Dentists are healthcare professionals who provide preventive and restorative treatments for problems that affect the mouth and teeth. Most dentists work as self-employed practitioners in general practice, providing dental care to the public. Others work in salaried posts within a variety of specialties in hospital dentistry, community dentistry, the armed forces, corporate practices, industry, or university teaching and research. A general dental practitioner (GDP) typically leads a team made up of dental care professionals including dental hygienists and treats a wide range of patients, from children to the elderly. A dentist is typically responsible for educating patients on oral healthcare; examining teeth and diagnosing patients' dental conditions by using tools such as x-rays; assessing treatment options and agreeing treatment plans with patients; carrying out agreed clinical treatments such as restoring teeth affected by decay and treating gum disease; maintaining patients' dental records; and other office-based activities. Hospital dentists usually treat patients who have been referred by a GDP and provide more specialized and complex dental care. Additional postgraduate qualifications are required for career progression; the amount of time spent in postgraduate training varies according to the specialty chosen.