SRM Journal of Research in Dental Sciences

REVIEW ARTICLE
Year
: 2012  |  Volume : 3  |  Issue : 3  |  Page : 198--203

Surgical and orthodontic management of impacted maxillary canines


Anila Charles1, Sangeetha Duraiswamy2, R Krishnaraj2, Sanjay Jacob1,  
1 Department of Orthodontia, Madha Dental College, M.G.R University, Chennai, Tamil Nadu, India
2 Department of Orthodontia, SRM Dental College, SRM University, Chennai, Tamil Nadu, India

Correspondence Address:
Anila Charles
Department of Orthodontia, Madha Dental College, Dr. MGR Medical University, Madha Nagar, Somangalam Road, Kundrathur, Chennai, Tamil Nadu
India

Abstract

Impaction of the maxillary canine is a frequently encountered problem in orthodontic practice. Maxillary canines are the most commonly impacted teeth next to the third molars. Alignment of an impacted canine requires a combined surgical and orthodontic approach. Maxillary canines present a high esthetic and functional demand, hence, a precise diagnosis and treatment planning with soft tissue considerations is essential for a favorable and stable outcome. An overview of the etiology, incidence, and diagnosis of the factors affecting the management of impacted maxillary canines, the soft tissue consideration, and various surgical and orthodontic techniques have been discussed.



How to cite this article:
Charles A, Duraiswamy S, Krishnaraj R, Jacob S. Surgical and orthodontic management of impacted maxillary canines .SRM J Res Dent Sci 2012;3:198-203


How to cite this URL:
Charles A, Duraiswamy S, Krishnaraj R, Jacob S. Surgical and orthodontic management of impacted maxillary canines . SRM J Res Dent Sci [serial online] 2012 [cited 2022 Dec 5 ];3:198-203
Available from: https://www.srmjrds.in/text.asp?2012/3/3/198/107403


Full Text

 Introduction



Impaction of the maxillary canine is a condition in which the tooth is embedded in the alveolus and its eruption is prevented. [1] The reported incidence of impacted maxillary canine in adults, varies from 0.92 to 1.7 %, as reported by Ericson and Kurol [2] , and the incidence is greater in females (1.17%) than in males (0.51%), as reported by Dachi and Howell. [3] Thilander and Myrberg reported a higher incidence of 2.2% in 7-13 year-old children. [4] The incidence of permanent canine impactions was 20 times higher in the maxilla than in the mandible. [5] Johnston reported that the palatal impactions were twice as common as the labial impactions. [6] However, Becker et al. reported that the palatally displaced canines occurred three times more frequently than those found buccally. [7] The various treatment options available for the management of an impacted maxillary canine included interceptive removal of the deciduous canine [8] or surgical removal of the maxillary canine, followed by prosthetic replacement or orthodontic space closure, surgical exposure followed by orthodontic management, or auto transplantation of the impacted canine. [9]

 Etiology



The etiology of canine impaction is multifactorial and may be due to genetic or environmental factors [Table 1].The environmental factors can be generalized as endocrine deficiencies, Vitamin D deficiency, febrile diseases, or irradiation. The local environmental factors play a major role in the etiology of maxillary canine impaction compared to the genetic and systemic factors. [10],[11] Maxillary canines have the longest period of development. [12] The calcification of a maxillary canine begins at four months and the enamel formation is complete around six to seven years. The tooth erupts into the oral cavity between 11and 12 years, and the root formation is completed at 13-15 years. [13] They develop at the level of nasal floor and take a long tortuous route from the point of development to occlusion. [14],[15],[16] The maxillary canine is present superior to the deciduous canine, angulated medially, with its crown lying distal and buccal to the lateral incisor. The canine follows a mesial path until the crown reaches the distal aspect of the lateral incisor root. The erupting canine is gradually uprighted to a more vertical position and is guided by the lateral incisor root, until it is fully erupted. [12]{Table 1}

The maxillary canine is the last tooth to erupt in the upper arch, with a deciduous predecessor, making it more prone to arch length tooth material discrepancy, which is the major cause for labial impactions. [17] Two theories have been put forward to explain the etiology of palatal impaction: The guidance theory and the genetic theory. [18] The guidance theory states that canine impaction is a result of local predisposing causes including lack of guidance provided by the root of the neighboring teeth due to hypoplastic or missing upper lateral incisors. The canine may get displaced by a supernumerary tooth, odontoma, or transposition of the adjacent teeth that interferes with the path of eruption. [19],[20] The second theory focuses on a genetic cause for impacted cuspids. Palatally impacted maxillary cuspids are often associated with other abnormalities, including tooth size, shape, number, and structure, such as, missing lateral incisor, hypoplastic enamel, infra occluded primary molar, and aplastic second bicuspids. Familial recurrence is seen in palatally impacted canines. [21],[22]

 Sequelae of Canine Impaction



If left untreated, a canine impaction may lead to migration of the neighboring teeth and loss of arch length, internal resorption, dentigerous cyst formation, external root resorption of the impacted tooth as well as the neighboring teeth, infection, particularly with partial eruption and referred pain. The most common sequelae are, root resorption of adjacent teeth, usually the incisors. Following radiographic examination, Erickson and Kurol reported permanent incisor root resorption in 0.6-0.8% of the patients with impacted maxillary canines. [23] Walker et al. reported root resorption of the lateral incisors in 66.7% of the patients with canine impaction. These were reported when using cone beam computed tomography for three-dimensional localization of the impacted maxillary canines. [24] Resorption of the crown of the impacted maxillary canine is most likely to occur in adults, with an incidence of 14%. The frequency of cystic changes is estimated to be very low even though cases are reported. [25],[26]

 Diagnosis



The diagnosis of an impacted maxillary canine begins with a clinical examination. A canine impaction is suspected if the canine has not erupted past the chronological age of eruption or if the canine is not palpable in the buccal sulcus by the age of 10 to 11 years. The clinical examination is supplemented with radiographic evaluation for an accurate diagnosis and for deciding the prognosis for alignment. Advanced diagnostic aids like cone beam computed tomography can be used for three-dimensional localization of the impacted tooth.

 Clinical Evaluation



The amount of space available in the dental arch for the impacted canine is assessed clinically by performing a space analysis in a study model. The morphology of the adjacent tooth can give a clue about the position of the impacted tooth. [21],[22] The contours of the adjacent alveolar bone are observed, a canine bulge is present either on the buccal side above the primary canine or on the palatal side. The presence of the bulge can be confirmed by palpation. Mobility of the adjacent teeth is checked for any root resorption. [15]

 Radiographic Examination



After age 11, radiographs are indicated in all individuals with unerupted and non-palpable maxillary canines. [15],[16] A panoramic radiograph was taken in conjunction with a series of two intraoral periapical radiographs, utilizing the Clark's tube shift technique, to determine whether the un erupted tooth is located buccal or palatal to the other teeth in the arch. [27] Ericson and Kurol reported that intraoral periapical radiographs were more accurate and reliable for location of the teeth in 92% of the cases they evaluated, whereas, in determining the position of the canines relative to the midline, occlusal radiographs were more accurate. [8],[9],[23] Shaw suggested lateral cephalometric radiographs for assessing the anterior - posterior position of the displaced tooth, as well as its inclination and vertical location in the alveolus. [28]

Computer tomography (CT) has become more widely available and is recognized as a superior diagnostic tool, compared to radiographs, in the early detection of root resorption of the lateral maxillary incisor, by the ectopically erupted permanent canine, especially in the crowded field of mixed dentition. However, radiation exposure from a CT scan is greater and the radiation risk should be weighed against the benefits of the precise preoperative diagnosis of the impacted canine. [12] Cone beam computed tomography can be used for the localization of the impacted canine. [24]

It allows highly accurate localization of the impacted tooth and visualization of the associated structures, and the radiation exposure is very low, comparable to a full mouth series of intraoral periapical radiographs. [29],[30]

 Determining the Prognosis



The most common treatment options for an impacted maxillary canine are surgical exposure and orthodontic alignment or surgical removal. A number of factors should be considered before deciding the treatment of an impacted canine [Table 2].{Table 2}

Surgical removal is indicated in patients with poor general dental status, without motivation toward orthodontic treatment, and in situations where the radiographic and soft tissue factors affect the prognosis of orthodontic alignment. Surgical removal is followed by prosthetic replacement of the canine if adequate space is present in the arch. In dental arches with crowding or proclination, with an indication of first premolar extraction, the first premolar can be substituted in the place of the maxillary canine. [31] Although a large amount of information regarding an impacted canine can be obtained from radiographs, the labio palatal position of the crown and the canine angulations to the midline influence the treatment decision. Labially positioned canines have a poor prognosis due to the difficulty in managing the attached gingival width with a labial gingival flap access compared to the palatal flaps, where fenestration of the mucosa is less critical. [31] The closed eruption technique used for aligning labially positioned canines is more difficult to manage because of lack of access for rebonding, if the bonded attachment fails. [32]

Power and Short assessed the chances of canine impaction based on the angulation of the canine on an orthopantomograph [Figure 1]. They concluded that the chances of impaction were more if the angulation of the long axis of the canine to the midline was more than 31degrees. [33]

Wardford and Gandhi suggested that the canine located distal to the midline of the lateral incisor was more favorable than the canines located medial to the midline of the lateral incisor root [Figure 2]. [34] Increased canine angulation to the midline affected the prognosis of orthodontic alignment. More horizontally positioned canines were difficult to align orthodontically [Figure 3]. [31]{Figure 1}{Figure 2}{Figure 3}

In a study, Liu et al. used cone-beam computed tomography (CBCT) to evaluate the variations in the location of impacted maxillary canines. [35] They found that the position of the impacted maxillary canines varied greatly. Reports of maxillary canine impactions varied considerably in orientation, and CBCT provided this information to the dentists, so that they could properly manage impacted canines surgically and orthodontically. [36],[37]

 Labial Impaction



Labial impaction of an upper canine is either due to ectopic migration of the canine crown over the root of the lateral incisor or insufficient space in the arch caused by a midline shift of dental origin. Arch length tooth material discrepancy is the most common cause for the labial impaction of canines. [38] Extraction of the maxillary deciduous canine at an early age of eight or nine years will enhance the eruption and self-correction of labial or intra-alveolar maxillary canine impaction. [39] If sufficient space is not available in the arch opening space, an orthodontic ally may allow spontaneous eruption of an impacted canine. [40]

A surgical exposure of the impacted tooth is indicated when the tooth does not erupt spontaneously after creating enough space in the arch and should be attempted six months after the completion of root formation [Figure 4]. The flap designs for surgical exposure should preserve the band of the attached gingiva and should guide the tooth to erupt through its natural path of eruption. [41]{Figure 4}

Usually there is little or no bone covering the crown of a labially impacted canine, hence, an excision uncovering or an apically positioned flap or a closed eruption technique could be used. [32],[ 42] If the tooth is impacted in the center of the alveolus a closed eruption technique is indicated because an excisional approach and an apically positioned flap are generally more difficult to perform, as extensive bone might need to be removed from the labial surface of the crown. If the canine crown is positioned coronal to the mucogingival junction an excisional approach will be appropriate. If the crown is positioned apical to the mucogingival junction an excisional technique will be inappropriate, as it will result in lack of attached gingiva after eruption of the tooth. In this case an apically positioned flap is indicated. [38] In Closed eruption technique the flap is elevated and an attachment is placed on the impacted tooth. A ligature wire or chain is placed over the attachment to activate after a week. The raised flap is repositioned in its original location to permit eruption of the impacted canine in the normal direction.

If the crown is positioned significantly apical to the muco gingival junction an apically positioned flap will also be inappropriate, because it will result in the impossible re intrusion of the tooth after orthodontic alignment. The re intrusion of the tooth is due to the apical pull from the mucosa that has migrated coronally during orthodontic eruption of the tooth. [43],[44]

The excisional technique must be performed only when sufficient gingiva is present, to provide at least 2 to 3 mm of attached gingiva over the canine crown after it has erupted. If the crown is positioned mesially and over the root of the lateral incisor, the crown should be exposed completely with an apically positioned flap. [38]

After surgical exposure of the canine an attachment is bonded to the canine. Vanarsdall and Corn recommend placement of a surgical dressing to protect the tissues for seven to ten days if bleeding makes bonding of an attachment difficult or a moisture insensitive primer can be used for bonding. [41] After removal of the dressing, a direct bonded attachment can be placed in a dry field and tooth movement can then be initiated. The use of a ligature wire to facilitate traction is reliable rather than engaging a full arch wire.

 Palatal Impaction



Two basic surgical techniques are used to expose a palatal impaction closed eruption or an open window eruption technique. In the closed eruption technique the crown is surgically exposed, an attachment is bonded during the exposure and the flap is sutured back leaving a twisted ligature wire passing through the mucosa to apply orthodontic traction. The disadvantage of closed eruption is that during bonding of the impacted canine at the time of surgery, it may cause soft tissue injury from the acid etched in an open wound. Moreover, maintaining a dry field is difficult for successful bonding, especially when the impaction is deep. In addition, the eruption of the impacted tooth may be delayed because of resistance of the thick keratinized mucosa. [12] In the open window eruption technique a flap is raised, the bone covering the crown of the impacted tooth is removed, a small window or fenestration is made, and the flap is sutured into place. [45] The orthodontic attachment is bonded on the same appointment, [43] the wound is packed with a surgical dressing for one week, and the bonding is done later, after removal of the pack.

Methods of applying traction

The use of an eyelet attachment has a lower failure rate than the use of a conventional bracket. Orthodontic force on the impacted tooth must be as light as 20 to 30 g. Controlled tipping of the crown is recommended for aligning the canine in the arch, as the root of the impacted canine is usually in the ideal position. The direction of the applied force must initially move the impacted tooth away from the roots of the neighboring teeth.

Various force elements can be used to align the canine in the arch, including ligature wire, rubber bands, elastomeric chains, and elastic threads. Loops bent in arch-wire like mouse trap loops or ballista springs can be used for aligning a palatally impacted canine. Jacoby, in 1979, introduced the Ballista spring, which was constructed with 0.012 inch stainless steel. It is a simplified orthodontic system for managing impacted teeth. The impacted canine is retracted by a spring that delivers a continuous force on its long axis. The force exerted on the tooth is vertical, without compressing the impacted tooth toward the adjacent roots. This force is well controlled and easily modified. The necessary operation on the impacted tooth is simple and less traumatic. [46] Magnetic forces have been advocated by Vardimon (1991), as they are utilized to apply force to the ectopic canine for alignment. [47]

Crescini explained a tunnel traction technique for aligning deep infra osseous impacted canines, by providing an osseous tunnel toward the center of the alveolar ridge. This method is carried out when the deciduous canine is present, so that the socket of the deciduous canine can be used to form a tunnel, for movement of the impacted canine. [48]

Elastic traction using a lower fixed or removable appliance as anchorage can be used to make the tooth erupt vertically before aligning it. [49]

Roberts-Harry and Harradine used a 0.017-0.025-inch TMA sectional arch wire from the first molar to the canine, providing a low force. [50] Bennett and McLaughlin achieved vertical movement and then lateral movement of the impacted canine by using a 0.014 stainless steel auxiliary. [51]

The Kilroy Spring, a removable auxiliary spring that provides constant vertical and lateral eruptive forces and a K-9 spring designed by Varun Kalra can be used to erupt the impacted canine. [52],[53]

Any tooth that has been surgically uncovered under orthodontic traction forces should be periodically checked for excessive mobility or bleeding from the gingiva around the tooth. Care must be taken to ensure that the periodontal attachment follows the tooth as it is guided into the arch. [54]

 Retention Considerations



Relapse of rotations and spacing may occur after completion of the orthodontic treatment of an impacted canine. Supracrestal fibrotomy and fixed retainers should be considered to prevent the relapse. [55] The lingual drift of the palatally impacted canines, after alignment, can be prevented by removal of a half-moon-shaped wedge of tissue from the lingual aspect of the canine. [56],[57]

 Conclusion



Various surgical and orthodontic techniques may be used to recover impacted maxillary canines. The proper management of these teeth, however, requires the appropriate surgical technique to apply forces in a favorable direction and to have complete control for efficient correction, thereby avoiding damage to the adjacent teeth. The management of an impacted canine is a complex procedure requiring a multidisciplinary approach. The clinicians should communicate with each other to provide the patient with an optimal treatment plan based on a scientific rationale.

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