L88: Development of the Dentition Flashcards
What is orthodontics?
The branch of dentistry concerned with:
- facial growth;
- development of the dentition;
- occlusion;
- and with the diagnosis, interception and treatment of occlusal anomalies.
What are the stages of development of the dentition?
- Newborn;
- Primary (deciduous);
- Mixed;
- Permanent.
What are the features of a newborn dentition?
- Gum pads;
- Upper - rounded, lower - U-shaped;
- Appear skeletal class 2 (chin back).
What is a skeletal class 1 antero/posterior (AP) jaw relationship?
Mandible is 2-3mm posterior to the maxilla
What is a skeletal class 2 antero/posterior (AP) jaw relationship?
Mandible is retruded relative to the maxilla
What is a skeletal class 3 antero/posterior (AP) jaw relationship?
Mandible is protruded relative to the maxilla
What is the name of a tooth that is present at, or just after, birth?
A natal tooth
What is the typical age range for the primary dentition to erupt?
6 months - 3 years
In a primary dentition, do the lower or upper teeth erupt first? (typically)
Lower
What is the typical eruption pattern for the primary dentition?
a-b-d-c-e
What are three typical features of the primary dentition?
- Incisors are more upright than the permanent dentition;
- Spaced (>6mm);
- Worn towards the end of their lifespan.
A primary dentition with little or no spacing are prone to…
overcrowding permanent teeth.
At what age do you typically find a mixed dentition?
Age 6-13
What are the first permanent teeth to erupt and at what age?
First molars and incisors, 6-8.5 y/o.
At what age do the canines, premolars and second molars erupt?
10-12.5 y/o
Do the lower or upper 6’s erupt first? (typically)
Lower
What are two typical features of the permanent dentition?
- Incisors are wider than deciduous teeth, hence the need for spaces in the primary dentition;
- Teeth are less upright, and more proclined.
What is the typical time between pairs of teeth, e.g. central incisors, erupting?
6 months, i.e. is 11 erupts on 01/01, 21 should have erupted by 01/07, otherwise this could indicate a problem.
In a mixed dentition, do central or lateral incisors erupt first?
Central
What are additional teeth, to the normal series, called?
Supernumary
What is the term used for larger, than normal, teeth?
Macrodont
What is the term used for smaller, than normal, teeth?
Microdont
What is the typical eruption pattern for permanent canines and premolars?
- Lower: 3, 4, 5;
- Upper: 4, 5, 3.
What is the overall typical eruption pattern for permanent teeth?
Lower: 6-1-2-3-4-5;
Upper: 6-1-2-4-5-3.
How does the mouth accommodate for more teeth in the permanent dentition than in the primary dentition?
Increase/ growth in arc length posterior to the first molar. (N.B. No growth of the arc in front of this).
What is the term for spacing in between primary teeth?
Leeway Space
What is transposition?
The term used to describe the interchange in position of two teeth e.g. 3 and 4.
What is an ectopic tooth?
The malposition of a permanent tooth bud resulting in eruption of the tooth in the wrong place, e.g. at the roof of the mouth.
What are the six typical features of an ideal permanent dentition?
- Incisors slightly proclined, overjet ~2-4mm;
- The mesiobuccal cusp of the upper permanent molar occludes with the buccal groove of the mandibular first molar;
- Long axis of the teeth have a slight medial inclination, except the lower incisors;
- Tight approximal contacts;
- Flat occlusal plane or slight curve of Spee;
- The crowns of the canines back to the molars have a lingual inclination.
What is a class I incisor classification?
Lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors.
What is a class II, division 1 incisor classification?
- Lower central incisors lie posterior to the cingulum plateau of the upper incisors;
- Upper central incisors are proclined or of average inclination;
- Overjet increased.
What is a class II, division 2 incisor classification?
- Lower central incisors lie posterior to the cingulum plateau of the upper incisors;
- Upper central incisors are retroclined;
- Minimal overjet.
What is a class III incisor classification?
- Lower central incisors lie anterior to the cingulum plateau of the upper incisors;
- Overjet is reversed.
What is overjet?
Distance between the upper and lower incisors in the horizontal plane. 2-4mm is normal.
What is overbite?
Vertical overlap of the upper and lower incisors when viewed anteriorly. One third to one half coverage of the lower incisors is normal.
What is hypodontia?
Congenital absence of one or more teeth
What is reverse overjet?
When the lower incisors lie anteriorly to the upper incisors
What is malocclusion?
Variation from ideal occlusion which has dental health and/or psychosocial implications for the individual
What is ideal occlusion?
Anatomically perfect arrangement of teeth
What is normal occlusion?
Acceptable variation from ideal occlusion
What is buccal crossbite?
The buccal cusps of the lower premolars and/or molars occlude buccally to the buccal cusps of the upper premolars and/or molars
