Dr. John C. Stone, a cosmetic dentist of more than 30 years, explains that toothaches hurt more at night because of the increased blood pressure to the head that occurs when lying down. A persistent toothache causes a sharp, throbbing pain at irregular periods.
Sleeping in an elevated position reduces the pain of toothaches at night, advises Dr. Stone. Decay is the main cause of tooth pain. Other causes include gum disease, sinusitis, ear infection and similar conditions that lead to inflammation in the area around the mouth and jaw.
A toothache occurs due to the inflammation of the dental pulp, which is the innermost layer of the tooth, says the National Health Service. It contains soft, delicate tissue that consists of sensitive nerves and blood vessels. One of the causes of dental pulp inflammation is tooth decay, which leads to the formation of cavities in the hard surface of the tooth. Loose or broken fillings, a cracked tooth, receding gums and periapical abscess are other causes.
The National Health Service notes that a toothache that lasts more than one or two days must be checked by a dentist, as the pain will only get worse if the toothache is left untreated. The pulp inside the tooth can get infected, leading to a dental abscess which causes severe and continuous pain.