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• Dentistry

  The treatment of diseases and other conditions that affect the teeth and gums, especially the repair and extraction of teeth and the insertion of artificial ones

  
• Pediatric


  Branch of medicine dealing with children and their diseases
• Pedo

  Latin word meaning anything related to child
• Dontics

  Latin word meaning dentistry
• Development and Eruption of teeth

  1. Development of teeth

  2. Tooth eruption

  
• Development of teeth

  1. Bud stage

  2. Cap stage

  3. Bell stage

  4. Advanced bell stage

  
• Bud stage


  • Epithelial growth condensation of the ectomesenchyme of the jaw leading to bud shaped epithelia which is called enamel organ

  
• Cap stage

  • Regular changes in the size and proportion of the growing tooth germ, characterized by a shallow invagination on the deep surface of the bud

  
• Bell stage

  • Definite morphologic as well as functional changes, differentiation of odontoblasts that form the dentin and ameloblasts that form the enamel, arrangement of fibers resembling that later differentiates into periodontal fibers
• Advanced bell stage

  • Deposition of the matrix of the dental hard tissues
• Tooth eruption

  1. Pre-eruptive tooth movement

  2. Prefunctional eruptive or Eruptive movements

  3. Functional eruptive or Post-eruptive tooth movements

  
• Pre-eruptive movements

  • Movements made within the bone before the tooth begins to erupt, combination of total bodily movement and eccentric growth movement

  
• Eruptive movements

  • Eruption normally starts when the root formation begins and ends when the teeth reach occlusal contact, involving fibroblasts and reduced enamel epithelium

  
• Post-eruptive movements


  • Movements made by the tooth after it has reached its functional position in the occlusal plane, including readjustment of the tooth in the socket, occlusal wear, and interproximal wear

  
• Theories of tooth eruption

  • Root formation
  • Bony remodeling
  • Pulpal constriction
  • Vascular pressure
  • Periodontal ligament contraction
  • Hormonal
  • Dental follicle

  
• Root formation theory

  • The simplest and most obvious mechanism of eruption would be that the crowns of the teeth are pushed into the oral cavity by virtue of growth and elongation of the roots

  
• Evidence against the root formation theory: Rootless teeth often erupt without the concomitant elongation of the root, submerged teeth often continue the formation of their roots but do not erupt
• Bony remodeling theory

  • The inherent growth pattern of the mandible or maxilla supposedly moves teeth by the selective deposition and resorption of the bone in the immediate surroundings of the tooth

  
• When the developing premolar is removed without disturbing the dental follicle, an eruptive pathway still forms overlying the enucleated tooth. Whereas, if the dental follicle is removed no eruptive pathway is formed

  
• Pulpal constriction theory

  • The growth of the root dentin and the subsequent constriction of the pulp may cause sufficient pressure to move the tooth occlusally

  
• Evidence against the pulpal constriction theory: Pulpless teeth erupts at the same rate as the normal teeth, premolar will often "jump" into occlusion after the premature extraction of the deciduous molar without any appreciable growth of dentine or pulpal constriction

  
• Vascular pressure theory

  • The blood pressure that exerted in the vascular tissue which lies between the developing tooth and its bony surroundings is the active mechanical factor in the process known as eruption of teeth
• Periodontal ligament contraction theory

  • The contractility of fibroblasts in the periodontal ligament exerts comparatively large and sustained tractional forces that push the tooth in occlusal direction during eruption
• If the normal architecture of the periodontal ligament is disturbed experimentally by interfering with collagen synthesis, eruptive tooth movement is either slowed or stopped

  
• Factors influencing the timing of eruption

  • Genetic factor
  • Gender
  • Socioeconomic conditions
  • Birth weight
  • Systemic disorders
  • Hormones and vitamins
  • Local causes
• Genetic factor

  • Genes play a definite role in tooth eruption and has been estimated to be about 78%

  
• Gender

  • Teeth of girls erupt slightly earlier than those of boys, the difference may vary from 2 months to 10 months
• Socioeconomic conditions

  • Retarded eruption of anterior teeth and accelerated emergences of the posterior dentition has been linked to low socioeconomic status in all racial groups
• Birth weight


  • Low birth weight has been associated with delayed emergence of permanent teeth and conversely early eruption has been associated with increased birth weight
• Systemic disorders


  • Delay in permanent tooth eruption is associated with Down's syndrome, cleidocranial dysostosis, hypothyroidism, hypopituitarism and hemifacial atrophy. Precocious eruption is seen in precocious puberty, hyperthyroidism, hemifacial hypertrophy, Sturge-Weber syndrome and hyperpituitarism

  
• Hormones and vitamins


  • Thyroid, Pituitary [Growth Hormone], and Parathyroid hormones are essential for normal eruption of teeth. Vitamins like Vitamin B Complex, A, C and D aid either directly or indirectly for tooth eruption
• Local causes


  • Ankylosis of primary teeth delays the eruption of permanent tooth. Dental caries and periapical infection of primary teeth resulted in early eruption of permanent teeth

  
• Shedding of deciduous teeth

  1. Pattern of shedding

  2. Resorption of anterior teeth

  3. Resorption of posterior teeth

  4. Mechanism of resorption and shedding

  5. Remnants of deciduous teeth

  6. Retained deciduous teeth

  
• Pattern of shedding


  • Progressive resorption of the roots of teeth and their supporting tissues, the pressure generated by the growing and erupting permanent tooth dictates the pattern of deciduous tooth resorption

  
• Resorption of anterior teeth

  • The position of the permanent anterior tooth germ is lingual to the apical third of the roots of primary tooth, the resorption is in the occluso-labial direction, later the crown of the permanent tooth lies directly apical to the root of primary tooth causing horizontal resorption

  
• Resorption of posterior teeth

  • The growing crowns of the premolars initially are situated between the roots of the primary molars, the initiation is by the resorption of the inter-radicular bone followed by resorption of the adjacent surfaces of the root of primary tooth, the alveolar process grows to compensate for lengthening roots of the permanent tooth

  
• Mechanism of resorption and shedding

  • Loss of root, loss of bone, increased force, pressure from the erupting successional tooth plays a key role, forces of mastication are also synergistically involved

  
• Remnants of deciduous teeth

  • Association with the permanent premolars, root remnants may later be found deep in the bone, completely surrounded by and ankylosed to the bone

  
• Retained deciduous teeth

  • Deciduous teeth may be retained for a long time beyond their usual shedding schedule, usually without permanent successor, or their successors are impacted

  
• Low socioeconomic status


  Linked to delayed and accelerated emergences of the posterior dentition in all racial groups