Dental Anomalies: Number and Size

• Dental anomalies are variations or abnormalities in tooth development, number, size, shape, structure, or color.

Anomalies in Number

• Anodontia is the complete absence of teeth; it is rare and can be associated with systemic syndromes.
• Hypodontia is the absence of one or more teeth; it is one of the most common dental anomalies.
  • The teeth most frequently absent are the third molars, followed by the mandibular second premolars, and maxillary lateral incisors.
• Oligodontia is the absence of six or more teeth, excluding third molars.
• Hyperdontia is the presence of one or more supernumerary (extra) teeth.
  • Mesiodens is the most common supernumerary tooth, located between the maxillary central incisors.
  • Other common locations for supernumerary teeth include the maxillary molar region (paramolar) and the mandibular premolar region.

Anomalies in Size

• Macrodontia is when teeth are larger than normal.
  • True generalized macrodontia is rare and is seen in pituitary gigantism.
  • Relative generalized macrodontia refers to teeth that are normal-sized but appear large in a small jaw.
  • Isolated macrodontia involves a single tooth being larger than normal.
• Microdontia is when teeth are smaller than normal.
  • True generalized microdontia is rare and seen in pituitary dwarfism.
  • Relative generalized microdontia refers to teeth that are normal-sized but appear small in a large jaw.
  • Isolated microdontia is more common, with maxillary lateral incisors (peg laterals) being most frequently affected.

Anomalies in Shape

• Gemination occurs when a single tooth germ attempts to divide, resulting in a single enlarged tooth or a bifid crown.
  • Geminated teeth usually have a single root and root canal.
• Fusion results from the union of two separate tooth germs, leading to a single enlarged tooth.
  • Fusion can be complete or incomplete, depending on the stage of development.
  • Fused teeth will have separate roots canals.
• Concrescence is the union of two teeth by cementum only.
  • It typically occurs after root formation is complete.
  • It is most common in the maxillary molar region.
• Dilaceration is an abnormal bend or curve in the root or crown of a tooth.
  • It is usually caused by trauma during tooth development.
• Talon Cusp is an accessory cusp located on the lingual surface of anterior teeth in the cingulum area.
  • It often occurs in maxillary lateral and central incisors.
• Dens Evaginatus is an accessory enamel cusp found in the central groove or lingual ridge of premolars and molars.
  • It most commonly occurs in mandibular premolars.
• Dens Invaginatus (Dens in Dente) occurs when the enamel organ invaginates into the dental papilla.
  • It most frequently affects maxillary lateral incisors.
  • It appears as a tooth within a tooth on radiographs.
• Enamel Pearls are small, spherical-shaped enamel projections on the root surface.
  • They are most commonly found in the furcation areas of molars.
• Taurodontism is characterized by teeth with elongated crowns, short roots, and large pulp chambers.
  • It is commonly seen in individuals with Klinefelter syndrome.

Anomalies in Structure

• Amelogenesis Imperfecta is a group of hereditary enamel defects that affect the formation of enamel.
  • Hypoplastic amelogenesis imperfecta results in enamel that is thin but hard.
  • Hypocalcified amelogenesis imperfecta results in enamel that is normal in thickness but soft and poorly mineralized.
  • Hypomaturation amelogenesis imperfecta results in enamel that is normal in thickness but has a mottled appearance.
• Dentinogenesis Imperfecta is a hereditary disorder that affects the formation of dentin.
  • Teeth appear opalescent or translucent with an amber hue.
  • Enamel is normal, but fractures easily due to poor dentin support.
  • Radiographs show teeth with bulbous crowns, cervical constriction, and thin roots with obliterated pulp chambers.
• Dentin Dysplasia is a rare hereditary disorder of dentin formation.
  • Type I (radicular dentin dysplasia) is characterized by normal crowns and abnormal root formation with short, blunted roots.
  • Type II (coronal dentin dysplasia) is characterized by normal root formation and abnormal coronal dentin with thistle-tube shaped pulp chambers in permanent teeth.
• Regional Odontodysplasia (Ghost Teeth) is a rare developmental anomaly affecting enamel, dentin, and pulp.
  • Affected teeth exhibit a marked reduction in radiodensity, giving them a "ghost-like" appearance.

Anomalies in Color

• Intrinsic staining occurs when discoloration is incorporated into the tooth structure during development.
  • Tetracycline staining results from the ingestion of tetracycline antibiotics during tooth development, causing yellow-gray-brown discoloration.
  • Fluorosis results from excessive fluoride intake during tooth development, causing enamel mottling and discoloration, ranging from white spots to brown staining.
• Extrinsic staining occurs when discoloration is deposited on the tooth surface.
  • It can be caused by factors such as food, beverages, tobacco, and certain medications.
• Variations in color can also occur due to pulpal changes.
  • Pulpal necrosis can cause the tooth to darken.
  • Internal resorption can cause a pinkish discoloration of the crown (pink tooth of Turner).