CATEGORY 68 AUSTRALASIAN DENTIST LINICAL WHEN TO EXTRACT THE CANINE Extraction of the labially erupting and crowded canine is contraindicated. Such an extraction might temporarily improve the aesthetics, but may complicate and compromise the orthodontic treatment results, including the ability to provide the patient with a functional occlusion. The extraction of the canine, is an option in the following situations. u Tooth is ankylosed and cannot be transplanted, u If any external or internal root resorption and the root is severely dilacerated, u If the impaction is severe (e.g., the canine is lodged between the roots of the central and lateral incisors and orthodontic movement will jeopardize these teeth), u If the occlusion is acceptable, with the first premolar in the position of the canine and with an otherwise functional occlusion with well-aligned teeth, u If there are pathologic changes (e.g., cystic formation, infection), and/or the patient does not desire orthodontic treatment. 7. MANAGEMENT OF OTHER IMPACTED TEETH Impacted permanent mandibular canine The permanent mandibular canine fails to erupt less commonly than the maxillary and when this does occur, it is usually a consequence of crowding. These teeth are often vertically orientated, labially placed and will erupt spontaneously once space is available in the arch. If surgical exposure is required, care should be taken to ensure these teeth erupt through attached gingiva. Occasionally an impacted mandibular canine can fail to erupt andmigrate within the mandible, particularly if it is orientated horizontally. Then these teeth are not generally amenable to orthodontic traction and the options are then extraction or autotransplantation. When the crown of an unerupted mandibular canine is inclined more than 30 degrees to the median sagittal plane, orthodontic treatment may be necessary to correct the inclination. To uncover a bonding surface on the crowns; an apically and laterally retracted flap must be created without damaging the periodontal integrity of the adjacent lateral incisor. Once an attachment is bonded, the orthodontist can begin to move the impacted canine distally to correct its path of eruption. When insufficient space is available in the arch, the treatment plan may need to include extraction of premolars. When the unerupted mandibular canine has an inclination of more than 45 degrees, conservative treatment will be risky and uprighting the tooth into correct position will probably cause dehiscence of enveloping bone and serious periodontal defects. Impacted maxillary first permanent molar Impaction of a maxillary first permanent molar against the second deciduous molar occurs in around 4% of the population and is usually indicative of crowding in the posterior maxilla Management involves the following: u Clinical examination often reveals only the distal part of the offending first permanent molar erupted in the oral cavity. u Radiographic examination shows a mesially angulated first permanent molar impacted against the resorbing distal surface of the second deciduous molar. u Occasionally these teeth will spontaneously erupt but if this does not occur within 6–12 months, some intervention is indicated. u A separating elastic, spring or brass wire placed below the contact point between the permanent and deciduous molars, or distal grinding of the second deciduous molar can help to disimpact the first molar. u Extraction (or early loss due to resorption) of the second deciduous molar will relieve the impaction, but usually results in space loss affecting the second premolar region as the permanent molar drifts forwards into the space. Orthodontic intervention may then be required to upright a mesially angulated first permanent molar and regenerate the lost premolar space. u A removable appliance, incorporating a cantilever spring passing across the interproximal area mesial to the impacted tooth can be used to apply a distal force or a fixed appliance can also be used. 8. RETENTION Post treatment results of the impacted teeth in patients whose orthodontic treatment had been completed have an increased incidence of rotations and spacing on the impacted side in 17.4% of the cases. To minimize or prevent rotational relapse, a fibrotomy or a bonded fixed retainer may be considered. Clark suggested that after the alignment of palatally impacted canines, lingual drift can be checked by removing halfmoon shaped wedge of tissue from the lingual aspect of the canine which further improves retention. 9. CONCLUSION Early diagnosis and intervention could save the time, expense, and more complex treatment in the permanent dentition. With early detection, timely interception and well-managed surgical and orthodontic treatment, impacted maxillary canines can be allowed to erupt and be guided to an appropriate location in the dental arch. The management of impacted canines is important in terms of esthetics and function. When patients are evaluated and treated properly, clinicians can reduce the frequency of ectopic eruption and subsequent impaction of the maxillary canine. 10. SUMMARY The simplest interceptive procedure that can be used to prevent impaction of permanent canines is the timely extraction of the primary canines. This procedure usually allows the permanent canines to become upright and erupt properly into the dental arch, provided sufficient space is available to accommodate them. Various surgical and orthodontic techniques may be used to recover impacted maxillary canines. Careful selection of surgical and orthodontic techniques is essential for the successful alignment of impacted canines. u For a complete list of references email gapmagazines@gmail.com Dr Geoff Hall, Specialist orthodontist Founder and Director of OrthoED, Smilefast, CAPS and Clear Aligner Excellence Tel: 03 9108 0475 / geoff@orthoed.com.au Ceph of impacted molar angle to occlusal plane Impacted permanent mandibular canine
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