Preclinical Paediatrics · MU Sofia

27. Anatomical and physiological features of primary teeth.

Covers the anatomy and physiology of primary teeth, starting with the two dentitions and the tooth-group classification, then root form and canal shape, enamel and dentine thickness, pulp horn position and surface features. It then moves through each tooth type in turn: incisors, canines and molars, including pulp horn measurements, cusp and fossa counts, and root and canal numbers for the first and second molars.

Inside: 1 section · 15 flashcards · 7 min

Topic 27 of 40 in the MU Sofia syllabus for Preclinical Paediatrics (Dental Medicine, Year 3). The free AceMed note covers it in 1 section, about 1,000 words (7 min of reading), with 15 flashcards.

In this note

  1. ANATOMICAL AND PHYSIOLOGICAL FEATURES OF PRIMARY TEETH

ANATOMICAL AND PHYSIOLOGICAL FEATURES OF PRIMARY TEETH

Humans are diphyodont as they have two dentitions: primary and permanent

  • Humans are also heterodonts as they have different tooth groups
  • Primary dentition consists of 20 teeth and permanent dentition consisting of 32 teeth
  • Permanent teeth replacing the primary teeth are called successional teeth
  • Permanent teeth with no predecessors are called accessional teeth

PRIMARY TOOTH ROOT:

  • Shorter
  • Roots of Molar are more diverging
  • Curved roots with thinner walls
  • Have flat ribbon shaped root canals. Canals are not narrowed with age

PRIMARY TOOTH STRUCTURE:

  • Lower mineralization with thinner enamel and dentin
  • Cervical enamel rods are directed occlusally and cervical area constricted significantly
  • Have prism-less surface and reflects on the ability to etch the surface and provide an interface for attachment of sealants and other restorative procedures
  • Pulp horns are closer to the outer surface
  • Mesial pulp horn is much higher and relatively larger pulp
  • More irregular pulp canals
  • Root flare as they approach the apex

MANDIBULAR INCISORS

  • Mandibular central incisor is almost symmetrically flat when viewed from buccal aspect
  • No developmental grooves or mamelons
  • Crown is one third the length of root with a cingulum on lingual surface
  • Root is long and cylindrical
  • Lateral incisor is distinguished from central incisor by their distal incisal angle which is more rounded
  • Lateral incisor is longer and narrower than central incisor
  • Pulp approximately 2.6mm from incisal edge in central incisor, 1.7mm from distal enamel surface and 1.0mm from mesial
  • Pulp of lateral incisor has similar dimension but is somewhat smaller

MAXILLARY INCISORS

  • Crown shape is a square with slightly rounded incisal edge in the distal incisal angle
  • Crowns of maxillary lateral incisors are almost rectangular with an expressed distal incisal angle
  • Primary central incisor is unique in that it is the only tooth in human dentition that has a greater mesiodistal dimension than crown height
  • Contact points with adjacent teeth are broad, extending from incisal 1/3 to gingival 1/3
  • Similar to mandibular incisors as it has a flat, labial surface and prominent lingual cingulum
  • Root is conical and roughly 2.5x as long as crown height

PRIMARY CANINES

  • Crowns of canines is characterised by abrasion of incisal edge
  • Labial surface of crown is convex
  • Palatal surface is characterised by a pronounced expansion cusp
  • Enamel ends with expansion and with strong narrowing in neck of tooth
  • Roots are rounded and slightly curved buccally

PRIMARY MOLARS

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