Maxillary Impacted Canine

Maxillary Impacted Canine

By
Dr. Zaid Al- Dewachi
PH,D Ortho.Head Department of P.O.P

clinicians should be competent to perform the proper investigation,provide a correct diagnosis, &develop an optimum treatment plan, and render appropriate treatment for each individual patient so each patient realizes the best outcome possible

Incidence& prevalence

Permanent maxillary canine impaction has been reported in about 1% to 2% of the population. This makes the maxillary canine the second most commonly impacted tooth, after third molars.
Research indicates that women are twice as likely as men to have impacted maxillary canines. The prevalence of impacted maxillary canines is between 0.9% and 2%., it has been found that maxillary impacted canines occur palatally 85% of the time while only 15% of impactions occur labially. Palatal canine impaction occurred most frequently in subjects with a Class II division 2
Malocclusion. Among all patients with impacted canines, it was found that unilateral impaction is much more common than bilateral impaction. Maxillary canine impactions appear to be 10 to 20 times more frequent than those in the mandible.

The etiology of impacted maxillary canines is thought to be multifactorial, they are not likely to originate from modified conditions in modern civilization such as food texture or eating behavior; however, the exact etiology is still unclear. Possible causes for impacted canines may include one or more of the following local factors: inadequate space for eruption or early loss of primary canines; abnormal position of the tooth bud.
The presence of an alveolar cleft, a cystic lesion or neoplasm; ankylosis; dilacerations of the root; an iatrogenic origin; and an idiopathic condition for no apparent reason. Systemic conditions such as endocrine deficiencies, malnutrition, febrile disease, or irradiation can also account for impacted canines
Currently, there are 2 major theories that have been used to explain the cause of maxillary canine impaction:the guidance theory and the genetic theory. The guidance theory states that excess space in the canine area of the dental arch during developmentand eruption owing to an absent or malformed lateral incisor root causes the canine to lose its way and erupt improperly, because a permanent canine tooth needs the distal aspect of a lateral incisor’s root to guide it downward to the occlusion. The genetic theory titles that palatally impacted canines are the result of a combination of multiple gene expressions which cause dental anomalies such as congenital missing or peg shaped lateral incisors due to a developmental disturbance of the dental lamina.

CLINICAL DIAGNOSIS

Impacted canine teeth can be detected as early as age 8 years. Clinical examination includes overall arch inspection, palpation of canine bulges, mobility of primary canines, and a review of the patient’s chronological age and history of eruption/exfoliation patterns of the dentition. Clinicians should be responsive that there is a possibility of canine impaction in the absence of canine bulges, abnormality in shape, missing lateral incisors, or less mobility of primary canines.
Unusual movement of lateral or central incisors can also be a sign of root resorption due to pressure from malposed canines. When there is the clinical presence of any of these signs, radiographic examination should be performed to confirm the diagnosis

Radiographic Diagnosis

Periapical radiographs can be help ful by using at least 2 radiographs at different angles to determine the buccolingual position of a particular tooth. There are 2 methods that are widely used: Clark’s rule and the buccal object rule. Both use the different angulation of the x-ray beam to locate objects in different directions. These methods, also known as same lingual opposite buccal rule, will make the objects on the lingual side move to the same direction as the x-ray tube and objects on the buccal side move in the opposite direction. Panoramic radiographs are also widely used to locate the position of impacted canines. They are part of the fundamental imaging taken for dental records and treatment planning. They provide an overall look of the entire dentition including the temporo-mandibular joints (TMJs). Many prediction values proposed in the literature come from this type of radiograph.
Occlusal radiographs can identify the position of impacted maxillary canines accurately in conjunction
With routine periapical radiographs.When properly obtained, they provide information about the buccolingual direction of the crown and root of the canine. They also provide information related to the distance between the midline and the position of the canines. The disadvantage of this radiograph is that it cannot provide any information about the vertical position of the canines.

Lateral cephalometric radio graphs can help determine the position of impacted canines relative to other structures. They are helpful because they are some of the fundamental radiographs that all patients have taken prior to the beginning of orthodontic treatment. Maxillary canines can be located easily on this radiograph as early as age 8 or 9 years.
Posterior-anterior radiographs are also useful. Normal canines in this type of radiograph should angle medially, and crowns should be lower than the apex of the lateral incisors and the lateral border of the nasal cavity. This type of radiograph is not usually taken unless there are skeletal asymmetry.
CBCT has the great advantage of showing hard-tissue reconstruction in the area of interest in 3 dimensions, presenting a view without any superimposition, the orientation and location of the impacted canine and its relationship to neighboring
structures. This technique makes identification of the exact position and shape of impacted canines possible, which is critical in treatment planning. Furthermore, it be there very helpful in evaluating damage to adjacent teeth and the amount of surrounding bone The major disadvantage of CBCT is the increased amount
of radiation exposure, which is at least 4 times higher than with ordinary panoramic radiograms. Therefore, orthodontists should consider cost-benefit outcomes before ordering this radiograph.

C.B.C.T OF Impacted Canine

PREDICTION OF MAXILLARY IMPACTION
1.Predicting canine impaction using the angulation, distance, and sector of the canines from a panoramic radiograph to determine the chance of an impacted canine. That is, the deeper the cusp tip from the occlusal plane, the more perpendicular to the midline, and the closer to the midline, the greater the chance that tooth impaction will occur and the longer the duration of treatment.
2. Many studies have shown that the mesiodistal position gives the best prediction value, while angulation and vertical position showed no statistical significance.
3.Canine cusp tip which is mesial to the midline of the lateral incisor, is more likely to be palatally impacted, and root resorptions are also more frequent.

The management of impacted canines can be divided into 2 treatment categories: interceptive treatment and corrective treatment.
Interceptive Treatment :Preventive modalities should be performed in cases that have a strong possibility of canine impaction. Therefore, extraction of the primary canine is thought to be a proper interceptive treatment. extraction of the primary canines between the ages of 10 and 13 years will obtain a favorable result with most palatally erupted canines. If the cusp tip of a permanent maxillary canine in the panoramic radiograph does not exceed the midline of the lateral incisor, the chance of the canine erupting normally is 91%.

--if the cusp tip does exceed the midline of the lateral incisor, the chance for normally erupting drops to 64%. Many modifications have been added to the extraction of primary canines to improve the results, including the use of cervical pull headgear, double extraction of the primary canine and the primary first molar.

Corrective Treatment

Three techniques have been proposed by Kokich for uncovering a labially unerupted maxillary canine (gingivectomy, apically positioned flap, and closed eruption technique).
The orthodontists should evaluate 4 criteria to determine the correct method for uncovering the tooth so the outcome achieves the optimum periodontal health. These criteria include:
the distance between the canine cusp and the mucogingival junction; the labiolingual position; the mesiodistal position; and the amount of attached gingiva in the area of the impacted canine.
The first method(Gingiectomy) is a useful when
1. the canine has a correct axial inclination and needs no upright correction
during its eruption, but this method may increase treatment time and be
unable to control the path of eruption.
2. Performing this method before the beginning of orthodontic treatment or during the late mixed dentition because the tooth will erupt in a more favorable


3.this technique had minimal effects on the periodontium and that the overall effects on the impacted canine appeared better than those from the closed exposure and early traction techniques.
The second method(apical positioning flap) is used
1. when there is no eruption force left or the tooth does not lie in a favorable direction and orthodontic force is required to move the impacted tooth away from the roots of the adjacent teeth
and bring it to the proper position .After sufficient space has been created,
2. surgical exposure is performed and the attachment is placed. Light
orthodontic force (not to exceed 60 g or 2 oz) is then applied to move the
tooth to the desired position by various orthodontic techniques