1
Information Sheet on pH of Home Oral
Care Products
What is pH?
pH is a measure of the activity of hydrogen ions in solution. In aqueous solutions, pH is measured using a
logarithmic scale known as the pH scale, which is used to express the acidity or alkalinity of the solution.
A pH less than 7 indicates an acidic solution, and one with pH greater than 7 is alkaline. Because pH
values are logarithmic, each change of one pH unit is equivalent to a ten-fold change in the concentration
of hydrogen ions.
Numerous oral care products are sold over-the-counter (OTC) for oral hygiene or cosmetic purposes,
including toothpastes, mouthrinses, whitening gels/strips and oral moisturizers. Such products are
manufactured with formulations that include variable concentrations of therapeutic (active) and inactive
ingredients. They are also marketed for various accepted indications (e.g., reducing caries or gingivitis),
and are formulated at specific pH levels to accommodate specific ingredients and intended purpose.
1, 2
Questions have been raised about the overall safety and effectiveness of the pH in various oral care
product formulations.
3-5
Intra-oral pH
Intra-oral pH refers to a pH level or measurement (or range of measurements) taken within the oral
environment. Numerous studies have measured pH in various intraoral locations, including tooth
surfaces, mucosa, tongue, palate, floor of the mouth as well as in oral fluids (e.g., unstimulated or
stimulated whole saliva; gingival crevicular fluid).
6-10
Not surprisingly, saliva has a primary role in maintaining intra-oral pH and oral homeostasis.
11, 12
Saliva is
the clear, viscous, protein-rich biofluid continuously secreted by salivary glands. Although composed
primarily of water (about 99 percent), saliva is also comprised of protective ions, glycoproteins, amylase,
enzymes, mucins and other components.
Overall, intra-oral pH levels typically range between pH 6.5-7.8, although higher (more alkaline) pH
occurs in stimulated saliva and lower pH in unstimulated saliva.
8, 11, 13
Saliva pH may also vary depending
on adequate salivary composition/flow, time of day, or the location where saliva pH is measured,
6-8, 14-18
as well as variation in dietary exposures, bacterial metabolism, and antibacterial components in saliva
itself.
19-22
Saliva serves several protective functions, including cleansing the oral cavity, facilitating oral processing
and swallowing food or drink, protecting oral tissues against physical and microbial insults, maintaining a
neutral pH and helping to prevent demineralization.
19
Through these functions, saliva provides protection
against the primary forms of enamel demineralization (caries and dental erosion), which are both
modifiable by the buffering protection provided by saliva and the salivary pellicle.
23
Caries is the localized destruction of dental hard tissues that arises from exposure to organic acids
generated by bacteria within the plaque biofilm.
24
Decreased or impaired salivary secretion is a known
risk factor for caries, as well as candidiasis and other mucosal complications.
19, 25-27
Dental erosion (or
erosive tooth wear
) is the second-most common form of enamel demineralization, and occurs from
chemical dissolution of dental hard surfaces by exposure to acids not produced by bacteria in the mouth.
2
One primary risk factor for dental erosion is frequent exposure to low pH acids in beverages (e.g., soft
drinks), juices and food products (e.g., lemon) with acidic pH.
28
The buffering systems present in saliva
help with neutralizing the pH of potentially erosive acids, both extrinsic (e.g., soft drinks, fruit juice, energy
drinks) and intrinsic (e.g., gastric acid).
28, 29
One essential function of human saliva is its bicarbonate buffering system, which serves a primary role in
neutralizing intra-oral acids. Salivary pH is modulated by the ratio of the bicarbonate/carbonic acid
concentrations within the saliva,
30, 31
where increased bicarbonate concentrations can elevate pH and
assist with neutralizing exposure to plaque acid.
10
In general terms, when an individual’s salivary flow
increases, the bicarbonate concentration in saliva tends to increase, raising intra-oral pH.
Since the 1940s, researchers have investigated what’s known as the “critical pH” of saliva, which is the
salivary pH level below which dissolution of enamel can occur.
9, 25, 32, 33
The critical pH value for enamel
dissolution is about pH 5.5,
10, 34, 35
although the actual pH for demineralization varies based on other
factors including the concentrations of calcium and phosphate in saliva in contact with enamel.
32, 36
When
intra-oral pH rises above 5.5 (in tandem with adequate salivary composition and flow), conditions within
the oral environment help promote enamel remineralization.
Mature human enamel is the hardest mineralized material in the body and is primarily composed of
complex arrays of hydroxyapatite crystallites (formed through matrix-mediated biomineralization).
37, 38
To
support oral homeostasis, saliva’s complex mixture of calcium and phosphate ions help maintain a stable
environment on enamel surfaces.
11, 12
Other salivary constituents, such as mucins, assist in forming the
the enamel pellicle, which provides protective coatings for hard and soft tissues.
10, 11
pH of Toothpaste
American National Standards Institute/American Dental Association (ANSI/ADA) Standard 130 specifies
that the pH of dentifrice be less than 10.5.
39
Studies have demonstrated that acidulated (i.e., lower) pH in
fluoride-containing toothpaste improves fluoride uptake in human enamel and in plaque.
40-43
Toothpastes
with stannous fluoride salts are commonly formulated at lower pH to assist with product stability.
1
Manufacturers’ safety data sheets for fluoride-containing toothpastes are available in the
Household
Products Database, and many include information on pH. A review, in 2019, of toothpaste safety data
sheets in the Household Products Database found pH levels in the OTC toothpaste products ranged from
about pH 4.0 to 9.68. A Brazilian study of pH in seven fluoride toothpastes with calcium carbonate, a
common abrasive, found that product pH levels were primarily alkaline, ranging from pH 8.67 to 10.03.
44
Additionally, people can use OTC toothpastes that contain sodium bicarbonate (baking soda), which
typically have more alkaline pH levels and can assist with neutralizing plaque pH after sucrose
exposure.
45, 46
More information on active and inactive ingredients in OTC toothpastes may be found on
ADA.org Oral Health Topic page on Toothpastes
.
pH of Mouthrinse
The ANSI/ADA Standard 116
47
stipulates that the pH of oral rinses be between 3.0 and 10.5. For oral
rinses with a pH below 5.5, ANSI/ADA Standard 116 calls for further demonstration of product safety,
either through a demineralization test or erosion test or other appropriate methods.
47
OTC mouthrinses are generally grouped within three product categories: therapeutic mouthrinses that
contain fluoride to reduce caries risk; therapeutic mouthrinses to reduce plaque/gingivitis risk; and
mouthrinses that make cosmetic claims (e.g. reduce bad breath). There are, in addition, therapeutic
mouthrinses available by prescription that typically deliver an active ingredient in concentrations greater
than in OTC products or an ingredient (e.g. chlorhexidine) that is not available without a prescription.
3
Active ingredients in mouthrinses can be delivered at specific pH values within the oral cavity because
dilution with saliva is minimal.
5
Review of the manufacturers’ safety data sheets for ten widely available
OTC mouthrinse products (included in the Household Products Database
) found that their pH levels
ranged from 3.43 to 7.05.
pH of Home-Use Whitening Products
Several types of consumer whitening products are available for home use, including gels, rinses, chewing
gums, toothpastes, paint-on films and hydrogen peroxide whitening strips. These whitening products (by
group/category) differ in terms of application times and durations of treatment.
In the United States, most, if not all, extracoronal bleaching products available OTC for whitening of vital
teeth contain either carbamide peroxide and/or hydrogen peroxide. Peroxide-based materials are used in
home-use tooth whitening products because dental hard tissues are permeable to fluids, which allows for
diffusion of peroxide-based materials inside the tooth (within dentin and enamel).
48, 49
The whitening
process also includes pH-mediated interaction of hydrogen peroxide with the tooth structure, which can
also be influenced by temperature or light.
50
The pH of home-use whitening products is primarily related to the concentration of hydrogen peroxide.
51
Overall, tooth whitening products with hydrogen peroxide tend to be more acidic, and they are generally
manufactured as lower pH formulations to improve product stability, primarily because hydrogen peroxide
is less stable at higher pH.
52
When used according to manufacturer instructions, home-use whitening products are typically well
tolerated and have demonstrated a good safety profile.
50
Examples of reported adverse events include
tooth sensitivity and oral soft tissue irritation.
48, 50
Information on Specific Products
Clinicians and patients interested in the pH level of specific home oral care products can find information
about many products through the Household Products Database
, which is searchable by product name or
manufacturer.
Reporting Problems
Clinicians and individuals can report adverse effects related to oral care products (or any medication or
medical device) to the U.S. Food and Drug Administration’s MedWatch Program
.
Conclusions
• The pH of Oral Care Products Depends Primarily on Product Formulation and
Composition: Products are specifically formulated to accommodate ingredients and
purpose, and to provide therapeutic and cosmetic functions. Incorporation of fluoride into
hard tissues, for example, is maximized at lower pH, thereby enhancing caries
prevention.
41, 53, 54
Tartar control toothpaste may have an alkaline formulation to facilitate
the delivery of active ingredients.
1
Some OTC toothpastes are manufactured with small
amounts of sodium hydroxide to adjust formulation pH. Oral rinses may have an acidic
formulation to facilitate better dissociation of active ingredients within the oral cavity.
4
The safety of many OTC toothpastes, mouthrinses and other products has been
evaluated through a wide range of clinical testing, safety evaluations and post-marketing
surveillance.
2
On occasion, using an oral care product may result in an allergic reaction
or contact dermatitis, but such cases are not common, usually not severe, and usually
unrelated to pH. Allergic reactions may arise from the presence of specific ingredients
(e.g., flavoring agents, sodium lauryl sulfate) to which the individual reacts.
1, 55, 56
• Frequency of Oral Care Product Use: To support at-home oral hygiene, the American
Dental Association (ADA) issued recommendations for Home Oral Care
, which advise
people to perform:
- twice-daily brushing with fluoride toothpaste;
- daily cleaning between teeth; and
- for those with increased risk of caries or periodontal disease, follow the
personalized recommendation from their dentist regarding use of fluoridated
mouthrinse, and/or use of mouthrinse or toothpaste with antimicrobial activity.
• Safety Profile: Over-the-counter oral care products have a strong track record of safety.
Adverse events (e.g., dry mouth, gingival irritation, allergic reaction) may arise, especially
when product instructions about amount and frequency of use are disregarded. Within
the complex environment of the oral cavity, buffering by saliva helps protect teeth and
mucosal surfaces following changes in pH, returning and maintaining intraoral pH near
neutral (i.e., pH 7.0).
Disclaimer
Content on this ADA.org Information Sheet is for informational purposes only. Content is neither intended
to nor does it establish a standard of care or the official policy or position of the ADA; and is not a
substitute for professional judgment, advice, diagnosis, or treatment. ADA is not responsible for
information on external websites linked to this resource.
References
1. Lippert F. An introduction to toothpaste - its purpose, history and ingredients. Monogr Oral Sci
2013;23:1-14.
2. Moore J WD, Schneiderman E, Chen H. Development of a screening method to establish if pH of
oral care products affects hard tissues. J Clin Dent 2018;29(4):92-96.
3. Pontefract H, Hughes J, Kemp K, et al. The erosive effects of some mouthrinses on enamel. A
study in situ. J Clin Periodontol 2001;28(4):319-24.
4. Bruno M, Taddeo F, Medeiros IS, et al. Relationship between toothpastes properties and patient-
reported discomfort: crossover study. Clin Oral Investig 2016;20(3):485-94.
5. Delgado AJ, Olafsson VG, Donovan TE. pH and Erosive Potential of Commonly Used Oral
Moisturizers. J Prosthodont 2016;25(1):39-43.
6. Aframian DJ, Davidowitz T, Benoliel R. The distribution of oral mucosal pH values in healthy
saliva secretors. Oral Dis 2006;12(4):420-3.
7. Yosipovitch G, Kaplan I, Calderon S, et al. Distribution of mucosal pH on the bucca, tongue, lips
and palate. A study in healthy volunteers and patients with lichen planus, Behcet's disease and
burning mouth syndrome. Acta Derm Venereol 2001;81(3):178-80.
8. Choi JE, Lyons KM, McLean MC, Waddell NJ. Interarch comparison of intraoral pH and
temperature: a pilot study. BDJ Open 2016;2:16008.
5
9. Kleinberg I. A mixed-bacteria ecological approach to understanding the role of the oral bacteria in
dental caries causation: an alternative to Streptococcus mutans and the specific-plaque
hypothesis. Crit Rev Oral Biol Med 2002;13(2):108-25.
10. Edgar M, Higham SM. Saliva and the control of plaque pH. In: Edgar M, Dawes C, O’Mullane D,
editors. Saliva and Oral Health. 4th ed. London (UK): Stephen Hancocks Ltd; 2012. p. 97-114.
11. Loke C, Lee J, Sander S, Mei L, Farella M. Factors affecting intra-oral pH - a review. J Oral
Rehabil 2016;43(10):778-85.
12. Pedersen AML, Sorensen CE, Proctor GB, Carpenter GH, Ekstrom J. Salivary secretion in health
and disease. J Oral Rehabil 2018;45(9):730-46.
13. Gudmundsson K, Kristleifsson G, Theodors A, Holbrook WP. Tooth erosion, gastroesophageal
reflux, and salivary buffer capacity. Oral Surg Oral Med Oral Pathol Oral Radiol Endod
1995;79(2):185-9.
14. Kleinberg I, Jenkins GN. The pH of dental plaques in the different areas of the mouth before and
after meals and their relationship to the pH and rate of flow of resting saliva. Arch Oral Biol
1964;9:493-516.
15. Kubala E, Strzelecka P, Grzegocka M, et al. A review of selected studies that determine the
physical and chemical properties of saliva in the field of dental treatment. Biomed Res Int
2018;2018 May 9:6572381.
16. Loesche WJ, Schork A, Terpenning MS, Chen YM, Stoll J. Factors which influence levels of
selected organisms in saliva of older individuals. J Clin Microbiol 1995;33(10):2550-7.
17. Marsh PD, Devine DA. How is the development of dental biofilms influenced by the host? J Clin
Periodontol 2011;38(Suppl. 11):28-35.
18. Tenovuo J. Salivary parameters of relevance for assessing caries activity in individuals and
populations. Community Dent Oral Epidemiol 1997;25(1):82-6.
19. Dawes C, Pedersen AM, Villa A, et al. The functions of human saliva: A review sponsored by the
World Workshop on Oral Medicine VI. Arch Oral Biol 2015;60(6):863-74.
20. Farella M, Loke C, Sander S, et al. Simultaneous wireless assessment of intra-oral pH and
temperature. J Dent 2016;51:49-55.
21. Ghezzi EM, Lange LA, Ship JA. Determination of variation of stimulated salivary flow rates. J
Dent Res 2000;79(11):1874-8.
22. Humphrey SP, Williamson RT. A review of saliva: normal composition, flow, and function. J
Prosthet Dent 2001;85(2):162-9.
23. Lindh L, Aroonsang W, Sotres J, Arnebrant T. Salivary pellicles. Monogr Oral Sci 2014;24:30-9.
24. Selwitz RH, Ismail AI, Pitts NB. Dental caries. Lancet 2007;369(9555):51-9.
25. Dawes C, Wong DTW. Role of saliva and salivary diagnostics in the advancement of oral health.
J Dent Res 2019;98(2):133-41.
26. Plemons JM, Al-Hashimi I, Marek CL. Managing xerostomia and salivary gland hypofunction:
executive summary of a report from the American Dental Association Council on Scientific Affairs.
J Am Dent Assoc 2014;145(8):867-73.
27. Karbach J, Walter C, Al-Nawas B. Evaluation of saliva flow rates, Candida colonization and
susceptibility of Candida strains after head and neck radiation. Clin Oral Investig
2012;16(4):1305-12.
28. Reddy A, Norris DF, Momeni SS, Waldo B, Ruby JD. The pH of beverages in the United States. J
Am Dent Assoc 2016;147(4):255-63.
29. Magalhaes AC, Wiegand A, Rios D, Honorio HM, Buzalaf MAR. Insights into Preventive
Measures for Dental Erosion. J Appl Oral Sci 2009;17(2):75-86.
30. Cunha-Cruz J, Scott J, Rothen M, et al. Salivary characteristics and dental caries: evidence from
general dental practices. J Am Dent Assoc 2013;144(5):e31-40.
31. Whelton H. Introduction: the anatomy and physiology of salivary glands. In: Edgar M, Dawes C,
O’Mullane D, editors. Saliva and Oral Health. 4th ed. London (UK): Stephen Hancocks Ltd; 2012.
32. Dawes C. What is the critical pH and why does a tooth dissolve in acid? J Can Dent Assoc
2003;69(11):722-4.
33. Bowen WH. The Stephan Curve revisited. Odontology 2013;101(1):2-8.
6
34. Stephan RM. Changes in hydrogen-ion concentration on tooth surfaces and in carious lesions.
JADA 1940;27(5):718-23.
35. Stookey GK. The effect of saliva on dental caries. J Am Dent Assoc 2008;139 Suppl:11S-17S.
36. Anderson P, Hector MP, Rampersad MA. Critical pH in resting and stimulated whole saliva in
groups of children and adults. Int J Paediatr Dent 2001;11(4):266-73.
37. Simmer JP, Fincham AG. Molecular mechanisms of dental enamel formation. Crit Rev Oral Biol
Med 1995;6(2):84-108.
38. Robinson C, Shore RC, Brookes SJ, et al. The chemistry of enamel caries. Crit Rev Oral Biol
Med 2000;11(4):481-95.
39. American National Standards Institute ADA. ANSI/ADA Standard No. 130 for Dentifrices.
American National Standards Institute, American Dental Association. Chicago: American Dental
Association. 2013.
40. Wefel JS, Harless JD. The effect of topical fluoride agents on fluoride uptake and surface
morphology. J Dent Res 1981;60(11):1842-8.
41. Kondo KY, Buzalaf MA, Manarelli MM, Delbem AC, Pessan JP. Effects of pH and fluoride
concentration of dentifrices on fluoride levels in saliva, biofilm, and biofilm fluid in vivo. Clin Oral
Investig 2016;20(5):983-9.
42. Petersson LG, Lodding A, Hakeberg M, Koch G. Fluorine profiles in human enamel after in vitro
treatment with dentifrices of different compositions and acidities. Swed Dent J 1989;13(5):177-83.
43. Cardoso CA, Levy FM, Peres-Buzalaf C, Buzalaf MA. Dentifrice pH but not consistency may
affect fluoride uptake in plaque. J Dent 2015;43(2):219-24.
44. Brito AC, Dantas LR, De Brito AL, et al. Loss on drying, calcium concentration and pH of fluoride
dentifrices. Contemp Clin Dent 2015;6(Suppl 1):S72-6.
45. Dawes C. Effect of a bicarbonate-containing dentifrice on pH changes in a gel-stabilized plaque
after exposure to sucrose. Compend Contin Educ Dent Suppl 1997;18(21):S8-10; quiz S45.
46. Ciancio SG. Baking soda dentifrices and oral health. J Am Dent Assoc 2017;148(11s):S1-s3.
47. American National Standards Institute ADA. ANSI/ADA Standard No. 116 for Oral Rinses.
American National Standards Institute, American Dental Association. Chicago: American Dental
Association. 2010.
48. Carey CM. Tooth whitening: what we now know. J Evid Based Dent Pract 2014;14 Suppl:70-6.
49. Kwon SR, Meharry M, Oyoyo U, Li Y. Efficacy of do-it-yourself whitening as compared to
conventional tooth whitening modalities: an in vitro study. Oper Dent 2015;40(1):E21-7.
50. Eachempati P, Kumbargere Nagraj S, Kiran Kumar Krishanappa S, Gupta P, Yaylali IE. Home-
based chemically-induced whitening (bleaching) of teeth in adults. Cochrane Database Syst Rev
2018;12:CD006202.
51. Price RB, Sedarous M, Hiltz GS. The pH of tooth-whitening products. J Can Dent Assoc
2000;66(8):421-6.
52. Torres CR, Crastechini E, Feitosa FA, Pucci CR, Borges AB. Influence of pH on the effectiveness
of hydrogen peroxide whitening. Oper Dent 2014;39(6):E261-8.
53. Rosin-Grget K, Peros K, Sutej I, Basic K. The cariostatic mechanisms of fluoride. Acta Med Acad
2013;42(2):179-88.
54. Marquis RE, Clock SA, Mota-Meira M. Fluoride and organic weak acids as modulators of
microbial physiology. FEMS Microbiol Rev 2003;26(5):493-510.
55. de Groot A. Contact allergy to (ingredients of) toothpastes. Dermatitis 2017;28(2):95-114.
56. Herlofson BB, Barkvoll P. Sodium lauryl sulfate and recurrent aphthous ulcers. A preliminary
study. Acta Odontol Scand 1994;52(5):257-9.
Prepared by the Department of Scientific Information, ADA Science Institute
Reviewed by: Clinical Excellence Subcommittee, Council on Scientific Affairs.
Published: August 30, 2019
Copyright © 2019 American Dental Association. Reproduction or republication strictly prohibited without
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