Symptoms
Symptoms are often not noticeable until the disease is advanced. They include:

• Bad breath that won't go away
• Red or swollen gums
• Tender or bleeding gums
• Painful chewing
• Loose teeth
• Sensitive teeth

Diagnosis

• The dentist will ask about your medical history to identify underlying conditions or risk factors (such as smoking) that may contribute to periodontal disease. 
• The dentist or hygienist will examine your gums and note any signs of inflammation.
• The dentist or hygienist will use a tiny ruler called a 'probe' to check for periodontal pockets and to measure any pockets.  In a healthy mouth, the depth of these pockets is usually between 1 and 3 millimeters.
• The dentist or hygienist may take an x-ray to see whether there is any bone loss.
• The dentist may refer you to a periodontist, a specialist who treats gum diseases.