Shedding and Replacement Flashcards
What are the 3 physiological tooth movements to bring teeth into the occlusal plane?
- Pre-eruptive
- Eruptive
- Post-eruptive
How is pre-eruptive movement made?
Deciduous and permanent tooth germs
How is eruptive tooth movement made?
Tooth moving from its position in jaw to functional position in occlusion
How is post-eruptive tooth movement made?
Maintenance of the position of erupted tooth in occlusion while jaw grows
What is the first stage of pre-eruptive tooth movement?
Tooth germs grow rapidly and become crowded
What is the second stage of pre-eruptive tooth movement?
Jaws lengthen so deciduous 2nd molar tooth germs move backward and alleviate crowding
What is the third stage of pre-eruptive tooth movement?
Permanent tooth germs develop on the lingual aspect of deciduous predecessors
Where do the incisor and canine permanent tooth germs occupy?
Position on the lingual side of roots of their deciduous predecessors
Where do the premolar permanent tooth germs occupy?
Position between the divergent roots of the deciduous molars
Where do the maxillary molar permanent tooth germs occupy?
Occlusal surfaces face distally and swing into position when the maxilla has sufficiently grown
Where do the mandibular molar permanent tooth germs occupy?
Axes show a mesial inclination which becomes vertical when the mandible has sufficiently grown
Where does pre-eruptive tooth movement occur?
Interosseous location
What are 2 main changed which occur during eruptive tooth movement?
- Tooth moves from its developmental position in jaw to final position in occlusal plane
- Fibres of the periodontal ligament are remodelled
How do the fibres of the periodontal ligament remodel?
Fibroblasts simultaneously synthesise and degrade collagen fibrils as required
How does the dental follicle of permanent teeth retain connection with lamina propria of oral mucosa?
Gubernacular cord
What is the gubernacular cord composed of?
Fibrous tissue containing epithelial remnants of the dental lamina
What is the gubernacular canal?
Eruptive pathway of a tooth
Name a type of factor which influences and determines a tooth’s final position in the dental arch
Environmental
Name 2 types of environmental factors which help determine the tooth’s final position in the dental arch
- Muscle forces from tongue, cheeks and lips
2. Forces of contact from other erupting teeth
What are the 3 categories that post-eruptive tooth movement can be divided into?
- Movement to accommodate growing jaws
- Compensation for occlusal wear
- Accommodation for interproximal wear
What are post-eruptive tooth movements?
Movements that are made by the tooth after it has reached its function position in the occlusal plane
How does tooth position readjustment to accommodate for growth of jaws occur?
Formation of new bone at the alveolar crest and the socket floor
How is compensation for occlusal wear achieved?
- Additional cementum is produced around the apex of the tooth after movement occurs
How is accommodation for interproximal wear achieved?
Mesial drift
Where does the resorption of deciduous incisors and canines occur?
Lingual surface
What is the major difference between the resorption of deciduous incisors and canines and deciduous molars?
Much more resorption occurs in the deciduous molars, with pulp chamber, coronal dentin and sometimes enamel being resorbed
What cells resorb deciduous teeth?
Odontoclasts
From where are odontoclasts derived?
Monocytes
How do fibroblasts die during the shedding of teeth?
Apoptosis
What can delay the shedding of a tooth?
If the successional tooth is missing
