Biomedical subjects
Publications and source records attributed to W E LaVelle.
A procedure for duplication of cranial bone flaps used in cranioplasty is described. This procedure overcomes the difficulties inherent in direct duplication of irregular-shaped bone flaps through primary replication of the flap in wax. The wax pattern is used to fabricate the definitive prosthesis.
STATEMENT OF PROBLEM: Acquired midface defects may produce functional and psychologic impairments that adversely effects a patient's quality of life. Conventional prostheses may lack adequate retention and stability, diminishing the patient's confidence that the prosthesis will remain in place during routine activities. PURPOSE: The experience with and patient response to endosseous implants in prosthetic restoration of midface defects is presented in this study. MATERIAL AND METHODS: Five patients in age from 36 to 88 years were treated with 19 titanium endosseous root-form implants to provide retention and stability for prostheses. Patients responded to a questionnaire rating overall use, effectiveness, and satisfaction of their prosthesis, before and after the use of implants. RESULTS: All 19 implants were judged to be osseointegrated at abutment connection. Of the 17 implants used prosthetically, 14 (82%) remained osseointegrated and 3 (18%) failed. Analysis of the questionnaire tends to indicate an improvement of the quality of life for the patients with an implant-retained prosthesis.
STATEMENT OF PROBLEM: The anticipated length of service and reasons for replacement of fixed partial dentures (FPDs) are a frequent inquiry by patients. Previous reports have provided limited information on material and techniques used in restoration or standards in evaluations of restorations at delivery. PURPOSE: This study determined the reasons for failure and length of service for FPDs delivered with specific clinical, radiographic, and laboratory procedures. METHODS: A clinical and retrospective chart review was conducted on all patients with FPDs who were treated in the prosthodontic clinic at the University of Iowa Hospital for routine dental hygiene recalls during a 6-month period. Fifty patients were examined with a total of 89 FPDs. Of the 89 FPDs, 13, or 15%, were identified as failures or had been replaced because of failure. Dental caries was the most frequent cause of failure (38%), followed by periapical involvements (15%), perforated occlusal surfaces (15%), fractured post and cores (8%), defective margins (8%), fractured teeth (7%), and porcelain failures (8%). The mean length of service for failed FPDs ranged from 16.0 years, because of failure from dental caries, to 4.1 years, because of a fractured post and core. RESULTS: A linear regression model of years in service against number of failed FPDs indicated that the number of years in service provided no information on predictability of failure for FPDs. CONCLUSIONS: This study supported previous reports of dental caries as the primary cause for failure of FPDs, but specific radiographic, clinical, and laboratory procedures can increase the length of service of these restorations.
STATEMENT OF PROBLEM: Treatment for head and neck malignancies commonly involves radiation therapy. As a result of this therapy the vascular supply to irradiated structures is altered and results in decreased tissue perfusion. In addition to vascular changes, bony structures undergo a reduction in osteoblastic and osteoclastic activity. These tissue alterations, especially in the mandible, enhance the risk of osteoradionecrosis. To avoid this occurrence, many patients who have undergone radiation therapy do not receive elective preprosthetic surgeries, including implant therapy. PURPOSE OF STUDY AND METHODS: This report presents the preliminary results of placing 18 titanium screw implants into previously irradiated mandibles in conjunction with hyperbaric oxygen therapy. RESULTS: Of the 18 implants placed, 17 (94%) were judged to be osseointegrated at the abutment connection. One implant did not receive an abutment and was "put to sleep." The remaining 16 (88%) were used for prosthetic rehabilitation. CONCLUSION: The use of implants in irradiated tissues may provide a means of enhancing prosthetic rehabilitation while reducing the risk of tissue trauma that may develop into osteoradionecrosis.
The use of vascularized free-tissue transfers has given the head and neck surgeon the ability to offer enhanced oncologic therapy with less risk of exposing vital structures to the aerodigestive tract. Resulting free-flap tissue consistencies and contours inhibit the successful use of routine impression techniques. The technique described in this clinical report uses a previously reported procedure to obtain an accurate impression of residual palatal and free-flap structures. The significance of this technique is that it improves the tissue reproduction of surgically closed palatal defects.
As computer-interactive technologies become more widely used in neurosurgery, radiology, and radiation therapy, the need for an optimum skull fiducial marker system increases. In the past, intracranial localization methods required precisely machined metal frames and rigid pin fixation to the skull. Recently, this function has been performed using "frameless" computer-based systems that calculate brain position relative to a series of external reference points, the most accurate of which are screwed directly into the skull. A penetrating fiducial marker system, however, is not well suited for applications requiring multiple volume registrations over an extended time period. We describe a new skull fiducial marker system that attaches to the maxillary teeth and can be used repeatedly on different occasions. A curved bar, known as a Banana Bar (BB) extends backward from a custom mouthpiece around the side of the patient's head; the bar contains sites of attachment for screw-in radiographic fiducial markers. Repositioning accuracy was quantitated using a photographic technique. A BB prototype was constructed and tested in three subjects. The BB weighs less than 100 g and can be comfortably held in position for up to 30 minutes. It takes less than 1 minute to screw in the mouthpiece and only seconds to secure the BB to the teeth. One hundred twenty photographic measurements were analyzed from 60 repositionings over a minimum 3-week period. Standard deviations for the measurement series ranged from 0.29 to 0.86 mm. Results suggest that the BB may be an inexpensive, efficient, and accurate method for providing the external reference points needed for a wide range of emerging computer-interactive applications.
Six adult patients with cleft palate, ranging in age from 47 to 78 years, were treated with self-tapping titanium implants. Twenty-three implants, 7 to 15 mm in length, were placed. Of these, one (4%) was 7 mm, eight (35%) were 10 mm, nine (39%) were 13 mm, and five (22%) were 15 mm. Time between stage I and stage II implant surgeries was 5 to 14 months, averaging 8.3 months. Time from stage II surgery to the present is 1.5 to 5 years, averaging 3 years. Of the 23 implants placed, 21 (91%) achieved osseointegration. One (4%) implant was not used prosthetically. Two (9%) 10 mm implants failed to integrate in one patient. All patients were treated with a maxillary complete denture or overdenture. Five (83%) required the addition of a pharyngeal section for speech enhancement.
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The use of tissue-integrated fixtures for the retention of an extraoral prosthesis has simplified the placement, removal, and cleaning of the prosthesis by the patient. Tissue evaluation, structural designs, and retention mechanisms, combined with patient compliance and the ability to perform hygiene around retentive substructures, has produced an array of new problems. Clinical and technical problems are presented with techniques used in their resolution.
Osseointegrated implants can be used successfully to support maxillofacial prostheses. Six patients (aged 37 to 80 years; average age, 68 years) underwent orbital exenteration for eyelid neoplasms infiltrating into the orbit. Each patient underwent a two-stage osseointegration procedure in preparation for fitting an orbital prosthesis. In the first stage, three or four bone-anchored fixtures were placed into the bony orbital rim. Skin penetration and abutment placement were performed in the second-stage operation, performed 3 to 6 months later. Successful osseointegration was achieved in 17 (94.4%) of 18 fixtures in five nonirradiated patients. All five patients were successfully fitted with an implant-retained prosthesis. One patient who underwent irradiation lost all four fixtures that had been placed. This patient chose to wear a black patch rather than a conventional prosthesis held in with adhesive. Average follow-up was 16 months for the five patients who were successfully fitted with orbital prostheses (range, 6 to 30 months).
A client is described who exhibited a large number of characteristics consistent with developmental apraxia of speech (DAS). The exhibited symptoms included excessive nasal resonance and nasal emission of air due to velopharyngeal port dysfunction, for which successful management was achieved by use of a palatal lift prosthesis. The results of the client's use of the lift, in conjunction with her speech and language remedial programming, is presented.
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Osseointegrated dental implants provide a viable alternative of tooth replacement. Although certain patients may greatly benefit from this method of treatment, implants are not a panacea. Success is the culmination of good case selection, thoughtful treatment planning, meticulous clinical and technical attention to detail, and proper maintenance care.
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An effective means of obtaining maxillary expansion and obturation was presented. By use of split palatal orthopedic prosthesis incorporating a posterior fanscrew with an obturator, two patients showed improved speech, cosmetic appearance, and oral physiology while gaining the desired alignment of the maxillary segments before further surgery.
In order to determine the efficacy of applying Proplast to dental endosseous bladevent implants, this material was coated on half of sixteen such implants which were bilaterally placed in the mandibles of eight rhesus monkeys. No difference in the clinical acceptability could be ascertained between the two groups. Histologic examination revealed a loose connective tissue layer around the noncoated implants which was not evident around the coated ones.
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