455 patients with desquamative gingivitis were affected by erosive oral LP; 46.4% of them were positive for anti-Tg and 45.1% for antithyroid microsomal antibodies. The corresponding percentages were 27.5 and 30.3%, among patients with erosive LP but not gingivitis. For both groups of patients, differences in comparison with healthy controls were significant (p < 0.001). Overall, 210 patients were positive for at least one thyroid autoantibody, and TSH levels were normal in 84.3%, decreased in 6.7% and increased in 9% of them. This evidence concerns the gene TG and gingivitis.