Important Dental and Orthodontic Issues for Children with Kabuki Syndrome

Oral health is important for all children but is especially important for children with special medical and/or developmental challenges. Children with Kabuki Syndrome have a complex array of special features and functional challenges. Good oral health and proper dental follow up is an important element in the overall care pathway for these children. This paper outlines important issues in dental development, oral health care, facial growth and development and orthodontic care.

Facial Growth Patterns

Children with Kabuki Syndrome have characteristic facial features that have been well documented and described in the literature and this paper will not describe these in detail. As we well know, there is classically some flatness in the cheek areas below the eyes and lack of forward projection of the cheek bones. The lower portion of the face is often disproportionately long compared to typically developing children. This pattern of facial features is rooted in the growth patterns of the jaw structures and the neuromuscular environment. In this paper we will focus on the underlying facial development which has implications for facial pattern, jaw alignment, dental development, and oral health.

dental 1

Overall jaw growth and bite relationships are classified into three patterns (Class I, II and III). These patterns result from the relative growth of the two jaws and can be seen in Figure 1. If the upper and lower jaws are in balance this is called a Class I pattern. The bite will be ideal in the molars and the front teeth with the lower front teeth biting slightly behind the upper front teeth. The facial profile will be ideal as well. A Class II pattern occurs when the lower jaw is shorter than the upper which alters the bite on the molars and front teeth. In these children the lower front teeth fit well behind the upper front teeth and commonly these children are said to have an “overbite”. These children have a profile where the chin seems receded and/or the upper front teeth appear to protrude. A Class III pattern occurs when either the upper jaw is too short or the lower jaw is too long or both. In children with a Class III pattern the lower front teeth are in front of the upper front teeth and this is called a crossbite. The facial profile will seem like the chin is protrusive. Jay Leno is a good example of a person with a Class III jaw growth pattern.                                                                                    

dental 2                                dental 3                                                          

In the Caucasian population Class III patterns are seen in between 1 and 3% of the population. For children with Kabuki Syndrome this is much more common and is the most frequent jaw development pattern. In many children with Kabuki Syndrome this is due to underdevelopment of the upper jaw relative to the lower. Children who have this pattern of jaw growth have less projection in the cheek bone area and the face may appear flatter than ideal in this area. Due to the jaw growth pattern it is also more common to see a crossbite of the front teeth with the lower front teeth in front of the upper. Figures 2 and 3 show a laterali jaw x ray and tracing of a 12 year old male with Kabuki Syndrome. His Class III pattern shows the upper jaw behind the lower and lower front teeth which are ahead of the upper front teeth. Children with Kabuki Syndrome also often have a tendency to a long lower facial proportion. This relates to a lower jaw which is canted downwards more steeply than ideal. The feeling is that this relates to the neuromuscular pattern where the jaw muscles are more lax allowing the lower jaw to develop at a steeper angle. Figure 4 shows a jaw x ray tracing of a 7 year old girl with Kabuki Syndrome. The lower jaw angle is steep when compared to a tracing of a typically developing child (Figure 5).

dental 4                         dental 5                                                         

The tendencies to have length and angular imbalances in jaw development have significant implications for facial growth, the bite and for potential orthodontic treatment. From the parents perspective it can cause a disconcerting change in the bite as the child matures. Often when the baby teeth are present the bite may look fine to the parent but as the jaw development progresses the bite may become more noticeably irregular. This usually becomes more obvious when the permanent teeth are beginning to erupt. Often this is when the child will be taken for a consultation with an orthodontist. For children with Kabuki syndrome, it is especially important that the orthodontist do a thorough evaluation of the underlying jaw development pattern in advance of initiating any orthodontic treatment. The biting pattern of the teeth is most often a result of the growth pattern of the jaws and not just malposition of the teeth. Treatment options must be carefully assessed in order to optimize outcome. Given the pattern of the neuromuscular environment, children with Kabuki Syndrome may not have the same options for orthodontic treatment as typically developing children where sometimes during growth muscle forces can be harnessed to improve the bite and jaw positions. In children with Kabuki Syndrome with significant jaw length abnormality or vertical jaw imbalance ideal correction may necessitate integrating jaw repositioning surgery into the orthodontic management plan. Obviously careful evaluation of the child’s overall medical and developmental status is important prior to considering significant treatment like jaw repositioning surgery.

Other Important Oral Findings

Once there is an understanding of the overall jaw development pattern there are other important oral and dental development issues.

First it is important to realize that over 50% of children with Kabuki Syndrome have some significant cardiac anomalyi. For certain dental procedures and with certain types of cardiac issues it will be necessary to provide prophylactic antibiotic coverage in advance of many dental appointments. The American Heart Association has recently revised the guidelines for antibiotic premedication for children with cardiac irregularities (April 2007). It is important that your dentist be familiar with the new guidelines.

The literature shows that high arched palate is common in children with Kabuki syndrome. Cleft Palatei occurs in excess of 50% of the children. Cleft Palate has significant implications for breathing, feeding, speech, jaw development and dental development. Optimum management for children with cleft palate requires a coordinated management plan from the time of birth. The management plan should involve a team of specialists who will provide well coordinated care for all of these significant issues.

In addition to some degree of laxity of the muscles that position the lower jaw, children with Kabuki Syndrome also have a higher risk of laxity in the ligament and muscular structures that position the temporomandibular joint (TMJ) which is the hinge between the base of the skull and the lower jaw. Although the literature doesn’t indicate that a high proportion of the children have problems with dysfunction of the TMJ it is important for the child’s dental professional to monitor the function of the joint during routine checkup visits.

Children with Kabuki Syndrome commonly have dental anomalies that can affect the shape, size and number of teeth. The two upper front teeth (central incisorsi) often have a characteristic shovel shape where the lower edge of the tooth is narrower than the mid portion. This is opposite to the normal shape of this tooth where the lower edge is the widest part of the tooth. This is a dental anomaly that is very rarely found in other children and the presence of shovel shaped central incisors is one diagnostic sign that is helpful in formulation of a diagnosis of Kabuki Syndrome. The dentist can improve the shape of the central incisors with simple cosmetic bonding materials. Children with Kabuki Syndrome often have agenesisi or lack of formation of one or more permanent teeth resulting in missing permanent teeth. This most commonly involves the upper lateral incisors which are the teeth next to the big front ones (central incisors). When permanent teeth are missing there are a number of management options that your dentist can consider and discuss with you.

Maintaining Basic Dental Health

For any children with special health needs the maintenance of good dental health is very important. Children with Kabuki Syndrome can have intellectual and behavioral parameters which make dental treatment difficult. For these children it is extremely important to prevent dental disease in order to avoid the need for treatment which could be difficult to accomplish.

In simple terms there are two dental diseases that should concern any parent. One is dental cariesi or what is commonly referred to as decay or cavities. The second is inflammation or infection of the gum tissue which is periodontal disease. Usually in children severe periodontal disease is uncommon but gingivitis which is an early stage of the disease is much more common. Both cavities and gingivitis have a common cause in that certain types of bacteria in the mouth digest sugar containing foods and secrete acids and toxins which attack the teeth and the gum tissue.

Preventing cavities and gingivitis is therefore relatively straightforward with three key actions by parents and children being important. One is to disrupt the bacteria and food that is left around the teeth by at least twice daily tooth brushing. Also in a child who is cooperative, flossing is of great value in cleaning the areas between the teeth that can’t be reached by the toothbrush. Second, teeth can be strengthened by the use of fluoride which hardens the tooth enamel and makes it more resistant to decay. The fluoride can come in many forms including community water fluoridation, fluoride in toothpaste, fluoride supplements by prescription if you live in an area where the water is not fluoridated, or professionally applied fluoride treatments. The third factor in preventing dental disease relates to control of the diet. Sugar containing foods provide food for the bacteria and also if a child snacks frequently (or constantly) there are some natural cavity healing mechanisms in the mouth that don’t have a chance to work. Many of the dietary habits that increase a child’s risk for cavities also are unhealthy for other concerns like childhood obesity.

Regular ongoing dental care is an important part of good medical care for a child with Kabuki syndrome. The American Academy of Pediatric Dentistry recommends the first dental visit be around one year of age. This provides an opportunity to have a base line evaluation, have your questions addressed and with the dentist develop a long term plan to assure the child will grow with good dental health. In a child with complex long term health and developmental needs it is even more important to get a very solid and early start on good oral health.