Читать книгу Orthodontic Treatment of Impacted Teeth - Adrian Becker - Страница 30

Several systems of threaded pins (Figure 2.2) have been available for many years. Their original specific purpose was to provide retention for an amalgam or composite core and to allow the provision of a cast crown in a severely broken‐down tooth. However, these threaded pins have also been used in the past as the attachment for an impacted tooth [8, 9], although they have now been totally superseded by other methods of attachment. Some of the disadvantages of the threaded pins method include the fact that it is dentally invasive, necessitating subsequent restoration. Given the difficulties of access to many impacted teeth and the desirability of limiting surgical exposure as much as possible, it may be difficult to determine the orientation of the long axis of the tooth and the drilled hole may inadvertently enter the pulp. Moreover, unerupted and non‐functional teeth often have large pulp chambers. Even in the most favourable of circumstances, it seems that this unnecessarily aggressive method actually causes damage to a virgin tooth, in light of the fact that there are eminently suitable, non‐invasive methods and efficacious alternatives, as we shall discuss below. Nevertheless, the method was still in use and apparently recommended as late as 2004, which was, anachronistically, well into the present era of composite bonded attachments [8, 9].