Page 55 - REMOVABLE ORTHODONTIC APPLIANCES

Chapter 7

Class I malocclusions

A class I malocclusion is one in which there is late mixed dentition phase, without the use of
no skeletal discrepancy. The relationship any appliances (Figure 7.1).
between the upper and lower arches is essen- In view of the speed with which spontaneous
tially normal and (barring early loss of primary tooth movement can occur in children in this
molars) the molar relationship in the antero- age range, it is often wise to maintain the arch
posterior plane is class I. Within this generally
satisfactory occlusal relationship there may be
a number of local problems for which appliance
therapy can be appropriate. The role of the
removable appliance in dealing with such prob-
lems will depend upon the precise nature of the
tooth displacement and whether the simple
mechanics offered by removable appliances can
achieve the necessary corrective movements.
Two groups of cases can be identified. First,
those cases where the sole problem is one of
crowding and where the role of the appliance is
essentially one of space maintenance. Secondly,
those cases where there are local tooth
displacements which can be corrected with
active components (with or without associated
extraction).
Many of the appliances and tooth move-
ments described in this chapter may also be
used in the treatment of both class II and class
III malocclusions.

Space maintenance

In a small proportion of cases the primary prob-
lem is crowding and there are no specific local Figure 7.1 In a class I occlusion when 4|4 are
tooth displacements. Occasionally, such a extracted for the relief of buccal segment crowding, a
malocclusion may be treated by carefully space maintainer needs to be fitted when the space
planned extractions, usually at the end of the available for 53|35 reduces to 16 mm.