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HIDROTIC ECTODERMAL DYSPLASIA - A CASE STUDY.

Abstract

Ectodermal dysplasia is a multiple disorder disease, which affect two or more ectodermal structures such as the development or function of teeth, hair, nails and sweat glands. It occurs in two forms: Hy- pohidrotic form, or Hidrotic form. A case ectoder- mal dysplasia in hidrotic form was reported. Early dental treatment with implants supported pros- thesis improve patient's, both functionally and esthetically.

Introduction

Ectodermal Dysplasia is not a single disorder, but a group of closely related disorders known as the Ectodermal Dysplasias. The condition was first de- scribed by Thurnman in 1848 1 and was coined by Weech in 1929 2. Ectodermal dysplasias are heritable conditions in which there are abnormali- ties of two or more ectodermal structures such as the development or function of teeth, hair, nails and sweat glands 3. Freire-Maia and Pinheiro described numerous varieties of ectodermal dys- plasia involving all possible Mendalian modes of inheritance 4. More than 192 different syndromes have been identified till date 5; depending on the particular syndrome, ectodermal dysplasia can af- fect the skin, eye lens or retina, parts of the inner ear, development of fingers and toes, nerves and other parts of the body 6. Despite some of the syndromes having different genetic causes, the symptoms are sometimes very similar. Ectodermal dysplasia can be classified by its mode of inheri- tance or by which structures are involved. Diagnosis is usually conducted by clinical observa- tion often accompanied by family medical histories so that it can be determined whether transmission is autosomal, dominant or recessive. Ectodermal dysplasia can occur in any race but is much more prevalent in caucasians than any other group. From the clinical point of view, two main forms have been distinguished 7:

1. Hypohidrotic form/ Christ-Seimens- Tourian Syndrome

2. Hidrotic form/ Clouston syndrome The hypohidrotic ectodermal dysplasia is found to be the most common form among this large group of hereditary disorders, and is estimated to affect at least one in 17,000 people worldwide [8]. It exhibits the classic triad-hypohirdosis, hypotri- chosis, and hypodontia. Usually X-linked recessive inheritance is seen with this syndrome. Males are affected severely while females show only minor defects 9,10,11. In the hidrotic form of ectoder- mal dysplasia teeth, hair, and nails are affected, while the sweat glands are usually spared 12. It is commonly inherited as an autosomal dominant trait. GJB6, encoding gap junction protein 6 (con- nexin-30), is the only gene currently known to be associated with hidrotic ectodermal dysplasia 13,14. Most individuals with hidrotic ectodermal dyspla- sia syndrome have an affected parent. Offspring of affected individuals have a 50% chance of in- heriting the mutation and being affected. Other inheritance modalities like autosomal recessive have also been reported 15. Table 1

The characteristic facial features associated with ectodermal dysplasias are: frontal bossing, de- pressed nasal bridge, prominent supra orbital ridg- es and obliquely set ears, midface is depressed, the lower third of the face appears small due to lack of alveolar bone development, lips are protru- berant 16. A cephalometric study by Vierucci and collegues has shown significant differences in the craniofacial features of unaffected and affected children 17. In the oral cavity the most striking fea- ture is oligodontia; the condition of missing over 6 teeth or more, excluding 3rd molar. Teeth in the anterior region of the maxilla and the mandible are conical or pointed in shape 18. The enamel may also be defective. There is a wide midline dia- stema and hypoplastic labial frenum.

Commonly, there is only one molar tooth in the second molar region, which usually exhibits a bud crown form. Cosmetic dental treatment is almost always necessary and children may need dentures as early as two years of age 19. Multiple den- ture replacements are often needed as the child grows, and dental implants may be an option in adolescence, once the jaw is fully grown. Nowa- days this option of extracting the teeth and sub- stituting them with dental implants is quite com- mon. In other instances, teeth can be crowned in conjunction with orthodontic treatment. Due to the complexity of the dental treatment, a multi- disciplinary approach is best. This case report de- scribes the implant oral rehabilitation of a patient with ectodermal dysplasia with severe atrophy of the residual alveolar crest, and maxillary sinus pneumatization.

Case presentation:

A 21-year-old female diagnosed with genetic ec- todermal dysplasia present to Amiri Dental Center Dep. of Prosthodontics for implant rehabilitation of her partially edentulous maxilla and mandible. Her family history revealed that her grandmother, father, uncle, and her brother had the same condi- tion (Figure 1). Her chief complaints were unaes- thetic appearance and difficulty in chewing food. Her medical history revealed anemia, with no oth- er current pathologic conditions or allergies to any medications. She did report taking folic acid under the supervision of her physician. She assured a clinical history of normal sweating from birth with normal tolerance to heat (Figure 2).

The clinical examination revealed very fine and soft hair on the scalp, slow growing nails, multiple missing teeth (excluding third molars): #2, 3, 4, 5, 12, 13, 14, 15, 18, 23, 24, 25, 26, 28, 29 and 31. Enamel Hypoplasia was found on teeth #13, and 23. The panoramic radiograph assessment showed abnormal morphology of teeth: #7, 8, 9, 10, and 21. Also, horizontal bone loss in posterior mandibular area, super eruption of teeth #19, and 30, loss of occlusal vertical dimension, underdeveloped alveolar ridges, and bilateral infe- rior expansion of the maxillary sinus were noticed (Figure 3, and 4).

The treatment plan of the maxillary arch involved extraction of all teeth. A bilateral sinus lifting procedure, and alveolar ridge augmentation.

Followed by immediate complete denture, implant placement, and maxillary cemented fixed partial dental prosthesis on dental implant. In the man- dibular arch, crowns retained by natural teeth and cemented fixed partials dental prosthesis, along with cemented dental crowns retained by dental implants # 28, and 29. Initially, preliminary impres- sions were made, along with a centric relation occlusal record, and a face bow transfer. Study models were mounted, and a diagnostic wax-up with the new vertical dimension of occlusion was fabricated. A CT scan was ordered to evaluate the presence of sufficient cancellous and cortical bone volume at each potential implant position site, and for site-specific selection of the implants accord- ing to the surgical and prosthetic treatment plan (Figure 5, and 6). Finally, the case and the treat- ment plan were presented to the patient. Follow- ing patient consent, all the mandibular teeth were prepared and provisional restorations were placed based on the wax-up. A new bite registration with the maxillary wax rim was made to fabricate the maxillary immediate denture (Figure 7).

The second visit involved, extraction of all maxil- lary teeth and alveoloplasty procedure were per- formed under local anaesthesia. A bilateral sinus lifting procedure and a simultaneous alveolar ridge augmentation of the maxilla using autogenous corticocancellous particulate bone grafts from the maxillary crest were performed to reconstitute the lacking bone. This was followed by delivering of immediate maxillary complete denture. After 4 months of socket healing implant surgery was performed under local anesthesia. The reopening of the mucoperiostal flaps revealed that the aug- mented bone had been resorbed to a significant extends within four months. Using the prefab- ricated templates from the maxillary denture, 8 standard self-tapping implants (Dentium, IMPLAN- TIUMA Implant, Korea) were inserted in the maxil- la, and 2 implants in the mandible in site of teeth # 28, and 29 (figure 8). Bone augmentation around the dental implants was performed using a mix- ture (ratio 1:0.5) of Cadaver Freezed Dried Bone and Demineralized Freezed Dried Bone (GraftonA DBM Putty in a Jar and MinerOssA mixture of al- lograft mineralized cortical and cancellous chips, BioHorizons IPH, USA). Postoperative healing was uneventful. Following 4 months of healing, the im- plants were uncovered and healing abutment sur- gery was performed. All implants were completely osseointegrated in the new bone. Two weeks after replacing the healing abutments, final impressions for both arches were made with a light body-vinyl polysiloxane and heavy putty impression material in a custom impression trays. The working casts were then mounted on a semi-adjustable, non-ar- con type articulator using facebow records (Hanau 95H2, WhipMix, USA). Maxillary and mandibular metal frameworks were fabricated and returned from the laboratory for a try in. The frameworks were verified and new centric relation records were obtained. The new vertical dimension of occlusion was evaluated and verified. The final prostheses were cemented with glass ionomer luting cement (GC Fuji IA - GC America, Inc., USA). Oral hygiene instructions were given and reinforced to the pa- tient (figure 9, 10, and 11).

Discussion

It has been suggested that for a disorder to be classified as ectodermal dysplasia, abnormalities of at least two of the following structures must be present: hair, teeth, nails or sweat glands. There is, however, no universal agreement on the pre- cise number of abnormal features which should be present. In the case reported above, defective hair, slow growing nails, and Oligodontia were seen and a diagnosis of ectodermal dysplasia was made. However, no defective sweat glands were observed; the presence of a positive family history of this condition suggested an autosomal dominant mode of inheritance, thus excluding the hy- pohidrotic type. Historically, prosthetic treatment for ectodermal dysplasia patients involved remov- able partial dentures, complete dentures and fixed partial dentures. The advent of dental implants has provided an additional treatment modal- ity for restoration of the dentition in this group of patients 2. The oral rehabilitation of patients presenting with congenitally missing dentition is challenging because of the need for a multidisci- plinary approach. Additional considerations, such as the patient's age, stage of growth, inherent anatomic deficiencies present in conjunction with the missing teeth, soft tissue defects, existence of malformed dentition, severe diastemas and psy- chological status, must be considered 20. Since ab- sence of teeth induces alveolar bone loss, patients with ED are usually present with a "knife edge crest" morphology making implant reconstruction challenging. Therefore, patients frequently require bone grafting and sinus-lifting procedures 21, 22, 23. There are aesthetic, functional and psychological reasons that make it important to start oral reha- bilitation early in life. However, this is usually a dif- ficult condition to manage prosthodontically be- cause of the typical oral deficiencies and patient's age. Numerous clinical reports have demonstrated the importance of prosthetic dental treatment in ectodermal dysplasia patients for physiologic and psychosocial reasons.

Conclusion

The treatment of patients with severe oligodontia due to ectodermal dysplasia will differ according to the unique anatomic limitations, dental status, and age of patients. The clinical report we have presented is a typical example of the required mul- tidisciplinary treatment planning concepts neces- sary for successful rehabilitation of these patients. Furthermore, three years follow up data on this patient has shown that dental implants are the most dramatic and effective treatment modality for patients with ectodermal dysplasia if carefully planned. Importantly, aesthetic dental interven- tions in patients with ectodermal dysplasia and malformed teeth and malocclusion help with the development of a positive self-image and overall oral health.

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Date:Dec 22, 2012
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