Foaming at the bit - Sodium Lauryl Sulphate (SLS)-free toothpastes

Abstract

The oral cavity is exposed to oral health care products daily, even several times a day. Toothpastes protect dental hard tissues primarily through anti-plaque and anti-caries activity; the benefits of including fluoride salts in toothpastes are well established.

While true hypersensitivity, i.e. immunologically mediated reactions of oral soft tissues to toothpaste ingredients appear infrequent, irritant contact reactions can occur. When they do, they may cause discomfort and even mucosal desquamation, particularly in predisposed mouths.

This article focuses on sodium lauryl sulphate (SLS), a common foaming agent in toothpastes and mouthwashes that may occasionally act as an oral mucosal irritant.

Full text

Volume 202 March 2021 27
The oral cavity is exposed to oral health care products daily
even several times a day. Toothpastes protect dental hard
tissues primarily through anti-plaque and anti-caries activity;
the benefits of including fluoride salts in toothpastes are well
established.
While true hypersensitivity, i.e., immunologically mediated,
reactions of oral soft tissues to toothpaste ingredients
appear infrequent, irritant contact reactions can occur.
When they do, they may cause discomfort and even mucosal
desquamation, particularly in predisposed mouths.
This article focuses on sodium lauryl sulphate (SLS), a common foaming
agent in toothpastes and mouthwashes, that may occasionally act as an oral
mucosal irritant. The article complements an earlier article on over-the-counter
(OTC) strategies to manage oral ulcers,1 by providing updated information on
uoride-containing, but SLS-free toothpaste options available in New Zealand.
Non-uoridated SLS-free toothpastes, many of which have been aggressively
marketed,2 will generally not be considered here.
An overview of toothpaste ingredients
Toothpastes have been used since antiquity.3,4 However, the addition of
consistent and evidence-based active compounds to toothpastes to prevent or
treat oral diseases have developed signicantly over the last century. A recent
commentary by Hobbs and colleagues highlighted the history and importance of
the addition of uoride to toothpastes in New Zealand.5
As an active ingredient in toothpastes, uoride salts, such as stannous uoride,
sodium uoride and sodium uoride monophosphate, are effective in reducing
dental decay in the primary and permanent dentitions.6–10 Some also have been
shown to directly inhibit the accumulation of dental plaque.11,12 The New Zealand
Ministry of Health recommends twice daily toothbrushing with a toothpaste
containing ≥1000ppm uoride for all ages; a smear should be used in children up
to ve years of age and a pea-sized amount in children six years and over.13
Feature article
by Dr Natasha Paul BDS (Hons)
and Dr Hadleigh Clark
BSc, BDS, MBChB,
DClinDent (OralMed),
MRACDS (OralMed)
t
FOAMING AT THE BIT:
Sodium Lauryl Sulphate
(SLS)-free toothpastes

NZDA NEWS
Fluoride salts are just one of the active constituents in toothpastes. Others include:
non-fluoride anti-caries agents (e.g., calcium and phosphate salts, metals, xylitol
and antimicrobials);14 anti-calculus agents (e.g., pyrophosphates, phosphonates,
zinc salts and copolymers); whitening agents (e.g., silica and alumina abrasives,
often augmented by enzymes, peroxide, surfactants, citrate, pyrophosphates
and hexametaphosphate); anti-malodour agents and desensitising agents (e.g.,
potassium salts, arginine, stannous uoride, nano-hydroxyapatite).3,4,15.
Excipients, on the other hand, act to bulk up, stabilize or enhance the active
ingredients of toothpastes. These include: colours (e.g., clorophyll, titanium dioxide);
sweeteners (e.g., aspartame, sorbitol, saccharine); flavours (e.g., peppermint,
spearmint, menthol, lemon, eucalyptus, fennel, parsley); gelling or binding
agents (e.g., carboxymethyl cellulose, gums and alginates); film agents (e.g.,
cyclomethicone, dimethicone, polydimethylsiloxane and siliglycol); humectants
or moistening agents (e.g., water, glycerol, sorbitol, xylitol); preservatives (e.g.,
alcohols, benzoates, parabens, phenolics) and surfactants.reviewed in 3
Surfactants (a portmanteau of ‘surface active’ and ‘agent’) are compounds
that lower the surface tension of liquids and work as detergents, wetting agents,
emulsiers, foaming agents, and dispersants. Until the late nineteenth century,
the only man-made surfactant was soap and its critical shortage in Germany after
World War I along with its ineffectiveness in hard or acidic water, provided an
incentive for the development of soap substitutes.16
Chemically, all surfactants are composed of a branched, linear or aromatic
hydrocarbon chain or tail attached to a polar head group and are classied
according to the charge of that polar head moiety (non-ionic, anionic, cationic,
zwitterionic/amphoteric). Due to their relative ability to solubilize lipid membranes,
surfactants can elicit irritant skin reactions by direct cytotoxicity to oral epithelial
keratinocytes without prior or preceding immunologic sensitization.17
What is Sodium Lauryl Sulphate (SLS)?
SLS, also known as sodium dodecyl sulphate (SDS) or C12H25NaO4S (see Figure
1), is an anionic surfactant. It goes under several different chemical monikers (see
Table 1).
It is produced through sulfation of fatty alcohols, which in turn may be derived
from pure forms or through the hydrolysis and hydrogenation of coconut or palm
kernel oil. Due to its low manufacturing cost, it has become increasingly popular
as a detergent in a number of industrial and health care settings (see Table 2).18 It
is also used in several types of industrial manufacturing processes, as a delivery
aid in transepidermal, transmucosal, transnasal and ocular pharmaceuticals,
and in biochemical research.16 The similarly sounding sodium laureth sulphate,
while also being an anionic surfactant and found in several cosmetic products, is
chemically dissimilar.
Over the last 30-years, it has become the major or sole surfactant in most
toothpastes.19 It is also a frequent constituent in many mouthwashes.
Feature article
Figure 1: Sodium lauryl sulphate (SLS) chemical structure. The hydrocarbon chain common to all surfactants is
indicated, as is the anionic polar head. Image from: National Center for Biotechnology Information. PubChem Database.
Sodium dodecyl sulphate, CID=3423265, https://pubchem.ncbi.nlm.nih.gov/compound/3423265

Volume 202 March 2021 29
Table 1: Sodium Lauryl Sulphate Alternative Nomenclature
Dodecyl alcohol hydrogen sulphate sodium salt
Dodecyl sulphate sodium salt
Lauyl sodium sulphate
Lauryl sulphate sodium
Monododecyl sodium sulphate
Natrium laurylsulfuricum
s-Dodecyl sulphate sodium
Sodium dodecyl sulphate
Sodium n-dodecyl sulphate
Sulphuric acid monododecyl ester sodium salt
Sodium dodecanesulphate
Sodium monododecyl sulphate
Sodium monolauryl sulphate
Sodium N-dodecylsulphate
Sulfuric acid monododecylester sodium salt
Table 2: Examples of cosmetic and food products in which sodium
lauryl sulphate (SLS) can be found
Grooming products: shaving cream, lip balm, hand sanitiser, nail treatments,
makeup remover, foundation, facial cleansers, exfoliants, liquid hand soap
Hair products: shampoo, conditioner, hair dye, dandruff treatment, styling gel
Bath products: bath oils or salts, body wash, bubble bath
Creams and lotions: hand cream, masks, hair-removal products, sunscreen
Cleaning products: laundry detergents, spray cleaners, dishwashing detergents
Foods (emulsifying and whipping agent): dried egg products, some
marshmallow products, dry beverage bases
Why is SLS added to toothpastes?
Surfactants do more than just create foam. They directly contribute to the
perceived impression of ‘cleanliness’ of a toothpaste through enhancing their
foaming action,19 dispersing avour oils around the mouth20 and helping remove
plaque and food debris.15,21,22 SLS can also solubilise lipid-soluble antimicrobial
agents, directly kill bacteria and viruses through interference with cell walls and
viral envelopes,20,23,24 and interfere with bacterial enzymes involved in glucose
metabolism.19 SLS plays an important role in the anti-microbial and plaque-
removing efcacy of toothpastes, as well as their ‘mouth-feel’.
Toothpaste surfactants also act as whitening agents.3 Practitioners should be
aware of the latter—many toothpaste brands add SLS to whitening variants of
their formulations, where the non-whitening variant may be SLS-free.
Despite speculation that a preferred toothpaste has better compliance,
studies do not support clinical differences with respect to plaque growth and
gingivitis reduction between SLS-containing and SLS-free toothpastes.25,26
Notwithstanding, consumers prefer SLS-containing toothpastes due to their
perceived cleanliness and lower associated costs.25,27
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NZDA NEWS
Table 3: Common surfactants used in toothpastes
Surfactant type Name
Anionic Sodium lauryl sulphate
Sodium lauroyl sarcosinate
Sodium methyl cocoyl taurate
Cationic Amine uoride
Amphoteric Cocamidopropyl betaine
Non-ionic Steareth-30
Polysorbate 20
Poloxamer 407
Oral physiology & pharmacology of SLS
Surfactants are typically used at concentrations of 0.5 to 2.5% w/w in toothpastes.4
Through in vivo studies using an SLS-containing toothpaste and mouthwash,
Fakhry-Smith and colleagues demonstrated that minimal amounts of SLS are
retained in the mouth following oral care product use and the contact time with the
oral mucosa is relatively short, being in the matter of minutes.28 The small amount
of SLS ingested through toothbrushing, alongside residues on insufciently rinsed
utensils and contaminated drinking water, is rapidly taken up from the intestine,
colon and skin, with tissue distribution and excretion occurring over about 24-48
hours. Environmentally, SLS is highly biodegradable by a large number of naturally
occurring bacteria.16
SLS may interact with other oral health care ingredients, such as chlorhexidine.29
Chlorhexidine, being a cationic bisbiguanide is thought to ionically interact with the
anionic SLS to form a low solubility salt, neutralising chlorhexidine’s antibacterial
activity.30 This has led to the recommendation that toothbrushing with an SLS-
containing toothpaste and use of a chlorhexidine containing product be separated
by 30-minutes.31 However, recent studies, including a meta-analysis from 2016
have suggested that methodologic issues in some of the data supporting this
notion may be awed and that a chlorhexidine mouthwash can, in fact, be used
in combination with daily use of an SLS-containing toothpaste without signicant
need for temporal separation.29,32
Other interactions of SLS include those with triclosan, zinc and betaine. The
interaction between SLS and triclosan is now largely a moot point, due to its
recent removal from toothpastes.
SLS is also responsible for the peculiar effect toothpaste has on taste reception:
the so-called ‘orange juice’ effect, whereby orange juice drunk soon after
toothbrushing is rendered unpleasant and astringent. This is due to both direct
inhibition of SLS on taste receptors and indirectly through its dissolution of
phospholipids (in fats), that normally block bitter taste receptors.25,33
Toothpaste surfactants may damage gingival epithelium,34 and prolonged
exposure to SLS-containing toothpaste has been shown to cause a rise in
gingival blood ow, suggesting its ability to penetrate the mucous membranes.35
SLS also has a dehydrating effect on oral mucosa.22 Additionally, SLS can cause
oral mucosal epithelial desquamation or peeling—sometimes referred to as oral
epitheliolysis36—a condition which will be outlined later.
Feature article

Volume 202 March 2021 31
What alternative surfactants to SLS are used in toothpastes?
Alternative surfactants with lower irritating properties have been investigated and
found as alternatives to SLS. Amongst these, the most used is cocoamidopropyl-
betaine (CAPB), a zwitterionic/amphoteric agent. CAPB is a mixture of closely related
organic compounds derived from coconut oil and dimethylaminopropylamine.37
Although named Allergen of the Year in 2004 by the American Contact Dermatitis
Society, with a potential to induce type IV hypersensitivity reactions,38 a subsequent
analysis determined that allergic reactions to CAPB are rare and the vast majority
of positive reactions to CAPB are likely false positives.39 Notwithstanding, at least
one case report exists of contact cheilitis (a type IV hypersensitivity reaction) to
CAPB in oral care products, implicated through positive patch-testing results.40
CAPB has also been found to have a bitter aftertaste.15
Other surfactants used in toothpastes include sodium methyl cocyl taurate
(SMCT), derived from a fatty acid found in coconuts, poloxamers and Steareth-30.
Poloxamer 407, also known as Pluronic® F127, has been widely investigated.
Poloxamer 407 is liquid at room temperature but forms a gel at body temperatures
and does not appear to irritate mucosal surfaces.34,41 Steareth-30 is a non-ionic
polyethylene glycol ether of stearic acid and has been demonstrated to produce
signicantly fewer soft tissue lesions compared to SLS-containing toothpaste.25,42
t
Figure 2: Cocoamidopropyl betaine (CAPB) chemical structure. CAPB is a zwitterionic / amphoteric surfactant. Image
from: National Center for Biotechnology Information. PubChem Database. Cocamidopropyl betaine, CID=20280,
https://pubchem.ncbi.nlm.nih.gov/compound/20280
Contact irritation vs. allergy (hypersensitivity reactions)
The penetration of oral mucosa by environmental antigens or carcinogens and
subsequent host immune responses are thought to play important roles in the
pathoaetiology of several oral mucosal diseases—the oral epithelium is thus an
important physiologic barrier. It has been postulated that SLS in toothpastes,
through inuence on the barrier function of oral mucosa, may be a factor in
triggering auto-inammatory oral disorders, such as recurrent aphthous ulcers
(RAU).43
Understanding the differences between contact irritation and true hypersensitivity
(allergic) reactions is helpful.
Contact irritants damage skin and mucosa directly through physical and chemical
means, with damage occurring faster than the turnover of epithelial layers.
Contact irritations are non-allergic reactions, as immune responses (i.e., IgE or
T-cell mediated) are usually lacking. However, it may be difcult to discriminate
some irritant reactions from allergy, as a substance may act as both an irritant
and an allergen. Through the removal of oils and natural moisture in the epithelial
layers, irritants penetrate skin or mucosa and trigger inammation.

NZDA NEWS
A familiar clinical example of irritant reaction to dentists and those with young
children, is lick dermatitis or dribble rash. The frequent exposure of the perioricial
tissues to repetitive physical trauma from licking and alkaline saliva damages
the skin around the mouth, resulting in a characteristically distributed, and well-
demarcated perioral erythematous rash. This may further be complicated by
bacterial (i.e., Staphylococcus aureus) and fungal (Candida albicans) co-infection.
Usually, when the irritant is removed (or prevented from damaging the skin through
use of a topical barrier, such as parafn), the skin recovers. Additionally, the skin
and mucosa may develop tolerance to milder irritants over time.
In terms of surfactants, relative irritancy is directly related to the concentration
(and repeat application) of the surfactant,19 and also relates to the polarity of the
surfactant moiety. Generally, anionic and cationic surfactants are considerably
more irritant than non-ionic and zwitterionic/amphoteric ones.4 SLS is an anionic
surfactant.
Type I hypersensitivity (IgE) mediated allergic reactions are those typied
through mast cell and basophil degranulation, and often will be associated with
the symptom of itch and, in some cases, frank anaphylaxis. These do not appear
to play signicant roles in toothpaste reactions.
Type IV (or delayed hypersensitivity) immune reactions are T cell-mediated, and
occur in a genetically susceptible, sensitised individual on second or subsequent
contact exposure to an inciting substance. In the oral cavity, this presents as an
allergic contact stomatitis, which may present as painful erythema topographically
associated with the irritant or the drainage pathways of saliva carrying the allergen,
such as around sites of salivary pooling, for example, the oor of the mouth, or
the lateral surfaces of the tongue. These reactions are less common than their
skin counterpart (i.e., a contact allergic dermatitis), due to the diluent effects of
saliva and high vascularity and epithelial turnover of the oral mucosa reducing
the contact time between allergen and mucosa. Implicated allergens are usually
not SLS, but rather toothpaste avouring oils, in particular spearmint, menthol
and cinnamon, and overall, incidence is rare.44 Diagnosis of allergic contact
stomatitis usually requires referral to an Oral Medicine Specialist, Dermatologist
or Immunologist/Allergist and epicutaneous patch testing may be informative.
Oral mucosal desquamation (oral epitheliolysis) from SLS
Since the 1970s, it has been recognized that toothpaste surfactants are implicated
in oral epithelial desquamation, with SLS being implicated in the 1980s.45,46 This
holds true at low concentrations found in toothpastes, even at concentrations
as low as 0.25%.47,48 Through desquamation and subsequent mucosal atrophy,
other substances can more readily penetrate the mucosa and induce a burning
sensation.20,49 Patients with dry or ageing mouths, may be particularly susceptible,
as epithelial atrophy may already be present.
Rarely this may be seen as an isolated oral epitheliolysis: the patient describes
‘peeling’ of the buccal (and occasionally lingual) mucosal surfaces either
spontaneously or to low-grade physical interruption (e.g., application of a ngertip/
nail).36 A high index of suspicion and careful history are required: usually oral
epitheliolysis can be discriminated from more worrying immunobullous disorders
like pemphigus and pemphigoid, through its non-painful nature, absence of
blisters or ulcers and temporal association with an (SLS-containing) oral care
product. Oral epitheliolysis usually reverses quite rapidly on discontinuing the
offending product.
Feature article

Volume 202 March 2021 33
OK... So when should a SLS-free toothpaste be recommended?
Anecdotally, patients presenting to Oral Medicine clinics with ulcerative (e.g.,
erosive oral lichen planus, RAU) or salivary hypofunctional complaints (e.g.,
Sjögren’s syndrome), report improved oral comfort and decreased ulceration when
using SLS-free oral care products. Occasionally, those with suspected burning
mouth syndrome also respond positively to SLS-free toothpastes. Although not
well elucidated through robust clinical studies, adjunctive prescription of SLS-free
toothpastes in these situations may be helpful.
Some patients independently come to this appreciation, but select ‘natural’
toothpastes which lack both SLS and uoride. It is important to detail to patients
the importance of uoride in protecting the dental hard-tissues.
Additionally, at least one well-known NZ brand of ‘natural’ SLS-free toothpaste is
known to contain propolis. Propolis, which is produced by honey bees by mixing
beeswax with exudates from tree buds, sap ows and other botanical products
is a potent mucocutaneous sensitiser (i.e., may promote allergic reactions) and
has been implicated in contact allergic reactions of the lips, as well as frank oral
ulceration.50,51 Where oral mucosal inammation or ulceration is apparent, use of
such toothpastes should be discouraged.
Examples of SLS-free toothpastes, that do at least contain uoride, or other
anti-caries agents are detailed in Table 3.
Summary points
The oral healthcare team has a responsibility to stay current with the development
and marketing of toothpastes.3 Although, the evidence for prescribing an SLS-
free toothpaste in specic oral clinical conditions is not yet fully formed, clinical
experience alongside the available literature suggests that there are certain clinical
situations (oral ulceration, oral epitheliolysis, salivary gland hypofunction and oral
dysaesthesias), where this may be helpful.
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NZDA NEWS
Table 4: SLS-free uoridated toothpastes available to the New Zealand market
Brand Toothpaste(s) Surfactant(s) Fluoride
Content
Flavour(s) Availability*Unit
amount
ClōSYS®Sensitive Fluoride Toothpaste Surfactant free 1100ppm Gentle Mint Online:
Healthykiwis.co.nz
96g
198g
Colgate®Sensitive Pro ReliefTM Repair
& Prevent
Poloxamer
CAPB
1450ppm Mint Supermarket,
Pharmacy,
or Online
110g
Hello®Sensitivity Relief Fluoride
Toothpaste
CAPB 1100ppm Soothing
mint
Online:
Nz.iherb.co.nz
Hello-products.com
113g
Oral-B®Pure Enamel Care CAPB 1450ppm Eucalyptus Supermarket
or Pharmacy
110g
Pure Multiprotect Polysorbate 80 Soft Mint 110g
Oral-7®Moisturising toothpaste Surfactant free 1000ppm Gentle Mint Pharmacy or
Online
105g
Oranurse®Unflavoured toothpaste Glycerin 1450ppm Unflavoured Online:
Toothshop.co.nz
50g
Sensodyne®Daily Care CAPB 1000ppm Multiple Supermarket,
Pharmacy,
or Online
160g
Daily Care + Whitening CAPB + SMCT 1000ppm
Gentle Whitening CAPB + SMCT 1450ppm
Fresh Impact CAPB 1000ppm
Repair and Protect
(& Extra Fresh)
CAPB + SMCT 1450ppm
Pronamel CAPB + SMCT 1450ppm
Spry®
by Xlear
Xylitol & Aloe Fluoride
Toothpaste
Sodium lauroyl
sarcosinate
1100ppm Spearmint Online:
Toothshop.co.nz
113g
Squigle®Enamel Saver Poloxamer Sodium
Fluoride
No added
flavour
Online:
Tippy.com.au
125g
Tooth Builder (Sensitive)
Toothpaste
Methocel®None
(but 36%
xylitol)
Xerostom®Dry Mouth Toothpaste Betaine, EVO 1000ppm Lemon Pharmacy or
Online:
Toothshop.co.nz
Smilestore.co.nz
65g
* Website addresses provided in Table 4, are the most common hits of internet searches at the time of writing. Practitioners are encouraged to search for these independently.

Volume 202 March 2021 35
REFERENCES
1. Clark H. Over-the-Counter Products for Managing Oral Ulcers. NZDA News. 2019;196(December):45-53.
2. Ayers K, Hughes D. NZDA Response: uoride-free toothpastes. NZDA News. 2018;191(December).
3. Davies R, Scully C, Preston AJ. Dentifrices--an update. Med Oral Patol Oral Cirugia Bucal.
2010;15(6):e976-982. doi:10.4317/medoral.15.e976
4. Lippert F. An introduction to toothpaste - its purpose, history and ingredients. Monogr Oral Sci.
2013;23:1-14. doi:10.1159/000350456
5. Hobbs M, Clarke R, Wade A, Lee M. Commentary: it doesn’t work if it doesn’t have uoride in it. NZDA
News. 2020;198(May):31-36.
6. dos Santos APP, Nadanovsky P, de Oliveira BH. A systematic review and meta-analysis of the effects
of uoride toothpastes on the prevention of dental caries in the primary dentition of preschool children.
Community Dent Oral Epidemiol. 2013;41(1):1-12. doi:10.1111/j.1600-0528.2012.00708.x
7. Singh A, Purohit BM. Caries Preventive Effects of High-uoride vs Standard-uoride Toothpastes - A
Systematic Review and Meta-analysis. Oral Health Prev Dent. 2018;16(4):307-314. doi:10.3290/j.ohpd.
a40937
8. Santos APP, Oliveira BH, Nadanovsky P. Effects of low and standard uoride toothpastes on caries and
uorosis: systematic review and meta-analysis. Caries Res. 2013;47(5):382-390. doi:10.1159/000348492
9. Marinho VC, Higgins JP, Sheiham A, Logan S. Fluoride toothpastes for preventing dental caries in
children and adolescents. Cochrane Database Syst Rev. 2003;(1):CD002278. doi:10.1002/14651858.
CD002278
10. Walsh T, Worthington HV, Glenny A-M, Marinho VC, Jeroncic A. Fluoride toothpastes of different
concentrations for preventing dental caries. Cochrane Database Syst Rev. 2019;3(3):CD007868.
doi:10.1002/14651858.CD007868.pub3
11. Valkenburg C, Van der Weijden F, Slot DE. Is plaque regrowth inhibited by dentifrice?: A systematic
review and meta-analysis with trial sequential analysis. Int J Dent Hyg. 2019;17(1):27-38. doi:10.1111/
idh.12364
12. Valkenburg C, Else Slot D, Van der Weijden GF. What is the effect of active ingredients in dentifrice on
inhibiting the regrowth of overnight plaque? A systematic review. Int J Dent Hyg. 2020;18(2):128-141.
doi:10.1111/idh.12423
13. Ministry of Health. Guidelines for the use of uorides. Wellington; 2009.
14. Forward GC. Non-uoride anticaries agents. Adv Dent Res. 1994;8(2):208-214. doi:10.1177/0895937494
0080021201
15. Stovell AG, Newton BM, Lynch RJM. Important considerations in the development of toothpaste formu-
lations for children. Int Dent J. 2013;63 Suppl 2:57-63. doi:10.1111/idj.12083
16. Singer MM, Tjeerdema RS. Fate and effects of the surfactant sodium dodecyl sulfate. Rev Environ Con-
tam Toxicol. 1993;133:95-149. doi:10.1007/978-1-4613-9529-4_3
17. Effendy I, Maibach HI. Surfactants and experimental irritant contact dermatitis. Contact Dermatitis.
1995;33(4):217-225. doi:10.1111/j.1600-0536.1995.tb00470.x
18. Holmberg K. Surfactants. In: Ullmann’s Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag GmbH &
Co. KGaA; 2019:1-56. doi:10.1002/14356007.a25_747.pub2
19. Shim YJ, Choi J-H, Ahn H-J, Kwon J-S. Effect of sodium lauryl sulfate on recurrent aphthous sto-
matitis: a randomized controlled clinical trial. Oral Dis. 2012;18(7):655-660. doi:10.1111/j.1601-
0825.2012.01920.x
20. Waaler SM, Rolla G, Skjorland KK, Ogaard B. Effects of oral rinsing with triclosan and sodium
lauryl sulfate on dental plaque formation: a pilot study. Scand J Dent Res. 1993;101(4):192-195.
doi:10.1111/j.1600-0722.1993.tb01103.x
21. Brown RS, Smith L, Glascoe AL. Inammatory reaction of the anterior dorsal tongue presumably to
sodium lauryl sulfate within toothpastes: a triple case report. Oral Surg Oral Med Oral Pathol Oral Radiol.
2018;125(2):e17-e21. doi:10.1016/j.oooo.2017.11.017
22. Hitz Lindenmüller I, Lambrecht JT. Oral care. Curr Probl Dermatol. 2011;40:107-115.
doi:10.1159/000321060
23. Giertsen E, Scheie AA, Rölla G. Plaque inhibition by a combination of zinc citrate and sodium lauryl
sulfate. Caries Res. 1989;23(4):278-283. doi:10.1159/000261192
24. Piret J, Désormeaux A, Bergeron MG. Sodium lauryl sulfate, a microbicide effective against enveloped
and nonenveloped viruses. Curr Drug Targets. 2002;3(1):17-30. doi:10.2174/1389450023348037
25. Salzer S, Rosema NAM, Martin ECJ, et al. The effectiveness of dentifrices without and with sodium
lauryl sulfate on plaque, gingivitis and gingival abrasion--a randomized clinical trial. Clin Oral Investig.
2016;20(3):443-450. doi:10.1007/s00784-015-1535-z
26. Green A, Crichard S, Ling-Mountford N, et al. A randomised clinical study comparing the effect of
Steareth 30 and SLS containing toothpastes on oral epithelial integrity (desquamation). J Dent. 2019;80
Suppl 1:S33-S39. doi:10.1016/j.jdent.2018.11.005
27. Alli BY, Erinoso OA, Olawuyi AB. Effect of sodium lauryl sulfate on recurrent aphthous stomatitis: A sys-
tematic review. J Oral Pathol Med Off Publ Int Assoc Oral Pathol Am Acad Oral Pathol. 2019;48(5):358-
364. doi:10.1111/jop.12845
28. Fakhry-Smith S, Din C, Nathoo SA, Gaffar A. Clearance of sodium lauryl sulphate from the oral cavity. J
Clin Periodontol. 1997;24(5):313-317. doi:10.1111/j.1600-051x.1997.tb00763.x
29. Elkerbout TA, Slot DE, Bakker EWP, Van der Weijden GA. Chlorhexidine mouthwash and sodium lauryl
sulphate dentifrice: do they mix effectively or interfere? Int J Dent Hyg. 2016;14(1):42-52. doi:10.1111/
idh.12125
30. Van Strydonck DAC, Scale S, Timmerman MF, van der Velden U, van der Weijden GA. Inuence of a
SLS-containing dentifrice on the anti-plaque efcacy of a chlorhexidine mouthrinse. J Clin Periodontol.
2004;31(3):219-222. doi:10.1111/j.0303-6979.2004.00470.x
31. Barkvoll P, Rølla G, Svendsen K. Interaction between chlorhexidine digluconate and sodium lauryl sulfate
in vivo. J Clin Periodontol. 1989;16(9):593-595. doi:10.1111/j.1600-051x.1989.tb02143.x
32. Van Strydonck DAC, Timmerman MF, Van der Velden U, Van der Weijden GA. Chlorhexidine
mouthrinse in combination with an SLS-containing dentifrice and a dentifrice slurry. J Clin Periodontol.
2006;33(5):340-344. doi:10.1111/j.1600-051X.2006.00910.x
33. DeSimone JA, Heck GL, Bartoshuk LM. Surface active taste modiers: a comparison of the physical and
psychophysical properties of gymnemic acid and sodium lauryl sulfate *. Chem Senses. 1980;5(4):317-
330. doi:10.1093/chemse/5.4.317

NZDA NEWS
34. Moore C, Addy M, Moran J. Toothpaste detergents: a potential source of oral soft tissue damage? Int J
Dent Hyg. 2008;6(3):193-198. doi:10.1111/j.1601-5037.2008.00307.x
35. Herlofson BB, Brodin P, Aars H. Increased human gingival blood ow induced by sodium lauryl sulfate. J
Clin Periodontol. 1996;23(11):1004-1007. doi:10.1111/j.1600-051x.1996.tb00528.x
36. Hassona Y, Scully C. Oral mucosal peeling. Br Dent J. 2013;214(8):374. doi:10.1038/sj.bdj.2013.386
37. Nitsch C, Heitland H-J, Marsen H, Schlüssler H-J. Cleansing Agents. In: Ullmann’s Encyclopedia of
Industrial Chemistry. American Cancer Society; 2003. doi:10.1002/14356007.a07_137
38. Jacob SE, Amini S. Cocamidopropyl betaine. Dermat Contact Atopic Occup Drug. 2008;19(3):157-160.
39. Schnuch A, Lessmann H, Geier J, Uter W. Is cocamidopropyl betaine a contact allergen? Analysis of
network data and short review of the literature. Contact Dermatitis. 2011;64(4):203-211. doi:10.1111/
j.1600-0536.2010.01863.x
40. Agar N, Freeman S. Cheilitis caused by contact allergy to cocamidopropyl betaine in “2-in-1 toothpaste
and mouthwash”. Australas J Dermatol. 2005;46(1):15-17. doi:10.1111/j.1440-0960.2005.00129.x
41. Giuliano E, Paolino D, Fresta M, Cosco D. Mucosal Applications of Poloxamer 407-Based Hydrogels: An
Overview. Pharmaceutics. 2018;10(3). doi:10.3390/pharmaceutics10030159
42. Green A, Crichard S, Ling-Mountford N, et al. A randomised clinical study comparing the effect
of Steareth 30 and SLS containing toothpastes on oral epithelial integrity (desquamation). J Dent.
2019;80:S33-S39. doi:10.1016/j.jdent.2018.11.005
43. Healy C, Cruchley A, Thornhill M, Williams D. The effect of sodium lauryl sulphate, triclosan and zinc
on the permeability of normal oral mucosa. Oral Dis. 2008;6(2):118-123. doi:10.1111/j.1601-0825.2000.
tb00112.x
44. Francalanci S, Sertoli A, Giorgini S, Pigatto P, Santucci B, Valsecchi R. Multicentre study of allergic
contact cheilitis from toothpastes. Contact Dermatitis. 2000;43(4):216-222. doi:10.1034/j.1600-
0536.2000.043004216.x
45. Searls JC, Berg CA. The inuence of dentifrice detergents on oral epithelial slough. Dent Hyg (Chic).
1986;60(1):20-23.
46. Jenkins S, Addy M, Newcome R. Triclosan and sodium lauryl sulphate mouthrinses. (II). Effects of 4-day
plaque regrowth. J Clin Periodontol. 1991;18(2):145-148. doi:10.1111/j.1600-051x.1991.tb01704.x
47. Herlofson BB, Barkvoll P. The effect of two toothpaste detergents on the frequency of recurrent aphthous
ulcers. Acta Odontol Scand. 1996;54(3):150-153. doi:10.3109/00016359609003515
48. Perez-Lopez D, Varela-Centelles P, Garcia-Pola M-J, Castelo-Baz P, Garcia-Caballero L, Seoane-Romero
J-M. Oral mucosal peeling related to dentifrices and mouthwashes: A systematic review. Med Oral Patol
Oral Cirugia Bucal. 2019;24(4):e452-e460. doi:10.4317/medoral.22939
49. Ahlfors EE, Lyberg T. Contact sensitivity reactions in the oral mucosa. Acta Odontol Scand.
2001;59(4):248-254. doi:10.1080/00016350152509283
50. Hay KD, Greig DE. Propolis allergy: a cause of oral mucositis with ulceration. Oral Surg Oral Med Oral
Pathol. 1990;70(5):584-586. doi:10.1016/0030-4220(90)90403-f
51. Brailo V, Boras VV, Alajbeg I, Juras V. Delayed contact sensitivity on the lips and oral mucosa due to
propolis-case report. Med Oral Patol Oral Cirugia Bucal. 2006;11(4):E303-304.
Feature article
BIOGRAPHY
Dr Hadleigh Clark BSc, BDS, MBChB, DClinDent (OralMed), MRACDS (OralMed)
Hadleigh is a full-time oral medicine specialist with the ADHB. He has particular clinical interests in immune-mediated mucosal
and salivary disorders, as well as oral dysaesthesias. Passionate about interdisciplinary collaboration and education, he is a
regular educational presenter to dental, medical and allied health professional groups.
BIOGRAPHY
Dr Natasha Paul BDS (Hons)
Tasha graduated from the University of Otago in 2019 with rst class honours and was a recipient of the R.C. Tonkin Research
Scholarship awarded by the New Zealand Dental Association. Her honours research focused on dental education. In 2020,
she began working with the Auckland District Health Board as a dental / maxillofacial house surgeon and continues in this
role in 2021. She has been involved with Smile New Zealand initiative run by the NZDA and Southern Cross Health Trust,
assisting with providing free treatment to low income adults, and would like to be involved in this type of dentistry in the future.