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Alloplastic implants of the larynx.

Biocompatible Teflon fluorocarbon polymer (Proplast) and porous polyethylene (Plasti-Pore) are porous alloplastic implant materials that are widely used in reconstructive head and neck surgery. These two materials were used in our study as replacement grafts for defects in three groups of 12 canines. For the first time, Plasti-Pore was found equal and perhaps superior to Proplast in deep implantation, this in the anterior cricoid cartilage when the internal and external perichondrium were preserved. Rejection of both substances occurred when the implant was exposed to air and aerodigestive tract contaminants after the removal of the perichondrium, subglottic, and upper tracheal mucosa. Airway exposure to the alloplasts, even when lined with buccal mucosa, resulted in infection and extrusion, but at a much slower rate.

Animals↗

Experience with alternative material for nasal augmentation.

In the last six years, 101 Proplast II implants were used for correcting various nasal deformities. The time of observation ranged from one to six years. During this period, four implants were removed: two because of late postoperative infection and two others because of trauma. Our experience indicates that Proplast II is a good alternative in cases that require alloplastic implants to correct an existing nasal deformity.

Adult↗

Long-term study of temporomandibular joint surgery with alloplastic implants compared with nonimplant surgery and nonsurgical rehabilitation for painful temporomandibular joint disc displacement.

PURPOSE: The purpose of this study was to determine the long-term objective and subjective outcomes of temporomandibular joint (TMJ) implant surgery for the treatment of painful TMJ disc displacement using temporary Silastic (Dow Corning Corporation, Midland, MI), permanent Silastic, or Proplast (Vitek, Houston, TX) implants to replace the disc. These cases were compared with other cases of the same diagnosis treated with either nonsurgical rehabilitation or nonimplant surgery involving discectomy or disc repair procedures. MATERIALS AND METHODS: A cross-sectional study was conducted among 466 patients who received treatment for unilateral or bilateral TMJ disc displacement before January 1, 1990. The 5 treatment groups noted above were compared for long-term outcomes. Objective outcome measurements for jaw function were performed using a calibrated examiner and the Craniomandibular Index (CMI). Subjective (self-reported) outcomes were obtained relative to jaw function (Mandibular Function Impairment Questionnaire [MFIQ]), symptom severity (Symptom Severity Index [SSI]), and the impact of pain (Global Pain Impact [GPI] scale). RESULTS: The results, adjusted for gender, baseline tomogram score, and baseline symptom scores, showed that the nonsurgical rehabilitation group (n = 159) and the group having TMJ surgery without implants (n = 149) had statistically better results than the group who underwent surgery with a Proplast implant (n = 94). These between-group differences included both objective signs (CMI), and subjective reports of jaw function (MFIQ), symptom severity (SSI), and global pain impact (GPI). The MFIQ score associated with the nonsurgical rehabilitation group was also statistically better than for the Silastic implant groups, including both the temporary (n = 31) and permanent (n = 33) implants. Clinical differences between groups were slight. CONCLUSION: This study suggests that the use of interpositional disc implants in TMJ surgery is not associated with improved outcomes when compared with nonimplant surgery or nonsurgical rehabilitation.

Adult↗

A new fluorocarbon for keratoprosthesis.

Previous studies have demonstrated the potential use of microporous, biocompatible materials to improve the long-term stability of keratoprosthesis. To determine the factors that will influence corneal tissue ingrowth into biocompatible, microporous materials, we have compared three types of fluorocarbon polymers--Impra, Gore-Tex, and Proplast--after intrastromal implantation in rabbit corneas. Despite similar physicochemical structures, a great difference was observed in histologic and ultrastructural cross sections after 4- and 8-month follow-ups. For Gore-Tex, we observed extrusion of the implant and infiltration of necrotic and inflammatory cells. All implants of Proplast also led to significant corneal damage resulting in extrusion of the material. Through the use of electron and light microscopy and image analysis, this study demonstrates the presence of cell differentiation and collagen synthesis in the pores of the Impra implant. Apart from biocompatibility, this experiment demonstrates the influence of pore size, porous microorganization, and biomechanical factors on prosthetic corneal material. Only Impra offers satisfactory interface, allowing fibroblastic cells and neocollagen synthesis into its pores, and it can become transparent.

Animals↗

Lamina repair and replacement to control laminectomy membrane formation in dogs.

This study examined the efficacy of lamina repair by the use of various techniques to prevent postlaminectomy scar formation in a canine system. Five-level noncontiguous laminectomies were performed on six adult canines. The most caudal (Site 1) was left uncovered and served as the control. Exposed dura at each of the remaining four levels was covered with one of the following: Site 2, free autogenous laminar bone graft; Site 3, polymethylmethacrylate; Site 4, Teflon-Proplast composite; Site 5, collagen gel. The dogs used in the study were killed 16 weeks after surgery. Three specimens were examined by plain roentgenography and computerized tomography, two specimens were examined histologically, and the remaining four specimens were graded according to scar volume and scar adherence, as detected during gross dissection of the postlaminectomy scar. No repair technique interfered with roentgenography evaluation. The least scar and fewest adhesions were present under the free bone graft repair site. The Teflon-Proplast composite and polymethylmethacrylate both limited the amount and adherence of scar. Collagen gel and control sites were indistinguishable in this study. It is concluded that lamina repair with a solid material covering exposed dura significantly reduces the formation of postlaminectomy membrane and scar.

Aluminum Oxide↗

Effect of implants on healing of experimental furcation defects in dogs.

The present study was performed to find out whether implants placed around periodontally involved teeth during reconstructive surgery would support replaced flaps and prolong gingival coverage of the treated root surfaces facilitating new attachment. Through-and-through furcation defects were made in the mandibular second, third, and fourth premolars of 10 beagle dogs. Bone was surgically removed from the furcation and from the circumference of each tooth to a level 3 to 4 mm apical to the cementoenamel junction. Steel wires were passed through the furcations and ligated to enhance plaque formation. At 6 weeks, the wires were removed. At 12 weeks, during reconstructive surgery, 4 dogs received implants of autogenous intraoral cancellous bone, 2 of autogenous iliac cancellous bone and marrow, 2 of Proplast, and 2 of Avitene. The results demonstrated that none of 12 teeth implanted with Avitene or Proplast showed new attachment. Only 2 of 6 teeth implanted with autogenous iliac bone showed new attachment, combined with extensive root resorption and ankylosis. Of 12 teeth implanted with autogenous intraoral bone, 6 showed new attachment. Our findings suggest that flap support by intraoral cancellous bone implants may facilitate new attachment. A more predictable technique, however, needs to be developed.

Animals↗

Soft tissue response to polytetrafluoroethylene and silicone rubber in humans: morphological and immunohistochemical observations.

The objective of this study was by morphological and immunohistochemical means to investigate the cellular tissue response to the alloplastic materials polytetrafluoroethylene (PTFE polymer), and soft and hard silicone rubber over time. In seven healthy volunteers implants made of Proplast-Teflon, and soft and hard silicone were inserted subcutaneously in unloaded areas in the iliac crest region. After 1, 2, 4, 12, and 26 weeks, respectively, the implants with surrounding soft tissue were removed en bloc for histological and immunohistochemical examination using a panel of antibodies to various leukocyte markers. The tissue reaction to the various alloplastic materials varied greatly with the focus on macrophage and giant cell reactions and eventual formation of a peri-implant fibrous capsule. The most extensive changes developed next to porous Proplast, both with respect to degree of changes and endurance of tissue reaction. Less intense reactions were seen, in decreasing order, to soft silicone, Teflon, and hard silicone. The study gave no clues to a toxic, allergic, or traditional immunological pathogenesis of the tissue reaction induced by the test materials.

Adult↗

Evaluation of homologous bone graft versus biomaterials in the aesthetic restoration of the middle third of the face.

BACKGROUND: Bone deficits of the midface can be observed following tumor surgery, facial traumas or malformations, and can determine aesthetic deformities requiring surgical corrections. The goal of this study is to illustrate the 23 years experience of the Maxillo-Facial Department of the "La Sapienza" University of Rome, in surgical correction of middle third bone loss for aesthetic improvement, and to compare postsurgical results from the use of biomaterials and homologous bone grafts. METHODS: From January 1977 to January 2000, 18 patients were surgically treated with bone grafts for bone deficit of the midface requiring aesthetic improvements, and 23 received biomaterial placement in the same district. A retrospective analysis regarding aesthetic improvements following corrective (reconstructive) surgery was carried out in order to compare long-term results obtained with bone grafts and biomaterials. RESULTS: Of the 19 implants of the zygomatic bone, 1 patient suffered from infection, observ-ed on the 8th day, following iliac bone graft in the maxillary area. Of the 32 prostheses, 7 became infected and in 1 case the material became exposed: Proplast(R) became infected 2 times, Gore-tex(R) 3 times and 1 time became exposed; 2 of the 24 Medpor(R) implants resulted in infection. The employment of bone graft obtained a good short term aesthetic result. Medpor(R) employment, was evaluated as an optimal aesthetic improvement. We cannot evaluate the results obtained with Gore-tex(R) and Proplast(R) because of the few cases treated. Anyway we consider unsatisfactory the corrections obtained with these 2 materials. CONCLUSIONS: Homologous bone grafts are still considered as the best choice when a further fixture positioning is planned for prosthetic rehabilitation of the alveolar ridge of the upper jaw or mandible. At the present time, some biomaterials are the definitive solution for restoring facial harmony in the 3 spatial dimensions.

Biocompatible Materials↗

Chin augmentation with various alloplastic materials: a comparative study.

This retrospective study of 62 patients compared three alloplastic materials used in chin augmentation: Proplast I (PI), Proplast II (PII), and porous block hydroxyapatite (PBHA). There were 25 patients with PI implants (average follow-up of 44.8 months), 25 patients with PII implants (average follow-up of 32.8 months), and 12 patients with PBHA implants (average followup of 19.1 months). Average bone resorption was 1.25 mm (range 0.00 to 3.30 mm) beneath the PI and PII implants and 0.00 mm beneath the PBHA implants. Average posterior settling was 0.46 mm (range 0.00 to 2.00 mm) for the PI and PII implants and 0.03 mm (range 0.00 to 0.17 mm) for the PBHA implants. The percentage of soft tissue change at pagonion relative to the size of the implant was 83.0% (range 66.7% to 100.0%) for PI and PII and 86.8% (range 77.3% to 100.0%) for the PBHA implants. When PI or PII implants were used, younger patients had more resorption than older patients. Slightly more resorption was found with PI and PII implants when maxillary surgery was performed. The size of the PI or PII implants made no difference in the amount of bone resorption, although there was slightly less soft tissue change when larger implants were used. Males had slightly more bone resorption than did females. The bone resorption beneath the PI and PII implants occurred within the first 12 months postsurgery. It can be concluded from this study that PI and PII implants are acceptable materials for chin implants, but some resorption can be expected during the first 12 months postsurgery. The absence of detectable resorption and the excellent soft tissue change make PBHA an attractive alternative as a chin implant material, although it is technically more difficult to use.

Adolescent↗

Alloplastic reconstruction of the temporomandibular joint.

The Proplast TMJ condylar implant, the glenoid fossa implant, and the TMJ interpositional implants should be singled out as having provided a new and more predictable mode of TMJ reconstruction. The use of these implants in cases of ankylosis, degenerative joint disease, orthognathic deformities, and traumatic injuries has greatly contributed to the success of these reconstructions. These implants represent the state of the art in TMJ reconstruction and increasing data from longer-term follow-up have shown a rate of success much higher than any previous implant used in the TMJ. TMJ reconstruction requires careful surgical planning, meticulous surgical technique, and intelligent perioperative care. Postoperative physical therapy is considered essential in the management of these patients. Complications related to reankylosis have been virtually eliminated, as no postoperative immobilization is required in most cases. Long-term stability of these implants, due to the ingrowth of tissue into Proplast, appears to be assured. Continued experience with the implants and close follow-up of reconstruction patients is necessary in the future to adequately assess the performance of the newer glenoid fossa and TMJ interpositional implants. Certainly, a new era in TMJ reconstruction has begun, resulting in increased benefits to the patients whom we all serve.

Adult↗

In vitro adherence of bacteria to prosthetic grafting materials.

Adherence of bacteria to prosthetic grafting material is thought to play an important role in the ultimate development of prosthetic infections. To evaluate the role of bacterial adherence in the initiation and colonization of prosthetic materials, Proplast II, Gore-Tex, and silicone were evaluated for adherence of Escherichia coli and Staphylococcus aureus. Bacteria were radio labeled and incubated with the study material. Adherence was determined by scintillation. Adherence to Proplast II and Gore-Tex reached a maximum at approximately 45 minutes of incubation and demonstrated a detachment phenomenon with E. coli. Similar results were noted with S. aureus, but with a maximal attachment at approximately 30 minutes. Interestingly, bacterial attachment to silicone continued to increase throughout the time of the incubation. In addition, adherence of S. aureus was at a faster rate than E. coli. Attachment of bacteria is a multifactorial process. However, the PTFE graft demonstrates a slower rate of attachment, lower total number of attached bacteria, and faster detachment. The importance of this phenomenon may help explain the foreign body effect of increased susceptibility to infection of foreign materials.

Aluminum Hydroxide↗

Experimental myringoplasty.

Different materials were compared as implants in performing a myringoplasty on rats immediately after making a total perforation, (autologous fascia, homologous tympanic membrane, homologous collagen, heterologous collagen, heterologous amnion and proplast). As a reference one group of rats had no myringoplasty done after perforating their drums. The animals were examined regularly, then killed after 40 and 64 weeks. Macroscopically and microscopically proplast and homologous collagen were very inferior to homograft tympanic membrane and autologous fascia. The best results were obtained both macroscopically and histologically with heterologous collagen and heterologous amnion.

Amnion↗

Comparison of biomaterials for facial bone augmentation.

We compared the gross behavior of and microscopic response to implant materials currently in clinical use for facial bone augmentation at different sites in dogs. Materials evaluated include porous polytetrafluoroethylene carbon (Proplast), large-pore high-density polyethylene (Medpor), solid medical-grade silicone rubber (Silastic), polyamide mesh (Supramid), and autogenous rib bone. The subjects were 12 mixed-breed dogs and the materials were implanted directly on bone with periosteum removed at one of three sites in the dog's face (malar eminence, nasal dorsum, and chin). Animals were killed 3 months after surgery and stability of the implants was graded by manual manipulation. Blocks of tissue, including the study materials and underlying bone, were examined microscopically after sectioning. Stability results are tabulated and histologic appearance is described by site for each material evaluated. These data demonstrate marked variability of stability and cellular response depending on the site of implantation. From these data one may conclude that the site of implantation and implant movement are essential factors in determining the nature of the tissue response and fate of an implant. Solid and porous alloplastic materials show an acceptable tissue response, but neither demonstrates the ability to consistently provide an implant that is stable on underlying bone.

Animals↗

Surgical treatment of internal derangement of the temporomandibular joint: long-term evaluation of three techniques.

PURPOSE: The long-term outcomes of three different surgical treatments for internal derangement of the temporomandibular joint (TMJ), ie, discoplasty, discectomy without replacement, and discectomy with replacement of the disc with a Proplast-Teflon (Vitek Inc, Houston, TX) interpositional implant (PTIPI) are compared. MATERIALS AND METHODS: Forty-two cases of internal derangement of the TMJ were treated with disc repair and eminectomy (group A, n = 13), simple discectomy (group B, n = 17) and discectomy combined with insertion of a PTIPI (group C, n = 12). Preoperative and postoperative findings (more than 5-year follow-up) relating to pain, mouth opening, joint noise, and radiographic changes were compared. RESULTS: Decrease of symptoms after surgery was reported by 77%, 94%, and 83% of the patients (groups A, B, and C, respectively). The decrease in pain intensity ranged from 52% to 71%. Mouth opening increased in 50% to 60% of the patients. The percentage increase ranged from 15% to 26% in the respective groups. Development of osteoarthrosis after surgery was demonstrated in 93% and 100% of the cases in the discectomy and discectomy/disc implant group, respectively, but only in 62% of the discoplasty group. CONCLUSION: This study demonstrates the importance of a functioning disc in the TMJ. There was no significant difference between the groups concerning symptoms before and after surgery. The discoplasty group, however, showed a high frequency of relapse, which necessitated secondary discectomy. PTIPIs clearly accelerated the development of osteoarthrosis, which may be classified as iatrogenic damage. The need for further research to establish the long-term performance of autogenous grafts and the development of improved alloplastic disc replacement materials is discussed.

Adult↗

Clinical evaluation of patients with temporomandibular joint implants.

PURPOSE: An undetermined number of patients with temporomandibular joint (TMJ) symptoms have been treated with intra-articular disc implants composed of Teflon ethylene/propylene or Teflon polytetrafluoroethylene and aluminum oxide (Proplast-Teflon; Vitek, Houston, TX). These implants have shown the potential to fragment in situ resulting in nonbiodegradable particles that stimulate a giant cell reaction and lead to degeneration of local structures, pain, and limitation of mandibular opening. We examined the possible relationship between TMJ implants and persistent pain, responses to sensory stimuli, quality of life, and systemic immune dysfunction. PATIENTS AND METHODS: This case series (32 patients) were referred from university-based orofacial pain centers and private practices from across the United States. Laboratory and clinical assessments evaluated orofacial pain symptoms, neurologic function, clinical signs and symptoms of rheumatologic disease, physical function, systemic measures of immune function, and behavioral measures. RESULTS: We found that TMJ implant patients appeared to have altered sensitivity to sensory stimuli, a higher number of tender points with a diagnosis of fibromyalgia, increased self-report of chemical sensitivity, higher psychologic distress and significantly lower functional ability. Systemic illness or autoimmune disease was not evident in this series of TMJ implant patients. CONCLUSIONS: Significant problems were noted on clinical assessment of TMJ implant patients. This is a US government work. There are no restrictions on its use.

Adult↗

TMJ Concepts/Techmedica custom-made TMJ total joint prosthesis: 5-year follow-up study.

This prospective study evaluated the 5 to 8 year subjective and objective results of 42 consecutive patients who had TMJ reconstruction using the TMJ Concepts/Techmedica custom made total joint prosthesis. Criteria for use of the prosthesis included the following TMJ conditions: (1) multiply operated, (2) previous alloplastic implants, (3) osteoarthritis, (4) inflammatory or resorptive arthritis, (5) connective tissue or autoimmune disease, (6) ankylosis, and (7) absent or deformed structures. Thirty-eight of 42 patients (90%) with 69 TMJs reconstructed using the TMJ Concepts/Techmedica total joint prosthesis had appropriate data for inclusion in the study. The average age at surgery was 36 years and average follow-up was 73.5 months. The entire group and three subgroups were objectively evaluated for incisal opening, lateral excursions, and occlusal stability, while subjectively assessed for pain and jaw function. Paired t-test and comparison analyses were used to assess outcomes. For the group of 38 patients, there was statistically significant improvement in incisal opening (P=0.001), jaw function (P=0.001), and pain level (P=0.0001). Lateral excursion movements significantly decreased (P=0.04). The occlusion remained stable in all cases. Complications occurred in six patients. Comparison analysis of the three groups demonstrated significantly better outcomes for patients with fewer previous TMJ surgeries and without exposure to Proplast-Teflon or Silastic TMJ implants. This study demonstrated that the TMJ Concepts/Techmedica total joint prosthesis is a viable technique for TMJ reconstruction as a primary procedure and for patients with previous multiple TMJ surgeries and mutilated anatomy of the TMJ.

Adolescent↗

Aesthetic augmentation of the malar-midface structures.

Based on extensive experience with bone grafts for augmentation of the midface-malar region, an implant design has been developed using Proplast. After careful preoperative assessment, a very specific surgical method, described herein, allows precise implant positioning without the need for suture fixation. In many instances, the 6-mm implant can be inserted unchanged. One-hundred and six patients have been operated on using 176 implants over the past 6 years. There were four unilateral infections (2.3 percent of implants and 3.8 percent of patients). None had permanent motor or sensory nerve problems. Fifteen implants (8.5 percent) in 12 patients (11.3 percent) were either removed or repositioned. In those having augmentation for entirely aesthetic reasons, 3 of 60 patients (5.0 percent) required implant removal or repositioning. The incidence of needing to remove or reposition implants has decreased as the technique has evolved.

Esthetics↗

Prosthetic replacement of the condylar head for temporomandibular joint disease.

Temporomandibular joint replacement was performed in 8 adults who had intraarticular ankylosis, 6 who had end-stage osteoarthritis, and 12 who had rheumatoid arthritis. Three methods of replacement were used; an ulnar head prosthesis (8 patients), an interpositional implant (11 patients), and a Proplast-coated metallic prosthesis (7 patients). The mean age of the 26 patients (19 women and 7 men) at surgery was 38 years (range 17 to 58 years), and the mean follow-up was 36 months (range 3 to 84 months). Relief of pain was experienced by 23 patients, and maintenance or improvement of incisal opening was experienced by 21. Prosthetic replacement of the condylar head for end-stage disease is highly successful in the patients for whom it is indicated.

Adolescent↗