Oral health problems and their management in patients with Down Syndrome—a narrative review

Poor oral hygiene, improper brushing techniques, and a high frequency of carbohydrate consumption have been noted in some DS patients [23,24]. Some authors reported decreased saliva flow in patients with DS [25,26,27], associated with low pH [26,28] and buffering capacity [28], although in the study by Cogulu et al. salivary flow rate, pH, and buffering capacity were similar in the DS and control groups [29]. It has been suggested that psychosocial stress in the institutionalized individuals, who do not live with the family, decreases their saliva flow and salivary immunoglobulin levels [25] and aggravates immunodeficiency [30]. Besides, prescribed medications may cause xerostomia, which can further compromise oral hygiene in these patients [31].

Despite these challenges, individuals with DS generally have relatively low dental caries rates [7,27,31,32]. Several factors may contribute to this phenomenon, according to various studies.

The presence of congenital hypodontia and microdontia in individuals with Down syndrome may result in lower caries indices compared to healthy individuals of the same age. Additionally, spacing between teeth can lead to lower rates of interproximal caries [27,31,33].

The study by Cogulu et al. revealed that the patients with DS had significantly higher levels of salivary IgA, which resulted in lower susceptibility to dental caries [29]. Conversely, Chauschu et al. noticed that the salivary secretion rate of IgA in DS patients was 85% lower compared to the controls [25]. According to Areias et al. [27] the IgA secretion rate in Down syndrome children was 29% lower but not significantly different.

The reason for heterogeneity in the results of different studies could be the age of the participants with DS. Chauschu et al. have shown that older individuals with the syndrome have lower salivary IgA levels compared to younger individuals, due to immunodeficiency that intensifies with age [25].

Areias et al. [27] compared risk factors for dental caries in children with Down syndrome and their siblings. The results showed that children with DS had lower Mutans streptococci counts than their siblings, despite lower salivary flow rate. The authors concluded that the lower exposure to cariogenic microflora may contribute to the reduced caries rate in children with Down syndrome.

Although the above-mentioned studies have reported lower caries indices in individuals with DS, participants of the studies by Moreira et al. [34] and Hashizume et al. [35] had caries experiences similar to those of healthy children.

The variation in reported caries rates in children with Down syndrome can be attributed to possible differences in caregiver attitudes and practices towards maintaining oral hygiene and dietary differences, including the frequency of sugar intake, access to regular dental care, and preventive measures [36,37]. Socioeconomic factors may also influence caries rates in DS patients, with those in institutions often experiencing lower rates, possibly due to positive caregiver attitudes [33,36].

Regardless of dental caries susceptibility, early prevention is crucial for maintaining good oral health in individuals with DS. Dentists and hygienists should emphasize the importance of tooth brushing, fluoride application, fissure sealants, and dietary counseling as preventive measures to improve oral health outcomes in this population [32].

Patients with Down syndrome demonstrate an increased likelihood of developing periodontal disease at an early age [12]. Commonly observed periodontal problems in DS patients include gingivitis, prominent horizontal bone loss, advanced periodontitis, and remarkable tooth loss. The periodontium in DS patients shows higher levels of bacteria such as Streptococcus constellatus, Treponema socranskii, and Propionibacterium acnes, which are commonly associated with periodontal diseases [32]. Improper oral hygiene habits and inadequate dental plaque control may further deteriorate periodontal problems of DS patients [38].

The concentration of uric acid, an antioxidant that protects cells and tissues in the mouth from oxidative damage, is higher in DS patients compared to healthy individuals [30,39,40]. Elevated uric acid levels in the saliva of individuals with Down syndrome are primarily due to genetic factors, such as the overexpression of the superoxide dismutase 1 (SOD1) gene and altered purine metabolism, as well as physiological responses to increased oxidative stress [30,41,42].

Reuland-Bosma et al. have noted that DS patients are more prone to acute necrotizing ulcerative gingivitis (ANUG), which can lead to symptoms like gingival swelling, bleeding, and pain [30].

In a study by Satir, alveolar bone loss in DS patients was found to be more pronounced than in healthy individuals [8]. The most common type observed was horizontal bone loss, which tends to have an earlier onset and shows a more severe and generalized progression, often connected with a clinical attachment loss of more than 4mm [38,43,44].

The function of phagocytic cells is linked to the loss of periodontal attachment. However, the intensity of monocyte phagocytosis is identified as a more significant predictor of periodontal attachment level than the granulocyte phagocytic activity [43]. In individuals with DS, the correlation between monocyte phagocytic intensity and loss of attachment appears to be stronger than in individuals without DS. This could be due to the effect of having an extra copy of chromosome 21, which is known to encode various proteins involved in the generation of oxygen radicals [43]. High salivary levels of superoxide dismutase activity in DS patients confirm the significant impact of oxidative stress on the early onset of periodontal disease [45].

On the other hand, some DS patients exhibit lower expression of the TNFSF13B gene, which is involved in the activation and proliferation of B-cells. This reduced expression can lead to a higher susceptibility to periodontal disease due to immune and inflammatory deregulation [46].

The high incidence of type 1 diabetes mellitus and immunosuppression in DS patients [47] can lead to oral candidiasis [27]. DS individuals with oral candidiasis often show impaired antibody opsonization, which reduces phagocyte function and makes them more susceptible to bacterial and fungal infections [30]. Prophylaxis and preventative oral hygiene management are essential for DS patients. The use of mouth rinses with chlorhexidine gluconate and regular dental check-ups can help maintain their oral health [1,48].

Individuals with Down syndrome who have congenital heart defects may need prophylactic antibiotics before certain dental procedures. This precaution is to prevent infective endocarditis. This decision should be guided by current medical guidelines and tailored to the specific needs of the patient in consultation with their healthcare providers. It is crucial to assess the type of congenital heart defect and the nature of the dental procedure to determine the appropriate use of antibiotics [49,50].

Electromyography (EMG) examinations reveal that activation of the masticatory muscles in DS patients is often deficient, possibly due to hypotonic muscles and muscle hypotrophy resulting from anatomical abnormalities [19,51]. This muscle weakness may lead to difficulties in swallowing, feeding, and chewing [7,19,52].

Patients with DS often experience difficulties in all three phases of swallowing. During the oral phase, challenges such as atypical chewing patterns, inadequate lip closure, a relatively large tongue, and malocclusion extend the duration food remains in the mouth. Anatomical irregularities and weakened masticatory muscles contribute to prolonged chewing times and decreased chewing frequency. In the pharyngeal phase, delayed muscle responses can increase the risk of choking. Additionally, incomplete mastication combined with reduced muscle tone in the digestive tract can lead to food and gastric acid reflux. This reflux is a potential precursor to gastroesophageal reflux disease (GERD), chemical erosion of the teeth, and suboptimal nutrition [53,54].

To manage feeding difficulties, the caregiver can support the cheek and chin, reduce the time of feeding, and place the patient in an upright position to avoid improper reactions. Early intervention and regular monitoring of body weight are essential to ensure proper nutrition for the growth of DS patients [55,56].

Mouth drooling in patients with DS is often attributed to incomplete lip closure, reduced oral cavity space, and an enlarged tongue. Compared to controls, individuals with DS exhibit an approximate 36% reduction in salivary flow rate [27].

Behavioral issues significantly impact the provision of appropriate dental care for patients with Down syndrome (DS). These individuals often exhibit refusal and uncooperative behaviors during dental treatments. Their selective attention deficits can contribute to difficulties in remaining engaged in a task [2,4].

There are traditional behavioral methods useful in managing dental fear and anxiety in these patients. Methods such as tell-show-do, positive reinforcement, distractions, shaping, and systematic desensitization are recommended [1].

While audiovisual distraction is an effective method for healthy individuals to distract attention from anxiety and fear in a dental clinic, it is less effective for DS patients. Traditional methods have a better effect than the audiovisual method for DS patients for a number of reasons. One of these could be that DS patients may have cognitive disorders. Another reason could be that the dentist cannot directly communicate with the patient during the treatment if audiovisual methods are used [4].

Pharmacological behavior management is essential to effectively manage disruptive behavior during dental treatment in DS patients. General anesthesia is widely used in dental clinics to treat DS patients with behavioral disorders. Oral sedation, such as the administration of Midazolam before treatment, is a relatively safe and short-acting option, with effects lasting 20 to 30 minutes [2].

The family plays a crucial role in the oral care of individuals with DS. Therefore, prioritizing oral hygiene education for families and establishing effective communication with dental professionals is imperative to protect DS individuals from oral diseases [38,57].

Early treatment intervention shows some positive effects on improving gross and fine motor control of Down syndrome patients [58]. Orthodontic treatment with an orthodontic palatal plate therapy (OPPT) is a method to correct physiological dysfunction, especially when combined with other treatments such as speech or manually stimulated physiotherapy treatment [1]. An orthodontic plate can provide the maximum contact for the maxilla and mandibular arches to improve the occlusal surface contact. An intraoral orthodontic appliance can improve the patient’s mandible position, enhance activation, and increase masticatory frequency on the EMG, but it’s still uncertain whether it makes the masticatory function more efficient [51,59]. Giannasi et al. noticed that applying neuromuscular electrical stimulation (NMES) on the masseter helps strengthen and maintain muscle mass. It can be the treatment of choice for hypotonic muscles and can improve physiological problems such as swallowing and mastication [60].

Active muscle training exercises, such as myo-functional therapy, have been shown to improve functional movement in DS patients aged 9 to 18 years [61]. Regular home exercises for children with DS have a positive effect on lip seal, activation of facial expression and strengthening of the masticatory muscles, changing the tongue from a protruding position to a proper resting position, and establishing proper nose breathing [62,63]. After this exercise protocol, mouth breathing, the wrong position of the tongue, incomplete lip seal, and hypotonicity of masticatory muscles can improve [61].

Carlstadt et al. mentioned the positive effect of special physical exercise and speech intervention on swallowing pattern and occlusion by improving the coordination of masticatory and facial muscle groups [63,64,65].

Down syndrome patients with temporomandibular joint (TMJ) disorders present with myofascial pain, restricted mouth opening, and bruxism [66]. To help these patients, physiotherapists can educate them on reducing forward head posture and coordinating strengthening exercises. Electrotherapy and manual therapy with facial massages for relaxation can also improve TMJ conditions [67,68,69].

According to Chen et al., mechanical motor-assisted cycling and voluntary exercises with music improve motor ability, which can help maintain proper oral hygiene [67]. Riding the modified bicycle with machine-assisted pedaling at high speed increases the sensory input from the gross motor exercise, which stimulates the motor cortex to improve fine motor skills of the upper extremities [70,71].