Topic prepared by Dr. Salwa Almadani …
- Tooth impaction can be defined as the infraosseous position of the tooth after the expected time of eruption.
- Anomalous infraosseous position of the canine before the expected time of eruption can be defined as a displacement.
- Early diagnosis and intervention could save the time, expense, and more complex treatment in the permanent dentition.
According to Thilander and Ericson and Kurol :
The incidence of impacted maxillary canines is around 2-3% of the general population and mandibular canine impactions in approximately 0.2%.
Ngan P, Bishara the most common impacted tooth:
- maxillary & mandibular 3rd Molars
- maxillary canine
- mandibular Premolars
- mandibular canine
Proffit, Cooke J:
- maxillary impaction occur more commonly in females than males in the ratio of 2:1
Stivaros and Mandall (2000)*
- Impacted canine crown is palatal in 61% of cases
- In the line of the arch in 34% of cases
- Labial in 4.5% of cases.
Prof.Afify AR, Prof.Zawawi KH. (2012)**
The prevalence of impacted canine was the second frequent anomaly (3.3%) after congenitally missing teeth in the western region of Saudi Arabia.
Jacoby’s study found that 85% of palatally displaced canines had sufficient space to erupt, whereas 83% of buccally impacted canines had insufficient space to erupt.
Theories of palatal canine impaction
Two major theories associated with palatally impacted maxillary canines are:
The distal aspect of the lateral incisor is the guide for canine eruption.
In his study, Becker found that palatally impacted canines were very closely associated with spaced dentitions and lateral incisors that are peg-shaped, or congenitally absent.
This theory considers impacted canines are result of multifactorial inheritance.
They based their theory on the fact that palatally displaced canines are concomitant with other dental anomalies, such as premolar hypodontia and peg laterals.
Diagnosis of impacted canine
Clinical signs include Visual inspection of the canine bulge, whether it is buccal or palatal.
Palpation of the buccal surface of the alveolar process distal to the lateral incisor from 8 years of age may reveal the position of the maxillary canine and has been recommended as a diagnostic tool.
- Intraoral techniques (occlusal and periapical projections( SLOB ).
- Extraoral techniques (panoramic xray, lateral cephalometric radiographs ,CBCT).
- Periapical x-ray ( SLOB) : This was 1ST introduced by Clark( 1909)
OPG is a 2-dimensional view and it is a fundamental examination which gives an overview but does not permit precise localization of an impacted canine in three-dimensional space .
Lateral cephalometry :
Lateral cephalometric has overlap as its major disadvantage for evaluation of impacted maxillary canines.
It is 3-dimensional imaging.
CBCT was developed in the 1990s and is the most precise method of radiographic localization, maximizing diagnostic yield and reducing exposure.
The total radiation being approximately 20% of conventional CTs and equivalent to full mouth periapicals.
Surgical and orthodontic management
There are 4 criteria that must be evaluated to aid in selecting the best surgical option:
1- Labio-lingual position of the impacted canine crown.
2- The vertical position of the tooth relative to MGJ.
3- The amount of gingiva in the area of impaction.
4- The mesiodistal position of the canine crown.