Strittholt CA, McMillan DA, He T, Baker RA, Barker ML. 2016. A randomized clinical study to assess ingestion of dentifrice by children. Regul Toxicol Pharmacol 75:66–71.
This study investigated whether there was a difference in amounts of dentifrice ingested by children based on age using pea-sized instructions. The study had a randomized, single-blinded, 3-period, crossover design modelled after Barnhart et al. (1974) with one regular-flavored and two specially-flavored dentifrices used ad libitum. Subjects were enrolled in three groups: 2–4, 5–7, and 8–12 years. They were instructed to brush at home as they would normally with each dentifrice for 3 weeks (9 weeks total). On weekly study-site visits, subjects brushed with the assigned dentifrice containing a lithium marker to measure the amount of dentifrice ingested and used. Averaging across dentifrices, amounts ingested were: 0.205 g (2–4 yr), 0.125 g (5–7 yr) and 0.135 g (8–12 yr), demonstrating 2–4 year-olds ingested significantly more than older children (p ≤ 0.002). Averaging across dentifrices, amounts used were: 0.524 g (2–4 yr), 0.741 g (5–7 yr) and 0.978 g (8–12 yr) suggesting an age-related effect (p < 0.01). Findings also showed that ingestion amount for specially-flavored dentifrices may increase relative to regular-flavored dentifrice for children 2–7 years-old. This research demonstrated that dentifrice ingestion amount decreased significantly with age while usage amount increased with age. Importantly, ingestion and usage levels in younger children reflect “pea-sized” direction and were numerically lower than historical levels reported prior to this direction.