When adult smokers switched from cigarettes to on! nicotine pouches for 24 weeks, their gum inflammation dropped by 28%, bleeding fell by 23%, and tooth staining decreased by roughly 60% — all compared to a group that kept smoking.

Those are the headline findings of a randomised clinical trial published in Oral Health and Preventive Dentistry in March 2025. They sound like good news for the pouch industry's harm-reduction argument.

Here is the catch: every author on the paper is either an employee of Altria Client Services — the company that makes on! — or a consultant paid by Altria to conduct the study. The study was funded, designed, and written by the product's manufacturer.

That doesn't make the data wrong. Industry-funded studies can produce valid results, and this one went through peer review at a real journal. But it means the findings need to be read with the conflict of interest in full view — and weighed against independent evidence that tells a more complicated story.

What the study measured

Researchers randomised 155 adult smokers into two groups. One switched to on! nicotine pouches (available in 2, 4, or 8 mg strengths) and used them ad libitum — meaning as much as they wanted — for 24 weeks. The other continued smoking as usual.

Dental examiners assessed three oral-health endpoints at baseline, week 12, and week 24:

• Modified Gingival Index (MGI) — a standardised measure of gum inflammation
• Gingival Bleeding Index (BI) — the percentage of gum sites that bled on probing
• Lobene Stain Index (LSI) — a measure of tooth surface staining

Of the 155 who started, 85 completed the 24-week assessment — 40 in the pouch group and 45 in the smoking group. That is a 45% dropout rate, which the authors attribute to the length of the study and the commitment required for clinical visits.

What they found

The pouch group did not just maintain their oral health. It improved.

Gum inflammation (MGI): Down 20% at week 12 and 28% at week 24 compared to the smoking group. The reduction was statistically significant (p < 0.001) at both time points and also significant compared to each participant's own baseline.

Gum bleeding (BI): Down 30% at week 12 and 23% at week 24 versus smokers (p < 0.001). Bleeding on probing is a clinical sign of gingivitis — the earliest stage of gum disease.

Tooth staining (LSI): Down approximately 60% compared to the smoking group (p < 0.001). The smoking group showed no statistically significant change in staining at either time point.

One more detail: the pouch group reduced their cigarette consumption by more than 90% by week 12, and that held through week 24 — even though participants had not been trying to quit at the start of the study. They were smokers who agreed to try switching, not people enrolled in a cessation programme.

Why the results make biological sense

Cigarette smoke is devastating to oral tissue. It suppresses immune responses in the gums, alters the oral microbiome, impairs tissue repair, and is a major driver of periodontitis — the advanced gum disease that destroys the bone supporting teeth. A systematic review estimated that smoking increases the risk of periodontitis by 85%.

Nicotine pouches contain no tobacco leaf and produce no smoke. They deliver nicotine (which is addictive and not risk-free) through a small cellulose pouch held under the lip. Removing the smoke removes the primary mechanism by which cigarettes damage oral tissue.

The staining finding is the most intuitive: cigarette tar is the dominant cause of tooth discoloration in smokers. Stop the tar, and staining recedes. The gingival improvements are also plausible — removing smoke exposure allows gum tissue to recover from chronic inflammation.

The caveats that shape how to read this

The conflict of interest is the obvious one, but there are others:

• Every author is Altria-affiliated. Jianmin Liu, Jeffery Edmiston, Jingzhu Wang, Maria Gogova, and Mohamadi Sarkar are all listed as Altria Client Services employees. Kimberly Milleman, Jeffery Milleman, and Abigale Yoder are at Salus Research, which received grants from Altria to conduct the study. The corresponding author's email is an @altria.com address.
• 45% dropout. Of 155 randomised participants, only 85 completed the 24-week visit. High attrition can bias results if those who dropped out fared worse — though the authors report that completers and non-completers had similar baseline characteristics.
• Only 24 weeks. Periodontitis develops over years. Twenty-four weeks is enough to see gingival inflammation changes, but it cannot tell us whether pouch use affects long-term gum recession, bone loss, or oral cancer risk.
• Open-label design. Participants and examiners knew who was using pouches and who was smoking. Blinding would be difficult with this design, but its absence is a limitation.
• One brand only. The study tested on! pouches exclusively. Different brands use different filler matrices, pH adjusters, and flavour systems that could produce different oral-health effects.
• Surrogate endpoints. Gingival indices are well-validated clinical measures, but nobody in this study developed — or failed to develop — periodontitis. These are risk markers, not disease outcomes.

What independent evidence says

This study sits in a broader and more cautious evidence base.

A BDJ Team update published in April 2026 by NHS-funded dental public health researchers at King's College London noted that "the oral health effects are unknown but likely to be similar to other orally administered nicotine products." It flagged localised gingival recession and oral mucosal changes at pouch placement sites as observed side effects, and stated that there is "currently no evidence of [pouches'] effectiveness as a smoking cessation aid."

A Cochrane review updated in 2025 (Hartmann-Boyce et al.) looked at whether nicotine pouches help people quit smoking. Drawing on four studies with 284 participants, it concluded the evidence is "uncertain" — there simply is not enough data to say pouches work for cessation.

Two clinical case reports published in BMC Oral Health in November 2025 documented localised gingival recession and leukoplakia (a white patch that can be premalignant) in two young daily pouch users, at the exact sites where they habitually placed their pouches. Case reports cannot prove causation, but they raise questions this industry study does not address.

A separate University of Gothenburg study (also industry-funded, by Swedish Match) found that plaque acidogenicity decreased when snus users switched to ZYN pouches — a different population and outcome, but a directionally similar finding for oral-health markers.

What this study adds — and what it doesn't

The on! study is the first randomised clinical trial to directly compare oral-health endpoints between smokers who switch to nicotine pouches and those who continue smoking. That design matters: most pouch research compares pouch users to non-users or to snus users, not to the population most relevant for harm reduction — current smokers.

The finding that gum inflammation, bleeding, and staining all improved when smokers switched is biologically plausible and consistent with what we know about smoke's oral damage. If pouches genuinely help smokers reduce their smoke exposure by 90% — as this study reports — that is a meaningful harm reduction signal.

But this is a single 24-week study, funded entirely by the manufacturer, with a small completing sample and no long-term follow-up. The independent dental community — the BDJ Team authors, the Cochrane reviewers — is not ready to call pouches a safe or proven switch. The case reports of gum recession and leukoplakia, while anecdotal, are a reminder that pouch placement itself may carry local risks that a 24-week switching study is not designed to detect.

The honest read: this study adds a data point to the harm-reduction case. It does not settle it.

SOURCES:

• Liu J, Edmiston JS, Wang J, Milleman KR, Milleman JL, Yoder AL, Gogova M, Sarkar MA. "Oral Health Effects Among Adults Switching from Cigarettes to on!® Nicotine Pouches Compared to Those Who Continue Smoking." Oral Health Prev Dent 2025;23:189–201. Published 25 March 2025. DOI: 10.3290/j.ohpd.c_1925. Full text: PubMed Central PMC11966149
• Niven V, John JH. "Oral nicotine pouches and oral health – an update for the dental team." BDJ Team 13, 152–153 (2026). Published 17 April 2026. DOI: 10.1038/s41407-026-3283-0
• Hartmann-Boyce J, et al. "Oral nicotine pouches for cessation or reduction of use of other tobacco or nicotine products." Cochrane Database Syst Rev 2025;(10):CD016220. Cochrane
• Alkhatib OA. "Localized gingival recession and leukoplakia associated with nicotine pouch use: two clinical case reports." BMC Oral Health 25, 2004 (2025). Published 28 November 2025. DOI: 10.1186/s12903-025-07320-4

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