Eating acidic foods like tomatoes, citrus fruits, juices, sour foods and aerated drinks can erode enamel. Rinsing the mouth immediately is recommended. Having cheese also neutralises the acids.

Receding gums is one of the top reasons for sensitivity. When gums recede, the ultra sensitive roots are exposed. Such cases need dentist's help.

Some tooth whitening pastes may abrade or erode enamel. Stopping their usage may help.

Brushing too hard or with a very hard bristled toothbrush will erode enamel and push the gums away causing sensitivity. 

Munching on ice or hard candies etc can lead to broken, chipped or cracked teeth. Once the tooth is cracked, the nerve inside the tooth gets inflamed and irritated and causes pain. Such cases need dentist's intervention. 

Grinding or clenching your teeth wears away the enamel. Mouth guards, lifestyle changes and even diet adjustments can help combat clenching and grinding. 

Tooth decay exposes the inner sensitive dentin or maybe the nerve leading to pain on having hot, cold, sweet stuff and even air. Immediate dental treatment is recommended. 

Minor tooth sensitivities can be alleviated using desensitising toothpastes.