Dentists understand how pain works by looking at the structure of teeth and how the different nerves work. Using this knowledge the correct treatment can be prescribed for any given situation.

				Dentin forms the bulk of the structure inside the tooth. it decays far more easily than enamel and may harbour many bacteria once decay has started.
				The dentin has an open structure with many tubes running side by side from the enamel to the pulp where the nerve lives. Once decay has broken the enamel down the tubes are open to the inside of the mouth. Hot drinks and cold air can rush down the tubules to produce pain when they hit the nerve inside.

		With early decay pain tends to be sharp as large and fast nerve fibres transmit to the brain. These are accurate and produce pain which may be identified to a single tooth. These fibres are set off by a stimulus such as cold air or a hot drink.				Slow fibres are narrow and produce pain which is 'dull' or 'blunt' or 'throbbing'. The pain tends to be over an area and difficult to isolate to one tooth. The reason for this is that the nerves get mixed up and muddled when they enter the brain. These cross connections make the pain occur over a wider area.