Week 4- Tooth Impaction Flashcards
Outline the permanent eruption sequence for mx
1st Molar: 6.25
Central: 7.25
Lateral: 8.25
1st Premolar: 10.25
2nd Premolar: 11
Canine: 11.5
2nd Molar: 12.5
3rd Molar: 20
Outline the permanent eruption sequence for md
1st Molar: 6
Central: 6.25
Lateral: 7.25
Canine & 1st Premolar: 10.5
2nd Premolar: 11.25
2nd Molar: 12
3rd Molar: 20
What is the difference between biological/dental and chronological age?
They can be coincident but not always. Huge variations amongst children in terms of biological/dental age.
When do teeth finish erupting on average?
Females: 12.5 years
Males: 13 years
What is dental age determined by?
- Which teeth have erupted
- The amount of resorption of the primary teeth
- The amount of development of the permanent teeth
- Demirjian & Nolla’s staging methods
Why is dental age important?
Often determines the appropriate time for ortho intervention
What is a retained vs over-retained deciduous tooth?
- Retained: tooth that remains in place beyond its normal, chronological shedding time due to the absence or retarded development of the permanent successor
- Over-retained: tooth whose unerupted permanent successor exhibits a root development in excess of ¾ of its expected final length
What are systemic factors that can lead to eruption problems?
- Cleidocranial dysplasia
- Ectodermal dysplasia
- Gardner Syndrome
- Apert syndrome
What are local factors that can lead to eruption problems?
- Barriers in the eruption pathway
- Abnormal tooth position
- Tooth deformity
- Bone deficit (CLP)
- Lack of space
- Dilaceration
- Ankylosis
What is primary failure of eruption?
All posterior teeth fail to erupt despite clear eruption pathway. Caused by specific gene.
How should primary failure of eruption be treated/managed?
- Early ortho intervention
futile (and can even make things
worse) - Wait until completion of vertical
growth - Segmental osteotomy, distraction
osteogenesis, bone grafting and
implants
What is ankylosis?
Fusion of cementum or dentine with alveolar bone. Affected tooth remains in place while adjacent teeth continue to erupt. Teeth do not respond to orthodontic force
What is the definition of tooth impaction?
Failure of a tooth which exhibits more than ¾ of final root length to erupt into a normal functional position.
What are common causes of tooth impaction?
- Failure of resorption of deciduous teeth
- Abnormal eruptive pathway
- Supernumerary teeth
- Dental crowding
- Dentigerous cysts
- Disturbance in the eruption mechanism of the tooth
- Ankylosis
What is treatment of tooth impactions based on?
- Cause of the impaction
- Position of the impacted tooth
- Ability to move the tooth orthodontically
- Likelihood of causing damage to adjacent teeth
What are treatment options for tooth impaction?
- Extraction
- Make space +/- surgical exposure
- Make space and transplantation
What are common orthodontic indications for third molar removal?
- Distalisation of lower molars
- Preparation for orthognathic surgery
What is an ectopic tooth vs an impacted tooth?
- Ectopic: tooth is following an abnormal eruption path
- Impacted: eruption is delayed and tooth unable to erupt without assistance
Is ectopic eruption of first molars more common in mx or md and male or female?
- More common in maxilla
- More common in males
What is the aetiology of ectopic eruption of first molars?
- Larger than normal first molars
- Small mx
- Class III skeletal pattern
- More pronounced angle of eruption
- Genetic
- Association with other dental anomalies (impacted canines, peg laterals)
How is ectopic eruption of first molars diagnosed?
- Often indicated on BW’s
- Tipping of 2nd deciduous molar
- Infra-occlusion of 1st permanent molar
What is the issue with ectopic eruption of first molars?
- Loss of space
- Impaction of second premolars
- Over eruption of opposing first molar
How is the ectopic eruption of first molars managed?
- Brass wire
- Separator (elastomeric)
- Fixed appliances
- Extraction of deciduous molar
How can you diagnose impacted incisors?
- The eruption of contralateral tooth
occurred greater than 6 months prior - Both central incisors remain unerupted 12 months after lower central incisors have erupted
- Any deviation from normal sequence of eruption
What is the aetiology of impacted incisors?
- Supernumerary teeth
- Dilacerated teeth
- Early loss of deciduous teeth
- Retained deciduous teeth
How should children up to 9 years with incomplete root development of impacted permanent incisor be managed
- Remove obstruction
- Create space if required
- Monitor eruption for 18 months.
Why is it essential that impacted incisors are diagnosed early?
Late referral (over 10 years) means more invasive tx is required.
What happens if patients are referred over 10 years old for impacted incisors?
Surgical intervention likely required.
- Remove obstruction
- Expose and bond bracket
What are the most commonly impacted teeth after 3rd molars?
Maxillary canines
What is the aetiology of ectopic maxillary canines?
- Unclear
- Prolonged retention of primary canine
- Association with small/absent lateral incisors
- Family hx?
When should buccal sulcus be palpated for mx canines?
By age 10
If the canine cannot be palpated, radiographic investigation is indicated.
How are impacted canines diagnosed?
- OPG, PA, Occlusograph
- SLOB rule
- CBCT
What is the biggest complication of impacted maxillary canines?
Resorption of lateral or central incisors (not very common)
How can we prevent canine impaction?
If permanent canine is distal to midpoint of lateral incisors, can extract primary canine and should erupt spontaneously (91%) after 18 months.
How much impaction of the mx canine would not allow for spontaneous eruption if primary canine was extracted?
If permanent canine is past midpoint of central incisor
How can we treat canine impaction?
- No Treatment / Extraction
- Surgical exposure and alignment (usually best tx, not always possible, long tx time)
What age does resorption of incisors from impacted canines become unlikely?
After age 14
What is the management of impacted permanent 2nd molars?
- Ortho repositioning
- Exo and allow third molar substitution
- Exo of 2nd premolar and move lower 1st molar forwards
What are the following OPG’s of 12 year olds each indicating?
- LHS: delayed exfoliation
- RHS: delayed development
What age is spontaneous resolution of ectopic first molars unlikely?
Spontaneous resolution unlikely after age 7
Which of these photos is the correct time to refer for delayed eruption of central incisor?
Far left pic
What is the rationale for extracting impacted canines
If pt doesn’t want to go through long tx (2.5yrs+ of ortho)
Space can be closed orthodontically
May be only option if tooth can’t be moved orthodontically
What is the issue with leaving deciduous canine in place long term?
Poor prognosis as root will usually resorb and exfoliate by age 20-25
What is happening in this radiograph?
Ectopic eruption of first molar
What is happening in this radiograph?
Ectopic eruption of first molars
What tx is being performed here and why?
Separating elastic to manage ectopic first molar
What is happening in this radiograph?
Root resorption of 11 due to impacted mx canine
What is the issue in this radiograph?
Maxillary canine impaction
