8 - Interceptive orthodontics Flashcards
Describe the oral cavity at birth.
- gum pads
- upper is rounded, lower is more U shaped
- appears class III
- AOB
What are natal/neonatal teeth?
- abnormal dental development
- lower incisors are most common
- extraction is only indicated if mobile and are at risk of inhalation or causing difficulty breastfeeding
Describe the process of eruption.
- pre-eruptive phase (crown formation)
- eruptive phase (beginning of root formation to tooth reaching occlusal plane)
- post-eruptive phase (tooth movement as root forms)
Describe the pre-eruptive phase.
- developing crowns move within the jaws as response to jaws growing
- crowns are contained within bony crypts
Describe the eruptive phase.
- split into intra- and extra-osseous
- relative position of primary and permanent teeth change as jaws grow, primary roots are resorbed and neighbouring crowns move
Describe the intra-osseous eruptive phase.
- begins with proliferation of epithelial root sheath
- development of dentine and pulp
- movement of developing tooth occurs slowly over months
- reduced enamel epithelial fuses with oral epithelium
Describe the extra-osseous eruptive phase.
- quick penetration of crown through oral epithelial layers (1-2 weeks)
- crown continues to erupt to occlusal plane
- environmental factors affect tooth final position (eg lips, tongue)
What is the Gubernacular cord?
Fibres that form from the dental follicle to guide the tooth to erupt into the oral cavity
What causes teeth to erupt?
- root formation
- remodelling of alveolar bone
- development of PDL
What controls tooth eruption?
- dental follicle plays role in modulating cellular activity
- signalling cascade of cytokines (IL1, CSF1, RANKL/OPG)
Describe the role of the dental follicle.
- initiates resorption of bone overlying tooth
- facilitates connective tissue degradation and creates eruption pathway
- promotes bone remodelling at the base of the tooth
- provides traction within PDL
- cells contribute to root formation and cementum
Where do the permanent incisors develop?
Palatal/lingual to primary teeth
Where is space gained for permanent incisors?
- increase in inter-canine width though lateral growth of jaws
- incisors erupt more proclined
- leeway space
What is the leeway space in the upper?
1.5mm
What is the leeway space in the lower?
2.5mm
How do you manage an impacted 6?
- if younger than 7, wait 6 months to self correct
- orthodontic separator to disengage
- distalise 6
- XLA E
- distal disking of E
What are causes of unerupted centrals?
- supernumeraries
- trauma (dilaceration)
- other pathology
How do you manage supernumeraries preventing eruption of centrals?
- XLA of primaries and supernumeraries
- maintain or create space
- monitor for 12 months if younger than 9
- if fails to erupt or patient older than 9, expose and bond gold chain for orthodontic traction
What is the effect of early loss of primary teeth?
Localised crowding
How do you manage early loss of As?
No balancing or compensating extractions
How do you manage early loss of Bs?
No balancing or compensating extractions
How do you manage early loss of Cs?
Balancing extraction
How do you manage early loss of Ds?
- can cause small CL shift
- balance if under GA
How do you manage early loss of Es?
Consider space maintainer
