964H
Fig. 14.24 (a) Surgical exposure of unerupted |1. (b) Orthodontic alignment of |1.
(note the poor gingival contour as a result of exposure). (c) Poor gingival contour
persists for several years after treatment.
965H
Fig. 14.25 Supplemental lateral incisor causing localized crowding.
14.6.2 Hypodontia
Any tooth in the arch can be congenitally absent but, aside from third molars, the
teeth most commonly affected are lower second premolars and upper lateral incisors
(966HChapter 13). Where one or two teeth are absent the orthodontic options are to open,
maintain, or close the space. Where multiple teeth are absent orthodontic treatment
may be able to give a more favourable basis for restorative replacement.
Second premolars
Where the arch is aligned or spaced the primary second molar should be left in situ,
but where there is crowding the space can be used for arch alignment. In the upper
arch, and in a significantly crowded lower arch, the primary second molar should be
retained until the start of orthodontic treatment. Where there is mild lower arch
crowding which is to be treated, the primary second molar can be extracted earlier to
allow some of the space to be lost to mesial drifting of the first molar.
Upper lateral incisors
Where one or both upper lateral incisors are absent in an uncrowded arch the excess
space is often distributed as generalized anterior spacing (967HFig. 14.26 (a)-(e)). An
upper fixed appliance can be used to localize the space in the lateral incisor area prior
to provision of bridgework. Some overbite reduction is often needed to create enough
interocclusal space for the retaining wings of the bridge. The bridge should not be
made for at least 6 months after removal of the fixed appliance, during which time a
removable retainer should be worn which has wire spurs to prevent any drifting into