Anxiety prevention: Implementing the 4 S principle in conservative dentistry

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24 auxiliary September/October 2007
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High levels of dental anxiety is a problem that
many dental patients experience. Most
recent studies in the international literature
show that the prevalence of severe dental anxiety is
approximately one in every 7 adults, and the same
rate was documented in Australian adults in a 2006
telephone interview survey.1Most studies also show
that females in the middle adult years have the
highest prevalence, which also is true in Australia.
Known effects of dental anxiety are many (Table 1)
and impact upon the dental practice as well as upon
the individual patient. Altered patterns of care are
perhaps the most obvious impact of dental anxiety
with disease having progressed to a stage too late
for conservative measures to be effective. A
surprising statistic from 2006 is that only 25% of
visits in private general practice in Australia were
for recall or maintenance - the same percentage as
for treatment of dental caries as the presenting
problem!2This figure was not greatly different from
the Brisbane Statistical District Survey of Adult
Dental Health conducted in 1984,3in which the
author participated as a field clinical examiner.
Clearly, dental anxiety has not altered significantly
over the quarter century period.
Severe dental anxiety is a multifaceted problem
with no one common single causal factor in all
patients (Table 2), although for most patients the
stimuli for dental fear are sensory in nature. By
focussing on these stimuli, the clinician aims to
reduce the anxiety response at its sources, as
opposed to dulling the response pharmacologically
or by using distraction methods. The 4 S principle
is based on removing four of the major sensory
triggers for dental anxiety, and it is used in con-
junction with other measures to mitigate anxious
behaviours and their consequences.
The 4 S Principle is to reduce the 4 primary trig-
gers of stress when in the dental setting, namely:
• Smells (e.g. eugenol and cut dentine);
• Sights (e.g. needles, air turbine drills);
• Sounds (drilling); and
• Sensations (high frequency vibrations - the
annoyance factor).
Anxiety prevention:
implementing the 4 S principle
in conservative dentistry
By Professor Laurence J. Walsh
“for most
patients the
stimuli for dental
fear are sensory
in nature. By
focussing on
these stimuli,
the clinician
aims to reduce
the anxiety
response at its
sources...”
Table 1. Consequences
of severe dental anxiety
• Avoidance of dental treatment
• Cancellation of appointments
• Greater economic risk for the practice
• Poor compliance with follow-up treatment
• Negative expectations of treatment visits
• Longer time required for dental treatment
• Higher caries prevalence and severity (DMFT)
• Greater need for oral rehabilitation
• Poor oral health
• Reduced self confidence
• Feelings of shame and inferiority
• Negative thoughts
• Sleep disturbances
• Crying and aggression
• Lower satisfaction with treatment provided
Table 2. Causes of dental anxiety
• Fear of pain
• Fear of loss of control
• Conditioning experiences, such as past trau-
matic dental experiences in childhood Influence
of dentally anxious family members or peers
• Sights, sounds and sensations of the dental drill
• Sights and sensations of dental local anaes-
thetic injections
• Angry and aggressive dental staff

September/October 2007 auxiliary 25
A range of approaches can be used for
this, and they can be mixed and matched to
meet the particular needs of the situation.
Table 3 shows four commonly used alterna-
tive methods for dental restorative care
(Ultra-low speed cutting, atraumatic restora-
tive treatment (ART) with hand instruments,
chemo-mechanical caries removal with
Carisolv, and Erbium lasers), each of which
reduces the smells, sights, sounds and sensa-
tions experienced during restorative dental
care. This list is not meant to be exclusive, as
there are other approaches that could equally
be included, for example polymer bur cut-
ting, air abrasion (alumina powder streams),
particle streams in fluid media (e.g. Durr
Vector ultrasonic with silicon carbide parti-
cles in a fluid medium), and ultrasonic tips
coated with diamond particles.
To these methods should be coupled
effective communication with patients,
expressing sympathy and providing reas-
surance. The next higher level of
intervention is training in relaxation and
breathing techniques. In the most severe
cases, these measures can be used after
providing pharmacological support by
conscious sedation techniques including
oral, inhalation and intravenous sedation.
Relaxation techniques are safe, have no
side effects and give patients control over
their anxiety levels. Like the 4 S methods,
they work by eliminating or reducing the
problem at its cause.
Ultra-low speed cutting leverages the
reduced physical properties of infected car-
ious dentine with its broken and degraded
collagen crosslinks. A slow rotating instru-
ment (e.g. 200 rpm with a #3 or #5 round
bur) will remove this dentine but will not
cut sound dentine to any great extent. This
non-viable dentine has no viable odonto-
blast processes and can also be excavated
by hand (as in the ART method), although
care must be taken that the excavator is
used with a whisking action so that exces-
sive penetration pulpally does not occur.
Patients who are not given LA and undergo
ultralow speed cutting or ART provide
interesting feedback on the experience. In a
classic study in 1987, Ken Anusavice4
(who in the same year authored the interna-
tional guidelines on indications for placing
and replacing restorations) in Florida con-
ducted an intriguing clinical study in which
some 47 patients who were not given an
LA injection underwent restorative care.
Some 34 of these (72%) did not request
local anaesthesia for treatment, although
nearly half (47%) experienced pain. Cut-
ting or removing infected carious dentine,
however, elicited little or no painful sensa-
tions, even though the patients could in
some cases sense diffuse low frequency
vibrations. The pain which was reported
occurred once vital affected or sound den-
tine was cut. The nature of the pain (sharp,
well localized, pin-prick) belies the fact
that the tissue being cut is vital - and there-
fore amenable to healing. This begs the
question, should dentine that can heal be
cut away in the first place?
The same minimal intervention philos-
ophy underlies the chemo-mechanical
caries removal method. This targets col-
lagen in infected dentine because of its
broken crosslinks, which are susceptible
to proteolysis by sodium hypochlorite
and chloramines.5,6
Laser technology for caries removal in
anxious dental patients has been in use for
more than 20 years.7Avoidance of the under-
lying affected and healthy vital dentine is
possible because of selective photo-mechan-
ical and photo-acoustic effects that occur
because of the volume expansion of rapidly
heated water within the carious dentine.8
Typically, patients undergoing cavity prepa-
ration with erbium lasers do not need local
anaesthesia, a fact established from large
scale clinical trials, in which only 2-5% of
patients requested LA - even though many
noted slight, intermittent sensations of
cooling or vague shock-like sensations
during laser pulses. There is a short-term
analgesic effect created by the laser which
attenuates these responses in most cases.
Using one of these four alternative
methods of caries removal (or others), the
clinician can apply the 4 S principle for
restorative care in dentally anxious adult
and child patients. As can be seen from
Blood-injury fear
Dentist/Staff
Communication
techniques/skills
(condescending remarks,
bad comm’s skills)
Bad Manners
Angry Dentist/ Staff
Unsympathetic/
non-supportive staff
Negative dental
team behaviours
(unfriendly, unaccepting
or reassuring)
Place
Sounds of drills
Smell
Waiting room (lay out
and design, content)
Waiting period
Sounds of
screaming patient
Procedure
Sight of needle
Sensation of drill
Extraction
Root Canal Treatment
Scaling and root planing
Fillings and
crown preparations
Gag-inducing
procedures
Patient
Fear of pain
Vicarious learning
(fearful family members,
bad stories from
friends, movies)
Past trauma and
dental experience
(Conditioning
experiences)
Personality
characteristics:
e.g: neuroticism
Figure 1. Some possible interactions in factors relating to dental anxiety. Adapted from Reference 9.

26 auxiliary September/October 2007
Table 3, these methods vary in their
implementation but can all achieve a more
pleasant patient experience. If we con-
sider the high number of patients who
currently avoid dental care, the impact of
using these methods on those population
subgroups can be very significant - as well
as being professionally worthwhile.
References
1. JM Armfield, AJ Spencer, JF Stewart. Dental fear in
Australia: who’s afraid of the dentist? Australian
Dental Journal 2006; 51(1): 78-85.
2. Brennan DS, Spencer AJ (ARCPOH). Practice pro-
files of Australian private general dental practitioners
Australian Dental Journal 2006; 51(1):91-93, 2006.
3. Powell RN, McEniery TM. The Brisbane Statistical
Division Survey of Adult Dental Health 1984. 2. Soci-
ological aspects of the survey. ADJ 1988; 33(1):14-17.
4. Anusavice KJ, Kincheloe JE. Comparison of pain asso-
ciated with mechanical and chemomechanical removal
of caries. J. of Dental Research 1987; 66(11):1680-1683.
5. Ericson D, Zimmerman M, Raber H, Gotrick B,
Bornstein R, Thorell J. Clinical evaluation of efficacy
and safety of a new method for chemo-mechanical
removal of caries. A multi- centre study. Caries
Research 1999; 33:171-177.
6. Maragakis GM, Hahn P, Hellwig E. Chemomechanical
caries removal: a comprehensive review of the literature.
International Dental Journal 2001; 51:291-299.
7. Hibst R, Keller U. Experimental studies of the
application of the Er:YAG laser on dental hard sub-
stances: I. Measurement of the ablation rate. Lasers in
Surgery and Medicine 1989; 9:338-344.
8. Walsh LJ. The current status of laser applications in
dentistry. Australian Dental Journal 2003; 48:146-155.
9. Hmud R, Walsh LJ. Dental anxiety: causes, compli-
cations and management approaches. International
Dentistry, 2007. In press.
About the author
Professor Laurence J. Walsh is the tech-
nology editor of Australasian Dental
Practice magazine. He has worked in
clinical practice in special needs dentistry
for the past 20 years and contributed to
the development of preventive protocols
for special needs patients.
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Table 3. Comparison of four approaches from the 4S perspective
Parameter Ultra-low ART with Carisolv Erbium lasers
speed cutting hand instruments
Reduced need for injected LA Yes Yes Yes Yes
Dominant physical sensations Low freq. vibration Scraping Scraping Popping: shock waves
Likelihood of odontoblastic Moderate Low Very low to nil Very low to nil
pain during caries removal
Basis of selectivity for Lack of Lack of Lack of Increased water
infected carious dentine collagen crosslinks collagen crosslinks collagen crosslinks content
(shear strength) (shear strength) (chemical reaction) (ablation threshold)
Suppressed nociceptor firing No No Possibly, because Yes
of low pH (analgesic effect)
Annoyance factor during Low Low Low Very low
restorative treatment
Dentine ablation
Smell and vapours Dentine cutting Nil Hypochlorite vapour if suction
and chloramines inadequate;
typically nil
Cost of implementation Nil, as existing Nil, as regular Low. Gel is stored Medium to
in terms of equipment burs and low speed spoon excavators refrigerated and high for initial
handpieces are used are used mixed when needed purchase
Tactile sense Yes Yes Yes No, unless
sapphire tips used
Conservative Conservative Gel has no effect Laser will remove
Accessing the carious dentine access form access form on sound tooth structure resin and GIC,
or restorations but not amalgam
Learning curve Low Low Low Medium
Ancillary guides Patient response Patient response Loss of opacity Ablation sound, change
for caries removal in the gel change in fluorescence
Speed of dentine removal Medium Low Low Medium to high
Suitable for adhesive Ye s Ye s Ye s Ye s
materials such as GIC
Antibacterial action No No Yes (sodium Yes (photothermal
hypochlorite) ablation)