Tooth sensitivity to hot and cold

IMI Clinic

What is pyorrhea?

Pyorrhea is a bacterial inflammation that afflicts the tissues supporting the teeth, especially the periodontium: in fact, it is also known as periodontitis or periodontal disease.

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tooth-sensitivityThe dentin is the layer of hard tissue right under the enamel in the crown area and under the cementum near the roots, thus covering the dental pulp. Throughout the dentin, there are many microscopical canals called dentinal tubules, which contain particular extensions of the cells of the pulp called odontoblastic processes and dentinal fluid in which the odontoblastic processes float.

Tooth sensitivity is caused by an anomalous exposure of the dentinal surface of the roots or crowns, which exposes the dentinal tubules.

The exposure of the dentin causes an increased sensitivity of the teeth because the stimuli capable of causing pain are of three kinds:

  • Mechanical (brushing, bruxism)
  • Thermal (75% cold, 25% heat)
  • Osmotic contact with acidic food (orange juice, lemon juice or other such drinks) or excessive sugar

These stimuli cause pain because they provoke movements with related change of pressure of the dentinal liquid present in the dentinal tubules.

According to the hydrodynamic theory, an external stimulus causes the movement of the liquid inside the tubule to deform the odontoblast, stimulating the nerve fibers that surround it and those of the predentin. Cold is capable of causing a hydrodynamic outward movement (centrifugal movement) with a consequent acute and brief stimulation of the odontoblast cells with a negative pressure on their cytoplasmic extensions; while heat will be responsible of centripetal movements with an increase in the pressure that leads to dull and persistent pain.

Sensitivity appears in 30% of cases in which the dentin becomes exposed near the neck of the tooth, where the enamel ends and makes way for the radicular cementum.


Causes of dental sensitivity

Among the causes of tooth sensitivity, there is the exposure of the dentin to the exterior because of:

  • Poor oral hygiene
  • Accumulation of plaque with consequent demineralization of the enamel and exposure of the underlying dentin
  • Use of abrasive toothpastes
  • Improper brushing technique
  • Gingival recession
  • Periodontal disease
  • Bad eating habits with excessive consumption of acid food
  • Acid reflux
  • Behavioral disorders such as anorexia, bulimia, or induced vomiting
  • Bruxism
  • Occlusal trauma with loss of hard tissues of the neck of the tooth
  • Dentoskeletal causes with the roots of the teeth external to the maxillary or mandibular bones
  • Iatrogenic damage caused by previous orthodontic movements or tooth whitening


The effects of tooth sensitivity

The main, if not the only, effect of tooth sensitivity is acute pain when eating very cold or hot food,  or acidic or sugary beverages.

How can you treat tooth sensitivity?

There are various different treatments and therapies for tooth sensitivity, and the dentist will have to decide which to chose.

In general, tooth sensitivity is cured:

  • Using desensitizing toothpastes containing compounds that form a deposit on the tubules, closing them and reducing the nerve impulse transmission
  • With a proper oral hygiene with soft toothbrush, mouthwash, and dental floss, avoiding brushing too vigorously
  • Using fluoride toothpaste
  • Treating the periodontal disease with photodynamic therapy
  • Reducing consumption of acidic food (alcoholic drinks, citrus fruit juice, grapefruit, wine)
  • With conservative therapies with adhesive techniques: composite reconstruction of lesions caused by cavities
  • With lasers, with vitrification of the dentin
  • With the use of a bite in case of bruxism

“Wedge-shaped” lesions

The loss of enamel or cementum, with related exposure of the dentin, causes a “wedge-shaped” lesion, because the dentin isn’t as resistant as the enamel to the abrasion caused by brushing.

The gum recession caused by the periodontal disease, instead exposes the cementum to the abrasive action of brushing, with consequent loss of hard tissues, uncovering the neck of the tooth and exposing it to cavities. Improper horizontal brushing contributes to the loss of dentin.

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