Physical and Learning Disabilities II
Down syndrome (DS), the most common cause of mild–moderate learning disability, is a chromosomal anomaly that results from the presence of an additional third chromosome 21. Due to its characteristic appearance and chromosomal disorder, Down syndrome has also been known as mongolism or trisomy 21. The incidence varies between one in 800 to 1000 live births. Increasing life expectancy of affected individuals means that most dentists will be called upon to treat children and adults with DS.
Learning disability is a universal feature of DS although the degree of learning disability in DS patients differs from individual to individual. However, most are able to communicate well and live semi-independently.
The oral/dental features are shown in Box 46.1.
- Open mouth posture due to the underdevelopment of the middle third of the face and poor muscle tone
- The tongue may be absolutely or relatively large and is often fissured, protrusive (tongue thrust)
- Lips tend to be thick, dry and fissured
- High incidence of severe, periodontal disease
- Palate often appears to be high, with horizontal palatal shelves but a short palate is more characteristic
- May exhibit congenital deformities such as bifid uvula, cleft lip and cleft palate
- Anterior open bite, posterior crossbite and other types of malocclusion common
- Maxilla is small and mandible is somewhat relatively protrusive
- Delayed development and eruption of teeth
- Hypodontia, with upper laterals and third molars missing most commonly
- Microdontia (in 30–50% of the cases)
- Hypocalcification and hypoplastic defects
- Low caries activity usually
- Short, small crowns and roots of teeth
- Parafunctional habit
- Difficulties in swallowing, speech and mastication
Specific Management Issues
Most DS children are amicable and can be managed with local analgesia with or without inhalation sedation, and good behaviour management. However, for the uncooperative DS patient, treatment under general anaesthesia may have to be considered. General anaesthesia, if required, should be administered by a specialist in a hospital. There is increased risk involved for DS patients due to the cardiac defects, intubation difficulties, increased susceptibility to respiratory infections and possibility of atlanto-axial subluxation.
Congenital heart defects (CHDs) affect around 40% of DS infants. The child may suffer from early pulmonary hypertension if the defect is large. Careful liaison with the paediatrician is essential. For patients who have no history of cardiac examination, it would be prudent to have one arr/>