Profound hypomineralization leads to teeth so soft that they are reduced in size
although this is, in fact, a later change.
Molar-incisor hypoplasia
In recent years reports have been published of children with mineralization defects of
the first permanent molars and, sometimes, the permanent incisors. This has been
referred to as molar-incisor hypomineralization or hypoplasia and also as 'cheese
molars' because of the friable nature of the enamel of the molar tooth enamel.
Although the condition would seem to have a chronological distribution (833HFig. 13.29
(a) and (b)), close inspection will often show 'un-matched' teeth to be affected⎯teeth
that would have been forming at the same time do not present with symmetrical
affliction. Only one molar, or perhaps three of the four, may be affected. The defects
in the incisors⎯which are usually less severe and most likely to show isolated
mottling⎯will likewise be irregularly distributed. (834HFig. 13.30 (a,b, and c)). To the
best of our knowledge, this is the first publication of such a familial association.
The cause of this anomaly, and even whether it represents a new phenomenon, is
uncertain. It has been suggested that there might be a genetic predisposition
combining with an environmental insult that produces these changes, but this has yet
to be substantiated.
Treatment
The condition is problematic for both patients and practitioners. The destruction of the
molar teeth in particular, although probably a post-eruptive change, presents in many
cases at a time when children are not acclimatized to dental treatment. Treatment
options should include a careful analysis of the occlusion, since many of the molar
teeth are severely compromised, and the child may benefit in the long term by their
elective loss as part of a comprehensive treatment plan. For the 2 years between the
eruption of the first permanent molar teeth and the commonly recommended time for
their removal, management may be difficult. It is clear that many children with this
condition are apprehensive patients for dental treatment. This is likely to be because,
in its early stages, practitioners adopt a minimalist approach with the attempted use of
fissure sealants and adhesive restorations. These are often applied without local
anaesthesia, are painful in the process, and frequently unsuccessful anyway.
Preformed metal crowns applied under local anaesthesia provide a useful measure in
these cases.
The incisor defects are not noticeably uncomfortable and should be managed with the
techniques described in 835HChapter 10.
'Environmentally determined' enamel defects
Enamel defects may arise as a result of an 'environmental' insult. Within this sense we
include both a systemic upset and the result of a local factor involving a developing
tooth (as discussed previously in 836HSection 13.7).
Where there is a systemic insult the teeth will be affected in a chronological pattern,