Maxillary Impacted Canines: A Clinical Review

Impacted permanent maxillary canine occur in 1-2% of the population. The Occurrence of impacted permanent maxillary canines are; 85% palatal and 15% labial.1,2,5,6 The prevalence of palatally displaced canines (PDC) fluctuates between 0.8-5.2%.2,3,15,12,16,17 Palatally erupting or impacted maxillary canines occur twice often in females than males, and are five times more common in Caucasians than Asians.3,18,19 Of all patients with maxillary impacted canines, 8% have bilateral impactions.


INTRODUCTION
Impacted teeth are those with a delayed eruption time or that are not expected to erupt completely based on clinical and radiographic assessment. 1,2 Palatal displacement of the maxillary canines is defined as the developmental dislocation to a palatal site often resulting in tooth impaction requiring surgical and orthodontic treatments. 3,4 Impacted permanent maxillary canine occur in 1-2% of the population. The Occurrence of impacted permanent maxillary canines are; 85% palatal and 15% labial. 1,2,5,6 The prevalence of palatally displaced canines (PDC) fluctuates between 0.8-5.2%. 2,3,15,12,16,17 Palatally erupting or impacted maxillary canines occur twice often in females than males, and are five times more common in Caucasians than Asians. 3,18,19 Of all patients with maxillary impacted canines, 8% have bilateral impactions.

Etiology and Developmental Considerations
The exact etiology of palatally impacted maxillary canine is unknown; however, two common theories may explain the phenomenon: the guidance theory and the genetic theory. Guidance theory of palatal canine displacement proposes that the congenitally missing lateral incisors, supernumerary teeth, odontomas, transposition of teeth and other mechanical determinants interfere with the path of eruption of the Canine. 1,2,8,15,21 Maxillary canines develop high in the maxilla, are the last teeth to develop, travel longest and most complicated eruption path among all teeth. Between the age 5 to 15 years, normal eruption path of the maxillary canine is altered causing impaction. 3,19,12,20 The second theory focuses on genetic cause stating that the palatally impacted maxillary canines often accompany other dental abnormalities like tooth size, shape, number, structure. Studies show that upto 47.7% of patients with palatally impacted canines also possess small, pegshaped or missing lateral incisors. Palatally impacted maxillary canines are also associated with hypoplastic enamel, infra-occluded primary molars and aplastic second bicuspids. 1,21 over retained primary cuspids, 1,29 no significant mobility of deciduous canine at age of 13 years, 1,29 an exaggerated distally tipped incisor, 1,28 retroclined and rotated lateral incisors, 1,28 and malpositioned central incisor crown. 1,30 Palpation of canine bulge shows an obvious palpable bilateral asymmetry in patients older than 10 years. 1,31,32 Radiographic evaluation includes panoramic view (OPG), lateral cephalogram, IOPA x-rays with parallax technique (horizontal/vertical) and occlusal view. Specialized views include CT and CBCT (Figure 1

Preventive & interceptive measures
The procedure of reducing the occurrence of

Surgical exposure
It is recommended that the surgical procedure designed to expose impacted canine through alveolar mucosa should simultaneously provide a band of attached gingival to the exposed tooth. Otherwise, improper soft-tissue management may lead to mucogingival recession and loss of alveolar bone. Before a labially impacted canine is exposed, consideration should be given to create the sufficient space to allow the canine to be moved in the area.
The most common surgical methods are: a. Apically positioned flap (Figure 9) b. Excisional gingivectomy (Figure 10) c. Closed eruption technique ( Figure 11) Among the above mentioned methods, closed eruption technique is the best method of uncovering labially impacted tooth. It involves elevating a flap, placing an attachment on the impacted tooth and returning the flap to its original location. If the tooth is displaced near the nasal spine; pedicle flap is reflected, orthodontic attachment is placed and the flap is returned to its original position for complete closure. The orthodontic traction force is applied one week after creating a normal direction of tooth eruption.

Methods of orthodontic attachment
1. Polycarbonate or gold crowns cemented onto the exposed crown 2. Wire lasso (Figure 12   1. If it is ankylosed and cannot be transplanted.
2. If it is undergoing external or internal root resorption.
3. If the root is severely dilacerated.

If the impaction is severe on central and lateral
incisors and orthodontic movement will jeopardize these teeth.