Laura Valdez
Dental Hygiene Program
Spring 2000, Phoenix College
  Printed with the permission of Debby Kurtz-Weidinger, RDH, M.Ed.
Department of Dental Programs
Phoenix College

Individuals with Down syndrome are now living more productive, fulfilling and independent lives. Routine dental visits will play an important role in the overall health of the patient with Down syndrome.

Down syndrome is the most prevalent chromosomal disorders and most frequently recognized cause of intellectual disabilities, it occurs approximately once in every 700 births and is seen in all ethnic groups (Selikowitz, 1997). The earliest recording of Down syndrome is believed to have been painted in Aachen, Germany around 1505 A.D.. Down syndrome was recognized in 1828 by Dr. John Landon Down. But not until 1932 was Down syndrome recognized as a possible chromosome abnormality and confirmed in 1959 by Dr. Lejeune in Paris.

Down syndrome is a developmental disorder and associated with an extra chromosome involving number 21 chromosome pair. Normally the cells in the body have 46 chromosomes, except for the sex genes, which contain 23. Down syndrome is caused by the faulty chromosome separation during conception. There is a slight predominance in males over females. Down syndrome has three chromosomal disorders, which attribute to its cause, Trisomy 21, translocation and mosaicism (Selikowitz, 1997).

When Down syndrome is caused by an extra whole chromosome 21, it is known as Trisomy 21, it is the commonest form, responsible for 95% of the cases (Selikowitz, 1997). Instead of each chromosome moving in opposite direction to become part of one of the two new cells, they both move together failing to separate (Selikowitz, 1997). This process is known as non-disjunction, because the pair of number 21 chromosomes in the original cell dose not separate (disjunct), but remains together in one of the new cells (Selikowitz, 1997).

Many factors have been noted; genetic predisposition, exposure to radiation and presence of thyroid antibodies have been linked, but the most significant factor is the age of the mother, over 35 years. The eggs in a woman are present at birth, maturing as she ages vs. a male, sperm formation begins at puberty and regenerate in a 10 week cycle (Selikowitz, 1997). Which would reduce chances for genetic error.

Translocation is responsible for 4% of the cases with Down syndrome, it occurs when the presence of an extra part, rather than the whole of chromosome 21 stick to another chromosome (Selikowitz, 1997). Usually this occurs on chromosome 13,14,15 or 22 the most common is 14. Children with translocation or Trisomy 21 are equally affected genetically. There is no significant difference in the severity of mental or physical involvement (Selikowitz, 1997). One third of sperm or eggs can be carriers for translocation, it is this reason why testing is done on children with Down syndrome.

Mosaicism is usually associated with less markedly affected individuals, because of the counteracting effect of the normal cells (Selikowitz, 1997). Individuals with mosaicism often have less prominent physical features of Down syndrome and develop and function closer to the normal range (Selikowitz, 1997). Mosaicism is thought to be due to an error in one of the first few cell divisions, later when the baby is born one can find some cells with 47 chromosomes and others cells with the normal number of 46 chromosomes (Pueschel, 1990).

The physical characteristics of Down syndrome are as followed:

Head - brachycephaly (flat back of head), small rounded, fontanels are larger and sometimes take longer to close. The face is rounded with a flat profile. The ears are prominent, malformed with small or absent lobes. The eyes tend to slant upward and epicanthic folds (small folds of skin which run vertically between inner corner of the eye and bridge of nose). Brushfield spots can also be present in the eyes (white or light yellow speckling around the rim of the iris). The hair tends to be soft and straight and the neck is broad and short.

Body size is smaller at birth and usually shorter than expected compared to other family members. The chest tends to be funnel shaped (concave) or pigeon breast (convex).

The hands are short, broad with horizontal creases across the palms. The fingers are also short; with the pinky usually only having one joint and it is slightly more curved when compared to the other fingers. The fingerprints often have a characteristic pattern (Selikowitz, 1997). The feet tend to be stubby with a gap between the first and second toe and a gap is present across the sole of the foot.

Down syndrome individuals tend to have diminished muscle tone, which cause subluxation (dislocation of two bones) of the knee caps or hips (Selikowitz, 1997). Low muscle tone also affect the head and neck region. Atlanto-axial instability is a condition of increased mobility between the C1 and C2 cervical vertebrae and may be seen in 10-20% of individuals with Down syndrome, which would lead to spinal cord compression (Pilcher, 1998).

The orofacial characteristics are as followed:

The face tends to be somewhat flat contour, due to underdeveloped facial bones and small nose (Pueschel, 1990). Absent or reduction in size of frontal and maxillary sinus is common (Pilcher, 1998). The oral cavity tends to be underdeveloped and the palate is narrow and higher than normal. Crowding and delayed eruption of the primary and permanent teeth are common. True macroglossia is rare, rather a relative maroglossia is found where the tongue is normal size but the oral cavity is decreased in size due to the underdevelopedment of the midface (Pilcher, 1998).

Although individuals with Down syndrome can be recognized because of their similar physical appearance, not all such individuals look the same; some of the features will change over time (Pueschel, 1990).

Individuals with Down syndrome develop at a slower rate and stay at that stage longer than an individual without disabilities. Language, communication, social, emotional and cognitive developments are all closely related to all areas of development (McClurg, 1986). Most Down syndrome individuals have a mild to moderate range of IQ (Pilcher, 1998). As more is learned about how to tap their potential and just what the full extent of that potential is, people with Down syndrome will become even more intergraded into their schools and communities (Kumin, 1994).

Although 40 to 50% of individuals with Down syndrome are born with some type of cardiac abnormality, most receive surgical corrections within the first few years of life (Pilcher, 1998). Atrioventricular septal defect, ventricular septal defect, patent ductus arteriosus and Tetralogy of Fallot are a few of the heart conditions that may be encountered by Down syndrome individuals. These conditions can lead to the abnormal blood flow through the heart, which may encourage bacteria to multiply and cause infection within the heart (Selikowitz, 1997). Approximately 50% of adults with Down syndrome have Mitral Valve Prolapse requiring subacute bacterial endocarditis prophylaxis (Pilcher, 1998).

Compromised immunity is more common in Down syndrome individuals leading to upper respiratory infections, glue ear (bacterial infection in the Eustachian tube of the middle ear, which prevent drainage to back of the throat) and periodontal disease. Investigation have reported that individuals often have fewer blood cells (specific lymphocytes), which are important in the general defense of the body (Pueschel, 1990).

Hypothyroid can be seen at birth or acquired later in life. Down syndrome individuals are affected by Hashimoto thyroiditis (inflammation of the thyroid gland) at a rate of as many as one out of five and 20% of children are detected with thyroid disorders. It is important to examine thyroid function to prevent any further brain damage. Regular medical checks to detect health problems are recommend for Down syndrome individuals.

The most devastating dental concern relates to periodontal disease and gingivitis. Early to severe periodontal involvement is seen in about 90% to 96% of adults with Down syndrome, this is thought to be related to a lower host immune response due to the compromised immune system (Pilcher, 1998). The amount of plaque and calculus are not significant enough to cause the severity of periodontal disease found in Down syndrome individuals. The mandibular incisors and maxillary molars tend to be more involved.

Dental decay in Down syndrome is extremely low and this may be due to delayed eruption of the teeth, increased spacing between teeth or possible differences in the chemical content of the saliva (Pilcher, 1998). Microdontia and hypodontia are common in the primary and permanent dentition (Ilsem/Phelan, 1996); in spite of this Class III malocclusions are still common with severe crowding.

Mouth breathing leads to xerostomia and deep fissures in the tongue tend to trap bacteria, which causes halitosis. Angular cheilitis, aphthous ulcers, oral candida infections and acute necrotizing ulcerative gingivitis occur at a greater incident (Pilcher, 1998). Sleep apnea has been reported as high as 31% in children with Down syndrome (Pilcher, 1998).

Early aggressive treatment and frequent visits, as often as every three months for scaling and root planning and also benefits from the use of chlorhexedine mouth rinse and possibility of systemic antibiotic therapy (Pilcher, 1998) may be necessary to control any periodontal disease.

Due to delay of eruption in permanent teeth, the primary dentition should be maintained as long as possible (Pilcher, 1998). Solution for severe crowding is selective extractions under supervision of an orthodontist (Pilcher, 1998).

The use of topical and systemic fluoride can greatly reduce the rate of decay for Down syndrome patients. If no fluoride is provided in the water, supplement fluoride tablets can be used along with fluoride containing toothpaste, a fluoride varnish can also be applied in the dental office. The use of sealants also plays an important role in prevention of decay.

Determining the level of communication is very important in developing a cooperative relationship with the Down syndrome patient. The assistance of the patient's family or caregiver will be necessary in conveying to the dentist and staff what level of communication should be used (Pilcher, 1998).

Early assessment of oral hygiene facilitates treatment planning and provides an opportunity to asses the patient's or caregivers understanding of and motivation for preventive dental procedures (Lange, 1983). Show and tell instructions on brushing and flossing should be presented at a slower pace and should involve the parent or caregiver since many Down syndrome patients do not have the dexterity to properly floss or brush. Supervision is a must and a controlled diet with limited low sugar snack should be the rule of thumb starting at an early age.

There is a higher incidence of epilepsy, diabetes, leukemia and other conditions, therefore the importance of a thorough medical history including a work up by a physician can not be over emphasized (Pilcher, 1998). Due to the Atlanto-axial instability caution should be used when positioning the dental chair to avoid any harm to the spinal cord (Pilcher, 1998).

Dental care for people with Down syndrome can be met in a general dentist office (Pilcher, 1998). If provided with the best medical and dental services, the quality of life of individuals with Down syndrome will be enhanced and their contributions to society will be greatly increased.

Reference List

Ibsen/Phelan, Olga A.C., Joan (1996) Oral Pathology for the Dental Hygienist. 2nd edition, W.B. Saunders Company.

Kumin, Libby (1994) Communication skills in children with Down syndrome: A guide for parents. Woodbine House Inc.

Lange, Brian Mark (1983) Dental Management of the Handicapped. Lea & Febiger.

McClurg, Eunice (1986) Your Down's Syndrome Child. Doudleday & Company, Inc., New York.

Pilcher, S. Elizabeth (1998) Dental Care for the patient with Down Syndrome. Down Syndrome Research and Practice, Vol. 5, No. 3, 111-116.

Pueschel, Siegfried M. (1990) A Parent's Guide to Down Syndrome: Toward a brighter Future. Paul H. Brookes Publishing Co.

Selikowitz, Mark (1997) Down Syndrome: the facts. 2nd ed. Oxford University Press Inc., New York