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Topical Anesthesia
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Table12.7 Tetracaine.
Pharmacological factors Reference
● Name and synonyms: Tetracaine, Amethocaine, Pontocaine
● First synthesized in 1928 by Otto Eisleb
● Chemical name: 2- dimethylaminoethyl 4- butylaminobenzoate Council on Dental Therapeutics (1984)
● Formula: C
15H24N2O2
4H9
HN
COO–CH2–CH2N
CH
● Molecular weight: Base 264.4
Martindale (1982)
Hydrochloride 300.8
● Clearance: ? Annex 11
● Volume of distribution: ? Annex 11
● Half- life: ? Annex 11
Physicochemical properties
● pKa value or dissociation constant: 8.5 Annex 6
● Lipid solubility or partition coefficient: N- heptane 4.1
Annex 7
n-octanol 220
Indicates high anesthetic potency and topical anesthetic capability
● Binding to plasma proteins: 85%
Annex 9
Indicating long duration of anesthesia
● Vasodilation: ++ (high) Martindale (1982)
Clinical properties
● Relative anesthetic potency: 8
● Relative toxicity: 8 Annex 8
● Absolute maximum dental dose: 20 mg (0.3 mg/kg) Carabelli (1952)
ADA guide (2003)
● Use during pregnancy: Yes (FDA category=C)
Indicating that it is safe
● Use during breastfeeding: Yes
Indicating that it is safe
● Use in children: NOT in children aged <12 years
Haas (2000)
(Table5.11)
Haas (2000)
(Table5.11)
ADA guide (2003)
Not established in the USA
Clinical efficacy (mouth)
Formulations of tetracaine 1%
● Onset of action: 1–2 min
● Maximum effect: ?
● Duration of effect of topical anesthetic: 50 min
Main pharmacological factors, physicochemical properties, clinical factors, and clinical efficacy.
Surprisingly for an anesthetic as old as tetracaine, data on pharmacokinetics are lacking (clearance, volume of distribution, and half- life)
(Annex 11).
Annexes 19 and 20
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Cocaine
Cocaine is an ester anesthetic that appears naturally as an
alkaloid in the coca leaf (Erythroxylum coca), which grows
in South America, mainly in Bolivia and Peru. The drug
accounts for 0.7–1.8% of the weight of the leaf (Caldwell
and Sever 1974; Van Dyke and Byck 1982). Cocaine was
isolated in 1860 by Albert Niemann, who also gave it the
name “cocaine” (Niemann1860). The drug was artificially
synthesized in 1923 by Richard Willstätter (Willstätter
etal.1923).
Cocaine has a pKa of 8.8 (Annex 6), therefore its onset of
action should be late. However, in practice, this latency
period is very short and its action manifests itself very
quickly for various reasons: (i) the high concentration (it is
generally used at ≥20%) (Adriani1963; Adriani etal.1964;
Adriani and Zepernick 1964) and (ii) its vasoconstrictor
effect, which becomes apparent when it blocks the monoaminoxidase enzyme and prevents reuptake of norepinephrine from the nerve endings (Muscholl1961; Covino
and Giddon1981).
It is worth highlighting that plasma pseudocholinesterases rapidly inactivate cocaine in blood. However, the drug
persists in the mucosa (especially the nasal mucosa) for
4–6 hours, with a peak at 60 minutes and a half- life of
minutes (Annex 11). This is due to the slow passage to
95
the bloodstream resulting from the vasoconstrictor effect
(Van Dyke etal. 1976). Also interesting is the fact that in
addition to catabolism by plasma cholinesterases, cocaine,
like all ester anesthetics, is metabolized slowly in the liver
(McLure and Rubin2005). Table12.8 summarizes the main
characteristics of cocaine.
Maximum Dose
Cocaine is a safer topical anesthetic than originally thought
because its vasoconstrictor effect reduces its systemic toxicity, with the result that, paradoxically, the drug is less toxic
at higher concentration, since it increases vasoconstriction
in the affected mucosa (Campbell and Adriani1958; Adriani
etal.1964; Van Dyke etal.1976). The maximum dose for
injectable anesthetic was set at 50 mg at the beginning of
the twentieth century (Fischer 1912; Bieter 1936). The
American Dental Association (ADA) guidelines recommend a maximum topical dose of 400 mg, although in a
1–4% solution (American Dental Association 2003). We
favor using higher concentrations (≥20%), therefore we suggest a smaller maximum dose than that recommended by
other authors, that is, a maximum absolute dose of 100 mg
(1.5 mg/kg) for an adult weighing ≥70 kg (DiFazio 1981;
Martindale1982). As the most widely used concentration is
20%, this would be equal to 0.5 ml of solution, gel, or ointment, therefore it should be applied in small dabs.
Advantages andDisadvantages
The main advantage is its potent and rapid effect (30 seconds), which is long-
lasting (55 minutes) (Table12.8). Its
disadvantages are drug trafficking and illegal recreational
use (Anonymous1979) and its ability to create dependence
with repeated use, especially in the case of recreational
inhalation (Caldwell and Sever 1974; Van Dyke and
Byck1982). Due to reuptake inhibition of norepinephrine,
cocaine may not be well tolerated in patients with cardiovascular disease.
Specific Adverse Effects
Allergy and sensitization, since this is an ester anesthetic,
as well as the problems of trafficking, illegal recreational
use, and drug addiction through repeated use (see above)
(Caldwell and Sever1974; Van Dyke and Byck1982).
Formulations forUse inDentistry
There are no commercial formulations (except for
compounded formulas such as TAC gel; Kravitz2007), only
the generic form, although it can be obtained in pharmacies with special prescriptions for controlled substances.
The most popular formulation in Europe is a solution that
has been used in ear, nose, and throat medicine since
1898 known as BONAIN, which comprises onecocaine (anesthetic), oneone-
third menthol to improve the taste (Martindale1982;
third phenol (disinfectant), and
third
Jyväkorpi1996; Tainmont2007).
Topical Anesthetic Compounds
These are compounded formulas obtained by mixing various topical anesthetics and a vasoconstrictor (Table12.9).
They are very popular in the United States, although their
main drawback is that they carry very high doses (see
below). They are mainly used in orthodontic surgery for the
placement of intraosseous anchors (microscrews or orthodontic mini- implants).
Composition
The formulations are very diverse. The most popular for
dentistry are shown in Table 12.9. Their components
include the following (Kravitz etal.2015):
1) Local anesthetics that are generally a mixture of several
components and may be amide- and ester- type.
2) Vasoconstrictor. The vasoconstrictor in this case is phe-
nylephrine, which has fallen into disuse in injectable
solutions and whose vasoconstrictive potency is 5% of
that of epinephrine (Furchgott 1972). Furthermore,
when the formulation contains this vasoconstrictor, its
expiry date is 90 days after the preparation (Kravitz
etal.2015).
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Table12.8 Cocaine.
Pharmacological factors Reference
● Name and synonyms: Cocaine
● First synthesized in 1923 by Richard Willstätter
First isolated in 1860 by Albert Niemann
● Chemical name: Benzoylmethylecgonine Caldwell and Sever (1974)
● Formula: C
17H21NO4
COO–CH
2
CH
2
N CH
CH
2
Niemann (1860)
Willstätter (1923)
Council on Dental Therapeutics (1984)
Martindale (1982)
3
● Molecular weight: Base 303.4
● Clearance: 1.83 l/min Annex 11
● Volume of distribution: 207 l (intranasal) Javaid (1983)
● Half- life: 95 min (intranasal) Annex 11
CH CHCOO
Hydrochloride 339.8
Martindale (1982)
Council on Dental Therapeutics (1984)
Physicochemical properties
● pKa value or dissociation constant: 8.8 Annex 6
● Lipid solubility or partition coefficient: ?
● Binding to plasma proteins: 98% McLure and Rubin (2005)
● Vasodilation: − (marked vasoconstriction) Muscholl (1961)
Clinical factors
● Relative anesthetic potency: ?
● Relative toxicity: 3? Annex 8
● Absolute maximum dose in dentistry: 100 mg (1.5 mg/kg) DiFazio (1981)
Martindale (1982)
● Use during pregnancy: ? (FDA category=C) ADA guide (2003)
● Use during breastfeeding: ?
● Use in children: NOT in children aged <6 years
● Not established in the USA
ADA guide (2003)
Clinical efficacy (mouth)
Formulations at 20% or higher Annex 20
● Onset of action: 30 s (very fast)
● Maximum effect: ?
● Duration of effect of topical anesthesia: 55 min
Main pharmacological factors, physicochemical properties, clinical factors, and clinical efficacy.
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Table12.9 Popular topical anesthetic compounds used
on the mucosa in the USA: mixtures and high concentrations
(Kravitz2007; Kravitz etal.2015).
Topical
compound Drug %
TAC 20%
Tetracaine 4 40 mg
Amount
per
milliliter
Absolute
maximum
dose
a
b
20 mg
Alternative
Profound
Lidocaine 20 200 mg 250 mg
Phenylephrine 2 2000 μg 4000 μg
Tetracaine 4 40 mg
a
20 mg
c
d
b
PET gel
c
d
d
b
Baddest
Lidocaine 10 100 mg 250 mg
Prilocaine 10 100 mg 250 mg
Phenylephrine 2 2000 μg 4000 μg
Tetracaine 12.5 125 mga20 mg
Topical in
Town
Lidocaine 3 30 mg 250 mg
c
(BTT)
e
d
b
Best Topical
Prilocaine 12.5 125 mg 250 mg
Phenylephrine 2 3000 μg 4000 μg
Tetracaine 12.5 125 mga20 mg
Ever
Lidocaine 12.5 125 mg 250 mg
Prilocaine 3 30 mg 250 mg
Phenylephrine 3 3000 μg 4000 μg
a
Indicates values that already exceed the maximum recommended
doses in the milliliter amount, without taking into account the
cumulative effect of other drugs.
b
Carabelli (1952), ADA guide (2003).
c
Adriani etal. (1964), ADA guide (2003).
d
Jastak and Yagiela (1983), Malamed (2004).
e
Estimated to be equal to lidocaine in topical anesthetic.
c
e
d
3) Wetting agent. This is usually alcohol, propylene glycol,
or ethoxydiglycol. It serves as a base for the mixture of
the drugs mentioned above, displaces air, and enhances
penetration of the active ingredients into the mucosa.
4) Base for drug transport, to formulate creams, gels, and
ointments. This has a soft, creamy consistency.
5) Favoring and colorant to sweeten and suppress the bit-
terness of these products.
Advantages andApplication
The main advantage for orthodontists is that they do not
have to administer local anesthetic injections to place
mini- implants. In addition, the compounds are very easy
to apply.
The compounds are applied on clean mucosa at a volume of 0.2–0.4 ml (Kwong et al. 2011; Lamberton
etal.2016), although some authors consider that up to 2 ml
can be applied (Kravitz 2007; Kravitz et al. 2015). This
amount is excessive (see Table 12.9). It is left to act for
2–4 minutes, reaching its maximum effect in 5 minutes,
and lasts 25–30
minutes (Kravitz2007; Kravitz etal.2015).
Adverse Effects
The main drawback of these compounds is that they have a
low therapeutic margin, that is, a very narrow margin
between the effective dose and a toxic dose. In addition, their
formulation (cream, ointment, or gel) makes it difficult to
calculate and monitor the dose administered (Kravitz2007).
Two cases of severe reactions to the formulations and two
deaths (caused by application of the compound on the skin
for depilation) have been reported in theUnited States, therefore, in 2006, the FDA published an alert on the potential
risks of these compounds (Kravitz2007; Baumgaertel2009).
Other drawbacks include irritation of the mucosa
(probably
because of the high concentrations of active ingredient) and
the bad – generally bitter – taste, which is managed with
sweeteners and flavorings (Kravitz2007; Kravitz etal.2015).
Clinical Efficacy
Clinical trials have shown that these formulations are efficacious (Kravitz and Kusnoto2006; Reznik et al. 2009),
even more so than benzocaine 20% (Reznik etal.2009) and
Oraqix (Kwong etal.2011), although they are less effective
than the traditional 0.45- ml injection (one- quarter of a
1.8-
ml cartridge) of the standard solution of lidocaine 2%
with epinephrine 1:100
000 (Lamberton etal.2016).
Other Experimental Formulations
Over time, variants or new methods have been sought to
achieve a potent, rapid, efficacious, and safe topical anesthetic, although the results have ranged from poor to
encouraging in some cases, as follows:
● Mixtures of topical anesthetics with detergents, cations,
diffusion agents (Hyaluronidase) (Adriani and
Zepernick 1964), and vasoconstrictors (Adriani and
Campbell 1956; Campbell and Adriani 1958; Adriani
1964; Nakamura et al. 2013) have not improved topical
anesthesia or diminished its systemic absorption.
● Similarly, alkalization and acidification of topical anes-
thesia formulations have been unable to improve the
results (Adriani etal.1964; Adriani and Zepernick1964).
● Mixtures of two or more topical anesthetics have not
shown a cumulative anesthetic effect (Adriani and
Zepernick1964), although they have– unfortunately –
led to cumulative systemic toxic effects (Adriani 1963;
Adriani etal.1964). Compound topical anesthetics have
become popular in the United States. These compounded
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formulas are composed of a mixture of several topical
anesthetics and a vasoconstrictor (see above). The exception to the lack of recommendations in favor of mixtures
is EMLA cream (or its oral variant, Oraqix), which, as we
have seen, is not included in this section owing to its
pharmaceutical peculiarities and its low doses (5%, that
is, 2.5% of lidocaine and 2.5% of prilocaine).
● Iontophoresis. This process involves placing a positively
charged topical anesthetic on the oral mucosa (e.g. lidocaine 2% with epinephrine, both drugs are positively
charged) and placing an electrode on top of the anesthetic to enable current to flow for about 10 minutes
minutes) (Gangorosa 1974; Won et al. 1995).
(5–15
Iontophoresis has proven successful in mobile primary
tooth extraction, and the local anesthetic is not painful
(Gangorosa1974). This is a promising proposal, although
it is time-
● Liposomes. Liposomes are small empty spheres
(0.03–10
consuming and cumbersome.
μm) with a double- phospholipid wall that act as
vehicles by encapsulating the topical anesthetic before
transport and helping them to penetrate the oral mucosa
(McLure and Rubin 2005; Franz-
Montan et al.
2007,2012). They have been used with tetracaine 5% (Zed
et al. 1996) and with ropivacaine 1–2% (Franz- Montan
etal.2007,2010); outcome has been standard to promising.
● Sonophoresis. This technique involves using ultrasonic
energy to generate microchannels across lipids between the
keratinized cells of the stratum corneum and thus facilitate
penetration of topical anesthetic. The results are no different from those of standard techniques (Packer etal.2013).
Finally, Table 12.10 summarizes data on all recommended topical anesthetics, with all their clinical characteristics and maximum recommended doses.
Topical Cooling
Cold reduces the velocity of nerve conduction, which
ceases when the temperature falls from 10 to 0
(Harbert1989), thus inducing anesthesia. Topical cooling
techniques are only used before injection of local anesthesia
to ensure that the procedure is as painless as possible. The
only contraindication would be in patients who cannot tolerate cold (Harbert1989).
Cold Aerosols
Cold aerosols are the old, traditional method. The aerosols
contain ethyl chloride, which is a highly volatile component. On evaporation, the aerosol quickly reduces the
temperature of the mucous membrane at the application
site. Ethyl chloride is the model on which newer aerosols
are based and exits the container at –10 or –16 °C (Cohen
etal.1993; Nusstein etal.1998).
The main advantage of these aerosols is their rapid
action, which is almost instantaneous. Moreover, there is
no maximum dose since they do not enter the bloodstream
and their action is limited to cooling the surface of the
mucous membrane. When the surface of the membrane is
covered with white frosting, the solution can be injected.
The main drawback is the short duration of effect, which
lasts only a few seconds (Roberts and Sowray1987). The
other drawbacks of these formulations are as follows:
● They can be inhaled, especially when applied to the back
of the mouth. In addition, given that they are derived
from ethyl chloride, they have a general anesthetic effect
and thus carry a risk of loss of consciousness (Roberts
and Sowray1987).
°C
Table12.10 Summary oftopical anesthetics intheir most widely used formulations: clinical effect, absolute maximum dose, anduse
inpregnancy (FDA, risk ofpregnancy), breastfeeding, andchildren.
Topical anesthetic Clinical effect (minutes) Maximum dose Clinical factors
Anesthetic Formulation
Benzocaine 20% gel/ointment 0.3–0.5 — 5 1050 15 5.5 C Yes Yes Yes
Lidocaine 5% gel/ointment 1–2 5 12 250 3.6 5 B Yes Yes Ye s
Lidocaine 20% patch 2–5 15 25 250 3.6 5.5
EMLA 5% cream 3 5 20 400 5.7 8 B Ye s Ye s Not
Tetracaine 1% 1–2 — 50 20 0.3 2 C Yes Yes Not
Cocaine 20% 0.5 — 55 100 1.5 0.5 C ? ? Not
a
In the case of lidocaine adhesive patches, the maximum dose is in the number of 20% patches, with 46 mg per patch, so 5.5 patches.
Onset
minutes
Maximum
effect Duration mg total mg/kg ml
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risk Pregnancy
a
B Yes Yes Not
Breastfeeding Children
years
<12
<12 years
<12 years
<12 years
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● They are not recommended in children because the
noise of the aerosol and the bad taste resulting from their
dispersion in the mouth could lead the child to behave
badly (Frasier1967; Evers and Haegerstam1981).
● They can cause sensitization to cold in sensitive teeth
since it is difficult to control the area of application
(Roberts and Sowray1987)
Refrigerants
Even colder compounds can also be used in dentistry.
Initially, the substance used was dichlorodifluoromethane (DDN) (Fuss etal.1986; Duncan etal.1992), which
exits the container at −50
etal. 1993; Nusstein etal. 1998; Hsiao-
°C (Fuss et al. 1986; Cohen
Wu et al.2007)
and which was initially used in vitality testing. It has
been replaced by 1,1,1,2 tetrafluoroethane spray (TFE)
(Green Ice or Endo–26
°C (Nusstein etal.1998; Hsiao- Wu etal.2007), has a
weaker ozone-
Ice), which exits the container at
depleting effect (Nusstein et al. 1998;
Kennedy etal.2003; Lathwal etal.2015), and is not flammable. It was approved by the US FDA in 2004 (Lathwal
etal.2015).
The main advantage of these refrigerants is their rapid
action, which is almost instantaneous (a few seconds). In
addition, they are not subject to maximum doses, since
they do not enter the bloodstream, and act only by cooling
the surface of the mucous membranes, as is the case with
cold aerosols. Furthermore, they are not toxic when inhaled
(Kosaraju and Vandewalle2009) and have proven superior to benzocaine 20% for 2 minutes (Kosaraju and
Vandewalle2009).
However, refrigerants do have a drawback, namely, they
can only be used on the palate (Duncan etal.1992; Kosaraju
and Vandewalle2009; Wiswall et al.2014) owing to the
nature of the palatal epithelium, which can resist low temperatures (Duncan et al. 1992). Nevertheless, they can
cause frostbite of the palatal mucosa in 80% of cases, with
erythema and soreness, which appear after 2–48 hours and
last 1–10 days (Wiswall etal.2014). Carbon dioxide (CO
2
snow, or dry ice, is not used for this purpose since its temperature is excessively low (−78 °C) (Fuss et al. 1986;
Loetscher et al. 1988) and it can severely damage
the mucosa.
The technique involves soaking the tip of a cotton swab
(Kosaraju and Vandewalle2009; Wiswall etal.2014) or a
cotton pellet held in tweezers (Duncan et al. 1992) in
1,1,1,2- tetrafluoroethane (Green Ice or Endo Ice). The
solution is then applied for only 5–10 seconds (never more,
owing to the low temperature) by pressing it against the
area of the palate that is to be injected. After this short
period, the tip of the needle is inserted in the immediate
area of the swab (pressed against the surface of the palate),
which is withdrawn. The anesthetic solution is then
injected (Kosaraju and Vandewalle2009).
Topical Ice
The use of ice was proposed by Henry Harbert
(Harbert1989). This approach has several advantages:
● Since the temperature of the ice is –4 to 0 °C, the mucous
membrane is not damaged by frostbite (Hindocha
etal.2019).
● It can be used throughout the mouth, not only in
the palate.
● As the ice contains no drugs, it does not cause allergic or
toxic reactions (Hindocha etal.2019).
● It is inexpensive, since it is composed of tap water
(Lathwal etal.2015; Hindocha etal.2019).
● In clinical trials, it has proven superior to benzocaine
20% gel for 1
minute (Harbert 1989; Aminabadi and
Farahani2009; Ghaderi etal.2013; Lathwal etal.2015),
lidocaine 2% gel for 1 minute (Mohiuddin et al.2015),
and refrigerants for 5
seconds (Lathwal etal.2015). It is
equally effective as lidocaine 5% gel for 1
(Hindocha etal.2019).
● It can be used in both children and adults.
The only problem with this approach is that it requires
the device to be prepared. The various systems available are
as follows:
● The empty glass cartridge is filled with water and stored
upright in the freezer at –4° (Ghaderi etal.2013).
● An ice cube, tube, or cone is made by cutting and filling
the little finger of a latex glove with water. The latex finger is closed and placing it in the freezer (Aminabadi and
Farahani2009; Mohiuddin etal.2015).
The main problem with these systems is that the ice is
contained in glass or latex and is not in direct contact with
the mucous membrane. Therefore, the surface of the ice
melts and surrounds the covered ice, thus reducing its
)
effect on the oral mucosa in a very short time (Hindocha
etal.2019). Furthermore, the dentist has to hold the frozen
device with his/her fingers.
● The tip of a cotton bud can be soaked in water and the
whole bud frozen (Jayasuriya et al. 2017). However,
this technique generates very little ice, which melts
very quickly. Consequently, contact between the ice
and the mucosa ceases after a short time (Hindocha
etal.2019).
All three methods are simple and relatively easy to pre-
pare, although they are subject to the drawbacks we have
minute
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mentioned. In our opinion, the two best methods are as
follows:
● A bar of ice is prepared with an empty glass anesthetic
cartridge or the protective sheath of a needle. The
empty sheath or empty cartridge is filled with water
and a toothpick is inserted through the silicone stopper
(as this is thinner, the toothpick can penetrate more
easily in the plunger), thus leaving an active part (the
anterior part of the frozen water) measuring around
mm. The sheath is then stored upright in the freezer
25
at −4
°C) (Harbert1989). Before use, the bar of ice is
removed from the sheath using the handle (toothpick)
(Figure12.2).
● A bar of ice is prepared with a small plastic syringe.
ml syringe is filled with water and placed in the
A2.5freezer at −4
°C. When this is frozen, the tip of the
syringe is cut with a scalpel (Figure12.3) and the plunger
is pressed so that the tip of the ice appears (Figure12.4)
(Hindocha etal.2019).
Figure12.4 The plunger is pressed to force the ice through the
tip of the syringe.
Redrawn from Hindocha (2019).
Bar of ice Toothpick
Figure12.2 Bar of ice with a toothpick get from an empty glass
of anesthetic cartridge.
stopper (plunger)
Figure12.5 The bar of ice in the syringe is pressed against
the area of the oral mucosa to be injected. Redrawn
from Hindocha (2019).
Application is simple. The bar of ice is applied directly
to the mucous membrane, with the ice held by the toothpick (Harbert1989) or via the plastic syringe (Hindocha
etal. 2019) (note that we do not touch the ice directly
with our fingers) and pressing firmly against the mucous
membrane for 45–60 seconds. The ice gradually melts
(Figure12.5) and the mucous membrane quickly changes
color from pink to white owing to the blanching produced
by the pressure and cold. After the recommended time,
the bar of ice is slightly withdrawn and the anesthetic
solution is injected at the point where the ice was applied.
The ice continues to melt, and the pressure is maintained.
Indications forTopical Anesthetic
Figure12.3 A scalpel is used to cut the anterior part of the
syringe containing frozen water. Redrawn from
Hindocha (2019).
The two main indications of topical anesthetic are preparation for injection of local anesthetic and use during periodontal treatments administered by the hygienist. We
examine these indications in more detail below, the first in
Chapter13 and the second at the end of the present chapter, with Oraqix. Other indications are as follows.
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For Symptomatic Relief ofPain
Topical anesthetic is indicated for symptomatic relief of
pain in the following situations.
Pain Resulting fromTooth Decay
Benzocaine has been used since 1926 (Sveen etal.1982) as
a topical anesthetic for relief of pain resulting from tooth
decay, loss of a filling, or a broken/cracked tooth. Clinical
studies have shown the efficacy of this agent at concentrations of 7.5% (Sveen et al. 1982) and10–20% (Hersh
etal. 2005; Hersh et al.2013) – both in the gel formulation– and report promising data for the 12% patches (Hersh
et al.2003). In order for it to function, the gel must be
placed on the gum surrounding the tooth.
Painful Ulcers andLesions onthe Mucosa
Clinical studies have also demonstrated the efficacy of
applying lidocaine 5% on painful lesions caused by recurrent aphthous ulcers, acute herpetic gingivostomatitis, or
mouth ulcers (Ship etal.1960). The anesthetic is applied
directly on the lesion using cotton swabs. Benzocaine
10–20% (three times daily) has also proven efficacious on
mucosa damaged by friction from removable prostheses
(Graser1984).
Indication asAnesthetic
Topical anesthetics cannot replace injectable solutions when
pulpal anesthesia is required (Annex 20), although, in some
cases, they can replace injections in minor procedures and
can help in specific interventions, as follows.
Minor Surgical Interventions
Topical anesthetic can be used for various minor interventions: superficial biopsies of the oral mucosa with lidocaine
adhesive strips applied for 5 minutes (DentiPatch) (Roller
and Ship 1975), removal of small soft tissue tumors, such
as palatal fibromas, with EMLA 5% cream for 15 minutes
(Meechan 2001), lancing a dental abscess (Roberts and
Sowray 1987), and placement of temporary orthodontic
mini- implants (Reznik et al. 2009; Kwong et al. 2011).
However, the results are poorer than with standard injectable anesthetics (Lamberton et al. 2016) (as seen with
topical anesthetic compounds).
Clinical Procedures
These include placement of retraction clamps that function
apically in children with budding teeth in whom the midpoint of the crown is still below the gum line. In these
cases, the anesthetic used is benzocaine 20% for 1 minute
(Stecker et al. 2002), DentiPatch for 5 minutes (Stecker
et al. 2002), EMLA 5% cream for 5 minutes (Lim
and Julliard 2004), or Oraqix for 2
Chussid 2009). All of these methods relieve discomfort
andpain, although they do not eliminate them completely.
Topical anesthetic in the form of EMLA 5% cream for
5 minutes can also be used to relieve discomfort during
removal of orthodontic bars (Pere etal.1992).
Management ofthe Gag Reflex
Topical anesthetics can be used to reduce gagging, which
can affect patients when taking impressions or periapical
radiographs (in the upper posterior part) (Ship etal.1960;
Graser1984; Roberts and Sowray1987). In such cases, it is
better to administer topical anesthetics in the form of aerosols on the soft palate, including the uvula and tonsillar
pillars (Roberts and Sowray1987).
minutes (Yoon and
Periodontal Oraqix® Gel
As mentioned above, Oraqix is EMLA cream adapted for
the oral mucosa, although it has been designed more specifically for periodontal work, therefore it is suitable for
regular periodontal examination and scaling and root planning. In addition, as these procedures are painful, they
require local anesthetic injections in 92% of cases (Van
Steenberghe etal.2004). The disadvantages of such injections are as follows:
1) Many patients are afraid of the needle and the injection
(Donaldson etal. 2003; Jeffcoat etal.2001; Magnusson
etal.2003). The local anesthetic injection is estimated
to cause moderate or intense pain in 35% of patients
undergoing periodontal procedures (Van Steenberghe
etal.2004).
2) The long duration of the anesthetic effect, with swelling
of the soft tissues (Donaldson et al. 2003; Jeffcoat
etal.2001; Magnusson etal.2003), is considered a disadvantage by more than 25% of patients undergoing
periodontal procedures (Van Steenberghe etal.2004).
3) Hygienists who usually perform tartar removal and
scaling and root planing are not authorized to administer local anesthetic injections in many countries of the
European Union (Stern and Giddon 1975; Svensson
etal.1994). In the United States, most states allow the
hygienist to administer local anesthetic injections under
the supervision of the dentist, although some states do
not authorize this practice (Boynes etal.2010).
It was therefore necessary to find alternatives to local
anesthetic injections. In 1975 (Stern and Giddon1975) and
in 2001 (Carr and Horton2001a), lidocaine patches applied
to specific quadrants for 5–15
minutes yielded promising
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results. In addition, in 1994 and 1995 (Svensson etal.1994;
Donaldson and Meechan 1995), EMLA 5% cream applied
to a specific quadrant with an intraoral splint for 5
minutes
also yielded promising results.
Oraqix System (Needle- free Anesthesia)
The Oraqix periodontal gel system came onto the market in
2005. This formulation, which is derived from EMLA
cream, contains 5% topical anesthetic in a 1:1 eutectic mixture of 2.5% lidocaine and 2.5% prilocaine. It is designed
specifically for use in the oral cavity. Since Oraqix is a thermosetting noninjectable anesthetic gel, it has low
at ambient temperature (fluid-
like), although when it is
viscosity
applied to periodontal pockets the heat of the body converts it into an elastic gel that remains at the application
site to produce anesthesia and reduce the risk of
dispersion
to other areas of the mouth (Friskopp and Huledal 2001;
Friskopp et al. 2001; Herdevall et al. 2003; Magnusson
etal.2003).
Oraqix comes in cartridges containing 1.7 ml or1.7 g,
with 5% anesthetic (Herdevall et al. 2003; Kwong
etal.2011), therefore it contains 2.5% lidocaine (42.5 mg)
and 2.5% prilocaine (42.5
mg), i.e. a total of 85 mg of anesthetic per cartridge. The maximum dose has been set at five
cartridges, i.e. 8.5 ml or 8.5 g (425 mg of anesthetic, thus
mg of lidocaine and 212.5 mg of prilocaine) (Herdevall
212.5
etal.2003; Kwong et al. 2011). Studies on peak levels in
blood show that these amounts are far from toxic
(Table12.1) and that methemoglobinemia caused by prilocaine also remains below 2% (i.e. normal levels) (Herdevall
etal.2003) (see Chapter23).
Oraqix can be applied using a cartridge-
type syringe or,
even better, a specially designed applicator (Figure12.6), in
such a way that each click administers 0.07–0.08 ml (Kwong
et al. 2011). The anesthetic is paced on a specific tooth,
semiarch, or the whole mouth, with a dose of 0.2 ml per
tooth (three clicks) or one-
eighth of a cartridge (Donaldson
etal.2003). In a specific quadrant, it is administered at a
dose of one to two cartridges (1.7–3.4
ml) (Magnusson
etal.2003; Van Steenberghe etal.2004). It is only authorized for adults. The absence of data for children (age
<12
years), means that it is not indicated in this population.
The system has special 23G blunt applicators (0.6
mm
external diameter) with a lateral outlet (Friskopp and
Huledal 2001; Friskopp etal. 2001; Jeffcoat etal. 2001);
hence the term “needle-
free anesthetic” (Van Steenberghe
etal.2004).
Method ofApplication
Below we provide a step- by- step explanation of how this
anesthetic is prepared before use in scaling and root
planing:
● The Oraqixis loaded into the applicator (Figure12.7) or a
cartridge-
type syringe and the 23G blunt applicator is
put into position.
● The quadrant is isolated with cotton roll (Donaldson
etal.2003).
● Saliva is aspirated to keep the mouth dry (Herdevall
etal.2003).
● The applicator is inserted into the periodontal pockets,
which are filled with Oraqix up to the gingival margin
until it begins to overflow (Friskopp and Huledal2001;
Friskopp etal.2001). The patient may experience minor
discomfort during this maneuver (5–20% of cases)
(Friskopp and Huledal2001; Friskopp etal.2001).
● If the procedure is to be performed by quadrants, the best
approach is to fill the most distal pockets and gradually
fill the remainder while moving forward (Jeffcoat
etal.2001).
● The gel should be applied as quickly as possible to maxi-
mize its extension and absorption (Friskopp and
Huledal2001).
● The dentist can begin to work 0.5–2 minutes after appli-
cation (Friskopp et al. 2001; Jeffcoat et al. 2001;
Donaldson et al. 2003;Van Steenberghe et al. 2004),
therefore the effect is very quick.
● The anesthetic effect lasts for 17–20 minutes (Friskopp
etal.2001).
Figure12.6 Oraqix device set up and ready for use.
Figure12.7 Different elements during the set- up of the Oraqix
device and order of assembly.
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● If the scaling process continues to hurt, then we can
apply the following measures:
⚪ Reinforcement, by re- administering Oraqix to the tooth
in question. This occurs in 30% of cases (Magnusson
etal.2003).
⚪ If the tooth continues to hurt despite reinforcement
with Oraqix, then a rescue strategy based on infiltration
with standard anesthetic can be adopted. This
situation
may arise in 5–10% of cases (Jeffcoat et al. 2001;
Donaldson etal.2003; Magnusson etal.2003).
● During treatment, the patient can expectorate/spit, but not
rinse (Herdevall etal.2003). If the patient’s mouth is very
dry and uncomfortable, then it can be moistened with the
water aerosol of the device (Herdevall etal.2003).
air-
● Once treatment is complete, the patient can rinse with
water to remove any remaining Oraqix (Friskopp and
Huledal2001).
Efficacy
Application of the above- mentioned method in scaling and
root planing has revealed the following:
● Oraqix is better than placebo (Friskopp and Huledal2001;
Jeffcoat et al. 2001; Donaldson et al. 2003; Magnusson
etal.2003).
● Oraqix is more effective in deeper pockets (Jeffcoat
et al. 2001; Donaldson et al. 2003; Magnusson
etal.2003).
● Seventy percent of patients prefer Oraqix, even though it
is not as effective against pain as standard local anesthetic injections (Van Steenberghe etal.2004).
Specific Adverse Effects
1) Between 10% and 30% of patients complain of the bad
taste of this anesthetic (Friskopp and Huledal 2001;
Friskopp etal.2001).
2) The anesthetic extends to the throat and tongue in 20%
of cases, since the gel flows out of an over-
filled periodontal pocket (Friskopp and Huledal2001; Herdevall
etal.2003).
3) In theory, there is a risk of toxic methemoglobinemia
induced by prilocaine in predisposed patients (see
Chapter23).
References
Adriani, J. (1963). Comparative potency and duration of
action of topical anesthetic drugs in man (Abstract).
Anesthesiology 24 (1): 120–121.
Adriani, J. and Campbell, D. (1956). Fatalities following
topical application of local anesthetics to mucous
membranes. JAMA 162 (17): 1527–1530.
Adriani, J. and Zepernick, R. (1964). Clinical effectiveness of
drugs used for topical anesthesia. JAMA 188 (8): 711–716.
Adriani, J., Zepernick, R., Arens, J., and Authement, E. (1964).
The comparative potency and effectiveness of topical
anesthetics in man. Clin. Pharmacol. Ther. 5(1): 49–62.
Aldous, W.K., Jensen, R., and Sieck, B.M. (1998). Cocaine and
lidocaine with phenylephrine as topical anesthetics:
antimicrobial activity against common nasal pathogens.
Ear Nose Throat J. 77 (7): 554–557.
Al-
Melh, M.A. and Anderson, L. (2007). Comparison of
topical anesthetics (EMLA/Oraqix vs benzocaine) on pain
experience during palatal needle injection. Oral Surg. Oral
Med. Oral Pathol. 103 (5): e16–e20.
Al- Melh, M.A., Anderson, L., and Behbehani, E. (2005).
Reduction of pain from needle stick in the oral mucosa by
topical anesthetics: a comparative study between
lidocaine/prilocaine and benzocaine. J. Clin. Dent.
16(2): 53–56.
American Academy of Pediatric Dentistry (2020). Use of
Local Anesthesia for Pediatric Dental Patients. The Reference
Manual of Pediatric Dentistry. Chicago IL: American
Academy of Pediatric Dentistry. 318–323.
American Dental Association (2003). ADA Guide to Dental
Therapeutics, 3e. Chicago: American Dental
Association. 1–16.
Aminabadi, N.A. and Farahani, R.M.Z. (2009). The effect of
pre- cooling the injection site on pediatric pain perception
during the administration of local anesthesia. J. Contemp.
Dent. Pract. 10 (3): 43–50.
Annex 6. Dissociation constant or pKa.
Annex 7. Partition coefficient or lipid solubility.
Annex 8. Acute experimental toxicity of local anesthetics.
Annex 9. Local anesthetic bonding to plasmatic proteins.
Annex 11. Pharmacokinetics of local anesthetics and
vasoconstrictors.
Annex 13. Toxic plasma levels of local anesthetics.
Annex 19. Topical anesthesia I. Results of clinical trials.
Annex 20. Topical anesthesia II. Clinical efficacy.
Anonymous (1964). Benzocaine. Med. Lett. Drugs Ther. 6: 86–87.
Anonymous (1979). Cocaine. Br. Med. J. 1 (6169): 971–972.
Aydin, O.N., Eyigor, M., and Aydin, N. (2001). Antimicrobial
activity of ropivacaine and other local anesthetics. Eur.
J. Anaesthesiol. 18 (10): 687–694.
Baumgaertel, S. (2009). Compound topical anesthetics in
orthodontics: putting the facts into perspective. Am.
J. Orthod. Dentofacial. Orthop. 135 (5): 556–557.
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