CATEGORY 62 AUSTRALASIAN DENTIST LINICAL Impacted teeth are those which are prevented from erupting by some physical barrier in the eruption path or when the crown remains at some distance from the alveolar crest after its scheduled eruption time because of an insufficient roomor an ectopic eruption pattern. Tooth impaction can be defined as the infraosseous position of the tooth after the expected time of eruption, whereas the anomalous infraosseous position of the canine before the expected time of eruption can be defined as a displacement. Most of the time palatal displacement of the maxillary canine results in impaction. The treatment of this clinical entity usually involves surgical exposure of the impacted tooth, followed by orthodontic traction to guide and align it into the dental arch. Bone loss, root resorption, and gingival recession around the treated teeth are some of the most common complications. 1. PREVALENCE u Maxillary canines are the most commonly impacted teeth, then third molars followed by premolars and maxillary second molars. u It occurs in approximately 2% of the population and is twice as common in females as it is in males. u Incidence in maxilla is more than twice that in the mandible. u Of all patients, 8% have bilateral impactions and approximately one-third of impacted maxillary canines are located labially and two-thirds are located palatally. Theories associated with Impaction Two major theories have been associated with palatally displaced maxillary canines: u Guidance theory proposes that the canine erupts along the root of the lateral incisor, which serves as a guide, and if the root of the lateral incisor is absent or malformed, the canine will not erupt. u Genetic theory points to genetic factors as a primary origin of palatally displaced maxillary canines and includes other possibly associated dental anomalies, such as missing or small lateral incisors. Baccetti (AO 1998) reported that palatally impacted maxillary canines are genetically associated with anomalies such as enamel hypoplasia, infraocclusion of primary molars, aplasia of second premolars, and small maxillary lateral incisors. 2. ETIOLOGY Most common causes of canine impaction are: u Arch length discrepancy u Abnormal developmental position of the tooth germ u A palatally impacted canine could be because of genetic predisposition. It could also be because of missing lateral incisors. u Deviation from the normal path of eruption is usually associated with subsequent impaction and in the vast majority of cases this occurs in a palatal direction, although the canine can also impact on the buccal side or within the line of the dental arch. Management of impacted teeth Dr Geoff Hall By Dr Geoffrey Hall A number of reasons have been suggested to explain the deviation of maxillary canine from its normal eruptive path: u A developmental position that begins high in the maxilla and results in a long path of eruption; u Relying upon the maxillary lateral incisor root for guidance of eruption, which can be lacking if these teeth are diminutive or congenitally absent; u Retention of the deciduous canine obstructing normal eruption; u Chronology of eruption, in the maxillary arch the canine often erupts after the first premolars and therefore space can be of significance; u A genetic susceptibility and occurrence of other dental anomalies in association with ectopic maxillary canines. 3. SEQUENCE OF CANINE IMPACTION Shafer et al (1963), suggested the following sequelae for canine impaction: 1. Labial or lingual malpositioning of the impacted tooth, 2. Migration of the neighboring teeth and loss of arch length, 3. Internal resorption, 4. Dentigerous cyst formation, 5. External root resorption of the impacted tooth, as well as the neighboring teeth, 6. Infection particularly with partial eruption, and 7. Referred pain and combinations of the above sequelae. 4. DIAGNOSIS OF IMPACTION The diagnosis of canine impaction is based on both clinical and radiographic examinations. a. Clinical signs might be indicative of canine impaction: u Delayed eruption of the permanent canine or prolonged retention of the deciduous canine beyond 14–15 years of age, u Absence of a normal labial canine bulge, u Presence of a palatal bulge, and
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