Читать книгу Orthodontic Treatment of Impacted Teeth - Adrian Becker - Страница 27

For most malocclusions, quality treatment is best provided by the use of one or other of the recognized fixed appliance treatment techniques. If the dental arches are correctly related and adequate space is present, then the teeth are initially ‘levelled’ to a labial archwire of standardized archform and a given coefficient of elasticity. Later, heavier round or rectangular steel archwires are substituted to activate root movements that will pave the way to achieving an optimal result. In cases of incorrectly related dental arches, the use of other appliances is recommended, such as headgear, functional appliances or intermaxillary means of traction, prior to or together with the fixed appliances. Here, space may be provided by the extraction of teeth or by lengthening the arches mesio‐distally or expanding them laterally.

When dealing with a malocclusion that incorporates an impacted tooth, this procedure will need to be modified. Unlike other teeth in the mouth, the impacted tooth may be severely displaced from its normal position in all three planes of space, and much anchorage will be expended in bringing it into alignment. Accordingly, a rigid anchor base must be developed against which to pit the forces required to resolve the impaction.

At the age at which an impacted maxillary canine is treated, the full permanent dentition (with the exception of third molars) is usually present. Accordingly, a fully multibracketed appliance would normally be placed in position. With the use of light archwires, the entire dentition will be treated through the stages of levelling and the opening of adequate space in the arch for the impacted tooth. A heavy and more rigid archwire is then placed into the brackets on all the teeth of the fully aligned and complete dental arch. The aim of this is to provide a solid anchorage base [5, 6], which will not allow the distortion that may otherwise result from the forces that will eventually be applied to the impacted tooth after its exposure. One should not underestimate the demands made on the anchor unit by forces designed to resolve a grossly displaced canine, particularly if the forces are applied for an extended duration.

By contrast, at the age at which an impacted upper central incisor needs to be treated, only first permanent molars and three permanent incisor teeth are present in the maxillary arch. Accordingly, in order not to compromise the remainder of the dentition, it will be necessary to employ alternative means of making the appliance system rigid in order to oppose the light forces that will be applied to the impacted tooth. The anchorage value of the appliance may be enhanced by including a soldered transpalatal bar or by bonding brackets to the deciduous molars and canines.