Hygiene Atlas

Atlas · Plate II · Dental Anatomy and Tooth Morphology · 10

Developmental anomalies

Developmental anomalies change tooth number, shape or structure. Third molars are the teeth most often missing, and a mesiodens between the maxillary centrals is the most common extra tooth. Gemination keeps the normal tooth count while fusion lowers it, concrescence joins roots by cementum, and a talon cusp adds an extra cusp on the lingual of an anterior tooth.

High-yield facts · 9

  1. Hypodontia most often affects third molars, then mandibular second premolars and maxillary lateral incisors.T5
  2. A mesiodens is a supernumerary tooth between the maxillary central incisors; it is the most common supernumerary.T5
  3. Gemination: one tooth germ tries to split (normal tooth count). Fusion: two germs join (one fewer tooth).T5
  4. Concrescence is the joining of two teeth by cementum only, after root formation.T5
  5. Dilaceration is a sharp bend in the root; taurodontism is an elongated pulp chamber with apically placed furcations.T5
  6. Dens invaginatus (dens in dente) most often affects maxillary lateral incisors.T5
  7. Talon cusp is an extra cusp on the lingual of an anterior tooth.T5
  8. Hutchinson incisors (screwdriver shape) and mulberry molars point to congenital syphilis.T5
  9. Enamel hypoplasia from a systemic event (fever, etc.) shows as a band across teeth forming at the same time; Turner tooth comes from local infection or trauma of a primary predecessor.T5

Facts are written in our own words; each tag links to its source. Values marked "sources vary" differ between references, so check the one your program uses.