Diagnosing oral lichenoid contact reaction: clinical judgment versus skin-patch test

Objective of this study was to compare the skin-patch test with the clinical diagnosis of oral lichenoid contact reaction (OLCR) as indicators for amalgam replacement.

Of 53 patients (38 female and 15 male; mean age 48.7) with oral lichen planus (OLP), 26 were identified as having OLCR, and clinically graded according to the proximity of their lesions with amalgam fillings: class I (weak association), class II (moderate association), and class III (strong association). All OLCR patients were skin-patch tested for both standard (Brazilian) and specific allergens (TROLAB, Germany). Patients were considered skin-patch positive only if they developed positive skin reactions for thimerosal and/or amalgam components. Amalgam replacement was indicated in all class II and III patients. For class-I patients, amalgam replacement was indicated only if they were skin-patch test positive. Readings for the skin-patch test were made at 48h and 96h.

Of the 26 patients with OLCR, two missed the follow-up and were excluded, leaving 24 cases. Of these, four were class-I, and all were negative for the skin-patch test. Twelve were class-II, of whom seven were skin-patch positive. Eight were class-III, of whom six were skin-patch positive. Following amalgam replacement in the 12 class-II patients, six showed improvement and six had complete resolution, while in the eight class-III patients, two showed improvement and six a complete resolution.

Clinical diagnosis of OLCR lesions is a more reliable indicator for the question of amalgam replacement than is the skin-patch test.