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At least 1,621 records · Page 90Linked to original sources
PubMed1996

Case report: prosthodontic treatment for the transmandibular implant.

The Transmandibular Implant is a transosteal implant developed to help improve masticatory function in patients with severe mandibular atrophy. It is a functional implant with a rigid box frame design which allows acceptance of masticatory loads in mandibles with minimal bone height. The implant is fabricated of a gold alloy and is placed between the mental foramina from a submental approach. The prosthesis is fabricated as an overdenture and retention is obtained by means of retention sleeves adapted to Dolder bar segments of the superstructure. Denture comfort and function can be greatly improved for patients with severely resorbed mandibles.

Alveolar Bone Loss↗
PubMed1992

A modified plaque pH telemetry method.

Previous plaque-pH telemetry studies reported the acidogenicity of various foods and dietary patterns to estimate potential cariogenicity. To avoid patient discomfort, improve compliance, and minimize electrode malfunctions, we have simplified our telemetry method and compared it to our previously published model. A removable partial prosthesis with a glass electrode set in the approximal space left by a missing first molar was used in 2 subjects. In the modified method, subjects suspended oral hygiene for 3 days, the prosthesis was then installed on the 3rd day, and accumulated plaque was spread on the electrode and covered with gauze for retention. In comparative tests, the same subjects wore the prosthesis in the mouth during plaque accumulation. Test sessions compared the plaque pH response to 4 treatments: a 10% sucrose rinse, a 10% sorbitol rinse, a snack roll with marmalade and coffee, and the snack followed by gum chewing. Overall, pH curves were similar (mean baselines and minimas) and no significant differences in mean pH response were noted between the 2 methods. The modified method improved subject participation, demonstrated greater reliability, and showed Stephan curves comparable to conventional methods.

Cariogenic Agents↗
PubMed1988

Control of prosthetic bacterial infection: evaluation of an easily incorporated, tightly bound, silver antibiotic PTFE graft.

Despite the use of prophylactic antibiotics in vascular surgery, prosthetic infection rate remains 2-5%. Antibiotics bound to vascular prostheses can control experimentally induced infection but prolonged antibacterial activity has not been achieved. This study evaluates the in vivo efficacy and antibiotic retention of an easily prepared silver-antibiotic prosthesis. Prostheses were prepared by combining silver with oxacillin or amikacin using an organic solvent. After evaporation of the solvent, the graft was left impregnated with the antibiotic complex. In vivo retention studies were performed by implanting PTFE 110Ag-oxacillin prostheses in four canine abdominal aortas. When prostheses were explanted at 1 week, mean antibiotic retention was found to be 20% of original activity, higher than the mean inhibitory concentration for Staphylococcus aureus. In three groups of five dogs, 20 X 7-mm prostheses of PTFE alone, PTFE silver-oxacillin, or PTFE silver-amikacin were implanted in the abdominal aorta and the grafts were inoculated with 10(7) S. aureus of a known bacteriophage type, in a closed retroperitoneal pocket. The animals were sacrificed at 1 week and the prostheses were excised for quantitative bacterial culture. PFTE silver-oxacillin, and PTFE silver-amikacin prostheses had 1.7 X 10(2) and 2.0 X 10(2) colonies, respectively, significantly less (P less than 0.05) than controls (1.3 X 10(6) colonies). These data suggest that antibiotic prostheses can be easily prepared without binding agents. They retain the bound antibiotic for a prolonged period and are effective in reducing graft infection in a stringent direct contamination model.

Amikacin↗
PubMed1997

The Dialine II graft: a new collagen-impregnated warp-knitted polyester arterial prosthesis.

The Dialine graft, a new prototype of knitted vascular prosthesis that uses a different brand of polyester fibers as an alternative to Dacron fibers, has been shown to offer excellent in vitro physical performance and in vivo healing. Although it still requires preclotting, the Dialine prosthesis was made impervious by impregnation of bovine type I collagen cross-linked with vapors of formalin. The purpose of the present investigation was to compare the in vitro physical characteristics of the Dialine II graft with those of the collagen-impregnated Hemashield graft. In addition, we studied the healing performance as a thoracoabdominal bypass in dogs for prescheduled periods of implantation ranging from 4 hours to 6 months. In vitro, the bursting strength, resistance to dilatation, and suture retention strength properties of the Dialine II prosthesis were all shown to exceed those of the Hemashield control graft. In the first weeks after implantation, the Dialine II grafts induced a discrete inflammatory response, as shown by the constant leukocyte counts observed both before implantation and when the animals were killed, as well as by the histologic observation of a few inflammatory cells in contact with the collagen. Consequently, the Dialine II grafts showed a slow rate of bioresorption of cross-linked collagen. At 1 month, a thin internal collagenous capsule was present at both anastomoses, laying over the original collagen coating. At 3 and 6 months, areas of thrombotic deposits and endothelialized areas were observed on the luminal surface. Because results of early clinical trials have been highly satisfactory, this prosthesis may be recommended for use without restriction as a medium- and large-diameter blood conduit.

Animals↗
PubMed1994

Morphological, physical and chemical evaluation of the Vascugraft arterial prosthesis: comparison of a novel polyurethane device with other microporous structures.

In this study the morphology, physical properties, surface chemical characteristics and microstructure of the Vascugraft arterial prosthesis have been investigated. This is a novel microporous polyurethane device, recently developed by the company Braun-Melsungen AG in Germany for use as a small calibre arterial substitute. This comparative study included two other synthetic grafts: the Mitrathane prosthesis, a hydrophilic prototype polyetherurethane urea graft with closed internal pores, and the commercially successful expanded polytetrafluoroethylene reinforced Goretex prosthesis with an open microporous structure. The Vascugraft prosthesis contains a network of fused microfibres of varying thickness and orientation which provide open and communicating pores similar in size to those in the Goretex material. In addition, they extend from one side of the graft wall to the other. As well as having superior longitudinal and radial compliance to the reinforced Goretex device, the Vascugraft prosthesis has more than adequate bursting and suture retention strengths. Through the use of contact angle measurements, electron spectroscopy for chemical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and molecular weight analysis by size exclusion chromatography, the surface of the Vascugraft prosthesis has been shown to be uniquely hydrophobic, as well as containing carbonate groups within an aliphatic polyesterurethane polymer. In addition, variations in micro-phase separation structure of hard and soft segment domains between different sizes and batches of product are marginal. Because of the interesting physical and chemical properties, it is recommended that in vitro biocompatibility and biostability studies be undertaken prior to using the prosthesis in animal or clinical trials.

Animals↗
PubMed2003

Maxillofacial rehabilitation of a large facial defect resulting from an arteriovenous malformation utilizing a two-piece prosthesis.

Large facial defects involving the oral cavity can be difficult to restore prosthetically because of a lack of anatomic undercuts, limited means of retention, mobility of soft tissue margins, and the weight of the prosthesis. Use of skin adhesives may be precluded because of the presence of persistent moisture and saliva. The maxillofacial rehabilitation, including the design and fabrication of a 2-piece silicone prosthesis retained by the teeth, of a patient with a large facial defect as a result of treatment for an arteriovenous malformation is described. The pathogenesis and therapeutic alternatives for arteriovenous malformations is also discussed.

Adult↗
PubMed2000

Effect of repeated closures on opening torque values in seven abutment-implant systems.

STATEMENT OF PROBLEM: Implant abutment screw joints tend to loosen under clinical conditions. During impression and prosthesis fabrication, repeated clinical closing and opening of abutment screws may cause component wear and decrease frictional fit of the mating parts, resulting in altered resistance to opening and potential for loss of preload in function. PURPOSE: This study recorded changes in opening torque values due to multiple consecutive closures at a constant torque within and between different abutment/implant (A/I) systems. MATERIAL AND METHODS: Repeated opening-closing cycles were used to simulate in vitro embedment relaxation and component wear of 7 A/I systems from 5 manufacturers. Screw opening torque values were recorded up to 200 consecutive closures at 20 N/cm. RESULTS: A progressive decrease in opening torque values was measured in all implant systems. Significant differences were found between A/I systems. Systems with morse tapered and spline connections consistently maintained a higher resistance to opening force. Percentage torque loss ranged from 3% to 20% on immediate opening, and from 4.5% to 36% for average of first 30 opening/closing cycles. CONCLUSION: Repeated opening and closing of implant abutment screws caused progressive loss of torque retention with variations between systems. This was probably due to a decrease in the coefficient of friction between the mating components.

Analysis of Variance↗
PubMed1992

Prosthodontic claims in the Swedish Patient Insurance Scheme.

The Swedish Patient Insurance Scheme includes a guarantee insurance for prosthetic treatment. Retreatments of failures, up to 2 years after cementation of fixed prosthodontics and 1 year after delivery of removable prosthodontics, are covered by the guarantee insurance scheme. Almost all private practitioners were included in this scheme at the time of the study in 1989. During a specific period all claims were studied at the time of reporting, when annexed radiographs and so forth could be analyzed. One hundred and thirty-six claims were recorded with regard to treatment injury, reasons for remake, latency times from cementation or delivery to diagnosis, and details about the teeth or constructions involved in the claim. The dentist's opinion of the cause of the failure was also recorded. The reports covered treatment injuries, most of them root perforations during preparation for a post. The guarantee claims for single crowns concerned porcelain fractures, loss of retention, and root fractures as the most frequent failures. For fixed partial dentures the failures were recorded as loss of retention, porcelain fractures, tooth or root fractures, and metal framework fractures in that order. The dentist gave information about his/her opinion of the reason for the failure in only 38.5% of the claims. There were, however, no clear findings about the reasons for the failures.

Crowns↗
PubMed1998

Thermoplastic resin used to modify an alveolar orthopedic prosthesis in a patient with cleft lip before cheiloplasty: a clinical report.

Correction of cleft lip and cleft palate is a multidisciplinary team effort. Severe bilateral clefts with protruded and rotated premaxillae may complicate surgical correction. Prosthetic intervention to reposition segments before surgical correction may improve the bony base for tissue molding and avoid excess tension at the surgical site. A conventional bulb prosthesis with bonnet and straps is often used as an extraoral device to retract a protruded premaxilla for severe cleft patients before cheiloplasty. Sometimes, because of lack of retention, stability, patient compliance, and controllable forces from a bonnet and straps, movement of the premaxillae to a desirable position is difficult to achieve. The use of thermoplastic resin to modify a bulb prosthesis as described in this clinical report is a simple method to provide good retention for the bulb prosthesis and to move a laterally displaced premaxillae to the facial midline. The wedging effect created by the thermoplastic resin generated "compressive forces" to the premaxilla that was more controllable than the pulling forces created by the bonnet and straps therapy. Thermoplastic resin is also a better material than a conventional chemically polymerized acrylic resin in dealing with an infant's delicate mucosa before cheiloplasty.

Cleft Lip↗
PubMed2006

Improved retention of anterior cantilever resin-bonded prostheses by design alteration: an experimental and finite element study.

STATEMENT OF PROBLEM: Anterior cantilever resin-bonded prostheses fail as a result of a labio-lingual peeling action, which creates a stress concentration within the adhesive layer. PURPOSE: The purpose of this study was to identify the factors that determine the retention of an anterior resin-bonded prosthesis and to seek to eliminate the stress concentration within the adhesive layer by fundamentally altering the prosthesis design. MATERIAL AND METHODS: The first experiment involved 40 Ni/Cr (Wiron 99) beams with a width of 5 mm, thickness of 0.5 mm, and lengths ranging from to 13 to 22 mm. The beams were cemented onto a block of the same material using an adhesive resin luting agent (Panavia 21). The length of the beam that was bonded ranged from 1 to 10 mm, resulting in a bonded area ranging from 5 to 50 mm(2). A load was applied onto the cantilevered portion of the beam 2 mm from the end, causing a peeling action. The force (N) required to debond these beams was measured using a pull-to-fracture test. Subsequently, a second experiment was undertaken, and 7 beams with an altered point of attachment (new design) were tested. The new design had the point of attachment of the cantilevered portion located centrally on the bonded area of the beam. Implementing this new design clinically would result in a cantilevered resin-bonded fixed partial denture that would have the connector arm attached more centrally on the retainer wing. The data were analyzed using a 1-way analysis of variance (alpha = .05), and a Tukey pairwise comparison test was used when the results was statistically significant. Two finite element analysis (FEA) models, one simulating the first experimental design and the other simulating the new design, were created. A load was then applied on the cantilevered portion of the beams similar to the experimental models, and the stress patterns were examined. The numerical values of these resultant stresses were plotted graphically. RESULTS: The direction of load application, which may be transferred to a clinical setting as labio-lingual forces, was identified as the dominant force responsible for debonding. The new design, which addressed this problem, showed a significant increase (P < .001) in retention. The FEA models identified the stress concentrations within the adhesive layer of the traditional design, which were eliminated when the new design was tested. CONCLUSIONS: For the in vitro model, loads that may be interpreted clinically as labio-lingual forces resulted in the lowest forces required to cause debonding, and these forces were independent of the surface area of bonding. Altering the point of attachment of the cantilevered portion onto the retainer caused a significant increase in the forces needed to cause debonding.

Biomechanical Phenomena↗
PubMed2003

Treatment of Vancouver B3 periprosthetic femur fractures with a fluted tapered stem.

Periprosthetic femur fractures around a hip arthroplasty associated with a loose stem and severely deficient or comminuted bone typically have been treated with substitution for the proximal femur using an allograft prosthetic composite or a tumor prosthesis. Eight patients (mean age, 68 years; range, 34-80 years) with Vancouver Type B3 femur fractures were treated with revision using a long modular fluted tapered uncemented stem with retention of the proximal femur. Access to the failed prosthesis and joint was gained through the fracture or osteotomy and soft tissue attachments to the fracture fragments were maintained. One patient died within 1 week. The remaining patients were followed up 1 to 2 years (mean, 1.5 years). At final followup, all patients had stable implants and all acute fractures were healed. Marked reconstitution of proximal femoral bone stock was observed consistently. All surviving patients were ambulatory and none had more than mild pain. The preliminary results of this method show a high rate of stable implant fixation and fracture healing with preservation and reconstitution of the host femur.

Adult↗
PubMedDate not supplied

Maxillary obturator prosthesis rehabilitation following maxillectomy for ameloblastoma: case series of five patients.

PURPOSE: The purpose of this case report is to demonstrate the benefits and applicability of appropriate maxillofacial prosthetic rehabilitation following surgical resection of ameloblastoma of the maxilla in Kenya. MATERIALS AND METHODS: Five patients presenting with ameloblastoma of the maxilla over 3 years were studied with respect to histologic type, site of tumor, resultant surgical defect, and form of definitive obturator prosthesis. Impressions were taken using irreversible hydrocolloid and poured with dental stone. Immediate surgical obturators were fabricated from casts using clear autopolymerizing acrylic resin. One patient had bilateral partial maxillectomy, whereas the rest had unilateral partial maxillectomy. Immediate surgical obturators were fitted intraoperatively and held in place using Adams clasps on the remaining natural dentition for all patients, except the one who had undergone bilateral partial maxillectomy, whose surgical obturator was held loosely using circumzygomatic wires. After 6 to 8 weeks, surgical obturators and packing were withdrawn, and new impressions were taken to fabricate definitive obturators. Patients were reviewed every 2 weeks for 3 months, then once every 3 months per year for 3 years, and thereafter once per year. RESULTS: The immediate surgical obturators facilitated retention of the surgical packing, promoting healing with minimal postsurgical infection and scar contracture formation. This ensured the restoration of acceptable esthetics and maintenance of oral function at a reasonable level during the initial postoperative period. Definitive obturators restored esthetics, oral function, and ability to handle secretions to a satisfactory level. CONCLUSION: Satisfactory functional and esthetic results are achievable in patients with extensive acquired maxillary defects by means of obturator prostheses fabricated using readily available materials.

Adult↗