Common eruption problems and management Flashcards
What is the order of eruption for permanent dentition?
State which teeth erupt for dental ages 6-12
2nd premolar is unerupted in a 11yo child. Is this abnormal?
not necessarily, dental age doesn’t always correspond to chronological age - dental age depends on growth and development
When does emergence curve of teeth tend to plateau?
Once 1st molars and all incisors have erupted, there tends to be a pause in exfoliation/eruption (dental age 8-10)
-> if ortho is to be done in mixed dentition this is a good time
When do girls vs boys get all their permanent teeth? (except 3rd molars)
Mean: girls 12.5, boys 13
Girls have a much larger SD, some may have them ~ just under 10 and some just under 14
Boys ~ just under 11 and just under 15
When should teeth erupt? (in terms of root formation)
when 2/3-3/4s of root has formed
When is root development of permanent teeth completed?
2.5-3 years after eruption
Explain the difference between dental and chronological age
They may not always be the same and you cannot base dental/ortho tx around chronological age. Dental age should be considered when planning tx (it is where the teeth are at)
What 4 factors determine dental age? Which factor alone is not enough and why? ***
- Which teeth have erupted
- Amount of primary tooth root resorption
- Amount of perm tooth development
- Demirjian and Nolla’s staging methods
Erupted teeth not enough as it can be influenced by local factors
Why is dental age an important assessment?
often determines appropriate time for orthodontic intervention
Why is dental age an important assessment?
often determines appropriate time for orthodontic intervention
Why should/shouldnt you extract deciduous teeth in these cases?
- Delayed exfoliation (well over 3/4s of perm roots developed)
- Delayed development (dental age 10 - all incisors and 1st molars perm but primary canines, 1st and 2nd molars)
What is retained deciduous tooth vs over-retained deciduous tooth?
Retained deciduous tooth = tooth that remains in place beyond its normal, chronological shedding time due to absence or retarded development of permanent successor
Over-retained deciduous tooth = tooth whose unerupted permanent successor exhibits root development greater than ¾s of expected final length
What is the difference between the two teeth with arrows in the same patient?
red = retained lower E, perm successor still not ⅔-¾s of root formation
blue = over-retained upper C, perm canine root is mature
What are some systemic factors causing eruption problems? (4)
- cleidocranial dysplasia (xtra)
- ectodermal dysplasia (less)
- Gardner sydnrome
- Apert syndrome
What are some local factors causing eruption problems? (7)
- barriers in eruption pathway
- abnormal tooth position
- tooth deformity
- bone deficit (LCP)
- lack of space
- dilaceration
- ankylosis
What are the 2 disturbances in eruption mechanism that cause failure of eruption?
primary failure of eruption
ankylosis
What is primary failure of eruption (PFE)?
affected posterior teeth fail to erupt despite a clear eruption pathway (bone resorption proceeds as normal but they don’t follow the cleared pathway) presumably due to defect in eruption mechanism
Which causative gene is identified in PFE?
And how are is PFE?
PTHR1
0.06% (F>M)
What malocclusion does PFE cause?
infraoccluded posteriors → as the alveolar bone grows → worsening posterior open bite
What is ankylosis? (2)
fusion of cementum or dentine with alveolar bone, affected tooth remains in place while adjacent teeth continue to erupt
cause not known, possibly genetic
DO NOT respond to orthodontic force (which requires changes to PDL) - if primary exo
Which tooth is most commonly ankylosed?
deciduous 2nd molars
What common cause of ectopic eruption of 1st molars is shown in this OPG?
M surface of perm upper 1st molar can get impacted at D surface of E
How can we diagnose ectopic 1st molars?
usually kids 6-7
- incidental on BWs (positioned superiorly or mesially, signs of E resorption)
- tipping of 2nd deciduous molar
- infra-occlusion of 1st permanent molar
What problems causes by ectopic eruption of 1st molars? (3)
- loss of space (due to early loss of Es - main job is to hold space)
- impaction of 2nd premolars (“”)
- overeruption of lower 1st molar
Label the pictures as late, correct, very late for refferal.
- correct (just starting to lateral erupting, no central - alarm bells
- late (obvious that lateral not central)
- very late (inexcusable, all perms have erupted)
If an impacted incisor is unable to be repositioned and extraction is chosen. What are some procedures which may be done?
- autotransplantation (tend to plan)
- implant
- close space
then make other teeth look like the incisors
What is a major problem caused by impacted mx canines?
root resorption of adjacent incisors
(radiographs showing 11 root entirely resorbed, not viable tooth anymore must be exo’d)
What affects the success of eruption of a permanent canine after extraction of deciduous canine at age 9-10
if D to midline of long axis of perm lateral (zone 1 or 2) → 91% erupt into correct position
if M to midline of lateral but still D to midpoint of central incisor(zone 3 or 4) → 64%
if M to midpoint of central → probably wont erupt
