Late Effects of Treatment to the Teeth

by Kevin Oeffinger MD and Nancy Keene
Source: Fall 2003 CCCF Newsletter

The development and appearance of teeth are sometimes affected by treatment for childhood cancer. Survivors at highest risk for problems are those whose teeth and gums were in the radiation field. Treatment with chemotherapy during the time teeth are developing can also affect dental health. Good dental care can help prevent these late effects from causing problems later in life.

Late effects to the teeth

Radiation to the jaws and teeth often causes dental problems. Abnormalities of the teeth that can develop include:

  • Absent teeth
  • Abnormally small teeth (microdontia)
  • Short or thin roots
  • Small crowns
  • Malocclusion (poor bite)
  • Poor enamel
  • Incomplete calcification
  • Frequent cavities
  • Enlarged pulp chambers
  • Baby teeth that don't fall out

These late effects are caused by direct radiation to the teeth-forming parts of the jaws. Cranial radiation (radiation of the whole brain sometimes used for children with medulloblastoma or leukemia) does not involve the jaw or mouth. Generally, cranial radiation does not cause problems with the teeth unless given to a very small child or baby. In these cases, the formation of the back molars is sometimes affected.

Little research has been done on the effect of chemotherapy on dental health. Some problems have been noted in small research studies, and many parents report problems with their children's teeth after treatment with chemotherapy only. Problems noted are:

  • More cavities than brothers and sisters
  • White or discolored patches on the tooth enamal
  • Grooves or pits in the tooth enamel

Because teeth develop slowly, it is possible that children treated for longer periods of time (children with certain types of leukemia or children who relapse) are more likely to develop these late efects than those treated for short periods of time.

The health of your teeth can also be affected if you have decreased saliva. Saliva is a mix of secretions from the parotid gland (near the ear), sublingual (under the tongue), and submandibular glands (under lower jaw) that lubricates the mouth and aids in taste and digestion. Diminished production of saliva (called xerostomia) affects overall well-being in many ways. A dry mouth can result in food not tasting good, teeth riddled with cavities, bad breath, and bone decay.

The dose of radiation to the saliva-producing glands and the percentage of the glands that are radiated affect the amount of saliva produced. Children treated for head or neck soft tissue sarcomas and medulloblastomas are most at risk. Survivors of Hodgkin's disease who had mantle radiation also can have problems with saliva production. Most glands regain the ability to secrete if the dose given was below 4000 cGy. The flow of saliva for leukemia survivors who had cranial radiation is usually not affected.

Frequent drinking and sometimes artificial saliva may be recommended if you have decreased salivary flow. Survivors with persistent problems with dry mouth can find information and support from the Sjogren's Syndrome Foundation at (800) 4-SJOGREN or www.sjogrens.org.

Evaluation

Survivors of childhood cancer should get a complete dental examination and cleaning every six months. Survivors who have crooked teeth, crowded teeth, or an improper bite need careful orthodonture. Before beginning any orthodonture, the orthodontist will need to carefully examine a panorex (full x-ray of the entire mouth) to evaluate root length and general health of teeth.

For many survivors, regular dental care and good home teeth care are all that is needed to maintain healthy teeth and gums. Others may need to take additional steps to protect themselves. For instance, survivors who were treated with chest or mantle radiation therapy sometimes have leaky heart valves. In the heart, there are four valves that act like one-way opening doors. When blood moves from one chamber of the heart to the next, or from the heart to the body, it passes through these valves. Radiation can injure the way these valves close, leading to some flow of blood back across the valve when the heart contracts. This backflow creates little eddy pools that stagnate on the back side of the valve.

When the teeth are cleaned, some bacteria that normally live in the mouth are released into the blood. This happens to all of us, and our bodies dispose of these bacteria without a problem. However, if someone has a leaky heart valve, some of the bacteria can get into the stagnant pool behind the valve and stick to it. This can rarely lead to a very serious problem where an infection can severely damage the valve.

This problem is very easily prevented by taking a dose of antibiotics one hour before having the teeth cleaned. This dose of antibiotic very effectively kills all of the mouth bacteria before they can cause a problem.

How do you know if you need antibiotics before getting your teeth cleaned? If you had chest or mantle radiation to treat your cancer, you should talk with your physician about having an echocardiogram (ultrasound of the heart) if you have not had one in the previous year. This test shows if there are any leaky valves. People with leaky valves require antibiotics before every dental cleaning. An excellent site containing the American Heart Association recommendations for antibiotic prophylaxis for dental procedures is:

www.qualitydentistry.com/dental/information/abiotic.html

Survivors who have an endoprosthesis (limb salvage surgery) are also at risk for bacteria attaching to the prosthesis. People with an endoprosthesis should also take an antibiotic before dental cleaning.

If you have any questions about these risks, talk with your health care provider and your dentist. Regular dental cleaning is very important to the health of your teeth!

Dr. Kevin Oeffinger MD directs a multidisciplinary program for young adult survivors of childhood cancer at UT Southwestern at Dallas TX and is partially supported as a Robert Wood Johnson Foundation Generalist Physician Faculty Scholar. He enjoys backpacking, running and hiking with his family.

Nancy Keene is the author of Chemo, Craziness And Comfort, My book about childhood cancer; Childhood Leukemia; Childhood Cancer (with co-author Honna Janes-Hodder); Your Child in the Hospital; Working with Your Doctor;and Childhood Cancer Survivors (co-authored with Wendy Hobbie RN and Kathy Ruccione). She is former Chair of the Patient Advocacy Committee of COG (Children's Oncology Group) and mother of a survivor of high risk ALL.