Impacted Teeth Flashcards
What are some hereditary factors that could result in delayed eruption of maxillary incisors?
Supernumerary teeth
Cleft lip and palate
Cleidocranial dysostosis
Odontomes
Abnormal tooth/tissue ratio
Generalised retarded eruption
What are some reasons for impacted 6s?
Bulbous Es
Crowding
Mesial path of eruption
PFE (primary failure of eruption)
What are some reasons for impacted teeth?
Delayed exfoliation of the deciduous tooth
Early loss of primary tooth
Abnormal position of tooth germ
Supernumerary teeth
Macrodont teeth
Dilaceration
Odontomes
Cysts
Trauma (e.g. trauma to A’s)
Ankylosis (fusion of alveolar bone & root cementum)
Tumours
Systemic causes
Genetic causes
Gingival fibromatosis
Endocrine abnormalities
Bone disease
What are the disadvantages of a lateral cephalogram?
Increased radiation – low dose but exposes all head & neck region (susceptible tissue)
2D image of a 3D shape
What are some disadvantages of OPGs?
Poor quality (especially in midline)
Narrow focal trough (we don’t always see the true picture)
Often require supplementary views to confirm location (parallax)
How does the abbrevitaion SLOB help us with the parallax technique?
SLOB
Same Lingual (palatal)
Opposite Buccal (labial)
The tube shift is up in occlusal, If tooth moves upwards (towards root apex) it is SAME, therefore Lingual/Palatal
What are the treatment options for impacted 5s?
- No treatment - Pt accepts (root resorpsion & cyst risks)
- Removal/incorporate into ortho ext pattern
- Expose & bond
Why are impacted teeth an indicator of a ‘great need’ for tx according to the IOTN?
5i on IOTN
Tx will provide the following:
- Minimise damage to adjacent teeth
- Speech benefits
- Occlusal function benefits
- Psychosocial benefits
What are the advantages and disadvantages of upper/lower standard occlusals?
Avantages
- Good detail
- Low dosage
Disadvantages
- Findings need to be compared against complementary radiograph (parallax)
What is usually the cause of imapcted 5s?
Likely premature loss of 2nd primary molars (E)
Which position do impacted lower 5s normally erupt and why?
Impacted lower 5’s will often erupt lingually (through lingual cortex) to avoid thicker buccal cortical bone
As teeth erupt into path of least resistance
What are some environmental factors that could result in delayed eruption of maxillary incisors?
Trauma to As
Early extraction or loss of deciduous teeth
Retained deciduous teeth
Cystic formation
Endocrine abnormalities
Bone disease
What are the risks of aligning impacted canines?
- Root resorption to adjacent teeth
- Canine root resorption
- Loss of vitality
- Ankylosis
- Poor tissue contour at completion of treatment
Increased pocket depths
What are some visual indicators of impaction?
- Obvious bulges buccally or palatal/lingually
- Angulation of lateral incisor
- Colour changes in deciduous teeth (indicates previous trauma or possible resorption from an impacted tooth)
What would you do during a clinical examination of an impacted tooth?
- Inspect
- Palpate (buccally)
- Compare charting to expected eruption dates & other arches/side of px mouth
What are the treatment options for impacted canines?
- No treatment
- Interceptive treatment - Removal of C’s (bilaterally to avoid centreline shift)
- Exposure & orthodontic alignment
- Surgical removal
- Surgical repositioning (autoimplantation)
(Transalveolar Implant)
How do you manage delayed eruption of maxillary incisors?
- Remove obstruction (primary tooth or supernumerary tooth and wait for impacted tooth to come through)
- Ensure sufficient space (9mm for central)(Sectional Fixed Appliance or Retainer)
- Review for 3-6 months
What is a Lateral Cephalogram used for?
Show A-P plane skeletal relationship
Trace various landmarks & compare to average values
Show position of unerupted canines (in A-P & vertical planes)
A-P = Anteroposterior
What may happen to lateral incisors if there is an impacted canine?
Resorption of the lateral roots
What are flared lateral incisors an indicator of?
Flared laterals are a good indication of unerupted canine presence
What is the most and second most common impacted tooth
- 3rd molars (25% incidence)
- 5s (20% incidence)
What are the risks of impacted teeth?
Internal resorption of impacted tooth
External resorption impacted/neighbouring teeth
Ankylosis
Infection
Crowding 2/4 contact and reduction in arch length
Cyst formation
Poor aesthetics
What are some reasons for impacted canines?
- Long path of eruption (Maxillary canine close to zygomatic process, high in maxilla)
- Earlier development than adjacent 2’s
- Small or absent 2’s – Lack of guided eruption by 2’s
- C’s resistant to resorption
- Polygenic inheritance
What information do OPGs reveal?
Unerupted teeth
Root position, shape & apex closure
Stages of tooth development
Bone support
Condyles
Pathology (e.g. cysts, supernumaries, tumours & periapical radiolucency’s)
When does delayed eruption of maxillary incisors require monitoring or intervention?
- There is eruption of contralateral teeth that occurred greater than six months previously
- Both central incisors remain unerupted and the lower incisors have erupted greater than one year previously
- There is deviation from the normal sequence of eruption (eg lateral incisors erupting prior to the central incisor)
What two radiographs are used in parallax to locate unerupted canines?
OPG and upper standard occlusal to locate un-erupted canines
What are the advantages of a lateral cephalogram?
Profile view – Helps localise tooth positioning in horizontal plane
Provides good idea of the degree of vertical impaction
What are some indications of surgical removal of impacted canines?
Poorly positioned, curved root or XLA need in tx plan
Uncrowded mouths will require prosthetic replacement (e.g. bridge)
What are the advantages and disadvantages of CBCT/MRI scans?
Advantages
- Good detail in 3 dimensions (3D)
- CBCT can give high degree of accuracy for relatively little radiation exposure
Disadvantages
- Expensive
- High resolution CBCT scans use higher dosage radiation
- MRI –uncomfortable for px
What are some advantages of OPGs?
Shows all teeth
Complete view of both jaws
Can be used to localise position as objects closer/further away from beam will be magnified/diminished
Define impacted teeth
A tooth that has failed to erupt due to identifiable obstruction/ barrier to eruption of normally positioned tooth
by bone, tooth or fibrous tissue.
How do you treat an impacted 6?
Observe & if persists after 8 y/o then Interceptive tx (Extract E & Disimpact 6)
What is the incidence of impacted central incisors?
0.13% in 5-12 yr olds
Why might early loss of a primary tooth cause impaction later on?
An abscess formation can affect the developing tooth germ, resulting in hypoplasia of the enamel of the permanent successor.
Early loss of primary= permanent eruption disrupted, therefore change in position & possible impaction
Late eruption = crowding
The tooth germ of permanent can also be damaged or scar tissue left from extractions/cleft palate surgery/trauma
What is dilaceration?
What is the aetiology?
What are the tx options?
A distortion or bend in the root of a tooth
Developmental
Usually affects an isolated central incisor
Trauma
Intrusion of deciduous incisor leads to displacement of the underlying developing tooth germ
Usually causes failure of eruption
Severe – extract affected tooth
Milder – expose the crown surgically & apply traction to align the tooth providing the root apex will be within cancellous bone.
What is ankylosis?
occurs when partial root resorption is followed by repair with either cementum or dentine that unites the tooth root with the alveolar bone.
How is ankylosis diagnosed?
Diagnosed by higher percussion note than adjacent teeth. Also when a fixed appliance is placed the ankylosed tooth will not move but the adjacent teeth may intrude with it.
You have pt under 9 with an impacted maxillary incisor. You remove the obstruction and maintain the space and monitor. Its been 18 months and the tooth has still not erupted. What do you do?
Expose the tooth
For best aesthetics avoid excision of attached gingivae and apical repositioning flaps.
You have pt over 9 with an impacted maxillary incisor. You remove the obstruction and maintain the space and monitor. How long do you monitor for it to erupt before you expose and bond?
12 months
You have a pt over 10 years old with an impacted maxillary incisor. How long do you monitor once removing an obstruction for it to erupt?
Remove obstruction, expose and bond bracket at first operation
Apply traction as soon as possible via either a URA or a fixed appliance
What is the incidence of impacted maxillary canines?
- 0.8-2.8% of population - (1.7% Ericson & Kurol 1986)
How many mm does the maxillary canine travel from 5-15yrs on average?
22mm
What age is it considered to be a late eruption of the maxillary canine?
F>12.3yrs M>13.1yrs (Hurme 1949)
At what age is it reccomended to take a radiograph if maxillary canines have not erupted and they cannot be palpated?
> 11 years old
What is parallax?
Parallax is the apparent displacement of an image relative to the image of a reference object and is caused by an actual change in the angulation of the X-ray beam
State the categories of prognosis of impacted maxillary canines
Kate Counihan
Describe the closed technique of managing impacted maxillary canines
Surgically uncovering tooth, cementing an attachment and repositioning the palatal flap (Lewis, 1971). Soon after surgery an orthodontic brace is applied to apply gently forces. Tooth moves in the correct position underneath the mucosa. Attachment often placed on palatal surface of canine because often the only side accessible during surgery.
Describe the open technique of managing impacted maxillary canines
(1. Open window 2. Apical repositioning flap-used mainly for buccal canines so they erupt through keratinized gingivae)
Open exposure and spontaneous eruption –when tooth in correct position and will erupt spontaneously
Open exposure and surgical pack
Surgically uncover the canine and remove a window of tissue from around the crown and placing a pack to cover the exposed area. After 10 days the pack is removed and the canine allowed to erupt naturally. Once erupted enough brace treatment commenced. Tooth moves into its correct position above the mucosa. Attachment placed on buccal surface of canine.
When would we take a CBCT when regarding ectopic canines?
When suspected significant root resorption of lateral and central incisor
Planning surgical procedures: Expose and bonding/surgical removal
What can we assess clinically for unerupted & possibly impacted canines
Palpate for swelling in palatal & buccal gingivae
Presence of c’s- mobility?
Presence/diminutive of 2’s
Eruption of contralateral canine
Tip/angulation of lateral incisor
Mobility/vitality of lateral and central incisor (testing for root resorption)
Amount of space available
If you see a proclined lateral incisor, what could this suggest about the position of an unerupted canine?
Labially ectopic
(canine in contact with labial aspect of lateral incisor roots)
Magnified appearance of an impacted 3 on a panoramic will suggest a canine is buccally or palatally positioned?
Palatally
Palatal are closer to the beam: more magnified compared to contralateral
Which is more favourable, buccal or palatally placed canine?
Palatal
They will be moved away from roots of lateral incisors: more bone which is protective
Labially placed: more likely to move position of lateral and cause root resorption
Which type of parallax has been shown to be more accurate?
Horizontal
How high is the prevalence of root resorption of lateral/central incisors with ectopic canines?
With CBCT: 66.7% of lateral incisors and 11% of central incisors caused root resorption
(note: reported all resorption, even if minor)
For interceptive tx of impacted canines, how long do we wait after extracting c’s before we opt to expose and bond?
1 year
What is the main determinant of prognosis of autotransplantation?
How well the PDL is preserved during extraction
(This is challenging)
Why do 4’s make a good substitution for poor prognosis ectopic canines?
Same buccal appearance
Space closure= easier than bringing a poor prognosis canine in alliance
