Impacted teeth - canines Flashcards
What is the second most commonly impacted tooth?
maxillary canine
What is the prevalence of maxillary canine impaction?
1.7%
If a maxillary canine is ectopically impacted, where would this likely be placed?
ectopic palatal more than buccal (80% are palatal)
When is the maxillary canine normally palpable in the labial sulcus?
10-11 years
Why are canines thought to become impacted?
essentially due to lack of space
What are the 2 theories of canine impaction?
the guidance theory (Becker et al) - loss of distal aspect of the lateral incisor as the guidance plane for canine eruption
the genetic theory (Peck et al) - result of polygenetic multifactorial inheritance
What are some examples of the aetiology of canine impaction?
- non-resorption of deciduous teeth
- ankylosis of impacted canine
- contraction or collapsed maxillary arch
- absence of lateral incisor to guide eruption
- presence of pathology, supernumerary, scar tissue in path of eruption
- trauma causing a disturbance in tooth germ axis
- cleft lip and palate, syndromes, cleidocranial dysplasia
- long path of eruption (22mm)
- displacement of the crypt
What are the clinical investigations for potential canine impaction?
- palpate
- evidence of rotation/tilting of adjacent teeth
- mobility/sensibility of adjacent teeth
- 6 months since contralateral tooth eruption
- presence of deciduous canine
What are the radiographical investigations for a potentially impacted canine?
- parallax films - PA x2, occlusal and DPT
- CBCT
What adjacent tooth would more likely be affected by an impacted canine (e.g. rotation/tilting, mobile etc.)?
lateral incisor
What does the horizontal parallax technique tell us about impacted canine position?
SLOB - same lingual opposite buccal
- if you move the x-ray cone and the tooth on the radiograph moves in the same direction as the cone, it is lingually/palatally placed
- if you move the x-ray cone and tooth on the radiograph moves away in the opposite direct, it is buccally/labially placed
What radiographic views are needed to use the vertical parallax technique for localisation of an impacted canine?
maxillary occlusal and DPT
What radiographic view is this?
lateral occlusal view of canine
What does this radiograph suggest is happening to the impacted canine?
follicular space enlargement - evidence of cyst formation
What kind of imaging is this?
CBCT of impacted canines
What do these radiographs suggest about the impacted canines?
dilacerated roots on canines
How are dilacerated impacted canines managed?
cannot be orthodontically aligned - can orthodontically close or create space for an implant, and surgically remove the dilacerated impacted canine
What are the sequelae of leaving impacted canines in place?
- resorption of incisor roots - incidence unknown up to 12.5%
- cystic change - incidence thought to be low
- infection of cyst when close to surface mucosa, possible sinus formation
What does this radiograph show?
marked resorption of the root of lateral incisor
How may this be managed?
extraction of lateral incisor and pulling the canine down into the space and masking it as a lateral incisor
or may extract both and place implant
What are the 5 treatment options for impacted canines (or any impacted tooth)?
- conservative
- interceptive
- exposure
- surgical removal
- transplantation
When would conservative treatment for an impacted canine be advocated?
- patient unwilling to have orthodontic treatment, or happy with appearance with good contact between the 2 and 4, or healthy C [40yrs], adjacent teeth vital.
- radiographs show tooth very high, no associated pathology or resorption- usual after 14 years of age
note: Cs will not look good long term due to attrition etc
What is interceptive treatment of an impacted canine?
extraction of the deciduous canine
When would interceptive treatment for an impacted canine be advocated?
if patient 10-13 years, minimal crowding, space maintenance.
Note: if no change in position after 12 months on radiographs alternative treatment, 78% erupt normally following treatment
When would exposure and alignment of an impacted canine be advocated?
- well motivated patient willing to have orthodontic treatment and good oral hygiene
- not grossly displaced with favourable root morphology
- best results if carried out early
What are the 2 techniques for exposure and alignment of an impacted canine?
Open technique = apically repositioned flap or palatal window
Closed technique = orthodontic bracket and gold chain allowing orthodontic traction (BEST)
When is the open technique for impacted canine exposure advocated?
when the canine is placed buccally or is in the line of the arch, and is quite superficial
Why is the apically repositioned flap/open not favoured over the closed technique?
not as good aesthetics - repositioning of the gingiva can result in root exposure when the canine erupts
How is a palatally impacted canine exposed?
palatal mucoperiostium flap lifted, overlying bone removed, follicle removed
In the open technique palatally, what is done to the flap before suturing it back in place?
a window is cut in the flap to allow the crown of the canine to be seen
What is this?
an acrylic plate/a dressing plate used as a barrier to protect the soft tissues after surgical exposure of a palatally impacted canine
What is this?
co pac soft tissue dressing - a sedative dressing placed on the acrylic plate/dressing plate which helps with post-op discomfort and almost acts as a cushion for the soft tissues
How long is an acrylic plate/dressing plate left in place post-operatively?
1 week - can still brush teeth that are away form the surgical site and use mouth wash to keep the area clean
What does this show?
bilateral exposed canines 1 week post-op when the acrylic plate has been removed
What technique of canine exposure is being shown here?
closed technique
What is the benefit of the closed technique using orthodontic brackets when compared to the open/apical repositioned flap technique?
mimics the physiological eruption of the canine, meaning it will erupt through attached gingivae giving superior gingival contour
Explain what is being shown here
closed technique where the gingivae has healed over the bracket placed on the impacted canine and the gold chain has been attached to the orthodontic chain, allowing traction to be applied to the canine to caused eruption through the gingivae
When would surgical removal for an impacted canine be advocated?
- patient non-compliant or satisfactory appearance with C or 2-4 contact
- advanced resorption of incisors (may extract the incisor and incisorise the canine)
- malpositioned canine with difficult root morphology
What is the technique of surgical removal of impacted teeth?
- same flap design as for exposure
- commonly palatal
- remover overlying bone to maximum convexity of tooth and elevate
- sectioning may be required if root morphology complex or position tight against adjacent teeth
- may need buccal approach to section (even if palatal)
- plate maybe required post operatively
What flap design is used for exposure/removal of palatally impacted canines?
envelope flap
What flap design is used for exposure/removal of buccally impacted canines?
3-sided or 2-sided depending on how much exposure is needed
Where do you incise for an envelope flap for exposure/removal of palatally impacted canines?
cut round necks of anterior teeth
- from premolar to premolar if bilateral
- from contralateral central incisor to first premolar if unilateral
What anatomical feature must be considered when creating a flap for bilateral palatally impacted canines?
the nerve bundle which exits through the incisive foramen - can sever this bundle, over time the innervation of the anterior hard palate is taken over by the greater palatine nerve
What is the arrow pointing at?
the follicular tissue - must all be removed as if left behind could undergo cystic change
When would transplantation of an impacted canine be advocated?
- very rarely done anymore
- poor patient compliance or limited treatment time desirable
- poorly positioned canine without ankylosis
- open apex desirable
- may simply rotate tooth around an axis
- need adequate space and bone
What is the technique for transplantation of impacted canines?
- access as for removal but atraumatic elevation avoiding contact with periodontal ligament/root, tooth ‘parked’ in tissues whilst prepare socket with bur or chisels
- socket ‘friction-fit’ avoiding heat generation
- minimal time >10mins
- may require splint immobilisation
- check is free of occlusion
- post op check vitality and resorption
What is the failure rate of autotranslation of canines, and for what reasons does this technique fail?
failure rate 30% over 9 years often due to poor surgical technique
- internal resorption, perform RCT post op
- external root resorption, particularly if excessive force on tooth in socket
- replacement root resorption, root replaced by bone until exfoliates
- infection
