Ronald P. Desjardins

Obturator prosthesis design for acquired maxillary defects

Fabrication of obturator prostheses does not require a special ability to fabricate a prosthesis extension into a defect or an arbitrary extension of a prosthesis into a defect. Fabrication of an obturator prosthesis depends on the application of basic prosthodontic principles that are used in the treatment of patients without maxillary defects. Some principles must be modified because of the defect and the character and position of the remaining structures. The defect, in conjunction with the remaining structures, must be used to provide support, retention, and stability of an obturator prosthesis. If basic prosthodontic principles are applied the size and extension of the obturator will be determined, and the extensive variation so commonly seen in obturators will be minimized. Acceptable prosthodontic care for the patient with the acquired maxillary defect should include cautious prosthesis design combined with routine maintenance care to provide comfort, function, cosmetics, and minimal change to the compromised remaining structures.

Endosseous implants in an irradiated tissue bed

Endosseous implants have been placed at the Mayo Clinic Department of Dental Specialties for over 12 years. On the basis of the clinical success of the osseointegration program, the use of implants has been expanded to include placement into tissue beds that have been exposed to therapeutic radiation. This article details preliminary data regarding implant survival in the previously radiated tissue beds. Presurgical evaluation and surgical technique are described and postprosthetic reconstruction complications are also related. Consideration is given to the relatively small number of patients in this review. It is suggested that the results should be shared among multiple institutions to create a meaningful data bank.

Dental Implants: Tissue-Integrated Prosthesis Utilizing the Osseointegration Concept

As an alternative to conventional removable dentures, osseointegrated dental implants can now be used in carefully selected edentulous or partially edentulous patients. The implant consists of a dental prosthesis and an anchorage unit made up of screw-connected components. The implantation procedure is performed in two phases: fixture installation and fixture uncovering and abutment connection. After completion of these surgical procedures, the dental prosthesis is fabricated and inserted. Follow-up examinations are scheduled at 1, 3, and 6 months and then annually thereafter. During a 2-year period at the Mayo Clinic, 358 osseointegrated dental fixtures were implanted in 70 patients. The overall success rate in this consecutive series of patients was 98%, and the associated complications were minimal and easily resolved.

Early rehabilitative management of the maxillectomy patient

Abstract Combined surgical and prosthodontic management of the maxillectomy patient is mandatory. Prosthodontic treatment should begin in the preoperative period if the patient is to be provided with the best rehabilitative care. The use of preoperative evaluation and/or treatment is the key to providing successful rehabilitation services. If the patients disease is cured but he is left a recluse because of his physiologic, esthetic, and psychological deficiencies, how valuable has the cure been to the patient?

Extraoral application of osseointegrated implants

The use of osseointegrated implants to provide support for craniofacial prostheses has provided the clinician with another approach to the treatment of complex craniofacial reconstructive problems. The surgical technique is reviewed and the Mayo Clinic experience is presented.

Occlusal considerations for the partial mandibulectomy patient.

The occlusal scheme fabricated for a patient with a mandibular defect varies extensively from patient to patient, with some limitations in occlusal efficiency. Some patients may expect little or no occlusal efficiency if the defect is large and if the associated mandibular deviation and the lack of muscle control and excessive. If the continuity of the mandible can be restored by secondary surgical management (Fig. 10, A), most of the problems of the discontinuity defect can be resolved. Whether the teeth in the region of the defect are replaced or not may be dependent on other factors, but the mandible can be treated as a stable entity within itself, and the prosthodontic approach can be similar to that discussed for the continuity defect (Fig. 10, B). The mandibulectomy patient is difficult to manage because the prosthodontist is limited in his ability to provide a reasonable and practical occlusal scheme. However, these patients need the definitive clinical and psychological support of the prosthodontist. Most patients recognize the limitations of their rehabilitation and are appreciative of the prosthodontic therapy that enhances their rehabilitative progress.

Comparison of Nerve Endings in Normal Gingiva with Those in Mucosa Covering Edentulous Alveolar Ridges

The morphology and quantity of neural elements in 109 tissue specimens of gingiva and edentulous mucosa were studied by the cholinesterase whole-mount technique. The microscopic findings were compared on the basis of morphology, sex and age of patient, location of the biopsy site in the mouth, edentulous state and time, and the presence of a prosthesis.

Fatigue strength of cantilevered metal frameworks for tissue-integrated prostheses

The design of the metal alloy framework in cantilevered sections of fixed tissue-integrated prostheses, is critical. Several cross-sectional designs have been advocated, including the popular L-shaped beam, which permits the economical use of space for tooth placement. The fatigue strengths of 15 L-shaped cantilevered framework sections of the same metal alloy were tested. The castings were divided into three groups of five according to vertical wall heights of 4, 5, and 6 mm. Fatigue durability of each sample was determined by counting the number of cycles of vertical forces required to induce catastrophic failure. Statistical analysis revealed significant differences between all three groups in the cycles counted at failure (p less than 0.0019). Fatigue strengths improved significantly with increasing vertical wall height of the L-shaped cantilevered frameworks. In addition, beam flexure was shown to be indirectly proportional to fatigue strength. Theoretical beam deflection was calculated and shown to correlate with the actual beam deflection during the testing. Theoretical calculations in static bending specific for a cross-sectional design may aid in the predictability of fatigue strength.

Tissue-integrated prostheses for edentulous patients with normal and abnormal jaw relationships

Diagnosis and treatment planning are keys to successful prosthodontic rehabilitation. The increasing interest in the use of the tissue-integrated prosthesis to resolve the problems of edentulous patients indicates caution in the selection of patients for this procedure. Even if patients are identified who could potentially benefit, application of the concept must meet the needs of the patient. The treatment planning phase must include all professionals participating in patient management and must consider the best placement of fixtures to improve patient findings to an optimal degree. Although many patient factors must be considered in treatment planning, this article discussed application of the tissue-integrated prosthesis concept as it relates to jaw relationship. The tissue-integrated prosthesis must not compound or create retention and stability problems found with complete dentures. This article suggests treatment considerations in planning the tissue-integrated prosthesis for normal and abnormal jaw relationships.

Prosthetic Rehabilitation After Cancer Resection in the Head and Neck

Because of the potential physiologic, cosmetic, and psychologic deficiencies that can be created by necessary treatment for cancer, the cure in many respects can be as frustrating as the disease. The rehabilitation should be considered before creation of the defect, so that the patient and the prosthodontist will be well aware of the rehabilitative needs and limitations in the particular case.