January, 2008
Orthodontic Characteristics of Thalassemia Patients
Dr. Mohamad Azhar Ibrahim Kharsa, DDS, PhD. Orth
Abstract
In this article, the author discusses the cephalometric characteristics of Thalassemia Patients, compares them to normal values, analyses the cephalometric radiographs and suggests appropriate treatment approaches for thalassemic patients.
Discussion
Thalassemia is an inherited disorder of hemoglobin (Hb) synthesis. [1] It varies, from an asymptomatic to severe, [1] and varies according to the blood hemoglobin chain affected. The chain affected influences the age of symptom onset (α Thalassemia affects the fetus, β Thalassemia the newborn). [1] The name Thalassemia is a Greek term derived from Thalassa meaning “the sea”, plus Emia “pertaining to blood”.
Thalassemia is also called Mediterranean anemia, however, it is not restricted to the Mediterranean area.
Thalassemia Classification
- Thalassemia Major: Thalassemia major is the homozygous form.
- Thalassemia Minor: Heterozygous form, usually asymptomatic.
- Thalassemia Intermedia: Homozygous form, however, it does not require transfusion, as patient maintains physiologically tolerable hematocrit levels. [1]
Other Thalassemia classifications are: α Thalassemia, β Thalassemia, γ Thalassemia and δ Thalassemia indicating which blood hemoglobin chains are affected. [1,2]
Roentgenographic Features
- The radiographic changes in thalassemia are derived from the erythroid hyperplasia of the bone marrow. [3]
- The erythroid hyperplasia of the marrow results in widening of the marrow space, thinning of the cortical plates, and a granular osteoporosis. [1]
- In the more advanced state: partial or total atrophy of the cortical plates is seen, with “hair-on-end” spiculation of bone.
- The frontal bones reveal the earliest and most severe changes, whereas the inferior bones usually remain unaltered [2] Figure 1.
Maxillofacial Structures of Thalassemia Major
- Marrow hyperplasia of the skull (may involve the facial bones as well) Figure 1. Figure 2.
- Expansion of the facial bones in infancy and early childhood inhibits pneumatization of the maxillary sinuses. [1,3]
- Maxillary alterations may laterally displace the orbits leading to hypertelorism or “pseudo-overgrowth of maxilla”, result in malocclusion of the jaws and displacement of the dental structures resulting in a “rodent” face, “or Chipmunk Appearance”. Figure 1. Figure 2. Figure 3.
- The intercanthal space has higher than normal values, as a result of facial expansion. Figure 6.
Figure 1. Rodent Face,”Chipmunk” Appearance
Figure 2. Chipmunk (or Rodent Face) Characterization of Thalassemia.
Figure 3. Thalassemic Patient (Thalassemia Major), patient’s profile reveals Rodent Face or Chipmunk appearance.
Figure 4. Patient’s profile reveals maxillary protrusion, with Brody Syndrome characterized by mandiblar inclusion within the maxilla. The Left photo reveals the maxillary protrusion before treatment, the right illustrates the same case after 18 months of treatment.
Figure 5. Maxillary protrusion because of expansion of the facial bones, consequent to medullary space expansion and thinning of the cortical plates.
Figure 6. The same case as Figure 5., after 18 months of active orthodontic treatment, the maxillary protrusion decreased, however, the expanded facial bones are obvious as is the increased intercanthal width.
Orthodontic Treatment of Thalassemia Patients
Thalassemia patients, especially those affected by thalassemia major, may develop a skeletal Class II malocclusion subsequent to maxillary protrusion and mandibular atrophy as a direct result of early fusion of the occipital sutures. The mandicular condyles (growth center) may be involved with the early fusion of occipital sutures impeding mandibular growth relative to the anterior maxillofacial structures.
The early fusion of occipital sutures takes place concomitantly with medullar hyperplasia of the anterior maxillofacial structures, causing maxillary skeletal protrusion Figure 1. Figure2. Figure 3. Often with thalassemia major patients, the whole mandibular arch fits within the maxillary arch (Brody Syndrome). Figure 4. Figure 5.
It is recommended that orthodontic treatment be intiated as early as possible concentrating on prophylactic approaches. In other words, it is crucial that preventive and interceptive orthodontics take precedent over “therapeutic orthodontics” per se.
Functional and extra oral appliances can be used, however, the “skeletal forces” in thalassemia patients must be less than what is used with normal patients. Figure 6. The clinician should keep in mind that the cortical plates are very thin in thalassemic patients so they should be followed more closely with shorter intervals between observations. Radiographs at 3 months intervals can be indispensable because the thin cortical plates can complicate orthodontic treatment.
In brief, the best forces used with thalassemic patients are low forces. Figure 7. The use of functional appliances during the growth period may also be helpful in lessening the side effects of this syndrome.
Figure 7. The previous case cephalometric radiographs, before (left) and after 18 months of treatment (right). It is evident that the maxillary protrusion has improved.
Figure 8. Study models of a thalassemia case before treatment illustrating maxillary “pseudo-overgrowth” a result of erythroid hyperplasia. The space analysis in this case reveals excess space. (The sum of dental sizes subtracted from the maxillary arch size.)
Figure 9. A Panoramic Radiograph of a 17 year old Thalassemic Patient, The OPG reveals thinner cortical plates than normal and a wider mandibular canal.
Figure 10. A Cephalometric Analysis of a 17 Years Old, male Thalassemic Patient.
Some Cephalometric Features of Thalassemic Patients Figure 10. Figure 11.
- Saddle Angle is higher in Thalassemia Patients than Normal Patients. (Greater than 123º) This is due to the early fusion of the base of skull sutures with maxillary “pseudo-overgrowth” and from erythroid hyperplasia. This displaces the orbits leading to hypertelorism or “pseudo-overgrowth of maxilla”.
- Anterior CRANIAL BASE N-S length in thalassemia patients is greater than Normal (Over 71.0 mm).
- Posterior CRANIAL BASE S-Ar length is less than normal (Under 32.0 mm).
- PFH:AFH is less in thalassemia (under 61%).
- ACB:MAND.BODY (Anterior Cranial Base to Mandibular Body) is larger in thalassemic patients (over 1:1).
- UI to SN (Maxillary Incisor to SN) is greater than 103º in some cases of thalassemia, as thalassemia major may be one cause of Class II, D1 development.
- UFH:LFH, (Upper Facial Height to Lower Facial Height) UFH is ≤ 45%, LFH>55%.
The Best Management for Thalassemia Patients
- The sooner the treatment, the best the results.
- It is recommended that force values be less in Thalassemic patients than normal patients.
- Preventive and interceptive orthodontic treatments are more crucial, especially in thalassemia major.
Figure 11. Ricketts Analysis of a Thalassemic Patient.
Conclusion
Thalassemia is an inherited disorder; however, the earlier it is managed, the fewer side effects. In thalassemia patients preventive and interceptive orthodontics are more important than the therapeutic orthodontics per se. It is recommended that orthodontic treatment is started at a younger age for thalassemic patients than their normal peers. The first steps of thalassemia orthodontic interceptive treatment may be functional and removable appliances, (according to each case). Extraoral appliances may be used, however, skeletal forces should be less than those used with normal patients. The orthodontist must keep in mind that thalassemia patients have thinner cortical plates. Finally, it is crucial that multidisciplinary team work among dental specialists, hematologists and orthopedists be coordinated to treat this syndrome efficiently and with the best results.
References
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Contributed by:
Dr. Mohamad Azhar Ibrahim Kharsa, DDS, PhD. Orth.
Consultant Orthodontist, King Fahad Hospital. MADINA. Saudi Arabia. Scientist Fellow of American Society for Laser Medicine and Surgery, WFO Fellow AOS Fellow, Member of Saudi Orthodontic Society and Saudi Ortho Club.
