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Definition of impaction
Diagnosis and management of Impacted teeth
Prepared by: Osama Ahmad haj
3rd Year Orthodontic Resident
Definition of impaction An impacted tooth : A tooth that is prevented from erupting into its normal functional position by bone, tooth or fibrous tissue
Ectopic eruption: The emergence or eruption of a tooth in a site located away from its normal location or position, including all three planes of space: vertical, horizontal and anteroposterior. Tooth transposition, is a special type of ectopic eruption
Because impacted teeth do not erupt, they are retained throughout the individual's lifetime unless extracted or exposed surgically
Most Commonly Impacted Teeth Mandibular 3rd molars. Maxillary 3rd molars. Maxillary cuspids . Mandibular 2nd bicuspids. Maxillary 2nd bicuspids . Maxillary central incisors. Mandibular 2nd molars .
Causes of multiple failure of eruption
I) Impacted Upper Canines A canine that is prevented from erupting into its normal functional position by bone, tooth or fibrous tissue. The palatal impaction of canines presents a special challenge in practice of orthodontics. Three questions that immediately come to the mind of the clinician after identification of an impaction are: Where, specifically, is the tooth? What is the appropriate treatment? How long will it take to align the impacted tooth?
Eruption of maxillary canine
Has long path of eruption from the infra-orbital place along the roots of upper laterals causing ugly duckling space which resolve later, and then pass along the buccal surface of the primary canine . Upper canine erupts at 11-12yrs. 3's palpable in buccal sulcus by 8-10 yrs. (Ferguson, 1990 )
Prevalence Developmentally absent 3's: 0.08% (Brin et al, 1986) Impacted 3's: 2% (Ericsson, 1986) F:M = 70%:30% Unilateral: bilateral = 4:1 Palatal: 61%; in line of arch: 34%; buccal: 4.5% (Mandal, 2000, Brin et al, 1986)Associated with peg lateral incisors (Brin et al 1986)High incidence associated with CI II div 2 malocclusions (Moosy, 1994)
Theories of impaction : Two main theories have been proposed :A ) Guidance theory : underlines a role of the lateral incisor root in guiding the erupting canine crown in the proper direction towards the dental arch. Evidences:With small or developmentally absent lateral incisors, the incidence are three times (Becker) Associated with peg lateral incisors (Brin et al 1986) High incidence associated with CI II div 2 malocclusions (Moosy, 1994)
Genetic theory: (Peck et al., 1994, 1995), The palatal displacement of the canine is genetically determined. This theory is supported by other dental anomalies frequently occurring in patients with the ectopically erupting canines, so-called microsymptoms (e.g. small teeth, enamel hypoplasia, aplasia of second premolars, infraocclusion of primary molars, etc.) Occurrence with specific race Occurrence in family Occurrence in female more than male Occurrence with specific syndrome Occurrence unilateral: bilateral is 4:1
Diagnosis of unerupted upper canine A ) History and examination : Practitioners should suspect ectopia if the canine is not palpable in the buccal sulcus by the age of 10-11years, if palpation indicates an asymmetrical eruption pattern or the position of adjacent teeth implies a malposition of the permanent canine. The patient with an ectopic maxillary canine must undergo a comprehensive assessment of the malocclusion, including accurate localization of the canine
B ) Inspection Clinical signs of impacted 3s :Delayed eruption. Asymmetrical eruption. Prolonged retained of C. Absence of buccal bulge at age of 10 years. Presence of palatal budges. Angulated or flared laterals. Change colour of centerls or laterals .
C) Palpation and percussion : Palpation of the upper canines is a vital step in assessing the developing dentition. Deciduous canines or adjacent permanent teeth should be checked for mobility, tenderness and vitality.
D) Diagnostic imaging of unerupted teeth
Radiography The use of various techniques has been advocated for localization of impacted canines including:Right Angle Technique (Broadway & Gould, 1960) - (Coupland, 1987).
Horizontal Parallax Technique SLOB Rule (Clark, 1909) .
Vertical Parallax Technique (Richards 1952, Rayne 1969, Keur 1986).
CT scans (Ericson & Kurol, 1987).
Cone Beam Computed Tomography (CBCT).The single panoramic radiograph .
Right Angle Technique & Tube Shift Technique :A periapical film will identify the location of an object vertically and in a horizontal (mesiodistal) direction. However, we cannot tell where the object is located buccolingually, since the periapical film is two-dimensional. Therefore, we need another method for locating objects in a buccolingual direction. The two primary methods of determining the buccolingual location of objects are:
1. Right-Angle Technique (Occlusal projection):
Primarily identifies buccolingual location, but may also confirm mesiodistal location seen on periapical
2. Tube-shift Technique (SLOB rule, Clarks rule):
Utilizes two films with different horizontal or vertical angulations
Right Angle Technique Once you have identified an object on the periapical film, you can take an occlusal film with the beam at a right angle (perpendicular) to the direction of the beam for the periapical. The beam may also be perpendicular to the film, especially in the mandible. The occlusal film below shows that the impacted canine is lingually positioned.
II. Tube Shift Localization SLOB Rule Same Lingual Opposite BuccalThe SLOB rule is used to identify the buccal or lingual location of objects (impacted teeth, root canals, etc.) in relation to a reference object (usually a tooth). If the image of an object moves mesially when the tubehead is moved mesially (same direction), the object is located on the lingual. If the image of the object moves distally when the tubehead moves mesially (opposite direction), the object is located on the buccal.
Horizontal Vs. Vertical Tube ShiftHorizontal Tube Shift: When the tube head is moved mesially, the beam must be directed more distally (from the mesial). If the tube head is moved distally, the direction of the beam must be more towards the mesial (from the distal).
Vertical Tube Shift: The SLOB rule also works for movement of the tube head in a vertical direction. Downward movement of the tube head requires that the beam be directed upward and when the tube head is moved upward, the beam must be directed downward
Horizontal parallax 1) Upper standard occlusal (midline view) and periapical (centered on the canine region) OR 2) Tow periapicals (one centerd on the upper central incisor and the other centered on the canine region )
Example of Horizontal ParallaxIn the second film, when the tube was shifted MESIALLY, the crown of the impacted tooth moved DISTALLY
Example of Horizontal ParallaxIn the second film, when the tube shifted DISTALLY, the crown tip also moved DISTALLY
vertical parallax 1) Upper standards occlusal and a panoramic
OR 2) Periapical and a panoramic radiograph .
Example of Vertical ParallaxIn the second film, when the tube was shifted UPWARD, the crown of the impacted tooth moved UPWARD
Vertical / Horizontal ParallaxIncreasing the vertical angulation of the X-ray tube from 60-65 to 70-75 increase the effect of parallax (Jacobs, 1999)
Horizontal parallax is more accurate than vertical parallax (83% of 3s were correctly located with horizontal vs. only 68% with vertical) (Armstrong et al., 2003)
DPT overestimates the angulation and underestimates proximity to the midline (Ferguson, 1990)
92% of palatal canines can be localized with two periapical radiographs (Ericson & Kurol, 1987)
Cone Beam Computed Tomography (CBCT)The best tool for evaluating the status of the impacted canine is the CBCT (3D CT) image since it establishes the link between 2D and 3D imaging. With this three-dimensional (3D) tool, the orthodontist (or any dental specialist) would be able to see the exact status of the impacted canine in question . Using CBCT with the maximum data available would help reduce unnecessary radiation exposure. In CBCT, there is much better visualization of the roots in their real position (Advantage over 2D radiographs)
CBCT (3D CT)
The single panoramic radiograph Chaushu, Chaushu and Becker (1999) have described a method of localizing maxillary canines using only a panoramic radiograph. This depends on the fact that objects nearer the x-ray source (and further from the film) project a larger image than objects closer to the film and further from the x-ray source. Thus palatal canines will appear larger than buccal canines (remember that the x-ray source from a panoramic radiograph comes from behind the head).
In the coronal and middle thirds of the adjacent incisor, the ectopic canines that were positioned buccally had a canine-incisor width ratio of 0.78-0.1.11 and the palatal canines a canine-incisor width ratio of 1.5-1.7. While not an infallible method of localizing canines, this can be a useful adjunct to other methods and may help to provide a positive diagnostic localization.
Canine-Incisor Index (CII)
Relates to prognosis and complexity of aligning canine.Therefore, the aim was to investigate