Recurrent Aphthous Stomatitis: This condition is characterized by the periodic appearance of benign, non-contagious ulcers in the mouth, often on the gumline, which can be erosive. It's a common condition that can be triggered by stress, trauma, or certain foods.

Oral Lichen Planus: An autoimmune condition that can cause erosive ulcers on the mucous membranes inside the mouth, including the gumline. It's often associated with a lacy white pattern and can be painful.
Traumatic Ulcers: Accidental bites or injuries from dental work, sharp teeth, or other oral trauma can cause erosive ulcers on the gumline.
Nicotinic Stomatitis: Associated with heavy smoking, this condition can lead to ulcers and other changes in the mouth, including the gumline.

Oral Cancer: Although less common, erosive ulcers on the gumline can be a sign of oral cancer, particularly if they are persistent, grow in size, or are accompanied by other symptoms like difficulty swallowing or a lump in the neck.
Infectious Diseases (e.g., Syphilis, Tuberculosis): Certain infectious diseases can cause oral ulcers, including on the gumline. These conditions require prompt diagnosis and treatment to prevent serious complications.
Autoimmune Disorders (e.g., Pemphigus, Lupus): Autoimmune diseases can sometimes manifest with oral ulcers, including erosive ulcers on the gumline, and are critical to diagnose due to their potential for significant morbidity.

Erythema Multiforme: A rare skin condition that can also affect the mucous membranes, causing ulcers, including on the gumline. It's often triggered by infections or medications.
Behçet's Disease: A form of vasculitis that can cause a wide range of symptoms, including oral ulcers, which can appear on the gumline. It's rare and requires a comprehensive diagnosis considering other systemic symptoms.
M MAGIC Syndrome: A rare condition that combines features of mouth and genital ulcers with inflamed cartilage (relapsing polychondritis). Oral ulcers can occur, including on the gumline.