Aetiology and frequency
- hypohidrotic ecotdoermal dysplaisa (HED) is usually transmitted as an x-lined reisccive trait in which the gene is carried by the female nad manifested in the male
- The prevalence in the population has been assesed as 1:10,000 and 1:100,000
- For x-linked HED, male incidence is significantly higher than female incidence
Diagnosis
- based on the episodes of hyperpyyerxia, lack of type of the hair, absence of teeth and tooth buds and tooth morphology
- Peeling of the skin at birth, eczema, asthma, and frequent respiratory infections may be additional clues
- However, during ealry infancy diagnosis is difficult because manifestations invloving teeth, hair and inability to sweat are hard to detect
- Other diagnnostic criteria have been dermatoglyphic analysis, characteristics of lacrimal secretion and distributino and pattern of scalp hair. Missing teeth can also be an important sign
Classification
Four primary defects
Ed1: trichodysplasia (hair dysplasia)
- fine scanty, light coloured hair which thickens and darkens as patient grows up
- eyebrows and beard hair are scant etc
ED2: dental dysplasia
- tooth abnormalities may become apparent during lactation as hypoplasia of the alveolar crests
- Anterior teeth exhibit more morphologic discrepencies
- within the famillies, same family or between the sexes a great degree of variatio ncan be seen regarding tthe number of missing and malformed teeth
- commonest abnormality would be a tooth with a cone or peg shaped crown
ED3: onychodysplasia (nail dysplasia)
- Nail disorders range from an almost normal appearance to miconychia (nails that are smaller than normal) or anonychia (failure to form nails)
- The nail plate may show thickining
ED4: Dyshidrosis (sweat gland dysplasia)
- The most common deffects are the hypohydrotic ectodermal dysplasia
- -consists of subgroup 1,2,3,4
- then its hydrotic
- subgroup 1,2,3 Case: five yera old male
- prominent forehead
- saddle shaped nose
- prominent lips
- sparse , dry scalp hair, eyelashes and eyebrows
- Apparent anodontia
- there will be very few teeth in the alveolar ridge
- Hand with convex nails
- Foot with nail dysplasia
- dehydrated foot
Terminology relevant to missing teeth
- anodontia is a rare genetic disorder characterised by the congenital absence of all primary or permanent teeth
- oligodontia is defined by the lack of at least six teeth
Oligodontia
- patients with oligodontia can be classfied into three different types according to their clinical presentation an dcomplexsity of their prosthodontic requirements
- The occlusal features regarded as being clinically relevant in determining the complexity of future prosthodontic needs for a patient with oligodontia and the pre- prosthetic tx reqruied to achieve these goasl
- number, location and type of missing permanent and retained primaries
- The presence and spance of current or potential edentulous spaces. The latter includes retained primary teeth with no permaent successeors. at this evaluatoin, an assessment is made as to wehther the spans could be orho reduce in size or eliminated
- the presence or absnce of occlusal contact involving a permanet tooth in the molar region
Type 1 Oligodontia
- The dental arch is often intact and well developed due to the presence of permanent teeth, and when absent, the retention of their primary predecessors
- There is always bilateral molar support. the large number of permanent and primary teeth means that there is generally ample alveolar bone with few areas of localized bone deficiency. These are associated with edentulous areas and the mandibular anterior region, even when primary teeth are retained
- if present edentulous spans are on to two teeth wide (6-14 mm)
Type 2 oligodontia
- large numbers of missing permanent teth in localized areas and the rention of variable numbers of primary teeth
- lack of uni- or bilateral posterior molar support and in some cases, the absnece of permanent teeth distal to the canine
- ample alveolar bone where teeth are preseent. significant areas of localized and in some cases generalized bone deficiency
- Potentially useful permanent teeth may be positioned unfavourably and in poor aesthetic and functional locations