Trisomy 21

Syndrome: Trisomy 21 (Down Syndrome)
Etiology: 94% caused by nondisjunction of chromosome 21. 1 in 600 to 1 in 700 births. Incidence increases with maternal age- 1 in 50 for mothers over 45 yrs old. Possible etiologies include unknown mosaicism in a parent, repeated exposure to the same environmental insult, genetic predisposition to nondisjunction, an ovum with extra chromosome 21
Diagnosis: chromosomal analysis is necessary. Prenatal diagnosis is widely available.
Systemic/Medical Conditions: Mental retardation (most mild-moderate, some severe) Congenital heart disease present in 30-45% of patients. One study showed 50% prevalence of MVP. Respiratory tract infections extremely common. T and B-cell function is affected. Thyroid dysfunction in 50% of all patients.
Oral Manifestations:
Craniofacial: brachycephalic skull, prominent forehead. Frontal and sphenoid sinuses are absent, hypoplastic sinus hypoplastic in 90% of patients. Midface skeletal deficiency, ocular hypotelorism, flattened nasal bridge, mandibular prognathism
Intraoral: fissured tongue, macroglossia, open mouth posture (mouth breathing, protruding tongue), high-arched palate, occasional bifid uvula or cleft palate. Perio disease very prevalent. Caries incidence no greater—increased buffering capacity of saliva due to increased calcium, bicarbonate in saliva possibly.
Dentally, eruption delay in both dentitions evident in 75% of cases. Hypodontia and microdontia common. Crown/root malformations often present. Enamel hypocalcification occurs in 20%. Posterior crossbites, anterior openbites, severe anterior crowding common.
Dental needs/considerations: PREVENTION! Follow AHA antibiotic prophylaxis guidelines for patients with CHD.
Recent Info: 2010 study found about 60% of DS patients had missing teeth.