Page 44 - REMOVABLE ORTHODONTIC APPLIANCES

36 Removable Orthodontic Appliances
Figure 5.1 An appliance to move a first molar
distally. To achieve maximum anchorage, the
larger section of the base plate contacts the
palate and all the teeth that are not being
moved.

however, the appliance should be split to take laboratory the overjet and the desired height of
into account the relative anchorage balance of the bite plane relative to the palate and the
the number of teeth to be moved and the teeth palatal surface of the upper incisors. This
required to resist the movement. If minimum enables the laboratory to construct the bite-
movement in the anchorage teeth is desired, plate to the correct size. The posterior limit of
the maximum number of anchorage teeth the bite plane should extend just sufficiently to
should be in contact with the acrylic of the engage the lower incisors and, ideally, the labo-
appliance (Figure 5.1). ratory should have the study models available to
check this dimension (Figure 5.2). Bite planes
should be made with the occlusal surface paral-
lel to the occlusal plane. Inclined bite planes
Bite planes
may sometimes be required, but may cause
The acrylic of the baseplate may be thickened proclination of the lower labial segment, which
anteriorly to provide an anterior bite plane or is usually an undesirable tooth movement.
extended to cover the posterior teeth to form a
posterior bite plane. Careful thought about the
design and construction of a bite plane can save
considerable chairside time later.

Anterior bite plane
The principal use of anterior bite planes is in
the reduction of overbite. This occurs primarily
by alteration in the rate of eruption of the
posterior teeth relative to the eruption of the
lower incisors that are in contact with the bite
plane. Overbite reduction by this method is
most successful in an actively growing patient.
In an adult, overbite reduction can sometimes
be successfully achieved using a biteplate, but
the amount of overbite reduction that can be
obtained is less than that for a child patient, Figure 5.2 An anterior bite plane to reduce the
takes time to achieve and may not remain overbite by allowing vertical development of the
posterior teeth. The bite plane should be thick
stable.
enough to separate the posterior teeth by 2-3 mm
When designing an appliance which includes and extend sufficiently to engage the lower incisors
an anterior bite plane, it is best to specify to the when the mandible is retruded.