ERUPTION

• Eruption


  • "erumpere" L. to break out
  • Cutting of the tooth through the gum
  • Only a part of the total pattern of tooth development
  • Axial or occlusal movement of the tooth from its developmental position within the jaw to its functional position in the occlusal arch
• Pattern of Physiologic Tooth Movement

  1. Preeeruptive tooth movement

  2. Eruptive tooth movement

  3. Posteruptive tooth movement
• Preeeruptive tooth movement


  • Movement positioning the tooth and its crypt within the growing jaws
  • Deciduous teeth differentiate, with good deal of space between them
  • Rapid growth of tooth germ with results to crowding
  • Changes in position of tooth germs: bodily movement of tooth germs, maxillary molars – occlusal surface face distally first then swing around, mandibular molars – occlusal surface face mesially and becomes upright when there is space available
• Histology of Preeeruptive tooth movement


  • Remodeling of bony crypt (selective deposition and removal of bone tissue)
• Eruptive tooth movement


  • The tooth moves from its position within the jaw to its functional position in occlusion, and the principal direction of movement is axial or occlusal
• Histology of Eruptive tooth movement

  • Formation of roots
  • Formation of periodontal ligament
  • Formation of dentogingival junction
  • Bone removal is necessary
  • Gubernacular canal and its contents, gubernacular cord is present in all permanent teeth with deciduous predecessor and is said to guide the permanent tooth as it erupts
  • The tooth breaks into the oral mucosa, continues to erupt until it reaches the occlusal plane and meet its antagonist
• Posteruptive tooth movement


  • Movements that maintain the position of the erupted tooth while the jaw continues to grow, and compensate for occlusal and proximal wear
• Histology of Posteruptive tooth movement

  • Axial growth is associated with condylar growth at age 14-18
  • Continuous cementum deposition at apices of teeth
  • Proximal drifting causes selective deposition and resorption of bone, remodeling of collagen in periodontal ligament
• Mechanism of the tooth movement

  • Bone Remodeling theory
  • Root Growth Theory
  • Vascular Pressure Theory
  • Ligament Traction Theory
• Bone Remodeling theory


  • Selective deposition and resorption of bone that brings about the eruption
• Root Growth Theory


  • The proliferating root impinges on a fixed base thus converting an apically directed force into occlusal movement
  • Existence of cushion hammock ligament that straddle the base of the socket from one bony wall to the other like a sling (fixed base)
• Vascular Pressure Theory


  • Local increase in tissue fluid pressure in periapical region is sufficient to move the tooth
• Ligament Traction Theory


  • Cells and fibers of periodontal ligament pull the tooth into occlusion
  • As long as periodontal tissue is available, tooth movement occurs
  • The contraction of fibroblast bring about eruptive movements
• Periodontal ligament and bone posses remarkable plasticity that enables tooth to erupt in the oral cavity
• Chronology of human dentition serves as our guide to the timing of eruption of teeth
• Premature eruption, premature loss of deciduous teeth may present clinical problem
• Retarded eruption may be caused by local or systemic factors
• Severe trauma may damage the dental follicle preventing formation of periodontal ligament
• Eruption may be delayed by cysts of presence of fibrous tissue
• Human evolution results to diminution of size of jaw without decrease in size of teeth
• In infants "teething" is often accompanied with pain, slight fever, general, malaise and all signs of inflammation
• The rule of six

  • 6 weeks old in utero: beginning of dental development
  • 6 months old: emergence of the first primary tooth
  • 6 years old: emergence of first permanent tooth