One of the questions pouch users ask most: will these things give me cavities?

A University of Gothenburg study published in BMC Oral Health in March 2026 tried to answer that. The short version: when regular snus users switched to ZYN nicotine pouches for six weeks, their dental plaque became less acid-producing, not more. Plaque acidogenicity — the process that drives tooth decay — dropped significantly.

But the picture has a wrinkle. The bacteria most associated with cavities, Streptococcus mutans, actually increased over the same period. More cavity bacteria, less acid. The study authors say that paradox is real and worth understanding.

What happened

Researchers at the Sahlgrenska Academy, University of Gothenburg, ran a two-part clinical trial with 74 participants who were regular tobacco-based snus users.

Part A was a single-dose test with 18 participants. Each person tried, in random order on separate weeks: a flavored ZYN pouch (Peppermint 3 mg), an unflavored ZYN pouch (Smooth 3 mg), a 10% sucrose rinse (the positive control — sugar is the gold standard for triggering plaque acid), and a 10% xylitol rinse (the negative control — xylitol is known to suppress acid).

The pouch stayed in the upper lip for 60 minutes. Plaque pH was measured at baseline and every few minutes up to 60 minutes using a microelectrode pressed directly into the dental biofilm.

Result: both ZYN products caused significantly less plaque acidogenicity than sucrose (p < 0.0001). They performed comparably to xylitol — the anti-cavity control. Flavored and unflavored pouches showed no difference.

Part B was a six-week observational follow-up with 56 participants. They replaced as much of their regular snus as possible with ZYN (3 mg or 6 mg, in Smooth, Peppermint, or Cinnamon). Compliance was strong: by week 6, ZYN accounted for 84% of their nicotine product use.

At each visit (baseline, week 2, week 4, week 6), researchers challenged the plaque with a sucrose rinse and measured how much acid the biofilm produced in response.

Result: plaque acidogenicity decreased significantly and progressively from baseline to week 6 (p < 0.0001). The effect size was large (Cohen's d = 2.18). The amount of plaque on the teeth did not change.

The paradox: more cavity bacteria, less acid

Here is the finding that makes this study more than a clean bill of health. Salivary S. mutans — the bacterium most closely linked to dental caries — increased significantly at weeks 4 and 6 compared to baseline. Lactobacilli, another acid-producer, stayed flat.

So the mouth had more of the bacteria that cause cavities, yet the plaque those bacteria lived in produced less acid when challenged with sugar.

The authors suggest the oral microbiome shifted in ways not directly proportional to S. mutans counts. The ZYN matrix — microcrystalline cellulose, maltitol, sodium carbonate (which raises pH), and the sweetener acesulfame K — may have altered the environment enough to change how the biofilm behaves, even if individual bacterial populations moved in different directions.

Acesulfame K, in particular, has been shown in prior research to suppress biofilm formation by cariogenic bacteria. Sodium carbonate raises the local pH toward alkaline, which inhibits acid production. These are the same pH-adjusting ingredients used in traditional Swedish snus, which has long been associated with no increased caries risk.

Why it matters

The cavity question is one of the most searched topics around nicotine pouches. The non-tobacco matrix — fillers, sweeteners, flavorings held against the gum for 30–60 minutes — looks superficially like it should feed bacteria. This study directly tested that concern in a controlled clinical setting and found the opposite of what a casual prediction would suggest.

It also adds to a pattern in Swedish oral health research on pouches: the Gothenburg group previously found that switching from snus to ZYN improved pre-existing snus-induced mucosal lesions, and a separate Karolinska Institutet / Folktandvården study of 272 young adults found no increased caries or periodontitis risk in pouch users compared to snus users or non-users.

The caveats that matter

This study has important limitations, and they should be stated plainly:

• Funded by Swedish Match. Swedish Match North Europe AB, the manufacturer of ZYN, provided funding and study materials. The authors state the company had no role in study design, data collection, analysis, interpretation, or writing. Still, industry funding of product research always warrants scrutiny.
• Tested ZYN only. The results apply to ZYN Dry pouches (3 mg and 6 mg). Other brands use different matrices — different fillers, sweeteners, pH adjusters — and may produce different plaque responses.
• Snus users, not new users. Every participant was an established snus user. The study measures what happens when you switch from snus to pouches, not what happens when a non-user starts using pouches. Snus itself is associated with low caries risk, so the baseline may already be favorable.
• Surrogate marker. Plaque acidogenicity is a well-validated proxy for caries risk, but nobody in this study actually developed — or failed to develop — cavities. The study lasted six weeks; caries develops over months and years.
• Old data, new publication. Data was collected November 2017 to June 2018. The study was published in March 2026. The authors do not explain the eight-year gap between data collection and publication.
• No power calculation. The authors note that limited prior data prevented a formal sample-size calculation.

What happens next

The study raises a question its authors do not answer: if S. mutans goes up but acid goes down, what else in the biofilm changed? Understanding that mechanism would require microbiome sequencing beyond the culture-based methods used here.

A registered trial at the ISRCTN registry (ISRCTN50779351) is currently recruiting to test prototype nicotine pouches' effects on plaque acid production, salivary pH, and oral mucosa — a sign that the research community is still working through these questions.

For now, the evidence points in one direction: switching from Swedish snus to ZYN pouches does not appear to increase cavity risk markers, at least over six weeks. But that is not the same as saying pouches protect your teeth — and it is certainly not a reason to skip the dentist.

SOURCES:

• Alizadehgharib S, Lehrkinder A, Alshabeeb A, Lingström P. "Single-use and six-week effects of a non-tobacco nicotine pouch on dental plaque characteristics: a randomized crossover study with observational follow-up." BMC Oral Health 26, 623 (2026). Published 24 March 2026. Open access. DOI: 10.1186/s12903-026-08119-7. Full text: Springer Nature Link
• ISRCTN50779351: "Effects of prototype nicotine pouches on acid production in dental plaque, salivary pH, and oral mucosa." Registered 9 December 2025. Status: Recruiting. ISRCTN registry

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