Impacted incisors, canines, premolars, and second molar are problems encountered frequently by general dentists, orthodontists, and oral and maxillofacial surgeons. The etiology of impacted teeth is multifactorial. Traditional radiographs can be used for location of the impacted tooth but 3-D CBCT is superior in evaluating the tooth’s position. Successful management requires an interdisciplinary approach with an orthodontist responsible for the overall success of the treatment plan. Surgical exposure of these impacted teeth is accomplished using an open or closed surgical procedure. Choosing the appropriate surgical procedure and orthodontic treatment plan will result in a stable, predictable, and aesthetic result.
The management of impacted permanent teeth requires a team effort with input from the orthodontist, general dentist, and surgeon to develop a satisfactory treatment plan.
It is important to evaluate the 3-dimensional position of the impacted tooth to the roots of the adjacent teeth to determine the proper treatment plan.
A full orthodontic evaluation is required before any surgical intervention.
The oral and maxillofacial surgeon must decide whether an open or closed exposure procedure should be performed and provide optimal condition for the orthodontist to apply the correct forces for alignment.
Bonding position on the impacted tooth depends on the intended direction on traction forces to be applied. The orthodontist should determine this position.
The management of impacted teeth other than third molars is one of the most challenging and complicated types of dento-alveolar surgery. Proper diagnosis and treatment planning requires interdisciplinary care by an orthodontist, general dentist, and oral and maxillofacial surgeon but the orthodontist is responsible for the overall success of the treatment plan.
The most common impacted teeth aside from the third molar are maxillary canines, maxillary second molar, mandibular second premolars, and mandibular second molar ( Fig. 1 ). There are systemic and local factors that contribute to the impaction of these permanent teeth. The contributing factors include arch length discrepancy, space deficiencies, ankylosed primary teeth, pathology, trauma, and some systemic and genetic factors. Although the incidence of impacted teeth differs in diverse populations, Dachi and Howell reported the incidence being as low as 0.92%for maxillary canines (with most being unilateral), 0.40% for mandibular premolar, 0.13% for maxillary premolar and 0.09% for mandibular canines. Although the overall incidence of impacted teeth, excluding third molars, is rare, it is important that every oral and maxillofacial surgeon understands all treatment options and their management. The appropriate surgical procedure and orthodontic treatment plan will result in a stable, predictable, and aesthetic result.
Surgical exposure of these impacted teeth is accomplished using various approaches. We discuss surgical techniques used to expose the impacted canine, central incisor, premolar, and second molar.
Impacted maxillary canine
Calcification of the maxillary canine starts at 4 to 5 months and erupts into the oral cavity in 11 to 12 years. It remains high in the maxilla above the root of the lateral incisor until the crown is calcified. The maxillary cuspid erupts along the distal aspect of the lateral incisor. This closes the physiologic diastema present between the maxillary central incisors. The maxillary canine travels almost 22 mm during the time of eruption. It should erupt before 13.9 years for girls and 14.6 years for boys. The etiology of impaction is unclear but most likely multifactorial. Because the maxillary canine has the longest path of eruption in the permanent dentition, alteration in position of the central and lateral incisor may be a factor. Arch length discrepancy and space deficiency may result in the canine becoming labially impacted. Studies have shown a higher incidence of palatally impacted canines in cases with missing lateral or peg-shaped incisors. Failure of the primary canine to resorb may cause palatal movement of the permanent canine ( Fig. 2 ). However, Thilander and Jacobassom considered failed of resorption of the primary canine to be a consequence rather than a cause of impaction. A genetic predisposition has been shown in some studies. For example, Pirinen found that palatally impacted canines are genetic and related to incisor-premolar hypodontia and preshaped lateral incisors.
Other possible causes are trauma to the anterior maxilla at an early age, pathologic lesions, odontomas, supernumerary teeth, and ankylosis. There is also a higher incidence of impacted maxillary canine following alveolar bone grafting in the cleft patient.
Diagnosis of the maxillary canine position is a key factor in the comprehensive assessment of the impacted canine. The position of the impacted canine is important when deciding management options for the patient. Localization requires inspection, palpation and radiographic evaluation. The position of the lateral incisor can also give a clue to the canine position. The crown of the lateral root may be proclined if the canine is lying labial to the lateral incisor. Occasionally the impacted canine can be palpated on the labial or palatal aspect. The surgeon can take a series of periapical radiographs along with a panoramic radiograph to locate its position. When taking the series of periapical radiographs, the cone head is shifted horizontally so Clark’s Rule can be used to discern the buccal or lingual position of the canine. The 3-dimensional (3-D) cone beam computed tomography (CBCT) is superior in determining the location of the impacted canine but is costly ( Fig. 3 ). If you need to extract the over retained primary canine, the resorption pattern on the root will give you a clue as to localization of the crown of the impacted canine. In some cases, you can feel the crown when giving your infiltration anesthesia on the buccal and palatal mucosa ( Fig. 4 ).
All patients require a thorough clinical evaluation, which should include a visual and tactile examination. The radiographic evaluation should include 2-D radiographs and possibly a 3-D CBCT if the tooth is not palpable, then a comprehensive treatment plan can be developed. An informed consent with discussion of treatment options and alternatives is a must to avoid misunderstanding, which could lead to legal problems. Proper management of the impacted canine can include one of the following treatment options:
No treatment with periodic clinical and radiographic observation.
Interceptive removal of the primary canine.
Surgical extraction of the tooth
Surgical exposure to aid eruption.
Surgical exposure with eruption aided by orthodontic guidance.
Autotransplantation of the canine
There are 3 methods used for surgical exposure and orthodontic alignment , .
Open surgical exposure.
Surgical exposure with packing and delayed bonding of the orthodontic bracelet.
A surgical exposure and bonding of orthodontic bracelet intraoperatively.
If the canine has the correct inclination, the open surgical exposure is the treatment of choice. It has been shown that excision of the gingival over the canine with bone removal is sufficient to allow eruption of the canine.
Chapokas and colleagues introduced a new classification for maxillary canine impactions that included guidelines for selecting the proper surgical approach. The classification included 3 categories. Class I for impactions located palatally, Class II for impactions located labial or center of the alveolar ridge and Class III for impactions located labial to the long axis of the adjacent lateral incisor root. Surgical technique was gingivectomy for Class I, closed exposure for Class II and apically positioned flap for Class III. ,
Flap design is dictated by the location of the impacted canine. If the impacted canine is located buccally, a gingival crest incision can be made in the gingival sulcus. If the impacted canine is high, the incision can be made horizontally above the papillae. Vestibular incisions made at the level of the mucogingival junction should be made only when the impacted canine is above the root apices.
If the impacted canine is palatal, a palatal incision placed in the gingival sulcus can be performed. Palatal incisions placed between the gingival crest and palatal vault should be avoided because trauma to the greater palatine artery could occur. Occasionally, the impacted canine can be positioned transversely in the alveolus. This would require mucoperiosteal flaps on the palatal and labial sides.
Surgical exposure with orthodontic alignment
If surgical exposure with orthodontic alignment has been chosen as the method of treatment, 3 surgical approaches can be used. The closed exposure technique replaces the mucoperiosteal flap over the exposed canine after the bracket and chain is applied. The disadvantage of this technique is that bonding can fail and reexposure is necessary. The window technique removes the gingiva overlying the crown of the impacted canine. The apically repositioned flap technique is used to preserve the attached gingival ( Fig. 5 ). Vermette and colleagues found that apically repositioned flaps resulted in more esthetic problems than the closed exposure technique. The goal is to choose a technique that exposes the canine within a zone of keratinized mucosa without involvement of the cemento-enamel junction. This minimizes potential periodontal and esthetic complications following orthodontic alignment.
If the inclination of the canine to the midline is greater than 45° then the prognosis for alignment worsens. The closer the impacted canine is to the midline the worse the prognosis.
Application of orthodontic traction devices
Many different devices can be applied to the crown of an impacted canine. These include a wire, pins, crown formers, orthodontic brackets, and temporary anchorage devices (TADs). Wires and pins are no longer placed around the crowns of impacted teeth because they can injure the crown or root of the tooth. The use of crown formers placed or cemented over the crown of the impacted tooth was popular for many years. However, the crown formers would also act as a foreign body causing inflammation and eruption. The device of choice is an orthodontic bracket or gold mesh disk with a gold chain bonded onto the canine crown surface ( Fig. 6 ).
There are 2 types of bonding agents that can be used. One is a 2-part self-cure bonding agent and the other is a light cure bonding agent. The advantage of the light cure materials is most can work in a partially wet field. The gold mesh disks work much better than the orthodontic brackets or buttons with the light cure bonding agent. The curing light is able to get at all the bonding agent through the mesh. Because it cannot cure the bonding agent under the bracket, a light cure bonding agent that will also self-cure is preferable.
The tooth surface must also be acid etched. Successful bonding of the bracket improves with hemostasis. Once hemostasis is achieved, the bonding agent is placed on the bracket and pressed firmly against the enamel surface of the tooth. If it is a light cure material, it should be light cured for 20 to 40 seconds ( Fig. 7 ).