There are two types of tooth sensitivity: dentinal and pulpal sensitivity, notes Simplestepsdental. Dentinal sensitivity occurs due to the exposure of dentin. It becomes exposed when the enamel wears out, and this is caused by brushing teeth hard, cavities, poor oral hygiene and receding gums. Pulpal sensitivity occurs due to the tooth's pulp reaction, and it tends to affect a single tooth. Some of its causes include decay, recent filling, excess pressure from grinding and broken tooth.
Sources: simplestepsdental.com, colgate.com, mayoclinic.org