Page 9 - REMOVABLE ORTHODONTIC APPLIANCES

Chapter 1

Introduction

Removable appliances are, by definition, appliance, but it may, nevertheless, continue to
orthodontic appliances that can be inserted and be the appliance of choice for selected cases.
removed by the patient. They comprise a Removable appliances can also have a role in
number of components, each of which will be combination with fixed appliances and can be
described, along with their clinical uses, in particularly useful in carrying out local, inter-
separate chapters. ceptive tooth movements in the mixed denti-
Removable appliances began to be used tion. They are effective space maintainers and
routinely in the 19th century, but these were are used almost universally as retention appli-
relatively crude devices, constructed from ances after the completion of active tooth
vulcanite, with precious metal wires and some- movements for cases treated with fixed appli-
times depending for their action on the expan- ances.
sion of hickory wood pegs when soaked by In some areas of clinical activity, removable
saliva. Complex removable appliances, often appliances have significant advantages over
relying upon the action of expansion screws, fixed appliances. A well-constructed maxillary
were evolved in the early part of the 20th removable appliance can be highly conserva-
century. tive of anchorage. Intraoral anchorage is not
Modern removable appliances generally use only provided by the teeth themselves but also
acrylic baseplates and stainless steel wires. supplemented by the contact of the acrylic
With the development by Adams of the modi- baseplate with the palatal vault. This is particu-
fied arrowhead clasp (1950) the scope and effi- larly useful where it is necessary to achieve
ciency of these appliances was greatly occlusal movement of misplaced or impacted
increased. Unfortunately, they often repre- teeth, for example in the correction of
sented the only available method of treatment unerupted incisors and canines. Traction can be
and, as a result, were commonly used to treat a applied to these teeth to bring them down to
wide range of malocclusions for which they the occlusal level using the palate as anchorage.
were inadequate and unsuited. In recent years A fixed appliance is, by contrast, much more
fixed appliance techniques have been trans- likely to intrude and tip the adjacent teeth.
formed, particularly with the introduction of Inexperienced practitioners often assume that
preformed bands and com.ponents, direct removable appliances demand little skill and
bonding techniques, pre-adjusted brackets and, that their design can safely be left to the labo-
more recently, by the advent of pre-formed ratory. In reality, considerable skill is required.
archwires in stainless steel as well as non- If an appliance is to be exploited to its full
ferrous alloys. These advances, coupled with potential it must be thoughtfully designed, well
the growth of orthodontic specialization, have constructed and carefully supervised. The
inevitably diminished the role of the removable general practitioner can, with suitable training.