absolute eradication of
the bioburden and remove the risk of cross infection.
2. The effect of clinical instrumentation and sterilization on the rate of instrument fracture
and cutting efficiency of their instruments.
Each of the above considerations plays a key role in deciding whether or not
Ireland should follow the example of the UK and treat endodontic files as single use items. It is also
important to consider the legal implications of this policy. Standard of care involves examination of
the behaviour of a particular clinician compared with a similar group of professionals. If one or
more jurisdictions of dental professionals has deemed this policy to be absolutely necessary based
upon analysis of the relevant evidence but Ireland were to opt against implementing the single use
policy, individual clinicians could possibly be held as negligent by a 'Bolam Test' of practice. That
is, the law will hold all dentists to the standard of what a reasonable and prudent dentist would do
under the same or similar circumstances . The aim of this study is to examine and analyze the
existing research, as well as the protocols adopted in other jurisdictions and their rationale, in order
to provide an informed answer to the question posed.
2
Aims and Objectives
The objective of this study is to examine the logic behind treating endodontic instruments as
disposable and to decide whether or not it is necessary for Ireland to follow the example of the U.K.
and other relevant jurisdictions and adopt a single use policy. This will require thorough
investigation of the effectiveness of current cross infection control techniques, their impact upon the
mechanical properties of endodontic instruments and the effect that clinical instrumentation has on
these properties. It will also be necessary to evaluate the likely impact that such a policy would have
on both the patient and the clinician, as it is clear that such a move poses both cost and legal issues,
each of which must be carefully examined. Once these objectives have been achieved it should then
be possible to satisfy the ultimate aim of this review, to decide whether or not this policy is an
unnecessary over-reaction
which is likely to raise the cost of treatment and restrict access to those most in need of it or if it is
the logical step for the profession to protect the interests of patients and dentists alike.
Methods
Searches were performed of The Cochrane Library, PubMed, Science Direct, GoogleScholar and
other relevant databases. Internet searches were also performed.
Key Words
Endodontics, endodontic file reuse, dental negligence, duty of care, standard of care, Cross infection
control, endodontic protocols.
Cross Infection Control
''Endodontic instruments, particularly files and reamers have been designated as single use
instruments in some jurisdictions. This action has arisen out of concern for the difficulties
encountered in their cleaning and sterilization after use and the possibility that they may act as a
vehicle for disease transmission when reused'' (Hartwell et al., 2011). ''Preliminary research findings
suggest that the potential risk of transmission of vCJD via dental procedures may be greater than
previously anticipated. The new research also suggests that dental procedures involving contact
with other oral tissues, including gingiva, may also be capable of transmitting vCJD '' (Spongiform
Encephalopathy Advisory Committee Report 2006).
The area of tort law known as negligence involves harm caused by carelessness, not intentional
harm. An individual practitioner may be held as liable under this tort if he/she breaches their duty of
care to their patient (Wikipedia 2011).
Cross infection control is probably the strongest driving force behind the adoption of the single use
policy in the U.K. Sonntag et al., (2007) found that even after meticulous ultrasonic cleaning and
decontamination tooth structure and organic matter was visible on the surface of Nickel Titanium
files. Part of the duty of care of any dentist to their patient is an obligation to prevent any
foreseeable harm. Failure to use equipment that is completely sterile would surely constitute a
breach of this duty.
Less recent evidence carried out by Velez et al., (1998) found that dry heat sterilization, a widely
accepted sterilization technique in dental practice only managed to achieve removal of 96.7% of
microbes from contaminated instruments in certain situations.
Research by Johnson et al., (1997) aimed to examine for the presence of viable microbes on
contaminated files which were subjected to sterilisation. The industry standard Bacillus
Stearothermophilus was used for the evaluations. This study concluded that while the bioburden
remained after sterilisation the infectious threat was negligent, and that better cleaning methods
should be utilised rather than disposing of endodontic files after single use due to the possible cost
implications of disposal. These conclusions whilst worth noting should be regarded as being of little
3
use due to the small sample size and the time since they were published (1997).
''Aseptic technique is especially important in endodontics as microbes are the major cause of
endodontic disease'' (Hurtt et al., 1996) This study investigated file sterilisation and found that root
canal disinfection is an essential part of the endodontic treatment process and microbiological
control coupled with aseptic technique are vitally important in order to guarantee success by
preventing cross-contamination. This study advocated sterilising and reusing files.
While these early studies provide an insight into past practice they are of little relevance to decision
making at this moment in time.
A more recent study by Smith et al. (2005), examined endodontic files and the cross
infection risk, if they are not disposed of, after single use. This study had a broad scope
incorporating 22 dental practices. The results highlighted the fact that endodontic files which have
been subjected to sterilisation still routinely contain residual debris and so pose an infectious risk.
The report concluded that endodontic files should be treated as single use instruments.
''Infection control procedures are regularly updated to accomodate advancing knowledge and
the emergence of transmissible disease'' (Perkaki et al. 2007). This article compared the sterilization
of endodontic instruments using an ultrasonic cleaner or a washer disinfector .This study found that
while both methods removed the majority of debris, neither succeeded in complete sterilisation of
all of the files. The examiner was blind to file identities to avoid bias but the sample size was small
and so caution is advised.
The issue of prion diseases such as vCJD, being transmitted during dental treatment has
been considered in the literature in recent years. Dello Russo et al., (2004) found that the prion
proteins associated with this disease are resistant to almost every sterilization method used currently
in dental practice. Merchant et al., (2004) concluded that due to the inability to guarantee
eradication of prion proteins through normal sterilisation practices, all endodontic instruments
should never be reused. Further to this, in April 2007 the Chief Dental Officer (CDO) in the U.K.
Issued guidance that was to apply to all dentists working in primary and secondary care. This
guidance was formulated following review of the most up to date relevant data, including the 2004
NHS Scotland Decontamination Study of dental surgeries, as well as the Spongiform
Encephalopathy Advisory Committee (SEAC) statement 2006. The CDO advised that all dentists
should treat all endodontic files and reamers as single use instruments to be disposed of after each
patient. This was based on the evidence that endodontic treatment has the potential to transmit
variant CJD (vCJD) between patients. The evidence used also highlighted inconsistencies between
the sterilisation methods used in different practices. In April 2007 similar advice was given to
dentists in Northern Ireland to bring them into line with practices in England, Scotland and Wales,
stating that ''endodontic files and reamers must be treated as single use instruments''. This was based
on evidence presented by the Health Protection Agency in England regarding the cross infection
risk with vCJD, that endodontic files and reamers pose.
On the other hand, the AAE/CAE Joint Committee 2011 (Hartwell et al., 2011) concluded
that the risk of vCJD transmission during dental treatment was not significant for them to advise
dentists in their jurisdiction to implement a single use policy for endodontic instruments. Messer et
al., (2003) considered the effects of sterilization, repeated use and the economics of single use
policies and concluded that there was no justification for Australia introducing a single use policy,
due to the low risk of prion disease transmission and the prohibitive cost implications of such a
policy.
4
Mechanical Properties
Risk of Fracture
From outset of research it was clear that cross infection was the central issue in this debate.
However, it would be remiss to not consider any evidence which could play a part in this debate. As
data was gathered and analyzed it became clear that the mechanical properties of the instruments
used in endodontics would play an important role in this discussion also. In order to deliver optimal
care, the clinician must use equipment that is in peak condition. A survey of 242 dental negligence
cases by Dr. Baxter et al., (2006) found that the fracture of an instrument in a root canal was the
reason for dentists being sued in 9 of these cases. Clearly it is vitally important to investigate the
potential causes of such a fracture and any policies likely to minimize them.
Saltapan et al., (2000) found that when endodontic files were used multiple times the fracture rate
can be as high as 21%. Spili et al., (2005) also raised concerns regarding the risks of instrument
fracture when using Nickel Titanium files. This research advised that implementation of a single use
policy for endodontic files would be likely to reduce the risk of file fracture significantly and related
complications, such as excessive loss of healthy tissue required to remove the file, and possible
apical perforation and eventual treatment failure.
Sonntag et al., (2007) reinforced the suggestion that fracture risk as well as cross infection risk
could be reduced by a single use policy. One of the most recent studies examined for this review
was Shen et al., (2009), which found that when Nickel Titanium files were restricted to single use,
the rate of fracture could be as low as 0% to 0.26%. This study was carried out over 12 months,
although it only involved a small population of clinicians (2 clinics) and so potential exists for
operator technique to distort results.
The research of Filho et al., (1998) went as far as to recommend specific lifespans for individual file
sizes. The authors concluded that all file sizes up to and including #30 should be discarded after
single use to maximize cutting efficiency and minimize fracture risk. This research used 200 strokes
rather than 450 as suggested by Newman et al., (1983) so questions remain about the validity of the
data. However, more recent research described above has reinforced their findings.
It should also be mentioned that various research articles (Hilt et al. 2000, Silvaggio et al., 1997)
have concluded that sterilization has little or no clinically significant on rate of instrument fracture.
The most up to date article reviewed in this area of research was by Casper et al., (2011). Although
the authors found that repeated cycles in an autoclave had little or no significant effect on the
torsional properties or the fracture resistance of three relatively new rotary file types, the results
may be of limited clinical value as the data was gained utilising a torsiometer which cannot
accurately recreate the torque stresses encountered in anatomically variable root canals.
Cutting Efficiency
Another area to consider when deciding whether or not to institute a single use policy is the effects
that endodontic treatment has on the cutting efficiency of files and deciding on how best to maintain
them in optimum condition.
The research of Kazemi et al., (1995) provided some valuable evidence regarding the consequences
for endodontic file cutting efficiency that machining dentine poses. Although not a relatively recent
article (1995), its results are of relevance as it was the first of its kind to examine cutting efficiency
using human dentine rather than plexiglas. This study had a relatively broad scope in that it
incorporated 7 different file types. The authors found that machining dentine did in fact produce a
significant reduction in endodontic file cutting efficiency. They also highlighted the importance of
dental professionals only using their instruments when they were optimally effective, as they would
otherwise be likely to cause patient discomfort, operator fatigue and reduced cost effectiveness from
increased treatment time. The authors concluded that endodontic instruments be considered single
use in order to guarantee their efficiency to be optimal. Although its value is clear, this report did
have a number of shortcomings not least of which was the decision to use 300 strokes as the
standard number of strokes required to complete clinical instrumentation of a root canal, even
5
though Newman et al., (1983) showed this to be 450 strokes through clinical examination.
All dental instruments, including endodontic files, if intended for reuse, must be sterilized after use.
The research of Rapisarda et al., (1999) examine the effect that subjecting nickel titanium
endodontic files to repeated autoclave cycles was likely to have on their cutting efficiency.
Rapisarda found that files showed a reduction in cutting efficiency with every sterilisation that they
were subjected to. It was also suggested that multiple use instead of single use of files could lead to
a prolonging of the time taken to carry out treatment. Although the sample size in this research was
small (36 files), the results reinforce the findings of previous research including Cooley et al.,
(1990), which showed a reduction in cutting efficiency in stainless steel files which had been
repeatedly autoclaved. Rapisarda showed that after 14 autoclave cycles, cutting efficiency can be
reduced by up to 50%. Limitations of this study include the fact that it only examined one
sterilization technique whilst focussing on just one file type.
Cost Implications
The area of cost and how a single use policy is likely to affect the price of treatment is another key
area of consideration. Cost is one of the key factors in determining whether or not patients have
access to treatment. In the guidance provided by the DOH through the CDO dentists were advised
that ''practices were not allowed to apply any additional patient charge in relation to these or any
other treatments. The Canadian and American authorities also reviewed the rationale for a single
use policy in 2011 (Hartwell et al., 2011). Coupled with what the committee perceived to be a very
low risk of prion transmission during endodontic treatment, the CAE/AAE Joint Committee decided
that if endodontic files and reamers were designated as single use instruments the likelihood was
that the cost of endodontic treatment would rise making these services less accessible to many
patients. The committee instead recommended that clinicians adopt a very vigilant approach and
sterilize their instruments in line with best evidence based practice.
Discussion
Any decision on policy in dentistry or any other healthcare field should always be evidence based.
This requires an in-depth examination of the available relevant research and literature in order to
establish the rationale for any such decision and to understand the implications and consequences of
such a move. From the evidence appraised, it was clear that a number of factors are likely to
influence the decision of whether or not to follow the U.K. example. Cross infection control was
highlighted as the central issue to this decision. The evidence base in support of a single use policy
was overwhelming. This is due to the documented inability to guarantee complete microbial
elimination through widely used sterilization methods. Evidence from Hurtt et al., (1996) and
Johnson et al., (1997) downplayed the risks of cross infection, focussing more on cost reduction.
However Smith et al., (2005) found that 76% of the files examined in their study, which had been
collected following sterilization in dental surgeries, remained visibly contaminated. This was
supported by Sonntag et al., (2007) as well as Morrison et al., (2009). Morrison found that the three
currently used sterilization techniques of steam application under pressure in a steam autoclave,
application of dry heat in a sterilizing oven, and chemical vapour sterilization to be inadequate, with
levels of contamination ranging from 15 to 58% after sterilization. The fact that the SEAC and the
U.K. Department of Health (DOH) reviewed all of the available evidence and decided, based on
that information, that a single use policy was the most effective way to protect patients in the U.K.
from cross infection risk is also significant.
Another issue which is likely to influence this decision is the potential for instrument
fracture, brought on by repeated use, and its litigatory consequences should a fractured file injure a
patient or cause treatment failure. Although much of the date examined was flawed, it appears to be
quite clear that the repeated use of endodontic files leads to an increased rate of of fracture as shown
by Saltapan et al., (2000) and Shen et al., (2009).
A more peripheral issue to this debate is the effect that repeated use has on the
6
cutting efficiency of endodontic files. This can have implications for patient discomfort and reduced
operator efficiency. Kazemi et al., (1995) presented evidence of this phenomenon.
Along with cross infection control, and instrument fracture, the cost implications of a
single use policy were highlighted in the research as being another key consideration. The CDO
mentioned the possible cost implications and expressly advised dentists not to pass costs on to
patients. This would clearly impact on the dentists overall budget. The American and Canadian
authorities on the other hand, having reviewed the available evidence, including the DOH advice,
concluded that the risk of reducing treatment access to patients through the cost implications of a
single use policy was a more significant consideration than any potential transmission of vCJD.
Conclusion
From appraisal of the relevant evidence, there is clearly a strong case for a single use policy. The
cross infection control evidence is very convincing, with the CDC, WHO, U.K. and German
associations considering it compelling enough for them to institute single use policies. The case for
instrument fracture prevention also supports such a policy. Also, the legal implications of Ireland
not adopting such a policy are not insignificant. The U.K. legal system, although entirely separate,
is known to have a persuasive authority in relation to the Irish legal system (Sills et al., 2009), and
failure to follow their evidence based decision could lead to the Irish courts deeming Irish clinicians
to be negligent under a 'Bolam Test'. Although the economic aspect is a considerable issue cross
infection and steps to minimize risk should always be the foremost consideration for any clinician.
Therefore, it must be concluded that until effective sterilisation methods, which can be applied to
every dental practice are created, the best way to safeguard the interests and welfare of patients and
dentists alike, would be to introduce a single use policy for endodontic instruments in Ireland.
7
References
Azarpazhooh A. , Fillery E.D. Prion Disease : The Implications for Dentistry. The Journal of
Endodontics, Volume 34, Issue 10, October 2008, Pages 1158-1166.
Baxter C. Malpractice Survey: A Survey Of 242 Dental Negligence Cases With Breakdown As To
The Sex Of The Defendant Dentist. 2006.
http://www.experts.com/Articles/Malpractice-Survey-A-Survey-Of-242-Dental-Negligence-CasesWith-Breakdown-As-To-The-Sex-Of-The-Defendant-Dentist-By-Dr-J-Crystal-Baxter
Casper R.B. , Roberts H.W. , Roberts M.D. , Himel V.T. , Bergeron B.E. Comparison of
Autoclaving Effects on Torsional Deformation and Fracture Resistance of Three Innovative
Endodontic File Systems. Journal of Endodontics 2011 ; 37:1572-1575.
Dello Russo N. Understanding prions. J Am Dent Assoc 2004 ; 135:554-556
Department of Health From Barry Cockcroft Chief Dental Officer for England April 2007.
Important : Advice for dentists on re-use of endodontic instruments and variant Creutzfeld-Jakob
Disease (vCJD).
Gagnon L. Infection prevention measures may limit liability.
Canadian Medical Association Journal - Volume 178, Issue 12 (June 2008)
Filho I.B. , Esberard R.M. , de Toledo Leonardo R. , del Rio C.E. Microspcopic Evaluation of Three
Endodontic Files Pre and Postinstrumentation. Journal of Endodontics July 1998 ; 24:461-464.
Haikel Y. , Serfaty R. , Bleicher P. , Lwin T.T.C. , Alleman C. Effects of Cleaning, Disinfection, and
Sterilization Procedures on the Mechanical Properties of Endodontic Instruments. Journal of
Endodontics January 1997 ; 23:15-18
Haikel Y. , Serfaty R. , Bleicher P. , Lwin T.T.C. , Alleman C. Effects of Cleaning, Disinfection, and
Sterilization Procedures on the Cutting Efficiency of Endodontic Files. Journal of Endodontics
December 1996 ; 22:657-661.
Hartwell G., Bowles W. , Peters O. , Peikoff M. , Torneck C. Joint AAE/CAE Special Committee on
Single Use Endodontic Instruments. Final Report January 11, 2011 Single Use Instruments.
Health, Social Services and Public Safety April 2007. Letter to All General Dental
Practitioners:Advice For Dentists on Re-Use of Endodontic Instruments and Variant CreutzfeldtJakob Disease (vCJD).
Hinds A.L. The Duty of Care in Irish Tort Law 2006 1-4.
Hurtt C.A. , Rossman L.E. The Sterilization of Endodontic Hand Files. Journal of Endodontics
1996 ; 22:321-322
Johnson M.A. , Primack P.D. , Loushine R.J. , Craft D.W. Cleaning of Endodontic Files, Part 1:
The Effect of Bioburden on the Sterilization of Endodontic Files. Journal of Endodontics 1997 ;
23:32-34.
Kazemi R.B. , Stenman E., Spangberg L.S.W. The Endodontic File is a Disposabe Instrument.
Journal of Endodontics September 1995 ; 21:451-455
Merchant V.A. Infection control and prions. J Am Dent Assoc 2004 ; 135:554-556
8
Messer H. , Parashos P. , Moule A. Should Endodontic Files Be Single-Use Only? A Position Paper
From The Australian and New Zealand Academy of Endodontists.
Australian Endodontic Journal 2003 ; 29(3):143-145
Perkaki K. , Mellor A.C. , Qualtrough A.J.E. Comparison of an ultrasonic cleaner and a washer
disinfector in the cleaning of endodontic files. Journal of Hospital Infection 2007 ; 67:355-359.
Rapisarda E. , Bonaccorso A. , Tripi T.R. , Condorelli G.G. Effect of sterilization on the cutting
efficiency of rotary nickel-titanium endodontic files. Oral Surgery Oral Medicine Oral Pathology.
September 1999 ; 88:343-347.
Shen Y. , Coil J.M. , Mclean A.G.R. , Hemerling D.L. , Haapasalo M. Defects in Nickel Titanium
Instruments after Clinical Use. Part 5: Single Use From Endodontic Speciality Practices.
Journal of Endodontics 2009 ; 35:1363-1367.
Sills E.S., Murphy S.E. Determining the status of non-transferred embryos in Ireland: a conspectus
of case law and implications for clinical IVF practice. Philosophy, Ethics, and Humanities in
Medicine 2009, 4:8
Smith A. , Letters S. , Lange A. , Perrett D. , McHugh S. , Bagg J. Residual protein levels on
reprocessed dental instruments. Journal of Hospital Infection 2005 ; 61:237-241.
Velez A.E. , Thomas D.D. , del Rio C.E. Journal of Endodontics 1998 ; 24:51-53.
9