955H
Fig. 14.21 Impaction of |6 causing distal resorption of teeth.
14.6 ANOMALIES OF TOOTH SIZE AND NUMBER
14.6.0 Introduction
These anomalies are discussed in 956HChapter 13, but their clinical management often has
orthodontic implications.
14.6.1 Supernumerary teeth
Supernumerary teeth are very common in the premaxilla, and can interfere with the
eruption of normal teeth, or cause localized crowding if they erupt. In terms of clinical
management, supernumeraries in the upper labial segment fall into three groups:
- Conical supernumeraries are usually close to the mid-line between the central
incisors (mesiodens), and are usually one or two in number. They are sometimes
inverted, and their positions can range from having erupted to lying above the incisor
apices. The majority do not prevent eruption of incisors, but may cause some
displacement or a median diastema, in which case they should be extracted (957HFig.
14.22). They should also be extracted if they erupt or if the adjacent incisors are to be
moved orthodontically. However, they can otherwise be left in situ if high and
symptom-free. - Tuberculate supernumeraries are the main cause of failure of eruption of upper
permanent incisors (958HFig. 14.23 (a) and (b)). Early detection improves the prognosis
for treatment. A central incisor which fails to erupt before the adjacent lateral incisor
should be radiographed, and any supernumerary teeth localized (see 959HSection 14.5.3).
These should be removed surgically as soon as possible, and it is essential that the
space is maintained or, if already lost, re-opened with an appliance. About 75% of
unerupted incisors erupt spontaneously within 2 years of removal of supernumeraries,
so it is worth waiting for at least 18 months before considering surgical exposure.