Congenital diseases of the oral mucosa. They including cysts of the oral mucosa, Fordyce’s spots, congenital epulis of the newborn, melanotic neuroectodermal tumor of infancy, haemangioma, lymphangioma, alveolar lymphangioma, congenital pits, congenital ranula and sucking pads.The remaining diseases discussed are divided based on the morphology of the presenting lesion and include:Papules and nodules of the oral mucosa. They include mucocele, oral abscess and parulis, squamous papilloma, eruption cyst and eruption hematoma, retrocuspid papilla, epulis, intraoral malignancy, focal epithelial hyperplasia (heck’s disease) and genodermatoses with multiple oral papules.Stomatitis and ulcerations of the oral mucosa. They include trauma, infections (bacterial, viral enanthems and fungal), genetic diseases (epidermolysis bullosa), diseases with altered immune reactivity (erythema multiforme), recurrent aphthous stomatitis, behcet’s syndrome and magic syndrome.White lesions including acquired white lesions (leukoplakia, trauma, candidiasis, angular stomatitis, leukoedema, koplik’s spots) and congenital white lesions (white sponge nevus, pachyonychia congenital, dyskeratosis congenital, Darier’s disease).Pigmented lesions of the oral mucosa. They include macular hyperpigmentation, addison’s disease, albright’s syndrome, thrombocytopcnic purpura, amalgam tattoo, melanocytic nevi, peutz-jeghers syndrome, generalized hyperpigmentation.