Principles; investigations - therapy; infections of the oral mucosa; recurrent oral ulceration; lips, tongue, and saliva - facial therapy; lesions of the teeth and periodontum; white patches - overgrowths and neoplasms; diseases of the skin - gastro-intestinal disease; blood and nutrition - endocrine changes and drug reactions; disorders of bone; facial pain - neurological disturbances and temporomandibular joint.