Dental patch testing in patients with undifferentiated oral lichen planus.

Background/objectives: Distinguishing between oral lichen planus (LP) and lichenoid reactions to dental restorations can be impossible on clinical and histopathological grounds. Epicutaneous patch testing is an investigation that may guide patients and physicians in making timely and costly decisions to replace or cover existing dental restorations. This study aimed to assess the role of epicutaneous patch testing with a battery of dental allergens in patients with undifferentiated oral LP.
Methods: A retrospective review of the medical records of patients with biopsy-proven oral LP referred by an oral medicine specialist and who presented for dental epicutaneous patch testing at a dermatology clinic in Perth, Western Australia between 2009 and 2016 was performed.
Results: In total, 68 patients were included, of whom 54 (79%) had positive patch tests. Gold 26 (48%), mercury 24 (44%), nickel 22 (41%), copper 19 (35%), potassium dichromate 14 (26%) and methylhydroquinone 13 (24%) were the most common allergens for which patients tested positive. Hypothyroidism and non-steroidal anti-inflammatory drugs were associated with negative patch tests (P = 0.01 and 0.04, respectively). Smoking history, other medications and comorbidities, the location of the dental restorations and unilateral or bilateral disease were not significantly associated with the patch test results. Restorations were removed in 23 patients: 21 of these (91%) had positive epicutaneous patch tests. Of the 20 patients followed up, 19 (95%) experienced some improvement, among whom 11 (58%) had complete remission.
Conclusion: Epicutaneous patch testing disclosed a high proportion of relevant positives. This guided the clinical decision to change dental restorations, with high rate of clinical improvement.
(© 2017 The Australasian College of Dermatologists.)