PAEDIATRIC DENTISTRY - 3rd Ed. (2005)

the supporting tissues, causing localized gingival recession (918HFig. 14.10). Early
correction encourages development of a class I occlusion, and treatment in the mixed
dentition is often straightforward provided that these criteria are met:

1. Normal skeletal pattern. Treatment of obvious class III problems should be delayed
   until the nature of the patient's growth pattern becomes clearer. However, it is
   essential to check for the presence of a forward displacement of the mandible, as this
   can make a normal facial pattern appear to be slightly prognathic.


2. Adequate space in the arch. There must be enough space to accommodate the tooth
   in alignment. In a crowded upper arch, space may be made for alignment of upper
   lateral incisors by extracting the primary upper canines (see serial extraction, 919HSection
   14.3.2). This treatment must be started fairly early while the permanent canine is still
   high, because labial movement of the lateral incisor will be prevented if the canine
   crown is labial to the root of the lateral. It is therefore essential to palpate the position
   of the permanent canine crown, and, if it has come down too far, treatment must be
   delayed until the first premolars have erupted.


3. Adequate overbite. Stable correction of the cross-bite depends on there being
   positive overbite after treatment. Labial tipping of upper incisors with a removable
   appliance tends to reduce overbite, and specialist advice should be sought where lack
   of overbite is a problem.

There are many designs of removable appliance to correct anterior cross-bites and a
typical example is shown in 920HFig. 14.11 (a) and (b). Its essential features are:

1. An active component such as a Z-spring or a screw palatal to the tooth to be moved.


2. Retention as far anteriorly as possible to resist the tendency of the spring to displace
   the front of the appliance.


3. Posterior capping to open the occlusion while the upper incisor moves labially over
   the lowers.

921H

Fig. 14.10 Localized gingival recession

associated with incisor cross-bite.

922H

Fig. 14.11 (a) and (b) Appliance to

procline upper incisor. Note posterior

capping to disengage occlusion and

retention anterior to 6|6 to resist the

displacing force generated by the Z-