The pH of various tooth-whitening products on the South African market.
Level 5 - mechanism / opinion, no new human data
In vitro bench research measuring chemical properties without human participants.
What was done
This in vitro study measured the pH of 21 commercial tooth-whitening products sold in South Africa across four categories: dentist-supervised home bleaching products (n = 5), in-office bleaching products (n = 5), over-the-counter (OTC) bleaching products (n = 4), and whitening toothpastes and rinses (n = 7). Each product was tested in triplicate using an Orion Expandable Ion Analyzer EA940 with a combination pH electrode. Category differences were evaluated using one-way ANOVA.
What was found
Product pH ranged widely from 3.76 to 9.68 across all 21 items. Mean pH values by group were: - Dentist-supervised home bleaching: 6.21 ± 0.76 (range 4.88 to 6.81) - In-office bleaching: 6.26 ± 1.19 (range 5.30 to 7.85) - OTC bleaching: 5.07 ± 1.74 (range 3.76 to 8.03) - Whitening toothpastes: 7.66 ± 1.19 (range 6.61 to 9.68) The OTC group had a significantly lower (more acidic) mean pH than all other categories (p < 0.05). Rapid-White gel had the lowest pH (3.76) and Colgate Advanced Whitening toothpaste had the highest (9.68).
Why it matters
Several OTC whitening products exhibit pH levels well below the critical threshold for enamel demineralization (typically ~5.5), suggesting unsupervised consumer use could carry a risk of enamel erosion.
Limits
The study tested only 21 products from a single regional market at one point in time. Because this was a purely chemical in vitro analysis, it did not assess salivary buffering capacity, exposure duration, enamel demineralization, or actual clinical tooth damage.
Cited by
- contradicts Crest Whitestrips have an acidity level equivalent to battery acid.