Use test with l-carvone in toothpaste on sensitized individuals

Area of Science:

• Oral Medicine
• Dermatology
• Allergology

Background:

• Carvone (l-carvone), a mint flavouring, is a known weak contact allergen.
• Contact allergy to carvone is disproportionately common in individuals with oral lichen planus or oral lichenoid lesions (OLP/OLL).

Purpose of the Study:

• To evaluate the effects of oral carvone exposure in sensitized individuals.
• To compare reactions to carvone-containing toothpaste versus a non-flavoured control using a use test.

Main Methods:

• Patch testing was performed on subjects allergic to carvone (n=14, 11 with OLP/OLL), OLP/OLL patients (n=20), and healthy controls (n=3).
• A month-long use test involved twice-daily brushing with either carvone or control toothpaste, with fortnightly examinations.
• Clinical signs were scored, and oral health-related quality of life was assessed using the OHIP-49 questionnaire.

Main Results:

• Allergic subjects using carvone toothpaste experienced aggravated oral lichenoid lesions (7/10) and perioral eczema (2/10).
• Significantly higher mucosal scores and OHIP-49 scores were observed in allergic subjects using carvone toothpaste compared to controls.

Conclusions:

• Oral exposure to carvone can exacerbate oral lesions and cause perioral eczema in sensitized individuals.
• These reactions can mimic OLP/OLL, potentially leading to delayed or missed diagnoses of flavour contact allergy.