Oral Nicotine Pouch Effects on Salivary and Phosphate-Buffered Saline pH

Objectives: Negative oral effects of long-term tobacco use are well-documented; however, there is limited research on a new generation of tobacco-free nicotine pouches (NPs). These tobacco-free NPs are placed between the buccal mucosa and gingiva. Limited data suggests that use produces an alkaline oral pH of unknown duration and degree of harm to the oral tissues with prolonged and/or chronic exposure. The purpose of this in vitro study was to determine pH changes over time in whole human saliva, phosphate-buffered saline (PBS), and deionized water, when exposed to different concentrations and brands of NPs.
Methods: Unstimulated, whole saliva from volunteers was collected, pooled, and refrigerated. Saliva, deionized water, and PBS 4 mL each, were placed into separate test tubes. Initial pH and temperature were recorded using calibrated digital probes. NPs of the same brand and concentration were placed into each medium and stirred for 15 seconds. pH was recorded individually every 15 minutes for one hour. The pouch was removed after 60 minutes, and pH was recorded after an additional 15 minutes. This protocol was repeated for 9 brands/concentrations of NPs. Measurements for most popular brands with specific concentrations were tested three times (n=3).
Results: Initial average pH for the testing mediums were saliva (6.92, +/-0.18), PBS (7.67, +/-0.04) and H₂0 (7.32, +/-0.16). For each of the four brands tested at 15-minute intervals, pH increased consistently over 75 minutes, including 15 minutes after removing the NPs. Based on commercial brand and concentration, the minimum pH increase in saliva was 0.28 (+/-0.10), while the maximum increase was 1.55 (+/-0.12). Average temperature was 23.74°C.
Conclusions: Study findings suggest that NP use can produce a sustained, alkaline effect on salivary pH, regardless of nicotine concentration. Alkaline pH increases are dependent on NP brand, potency, and possibly on individual product ingredients.