Insights Newsletter

May 2000 Volume 13, Number 1

Byline:
Zygoma Fixtures
Used To Correct Congenital Deformity:
Treatment Of A 20 Year Old Male

Congenital Anomalies are a broad category of health conditions that are present at birth and are a deviation from normal anatomic growth, development, or function. The congenital anomaly develops in utero or may have genetic origins.

Ectodermal Dysplasia is a congenital anomaly caused by a single abnormal gene or pair of abnormal genes. In congenital ectodermal dysplasia, teeth are absent at birth, reduced in number, or conical in appearance so that partial dentures are required from childhood. The birth prevalence of ectodermal dysplasia is approximately 1 in 100,000 and is known to be hereditary in nature.Ectodermal dysplasia may present in various degrees of severity, ranging from a slight malformation of the coronal portion of a single tooth, to the more commonly recognized "congenitally missing lateral incisors", or the advanced presentation of the syndrome with multiple missing teeth, thinning or absence of facial hair, and reduction of sweat glands.Congenital deformities in the craniofacial region are physically and psychologically devastating and can handicap the individual in many ways. In young adults these anomalies can have a great impact on the psycho-social component of life. Since ectodermal dysplasia is often accompanied by loss of adult teeth, it can also lead to underdevelopment of the jaws. A hypoplastic maxilla and mandible, having little if any dental support, produces bite collapse and narrowing of the alveolar ridges. This condition produces a diminished appearance of the lower third of the face. The reduction in size of the width of the jaws and supporting musculature is distractingly apparent in full face frontal view (Fig 1a). In profile, the underdeveloped jaws create a facial disharmony due to a retrognathic appearance (Fig 2).

In modern society, young adults, who have their entire business and social life ahead of them, are most likely to be affected by the psychological implications of esthetic deformities. The psycho-social peer pressure to have a beautiful or handsome appearance also weighs heavy in the academic environment. A distracting appearance due to congenital defects may inhibit normal social interactions and can subconsciously create a negative impact on academic performance.

Oral facial rehabilitation of young adults afflicted with severe Ectodermal Dysplasia can be successfully accomplished using modern treatment concepts. These concepts may include osseointegrated dental titanium implants to support non-removable teeth, bone grafting and tissue engineering, together with advanced esthetic prosthodontic artistry to create natural looking replacement teeth and an esthetically pleasing smile.The clinical treatment of a 20-year-old male is presented to illustrate the biomechanical and esthetic advantages of modern prosthodontic oral facial rehabilitation. It is of clinical interest, that the patient’s 22 year old sister also suffered from Ectodermal Dysplasia. Her reconstructive treatment consisted of surgical intervention with an iliac crest bone transplant inlayed into the maxillary antrum. Subsequent degeneration of the graft required complex retreatment seven years later.

Treatment planning this young man’s reconstruction illustrated a major change in prosthodontic philosophy and technology by being able to minimize the invasive nature of the reconstructive surgery. New and specially designed zygoma fixtures permitted a non-removable prosthodontic reconstruction by placing implants into the zygoma bone to provide posterior support for a complete maxillary arch reconstruction.This treatment approach avoided the hospital visit generally required for an iliac crest transplant, it reduced the total amount of treatment time by eliminating the ten to twelve months usually required for bone grafts to mature before implants can be placed, and negated the necessity of additional healing time required for implants placed in grafted bone.

As reported in the literature, implants placed in the maxilla in grafted bone may only be as high as 90% . Whereas, initial studies on zygoma fixtures conducted by Per Ingvar Brånemark, et al, revealed a 96.8% clinical survival rate to date .

This otherwise healthy ectodermal dysplasia patient initially presented with only two adult maxillary teeth, the central incisors (Fig 3a). Also present were six maxillary primary posterior teeth, six mandibular primary teeth, the canines, and both molars (fig 3b,c,d).

In order to appear in public the patient was using an all acrylic maxillary overdenture which overlaid his severely deteriorated posterior dentition, and an acrylic removable partial denture replacing the mandibular anterior teeth. Both of these "temporary" restorations were constructed at his existing decreased vertical dimension of occlusion.

After performing a comprehensive clinical and radiographic evaluation (Fig. 4a & b), a treatment plan was discussed with both the patient and his parents. This comprehensive plan recommended the removal of all the patient’s remaining teeth, both adult and primary, and simultaneous surgical placement of Brånemark titanium dental implants. The decision to proceed with treatment was made only after discussing and rejecting several treatment alternatives which included iliac crest bone grafting and long term using a complete removable prosthesis. The patient had a strong desire to avoid the removable prostheses and wanted to be restored with fully functional dentition that was not removable.Under medically monitored general anesthesia, in an out patient setting, the remaining natural teeth were removed and six Brånemark implants were placed in the mandible. All bone from the implant osteotomy sites was harvested for possible future use in the maxilla. Cover screws were placed over the implants and the site was thoroughly irrigated and sutured closed.The maxilla was operated with bilateral antral openings which created directional visibility for placement of the zygoma fixtures. Four additional implants were placed in the anterior maxilla and one in each pterygomaxillary area. Autogenous bone, harvested from the implant osteotomy sites, and a natural bovine derived bone substitute was combined with a platelet rich plasma gel treated to release growth factors. This graft material was placed in the antral floor of the maxilla and around the zygoma fixtures to increase the bone to implant surface area.

Post operatively the patient used a standard regime of medications and cold therapy for the first 48 hours to minimize swelling and post surgical discomfort. The sutures were removed ten days after the surgery and a soft lining was applied to the temporary removable complete dentures. Healing continued uneventfully for three months. The mandibular second stage surgery was completed in the normal fashion and a traditional implant supported fixed prosthesis was constructed with appropriate arch form and vertical dimension.Second stage surgery was completed for the maxilla five months after the implants were placed. Angulated abutments were used with each zygoma fixture to angle the prosthetic retaining screw toward the occlusal table. One pterygomaxillary implant was not utilized to support the prosthetic reconstruction due to sensitivity, despite the fact that it was clinically immobile (Fig 5a,b,c). The final porcelain fused to gold fixed prosthesis was constructed to fill the labial and buccal spaces which had been void due to underdevelopment of the maxilla (Fig 6). A positive smile line complimented the patients lip line (Fig 1b).

The patient will continue treatment with oral hygiene visits scheduled every three months during the first year, every four months the second post operative year, and then every six months thereafter.In summary, the treatment of a young man, born without many of his "permanent" adult teeth was successfully restored to complete function and esthetics using special zygoma fixtures. The esthetic beauty of this treatment is clinically enhanced by the brevity of the treatment process. Eliminating the need for extreme bone grafting substantially shortens the overall treatment experience and improves the predictability of success.

Authors note: For more information on sinus augmentation for implant reconstruction, refer to Prosthodontic Insights, February 1997, Vol. 10, No. 1.

Acknowledgments:
Robert Winkelman, CDT, MDT, Owner
Fort Washington Dental Lab, Inc.
Tel: 1-800-541-3490
215-628-4994
Email: fortwdental@aol.com
Web site: http://ftwashingtondentallab.com

References:

  • Jensen OT, Shulman LB, Block MS, Iacono VJ. Report of the Sinus Consensus Conference of 1996. Int J Oral Maxillofac Implants 1998;13(supplement)

  • Darle C. A New Procedure for Rehabilitating the Severely Resorbed Maxilla. Talk of the Times, 1999 Nobel Biocare

[Main] [Dir] [Zygoma Fixtures] [A New Procedure] [Analysis of 356] [Reconstructive Procedures] [Report] [Pics]

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