Treating Kids With Trisomy 21

Trisomy 21, or Down syndrome, is the most common chromosomal disorder, affecting approximately one in 700 live births.¹ It is characterized by an extra copy of chromosome 21, usually due to nondisjunction of the chromosome, resulting in physical and developmental disabilities. According to estimates, more than 250,000 Americans live with trisomy 21,² and between 1979 and 2003, there was more than a 30% increase in the number of babies born with the disorder.³ Additionally, survival rates have improved over the past several decades.^4,5 Due to the relatively large population of affected individuals and high frequence of occurrence (compared with other chromosomal disorders), there is an increasing need for oral health professionals to care for these patients. Many children with trisomy 21 can be seen in private dental settings for routine care—but in order to provide safe and effective treatment, clinicians should possess a thorough understanding of the patient’s condition.

Nondisjunction of chromosome 21 can occur in multiple ways. Most commonly, it happens on the maternal or paternal side during meiosis; however, most cases occur from the maternal chromosome set.⁶ Increasing maternal age is a known risk factor for nondisjunction.⁷ Trisomy 21 can also occur from other genetic abnormalities. For example, up to 5% of individuals with trisomy 21 have a rare form due to mosaicism, where some cells in the body have a normal chromosomal makeup, and a percentage of cells has the extra 21st chromosome.⁸ This happens due to abnormal cell division after fertilization. A third rare form, seen in up to 4% of affected individuals, occurs when a segment of chromosome 21 is transferred and attached to another chromosome, which is inherited along with two normal copies of chromosome 21.⁹ Because translocation trisomy 21 can be inherited from a parent with the translocation, families who have children with this form of trisomy 21 are at risk of passing on the abnormality in future pregnancies.⁹

Prenatal screening has become a routine step in diagnosing trisomy 21. The emergence of advanced, less-invasive screening techniques has led to relatively high specificity and sensitivity when screening for trisomy 21 during pregnancy.¹⁰ With the discovery of cell-free fetal DNA circulating in maternal plasma, it is now possible to screen with a false positive rate of 0.3%, compared with a false positive rate of 3.6% in standard serum biochemical assay screening.¹¹ This screening, along with traditional screening techniques—such as amniocentesis and chor­ionic villus sampling—offer valuable early diagnostic tools for families.¹²

COMMON CHARACTERISTICS

Typical features of trisomy 21 include upslanted eyes with prominent epicanthal folds, a small chin and head, flat nasal bridge, single deep crease in the palms, Brushfield spots (small pale spots in the iris of the eyes), and hypotonia.¹³ This disorder is also characterized by mild to moderate levels of cognitive impairment, and, in some instances, severe impairment. The severity of symptoms and clinical manifestations vary, particularly in mosaic trisomy 21, as the extent of the manifestations depends on the proportion of abnormal to normal cells in the body.

Children with trisomy 21 are at risk of other comorbidities as well (Figure 1), some of which can be fatal. For example, nearly 50% of these children are also born with congenital heart defects, most commonly atrioventricular septal defects, atrial septal defects, and ventricular septal defects.¹⁴ Mortality from congenital heart defects has decreased over the years, in part due to early intervention and advancing surgical techniques—but they are still a major cause of death.^14,15 Additionally, children with trisomy 21 face increased risk for developing leukemia; consequently, they must be carefully followed as they grow.^16,17 Many also have some degree of hearing loss or chronic otitis media.¹⁸ This can be treated early on with interventions, such as ear tube placements.^19,20 Other common comorbidities include eye disease, thyroid disease, epilepsy, and obstructive sleep apnea (OSA).^13,21

Trisomy 21 also presents with common orofacial findings. These include large, fissured lips, macroglossia, and a narrow, vaulted palate, which can contribute to OSA, as well as a heightened gag reflex. These patients may also have malocclusion related to an underdeveloped midface, resulting in a Class III appearance, as well as delayed eruption, congenitally missing teeth, or malformations of the teeth, including conical shapes, hypoplasia, and microdontia.^22,23

MEDICAL CONSIDERATIONS IN ORAL HEALTH CARE

Oral health professionals need to consider systemic health issues when treating a child with trisomy 21, starting with maintaining a diligent health record and coordinating consults among specialists when warranted. In children who have congenital heart defects or undergone recent cardiac surgeries, oral health professionals should verify any current cardiac concerns, and confirm with the child’s cardiologist if antibiotic prophylaxis is recommended as a preventive measure against bacteremia-induced infective endocarditis. Of note, the American Heart Association recommends a move away from antibiotic prophylaxis for at-risk children in the dental setting, and an increasing emphasis on maintaining proper oral hygiene and oral disease prevention.²⁴

Compared to the general population, children with trisomy 21 are at a greater risk for cervical spine instability (also known as atlanto­axial instability). This is an abnormality of the junction between the cervical vertebrae—the atlas (C1) and axis (C2)—that results in excessive mobility at the articulation of the two vertebrae. Cervical spine instability affects be­tween 10% to 30% of children with trisomy 21.²¹ Most children who have the congenital abnormality, however, are asymptomatic.²⁵ Because hyperextension or radical flexion of the hypermobile joint can result in spinal compression and neurologic injury, children with trisomy 21 may have imaging to screen for cervical spine instability, particularly if they wish to participate in sports.

Oral health professionals should be aware of any medical concerns for cervical spine instability in patients with trisomy 21, especially when considering restraint or protective stabilization for young or potentially uncooperative children during treatment. Prior to using protective stabilization, dental teams should confirm if a child’s cervical spine has been evaluated. For patients with cervical spine instability, parents and caregivers may offer valuable insight into best practices to protect the child’s spine in these situations, including the use of pillows and management of body positioning in the dental chair.

Due to an association between trisomy 21 and hypothyroidism, many affected children are followed regularly by a pediatric endocrinologist.^26,27 The American Academy of Pediatrics Committee on Genetics recommends annual thyroid screenings into adulthood for children with trisomy 21.²⁸ If thyroid dysfunction is uncontrolled or poorly managed, practitioners should be aware of the risks of hypothyroidism-induced low blood pressure, cardiac output, and respiratory rate in the dental setting.

Up to 13% of children with trisomy 21 may also have some form of seizure disorder.²⁹ These can vary in type and severity, and may neurodevelopmentally impact the growing child.³⁰ Having a discussion with the child’s parents/caregivers regarding how a typical seizure presents, as well as their established seizure protocol, provides crucial information for clinicians in the event of seizure activity in the dental office.

OROFACIAL CONSIDERATIONS

Children with trisomy 21 can present with dental needs complicated by the physical manifestations of the chromosomal abnormality. Because these children often have some degree of developmental delay, they may have poor motor skills, resulting in an inability to brush their teeth effectively, and may be unable to chew and cleanse food from the mouth with their tongue due to generalized hypotonia. While they are still generally at lower risk for caries than individuals without trisomy 21, these children are at higher risk of developing periodontal diseases.³¹ This may be due to generalized immunodeficiencies, malocclusion, malformed dentition, and high numbers of periodontal pathogens in their oral microbiome.³² Among this population, between 58% and 96% of patients younger than 35 have some degree of periodontal disease.³³ Early intervention is important, and these patients may benefit from more frequent recare appointments and the use of chemical adjuncts, such as chlorhexidine rinses, to improve periodontal therapeutic outcomes.³⁴

Parents/caregivers often have questions regarding the way their child’s teeth look, as well as how they are positioned, as they may associate malocclusions with poor oral health.³⁵ Encouraging parents/caregivers to bring the child in for routine visits as early as possible creates opportunities to provide anticipatory guidance to families. This includes discussing the possibility of missing or malformed teeth, crowding, delayed eruption, and malocclusion as the child develops. Obtaining a panoramic radiograph once the child is mature enough can aid confirmation and observation of dental anomalies, and facilitate any discussions about possible orthodontic interventions.³⁶

Craniofacial abnormalities associated with trisomy 21 play a significant role in the high prevalence of OSA in these patients. Approximately 70% of children with trisomy 21 also have OSA³⁷—and midface hypoplasia, macroglossia, a high and narrow palate, narrow nasopharynx, and generalized hypotonia are all contributing factors. Children diagnosed with OSA are at risk of neurodevelopmental consequences, regardless of whether a chromosomal abnormality is present.³⁸ While the use of continuous positive airway pressure to treat OSA can be highly effective, it can also increase the risk of xerostomia. In light of the typical mouth-breathing habits seen in these patients and potential intake of xerostomia-inducing medications, children with trisomy 21 should be evaluated for adequate salivary flow to help reduce caries risk. Encouraging parents/caregivers to provide ample fluoridated water and to use fluoride products can help alleviate this concern.

Due to the relatively high risk of leukemia in children with trisomy 21, clinicians should also maintain awareness of common oral manifestations of leukemia and be vigilant in screening for potential symptoms in this population. The most common early manifestations of leukemia include spontaneous gingival hemorrhaging and gingival enlargement;^39,40 however, this can be complicated by poor oral hygiene and other periodontal concerns.

ORAL HEALTH PROFESSIONALS AS ADVOCATES

Children with special needs can present challenges when providing routine dental care. Having a detailed appreciation of each child’s unique medical and orofacial considerations can help clinicians provide optimized care for children with trisomy 21. Some children may need protective stabilization to safely conduct an examination, or patients may have extensive dental needs requiring comprehensive care in a hospital setting. Others may have sensory and cognitive difficulties, resulting in challenges in tolerating dental prophylaxis and treatment, managing the gag reflex, or taking dental radiographs. Yet, many of these children can eventually succeed in any environment when given the opportunity, enough time, and proper encouragement.

Many children with trisomy 21 can learn to cooperate in the dental office. Behavior management techniques, such as desensitization, the tell-show-do approach, and positive reinforcement, can improve behavioral outcomes and encourage patients to practice good oral hygiene at home.²³ Combined with early intervention and education involving families and caregivers, children with trisomy 21 can maintain a healthy dentition, as well as a positive outlook on dental care. By devoting the time and effort to work with these patients to discover their motivators, stressors, and behavioral boundaries, dental teams can establish long-lasting relationships with these children and provide a dental home for their special health care needs.

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From Dimensions of Dental Hygiene. February 2020;18(2):26–29.