Orthodontics Flashcards
What is the eruption sequence of deciduous teeth?
A>B>D>C>E
Lowers before uppers except lateral incisors
From date of eruption how long does it take for primary tooth to complete apexogenesis?
1.5yrs
When does eruption start and end for primary dentition?
Eruption Begins at 3months and completed at 2.5yrs
What is the eruption sequence for permanent dentition?
Uppers;
6>1>2>4>5>3>7>8
Lowers:
6>1>2>3>4>5>7>8
Lowers before uppers except 5s
What are the dates for permanent eruption?
6yrs: lower and upper 6; lower 1
7yrs: lower 2, upper 1
8yrs: upper 2
9yrs: lower 3
10yrs: lower and upper 4, upper and lower 5
11yrs: upper 3
12yrs: lower and upper 7
From date of eruption how long does it take for permanent root tooth to complete apexogenesis?
3yrs
What is anthropoid space?
Mesial to maxillary primary canines and distal to mandibular canines
What is leeway space?
Primary canines and molars are larger than succeeding canine and premolars,
Greater in lower arch 2-2.5mm than upper arch 1-1.5mm
Describe class II div 1
Lower incisor edge lie posterior to the cingulum plateau of the upper incisors with an increased overjet.
Upper incisors are proclined or of average inclination
Management of class II div 1 cases?
Accept
Attempt growth modification
- headgear: restrain growth of maxilla
Functional appliances:
- twin block, medium opening activator and Herbert appliance that eliminate or guide forces to correct occlusion
- restrain maxillary growth and encourage mandibular growth
- must be used during growth and pubertal growth spurt 10-12yrs of age
URA: - limited use only for mild class 2 overjet
Fixed appliances
- before, during and after surgery
Orthognathic surgery
- when growth is complete and with every skeletal A/P discrepancy or vertical direction
Describe class II div 2
Lower incisor edges lie posterior to the cingulum plateau of the upper central incisors.
Upper incisors are retroclined and overjet is minimal or may be increased.
What is the management options for class 2 div 2 cases?
Accept
Growth modification
- used in growing patients with moderate skeletal 2 pattern using twin blocks and upper sectional fixed appliances
Camouflage - accept underlying and make class 1 incisor relationship
Orthognathic surgery
- only in severe cases
Describe class 3 malocclusion
Lower incisor edges occlude anterior to the cingulum plateau of the upper centrals. overjet is reduced or reversed.
What are the management options for class 3 cases
Accept
Intercept early with URA
- for incisor relationship and anterior crossbite
Growth modification
- functional appliances (reverse twin block/frankel III)l chin cup head gear with RME to reduce or redirect mandibular growth and encourage maxillary growth
Camouflage
- accept underlying skeletal and correct incisors
Combined orthognathic and orthodontic fixed appliances
What is the definition and prevalence of MIH?
Hypomineralisation of systemic origin of 1-4 permanent molars, frequently with affected incisors
Hypomineralisation is the disturbance of enamel formation resulting in reduced enamel content.
Prevalence:
- 10-20% population affected
- 14.5% of 7yr olds
When is the most suitable time to extract poor prognosis 1st permanent molars?
Ages 8-10yrs with radiographic evidence of early calcification of 2nd molar root formation
What is the management options for incisors affected by MIH?
- acid pumice microabrasion
- external bleaching
- localised composite placement
- crowns once gingival margin is stabilised after growth
When should you consider balancing extractions?
Balance primary canines to prevent centre line shift
Balance lower 1st primary molars if arch is crowded
What is the prevalence of midline diastema?
98% 6yr olds\
49% 11yr olds
7% 12-18yr olds
10% are due to supernumeraries
What causes midline diastema?
Generalised space Hypodontia Midline supernumerary Proclined uppers Prominent frenulum Cysts
What percentage of ectopic eruption of 6s self correct by 7yrs of age?
66% self correct within 6 months
What are the most important cephalometric measurements?.
SNA 81 SNB 79 ANB 3 Upper incisors to maxillary plane 108 Lower incisors to mandibular plane 92 Inter incisal angle 133 MMPA 27
What is the ANB values for the skeletal patterns?
Class 1 = 2-4
Class 2 = >4
Class 2 = <2
What is the IOTN?
Occlusal index that assesses the malocclusion and categories the need for orthodontic treatment based on a dental health component using MOCDO and an aesthetic component using coloured pictures representing most and least attractive dentition.
What malocclusion is always an IOTN 5?
Ectopic canines
Following early loss of a deciduous molar, which arch has more space lost?
Space loss usually greater in maxilla than mandible as 1st permanent maxillary molars are often dismally inclined and top forwards readily.
On a URA to push an upper central incisor over the bite. What baseplate modification is needed?
Posterior bite capping
In the management of an increased overjet, functional appliances cause what movement?
Retroclination of upper incisors
Restrain maxillary growth and encourage mandibular growth
What are the dental signs from persistent digit sucking habit?
AOB
Proclined upper incisors
Retroclined lower incisors
What is the main consequence of an impacted upper 1st permanent molar?
May cause premature loss of upper second deciduous molar.
At birth the crown of which permanent tooth has started to calcify?
Upper 1st molar
What would be a suitable active component on a URA to push an upper central incisor over the Bite?
A z spring in 0.5mm HSSW
