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PubMed1995

Effect of the number of ventricular leads on right ventricular hemodynamics in patients with permanent pacemaker.

During pacemaker replacement most of the old leads are not suitable for recent needs or may show signs of dysfunction. These leads are difficult to extract and are therefore left-in situ. In this study 32 patients with one ventricular lead (Group I) were compared echocardiographically with 18 patients with two ventricular leads (Group II) in regard to their right ventricular (RV) hemodynamics. Mean age of the patients in each group was sixty-one years. Patients were evaluated echocardiographically after two years of lead implantation. Two groups were compared for right atrial (RA) area, RA and RV diameters, tricuspid insufficiency (TI), and intravascular and intracardiac thrombosis. There were no significant differences between the two groups in terms of RA and RV diameters, RA area, and venous and intracardiac thrombosis. In group I, 15 patients with (46.9%) grade I, 14 (43.7%) with grade II, and 3 (9.4%) with grade III TI were detected. In group II 2 patients (11.1%) with grade I, 6 (33.3%) with grade II, and 10 (55.6%) with grade III TI were detected. In conclusion, the incidence of TI was more frequent and of higher degree in group II than in group I, but this finding was hemodynamically insignificant.

Adolescent↗

PubMed2007

Stability of clinical and radiographic results after guided tissue regeneration in infrabony defects.

BACKGROUND: The aim of this 5-year follow-up study was to evaluate clinically and radiographically the long-term results after guided tissue regeneration (GTR) therapy of infrabony defects using non-resorbable and bioabsorbable barriers. METHODS: Thirty-one patients with periodontitis and 50 infrabony defects that had been treated using GTR were recruited. Eleven defects were treated with non-resorbable expanded polytetrafluoroethylene membranes and 39 defects with bioabsorbable barriers. At baseline and 6 and 60 +/- 3 months after surgery, clinical parameters and standardized radiographs were obtained. During surgery and 60 +/- 3 months thereafter, the distance from the cemento-enamel junction to the base of the bony defect (vertical probing bone level [PBL-V]) was measured. Bone gain was evaluated using digital subtraction radiography. RESULTS: At 6 and 60 +/- 3 months after GTR, there was a statistically significant (P <0.001) reduction of probing depth (6 months: 4.31 +/- 1.76 mm; 60 months: 3.95 +/- 1.62 mm) and vertical clinical attachment level gains (CAL-V) (6 months: 3.34 +/- 1.66 mm; 60 months: 2.97 +/- 1.53 mm). From 6 to 60 months after GTR, three infrabony defects exhibited CAL-V loss >2 mm, and a small, statistically not significant mean CAL-V loss of 0.39 +/- 1.60 mm was observed. From baseline to 60 +/- 3 months, a significant PBL-V gain of 1.78 +/- 2.67 mm (P <0.001) and increase in bone density were observed (P = 0.003). CONCLUSION: The CAL-V gain achieved after GTR in infrabony defects using both non-resorbable and bioabsorbable barriers was stable after 5 years in 47 of 50 defects.

Absorbable Implants↗

PubMedDate not supplied

Shoulder prosthesis in reconstruction of the scapulohumeral girdle after wide resection to treat malignant neoformation of the proximal humerus.

Progress in preoperative chemotherapy and radiation therapy, both intra- and postoperative, has in time allowed for an increase in indications for shoulder implant surgery in malignant tumors, thus drastically reducing the number of amputations. The use of prostheses, particularly those of the more recent generation, respond to the needs to overcome the limits of loss of movement, as long as good anatomical reconstruction of the soft tissues, the premise for good functional and cosmetic recovery, is also possible. The current tendency is that of using modular shoulder prostheses that provide a wide variety of sizes. This type of prosthesis has surpassed custom made prostheses in terms of simplicity, adaptability and economy. The use of cementation in stabilization of the intramedullary stem has made them more stable even in the long term, allowing for early rehabilitation. The main problem in reconstruction with a prosthesis is the quantity of residual muscular tissue (deltoideus, extrarotators) and the stabilization system of the same to the prosthesis in order to avoid dislocation, which constitutes the main complication. It is the purpose of this study to present the clinical and functional results obtained in 23 implants carried out for primary malignant neoformation of the upper limb. The implants studied were of three types (custom made, modular in Cr-Co-Mb and Ti-Al-Va). The results reported show how a shoulder prosthesis can obtain good functional results, particularly when a part of the activator muscles of the shoulder such as the deltoideus and the extrarotators is preserved. When the contrary is true, the results obtained are modest because the prosthesis acts as a simple spacer.

Arthrodesis↗

PubMedDate not supplied

Nitric acid passivation does not affect in vitro biocompatibility of titanium.

PURPOSE: In general, both chemical composition and surface features of implants affect cell response. The aim of this study was to evaluate the effect of titanium (Ti) passivation on the response of rat bone marrow cells, considering cell attachment, cell morphology, cell proliferation, total protein content, alkaline phosphatase (ALP) activity, and bonelike nodule formation. MATERIALS AND METHODS: Cells were cultured on both commercially pure titanium (cpTi) and titanium-aluminium-vanadium alloy (Ti-6Al-4V) discs, either passivated or not. For attachment evaluation, cells were cultured for 4 and 24 hours. Cell morphology was evaluated after 4 days. After 7, 14, and 21 days, cell proliferation, total protein content, and ALP activity were evaluated. Bonelike nodule formation was evaluated after 21 days. Data were compared by analysis of variance and the Duncan multiple range test. RESULTS: Cell attachment, cell morphology, cell proliferation, total protein content, ALP activity, and bonelike nodule formation all were unaffected by Ti composition or passivation. DISCUSSION AND CONCLUSION: Although the protocol for passivation used here could interfere with the pattern of ions released from Ti-6Al-4V and cpTi surfaces, the present study did not show any effect of this surface treatment on in vitro biocompatibility of Ti as evaluated by osteoblast attachment, proliferation, and differentiation.

Alkaline Phosphatase↗

PubMed2004

Thermal and chemical modification of titanium-aluminum-vanadium implant materials: effects on surface properties, glycoprotein adsorption, and MG63 cell attachment.

The microstructure, chemical composition and wettability of thermally and chemically modified Ti-6Al-4V alloy disks were characterized and correlated with the degree of radiolabeled fibronectin-alloy surface adsorption and subsequent adhesion of osteoblast-like cells. Heating either in pure oxygen or atmosphere (atm) resulted in an enrichment of Al and V within the surface oxide. Heating (oxygen/atm) and peroxide treatment both followed by butanol treatment resulted in a reduction in content of V, but not in Al. Heating (oxygen/atm) or peroxide treatment resulted in a thicker oxide layer and a more hydrophilic surface when compared with passivated controls. Post-treatment with butanol, however, resulted in less hydrophilic surfaces than heating or peroxide treatment alone. The greatest increases in the adsorption of radiolabeled fibronectin following treatment were observed with peroxide/butanol-treated samples followed by peroxide/butanol and heat/butanol, although binding was only increased by 20-40% compared to untreated controls. These experiments with radiolabeled fibronectin indicate that enhanced adsorption of the glycoprotein was more highly correlated with changes in chemical composition, reflected in a reduction in V content and decrease in the V/Al ratio, than with changes in wettability. Despite promoting only a modest elevation in fibronectin adsorption, the treatment of disks with heat or heat/butanol induced a several-fold increase in the attachment of MG63 cells promoted by a nonadhesive concentration of fibronectin that was used to coat the pretreated disks compared to uncoated disks. Therefore, results obtained with these modifications of surface properties indicate that an increase in the absolute content of Al and/or V (heat), and/or in the Al/V ratio (with little change in hydrophilicity; heat+butanol) is correlated with an increase in the fibronectin-promoted adhesion of an osteoblast-like cell line. It would also appear that the thermal treatment-induced enhancement of cell adhesion in the presence of this integrin-binding protein is due to its increased biological activity, rather than a mass effect alone, that appear to be associated with changes in chemical composition of the metallic surface. Future studies will investigate the influence of the surface chemical composition of various implantable alloys on protein adsorption and receptor-mediated cell adhesion. In addition, by altering the properties of bound osteogenic protein enhancing exposure to cell integrin binding domains, it may be possible to develop implant surfaces which enhance the attachment, adhesion and developmental response of osteoblast precursors leading to accelerated osseointegration.

Adsorption↗

PubMed2005

Successful radiofrequency catheter ablation of idiopathic ventricular fibrillation presented as recurrent syncope and diagnosed by an implanted loop recorder.

As a palliative therapy, an implantable cardioverter-defibrillator (ICD) could not prevent the occurrence of ventricular tachycardia or fibrillation (VT, VF), but only suppress it by overdrive pacing or direct current shocks. Recurrent VT or VF followed by frequent ICD shocks might thus put patients in a painful disaster. We presented a case of recurrent syncope diagnosed as recurrent VF by an implanted loop recorder (ILR). The VF was eliminated by radiofrequency catheter ablation (RFCA) of triggering ventricular premature complexes (VPCs).

Adult↗

PubMed2002

PIXE micro-beam mapping of metals in human peri-implant tissues.

Previous investigations did not agree about the possible presence of titanium and other metals in the tissues around endosteal dental implants and joint prostheses. Indeed, while some authors reported diffusion of metals into the tissues, some others did not find evidence of this phenomenon. In the present study, four dental titanium implants, removed with the surrounding tissues from patients at various time intervals after the insertion, were studied by means of the micro-beam proton-induced X-ray emission (PIXE micro-beam) technique, which draws maps showing the tissue distribution of elements with a detection limit of about 1 ppm. One implant was built in commercially pure titanium, two others in titanium coated with titanium plasma spray, and the fourth in Ti-Al-V alloy. Their composition was confirmed by the PIXE micro-beam analyses. The removed samples were embedded in epoxy and processed with a cutting-grinding appliance, mounted on plastic holders, and ground up to a thickness of about 35 microm. Optical microscope examinations were also carried out, to compare the optical findings with the elemental maps obtained with the PIXE micro-beam. One implant, removed after 70 days because the patient had developed peri-implantitis, had some inflammatory soft tissue attached, with no evidence of metal leakage. The other three implants had been removed after 6, 7 and 9 years of valid clinical service, because of the fracture of the prosthetic abutment or the implant stem. At the optical microscope, all these fixtures were embedded in mature bone. The elemental maps indicated small titanium deposits in about 5% of the bone bordering the implants, while aluminum, when present in the fixture, leaked diffusely into the surrounding bone and vanadium was not found in the tissues. These results suggest that titanium may be found occasionally in peri-implantar tissues, but has very little tendency to spread, while the presence of aluminum in the implant alloy may cause an important leakage of this metal.

Journal Article↗

PubMed1989

In vitro substance loss due to galvanic corrosion in Ti implant/Ni-Cr supraconstruction systems.

To characterize the galvanic corrosion of supraconstructions consisting of Ni-Cr alloys that come in contact with titanium implants, the resultant substance loss was determined. The measurement of the released substance masses was conducted by analysis of the electrolyte solutions with the aid of atomic absorption spectrometry and by approximate calculation using current density time curves, according to Faraday's law. The results of this study show that both methods allow a clear differentiation of the corrosion behavior of various Ni-Cr alloys that come in contact with titanium.

Chromium Alloys↗

PubMed2006

Scanning electron microscopy and energy dispersive X-ray study of a recovered dental implant.

A recovered dental implant has been studied for surface contamination using SEM and EDS microanalysis. The implant had been in place for 4 years in an adult male (age: 56 years), who had poor oral hygiene and was a smoker. Loosening had occurred, and the implant was removed accidentally during the taking of an impression. Using SEM, three distinct regions were identified, a clear one where the metal appeared shiny and unaffected, a discoloured one, where the surface appeared smooth and uncoated, and a region where there was a distinct deposit. All three regions gave elemental compositions of approximately 85% Ti, 12% Al, 3% V, which is a little richer in aluminium than the nominal overall composition of the usual alloy employed in implants. All three regions showed the presence of carbon, with the highest levels being associated with the surface deposit, and the lowest with the clear region. Oxygen was also present in substantial amounts, with most being found in the discoloured region. No nitrogen was detected, which suggests that the organic surface contamination is not due to interaction with proteins, despite their presence in saliva and crevicular fluid within the mouth.

Dental Implants↗

PubMed1995

Comparison of bone-implant interface shear strength of hydroxyapatite-coated and alumina-coated metal implants.

We performed a transcortical push-out test to determine the effect of surface roughness of hydroxyapatite (HA)-coated implants on bone-implant shear strength in a canine model. Hydroxyapatite- and alumina-coated SUS316L with the same surface roughness (roughness average: Ra = 5 microns) and HA-coated Ti-6A1-4V (Ra = 8.4 microns), sintered HA (Ra = 0.9 micron), and dense alumina (Ra = 1.3 microns) were inserted into the dog's femur. The interface shear strength of the dense alumina was significantly lower than that of other implants at both 4 and 12 weeks after implantation. At 4 weeks after implantation, the interface shear strength of the alumina-coated SUS316L was significantly lower than that of other implants (P < .05) except the dense alumina, but at 12 weeks, there was no significant difference between the implant types except the dense alumina. This indicates that the surface roughness of the HA coating affects the enhancement of the bone-implant interface shear strength at the early period after implantation, and that a surface roughness of several micrometers does not influence the bond strength between bone and HA. A scanning electron microscopic study indicated that in almost all cases at 12 weeks, the failure site after push-out testing was the coating-substrate interface, not the coating-bone interface. Therefore, protection of the coating-substrate interface from direct shear loading is needed.

Alloys↗

PubMed2004

Contact profilometry and correspondence analysis to correlate surface properties and cell adhesion in vitro of uncoated and coated Ti and Ti6Al4V disks.

A fundamental goal in the field of implantology is the design of specific devices able to induce a controlled and rapid "osseointegration". This result has been achieved by means of surface modifications aimed at optimizing implant-to-bone contact; furthermore, bone cell adhesion on implant surface has been directly improved by the application of biomolecules that stimulate new tissue formation, thus controlling interactions between biological environment and implanted materials. Actually, methods for biochemical factor delivery at the interface between implant surface and biological tissues are under investigation; a reliable technique is represented by the inclusion of biologically active molecules into biocompatible and biodegradable materials used for coating implant surface. This paper focuses the application of three polymeric materials already acknowledged in the clinical practice, i.e. poly-L-lactic acid (PLLA), poly-DL-lactic acid (PDLA), and sodium alginate hydrogel. They have been used to coat Ti (Ti2) and Ti6Al4V (Ti5) disks; their characteristics have been determined and their performances compared, with specific regard to the ability in allowing osteoblast adhesion in vitro. Moreover, profilometry data analysis permitted to identify a specific roughness parameter (peak density) which mainly controls the amount of osteoblast adhesion.

Alginates↗

PubMed2005

The effects of implant composition on extensor tenosynovitis in a canine distal radius fracture model.

PURPOSE: Dorsal plating of distal radius fractures with titanium plates has resulted in clinically observed tenosynovitis and tendon rupture. The goal of this study was to investigate whether titanium-based implants result in more extensor tendon inflammation than matched stainless-steel implants in a canine fracture model. METHODS: An osteotomy was created in the distal radius of 18 beagles and fixed with 2.7-mm 4-hole plates composed of commercially pure titanium, titanium alloy (Ti-Al6-V4), or 316L stainless steel. Animals were killed at an average of 4 months. Tendon gliding was assessed by applying a force at the extensor musculotendinous junction and noting gliding. Histologic grading (mild, moderate, severe) was based on cellular hypertrophy, hyperplasia, and leukocytic infiltration. RESULTS: Tendons glided freely in 100% stainless-steel specimens, 75% of titanium alloy, and 43% of commercially pure titanium groups. A severe inflammatory reaction was identified in 60% of the titanium alloy (Ti-A16-V4) group, 57% of the pure titanium group, and 0% of the stainless-steel group. CONCLUSIONS: Dorsal plating of the canine radius with commercially pure titanium or titanium alloy implants produced a greater inflammatory peritendinous response than matched stainless-steel implants.

Alloys↗

PubMed2004

Surface modification of implant materials and its effect on attachment and proliferation of bone cells.

Osteoblast-like cell response in variation with the air plasma sprayed (APS) TiO2 coating process parameters correlated with coating properties were investigated to evaluate the durability and biocompatibility of the surface-modified implant. The Taguchi technique was used to determine the coating properties affected by plasma spraying parameters on Ti-6AI-4V alloy substrate. The coating properties were characterized by porosity and surface roughness using an image analyzer and surf analyzer, respectively. The MG-63 osteoblast like cell morphology and proliferation data on TiO2 coated substrate were measured by SEM observation and direct cell counting. It was demonstrated that surface roughness increased as spray distance decreased but gas flow rates and spray distance were major factors in the case of porosity. The osteoblast adhesion morphology and proliferation data indicated that osteoblast-like cell morphology was not influenced by process parameters, but cell proliferation was affected to some extent by surface roughness and porosity among TiO2 coated specimens. Specifically, the difference between those of substrate and coating layer was relatively more visible.

Animals↗

PubMed1988

Hydroxyapatite coatings.

Four coating techniques were evaluated to determine which is most suitable for producing a dense, highly adherent coating onto metallic and ceramic implant materials. Two of the selected coating methods have serious limitations for use in this particular application, and did not meet the specified criteria for satisfactory coating as defined in the initial stages of the study. For example, the dip coating-sintering technique was judged to be unsatisfactory because of the adverse effect of the high-temperature sintering cycle on the mechanical properties of the metallic substrate materials. These materials could not be used in load-bearing applications because of the excessive grain growth and loss of the wrought structure of both the commercially pure Ti and Ti-6Al-4V substrates, and the loss of ductility in the cast Co-Cr-Mo alloy. Another area of concern was that bond strength between the HA coating and the substrate was not high enough to insure that interfacial failure would not occur during the lifetime of the implant. The immersion-coating technique, in which the metal substrate is immersed into the molten ceramic, was shown in a previous study to be the best method of coating a bioreactive glass onto a Co-Cr-Mo implant. Heating HA above its melting temperature, however, caused undesired compositional and structural changes, and upon solidification very limited adherence between the modified ceramic and substrate material occurred under the conditions of this study. The HIP technique, in which the Ti powder substrate and the HA powder coating are sintered together in a high-pressure autoclave, shows great promise for the fabrication of high-quality composite implants. Initial studies have indicated that high-density Ti substrates with a small grain size that are well bonded to a dense HA coating can be produced under optimum conditions. Sintering and densification additives, such as SiO2 powder, do not appear to be necessary. The main drawback to this technique appears to be the reaction of the encapsulating material--whether soda glass, steel, or fused silica--to the HA coating. More extensive testing will necessary to determine the ideal conditions for the HIP technique, as efforts on this technique were discontinued in order to concentrate on the HIP technique, as efforts on this technique were discontinued in order to concentrate on the optimization of the sputter-coating technique so that coated implants for an animal study could be produced on schedule. Based on the results of this study, sputter coating appears to be the method of choice for forming a dense, adherent coating of HA onto a metal substrate.(ABSTRACT TRUNCATED AT 400 WORDS)

Adhesiveness↗

PubMed1996

Surface roughness modulates the local production of growth factors and cytokines by osteoblast-like MG-63 cells.

Titanium (Ti) surface roughness affects proliferation, differentiation, and matrix production of MG-63 osteoblast-like cells. Cytokines and growth factors produced in the milieu surrounding an implant may also be influenced by its surface, thereby modulating the healing process. This study examined the effect of surface roughness on the production of two factors known to have potent effects on bone, prostaglandin E2 (PGE2) and transforming growth factor beta 1 (TGF-beta 1). MG-63 cells were cultured on Ti disks of varying roughness. The surfaces were ranked from smoothest to roughest: electropolished (EP), pretreated with hydrofluoric acid-nitric acid (PT), fine sand-blasted, etched with HCl and H2SO4, and washed (EA), coarse sand-blasted, etched with HCl and H2SO4, and washed (CA), and Ti plasma-sprayed (TPS). Cells were cultured in 24-well polystyrene (plastic) dishes as controls and to determine when confluence was achieved. Media were collected and cell number determined 24 h postconfluence. PGE2 and TGF-beta 1 levels in the conditioned media were determined using commercial radioimmunoassay and enzyme-linked immunosorbent assay kits, respectively. There was an inverse relationship between cell number and Ti surface roughness. Total PGE2 content in the media of cultures grown on the three roughest surfaces (FA, CA, and TPS) was significantly increased 1.5-4.0 times over that found in media of cultures grown on plastic or smooth surfaces. When PGE2 production was expressed per cell number, CA and TPS cultures exhibited six- to eightfold increases compared to cultures on plastic and smooth surfaces. There was a direct relationship between TGF-beta 1 production and surface roughness, both in terms of total TGF-beta 1 per culture and when normalized for cell number. TGF-beta 1 production on rough surfaces (CA and TPS) was three to five times higher than on plastic. These studies indicate that substrate surface roughness affects cytokine and growth factor production by MG-63 cells, suggesting that surface roughness may modulate the activity of cells interacting with an implant, and thereby affect tissue healing and implant success.

Biocompatible Materials↗

PubMed2003

Sutures and suture anchors: update 2003.

PURPOSE: The purpose of this study was to evaluate recently introduced sutures and suture anchors for single-pull load-to-failure strength and failure mode. TYPE OF STUDY: Experimental laboratory biomechanical study. METHODS: Using an established protocol in fresh porcine femurs, anchors were tested in diaphyseal cortex, metaphyseal cortex, and cancellous troughs after threading them with either steel sutures or strong synthetic material to reduce the likelihood of suture breakage as a mode of failure. An Instron machine (Instron, Canton, MA) applied tensile loads parallel to the axis of insertion at a rate of 12.5 mm/second until failure, and mean anchor failure strengths were calculated. Mode of failure was recorded (anchor pullout, suture eyelet cutout, or wire breakage). Anchors tested included the RotorloC (Smith & Nephew Endoscopy, Andover, MA), TwinFix Ti 3.5, TwinFix Ti 5.0, and TwinFix AB (Smith & Nephew Endoscopy), Super Revo and UltraSorb (Linvatec, Largo, FL), Duet (Bionx Implants, Blue Bell, PA), AlloAnchor RC (Regeneration Technologies, Alachua, FL), Opus Magnum anchor (Opus Medical, San Juan Capistrano, CA), and the BioCorkscrew 5.0 and BioCorkscrew 6.5 (Arthrex, Naples, FL). Sutures tested were No.2 and No. 5 Ethibond (Ethicon, Somerville, NJ), No. 2 Panacryl (Mitek, a division of Ethicon, Somerville, NJ), and Nos. 2, 5, and 2-0 Fiberwire (Arthrex, Naples, FL). RESULTS: The sutures all broke in the midpoint of their tested strand away from the grips. The No. 2 Ethibond failed at a mean of 21 lb (92 N); No. 5 Ethibond failed at a mean of 44 lb (193 N); No. 2, No. 5, and No. 2-0 Fiberwire at means of 44 lb (188 N), 112 lb (483N), and 19 lb (82 N), respectively; and No. 2 Panacryl at a mean of 22 lb (99 N). The suture anchors all failed at levels higher than the associated sutures. CONCLUSIONS: Screw anchors showed higher load to failure values than nonscrew designs, and the new biodegradable anchors showed failure loads lower than the anchors. All anchors were stronger than the suture for which they are designed.

Animals↗

PubMed2001

[Failure of acetabular cups fixed with cement and thick embedded wire mesh].

PURPOSE OF THE STUDY: We report our experience with the SKH(R) cemented acetabular cup, analyzing the clinical and radiographic consequences of using cement armed with a thick embedded wire mesh. MATERIAL AND METHODS: Between June 1990 and June 1991, 118 total hip arthroplasties (THAs) were performed in 110 patients (8 bilateral cases) using the SKH(R) cemented acetabular cup, a self-blocking cemented femoral stem with anterograde injection made of a Ti-6Al-7Nb alloy and a 28 mm ceramic polyethylene articulation. Mean follow-up for 97 implants (91 patients) was 7.1 years (3 - 9 years). Mean age at implantation was 65 years (36 - 85 years) (43 men and 48 women). THAs were performed for degenerative joint disease (n=79) including 67 cases of primary disease, necrosis (n=11), rheumatoid disease (n=6), and fracture of the femoral neck (n=1). RESULTS: For the 118 procedures, there were 4 complications: 2 dislocations (no revision), one failure of the ceramic head and one implant infection (with revision). As assessed by the Postel-Merle-d'Aubigné score as modified by Charnley for the mobility criterion, clinical outcome was excellent or good in 82% of the cases, fair in 11% and poor in 7%. According to the Massin criteria at last follow-up, there were 13 cup loosenings (13.4%, 10 migrations and 3 total lucent lines > 1 mm); revision procedures were performed in 6 cases. A lucent line postoperatively, observed in 51% of the cases (p=0.025) and involving all or part of zone 1 in 44% (p=0.047), was predictive of acetabular failure. Linear polyethylene wear as measured manually was 0.08 mm/year (average) for non-loosened cups and 0.2 mm/year for loosened cups; the difference was significant (p=0.001). On the contrary, the thickness of the cement, measured at the limits of the three De Lee and Charnley zones, cup tilt and size, age, weight and patient activity level had no effect on failure rate. Actuarial survival of the cup at 9 years was 86.3% taking aseptic loosening (with or without revision) as the failure criterion and 93.8% taking revision for aseptic loosening as the failure criterion. DISCUSSION: These results were rather disappointing. The thick layer of cement reinforced with the wire mesh produces a metal back effect with the known consequences in terms of loosening, cement-bone lucent line, and polyethylene wear. A modification is now undergoing thermal and mechanical assessment. A thinner and tighter mesh would appear to be preferable.

Acetabulum↗

PubMed1998

Cytokeratin expression in human oral gingival epithelial cells: in vitro regulation by titanium-based implant materials.

To evaluate whether cytokeratin expression in human oral epithelial cells could be influenced by implant materials used in dental surgery, passaged human oral gingival epithelial cells were seeded on commercially pure titanium (CP-Ti) or on Ti6Al4V titanium alloy. Confluence was achieved after about 15 days on both substrates. Cells formed at that time, an organized layer of densely packed polygonal cells, and harbored a filamentous cytokeratin network typical of epithelial cells. Immunochemistry and immunoblot analysis were used to detect modifications of the amount of individual CK polypeptides (CK7, 8, 13, 18 and 19) in function of the culture substrate. Results showed that the level of CK8, CK18 and CK19 expression was not altered whatever the culture substrate used. The expression of CK13 was reduced in epithelial cells cultured on the titanium alloy, as compared with commercially pure titanium. Conversely, the level of CK7 was higher on the Ti6Al4V alloy than on commercially pure titanium. This study suggests that titanium-based implant materials could influence differently the phenotype of oral gingival epithelial cells.

Alloys↗