What can cause tooth pain if there seems to be no decay?

Many things: Infection, fracture, gum disease, bruxism, dying or dead nerve, decay that is there but you just don't know about it are just a few of the more common possibilities.

Multiple causes: Have you had a dentist diagnosis the tooth to see if there is any decay? Sometimes a tooth can look fine to you in the mirror, but there is decay under the enamel or in between the teeth. Only an x-ray and exam can tell for sure. Other causes of tooth pain are grinding, clenching, cracked tooth, gum disease, trauma or injury.

Many reasons: Tooth pain can come from trauma, grinding your teeth, decay that is not visible, or even nerve damage. Best to see a dentist to have it evaluated.

A few things.: Injury, infection, fracture, gum disease, bruxism, dying or dead nerve, cavity that you cannot see with cursory exam. See dentist for diagnosis. If he/she says no pathology, may be atypical odontalgia. If so, see orofacial-TMJ doc.