SEARCH · PubMed Health

Results for “Ti implants”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed2006

Focal adhesion contact formation by fibroblasts cultured on surface-modified dental implants: an in vitro study.

A major consideration in designing dental implants is to create a surface that provides strong attachment of the implant to bone, connective tissue and epithelium. The aim of the present study was to examine the influence of different treatments of titanium (Ti) implant surfaces on focal adhesion contact (FAC) formation in fibroblast cultures. Human gingival fibroblasts were cultured on glass sheets and polished Ti discs with different surface coatings (applied by physical vapor deposition (PVD): Ti, titanium nitride (TiN), zirconium nitride (ZrN)) or on Ti discs with different surface topographies. For characterization of all surfaces, modified estimation of surface roughness and spacing parameter was carried out using a contact stylus profilometer. Contact angle measurements were carried out to calculate surface energy. Fibroblasts were prepared for transmission electron microscopy at day 3 after seeding, and the number of FACs and the ratio FAC/cellular cross-sections was determined at a length of 300 microm in ultrathin sections. To visualize the extracellular fibronectin and vitronectin molecules and the intracellular actin and vinculin in FAC areas, immunogold labeling was performed. The results revealed a strong correlation between the number of FACs and the surface roughness. The highest number of FACs and the majority of the immunogold-labeled intra- and extracellular matrix molecules were counted on surfaces with the lowest surface roughness: glass sheets coated with either Ti, TiN or ZrN (roughness average=0.03-0.1 microm). These surfaces appear to favor cellular attachment of human gingival fibroblasts and moreover in previous studies the hard coatings have been shown to reduce bacterial adhesion.

Analysis of Variance↗

PubMed1990

Hydroxyapatite coating enhances fixation of porous coated implants. A comparison in dogs between press fit and noninterference fit.

Intimate contact at the bone-porous surface interface is not always achievable in noncemented prosthetic implantation. We investigated the effect of hydroxyapatite (HA) coating on skeletal attachment in noninterference fit 4 weeks after implantation in 6 mature dogs. The push-out test of HA-coated implants surrounded by a 1-mm gap showed a twofold increased shear strength and fivefold increased shear stiffness compared with titanium alloy (Ti) coated implants. The fixation of Ti implants was reduced by two thirds when inserted in a gap as compared with press fit, whereas HA-coated implants in gap showed anchorage close to implants in press fit. Only minor differences were found between HA and Ti implants in press fit. Histomorphometric analysis showed a significant increase in bone in direct contact to HA-coated implant as compared with Ti implants inserted both in gap and press fit. The study indicates that tightness of surgical fit is an important factor for sufficient fixation of the implant. However, our results demonstrate that hydroxyapatite coating almost eliminates the negative influence of noninterference fit between bone and unloaded implant.

Animals↗

PubMed2002

Osteoblast-mediated mineral deposition in culture is dependent on surface microtopography.

Osteoblast phenotypic expression in monolayer culture depends on surface microtopography. Here we tested the hypothesis that mineralized bone nodule formation in response to osteotropic agents such as bone morphogenetic protein-2 (BMP-2) and dexamethasone is also influenced by surface microtopography. Fetal rat calvarial (FRC) cells were cultured on Ti implant materials (PT [pretreated], Ra = 0.6 microm; SLA [course grit blasted and acid etched], Ra = 4.0 microm; TPS [Ti plasma sprayed], Ra = 5.2 microm) in the presence of either BMP-2 (20 ng/ml) or 10(-8) M dexamethasone (Dex). At 14 days post-confluence, a homogenous layer of cells covered the surfaces, and stacks of cells that appeared to be nodules emerging from the culture surface were present in some areas on all three Ti surfaces. Cell proliferation decreased while alkaline phosphatase specific activity (ALPase) and nodule number generally increased with increasing surface roughness in both control and treated cultures. There was no difference in cell number between the control and Dex-treated cultures for a particular surface, but BMP-2 significantly reduced cell number compared with control or Dex-treated cultures. Treatment with Dex or BMP-2 further increased ALPase on all surfaces except for PT cultures with Dex. Dex had no effect on nodule area in cultures grown on PT or SLA disks, yet increased nodule number by more than 100% in cultures on PT disks. Though the effect of BMP-2 on nodule number was the same as Dex, BMP-2 increased nodule area on all surfaces except TPS, where area was decreased. Ca and P content of the cell layers in control cultures did not vary with surface roughness. However, cultures treated with Dex had increased Ca content on all surfaces, but the greatest increase was seen on SLA and TPS. BMP-2 increased Ca content in cultures on all surfaces, with the greatest increase on the PT surface. BMP-2 treatment increased P content on all surfaces, whereas Dex only increased P on rough surfaces. Of all cultures examined, the Ca/P weight ratio was 2:1 only on rough surfaces with BMP-2, indicating the presence of bone-like apatite. This was further validated by Fourier transform infrared (FTIR) imaging showing a close association between mineral and matrix on TPS and SLA surfaces with BMP-2-treated cells, and individual spectra indicated the presence of an apatitic mineral phase comparable to bone. In contrast, mineral on the smooth surface of BMP-2-treated cultures and on all surfaces where cultures were treated with Dex was not associated with the matrix and the spectra, not typical of bone apatite, implying dystrophic mineralization. This demonstrates that interactions between growth factor or hormone and surface microtopography can modulate bone cell differentiation and mineralization.

Alkaline Phosphatase↗

PubMed1998

Osseointegration in implant-embedded mandible in rats fed calcium-deficient diet: a radiological study.

OBJECTIVE: The purpose of the present study was to investigate osseointegration using radiographs of titanium (Ti) implants into the osteoporotic mandible of rats. MATERIALS AND METHODS: Rats were divided into three groups: first group, which were fed a standard diet throughout (control group), second group which were fed a Ca-deficient diet for only 1 week before implantation (group A), and those which were fed the Ca-deficient diet before and after implantation (group B). On the 7th and 42nd days after implantation, bone changes in those rats were examined by microradiographs and autoradiographs. RESULTS: On the 7th day after implantation, calcification of newly formed bones was lower in groups A and B than in the control group, 45Ca uptake was seen in surrounding bones adjacent to the implant, as well as throughout the mandible. On the 42nd day after implantation, trabecular bone in group A showed radiopacity as seen in the control group. In the alveolar crest and peri-implanted bones in group B, thin bone formation with active 45Ca incorporation was found. CONCLUSIONS: It is suggested that irrespective of the calcium deficiency status in rats, trabecular bones around the implant are restored to a healthy state to some extent by resuming an intake of a necessary amount of dietary calcium. In continued calcium deficiency, osseointegration with the implant and alveolar bone was still observed as in the healthy rats suggesting calcium deficiency is not always a factor to regulate osseointegration of mandibular endosseous implants.

Alveolar Process↗

PubMed2006

Chemical surface modification of high-strength porous Ti compacts by spark plasma sintering.

The biological properties of a titanium (Ti) implant depend on its surface oxide film. The aims of the present study were to increase the specific surface oxide area on Ti using a porous structure and to study the relationship between the amount of apatite coating in simulated body fluid (SBF) and the actual surface area on titanium powders. Ti powders of 110 microm average diameter were sintered by spark plasma sintering. The sintered compacts had a porosity of 28%, a compressive elastic modulus of 7.9 GPa and an ultimate strength of 112 MPa. The compressive strength of the compacts was increased to 588 MPa by subsequent annealing in a vacuum furnace at 1000 degrees C for 24 h. The sintered compacts were treated with aqueous NaOH solution and subsequently heated at 600 degrees C. The pretreated compacts showed apatite crystal precipitation in SBF. The amounts of precipitates through the compacts were compared with those of the Ti plate substrates subjected to the same chemical pretreatment. It was confirmed that the amounts of precipitates through the compacts were more than one hundred times higher than those on the Ti plates. It was concluded that the metal porous compacts developed may be used as functional materials for immobilizing functional proteins and/or drugs, because the precipitated apatite can adsorbed these substances.

Apatites↗

PubMed2002

In vivo RANK signaling blockade using the receptor activator of NF-kappaB:Fc effectively prevents and ameliorates wear debris-induced osteolysis via osteoclast depletion without inhibiting osteogenesis.

Prosthesis failure due to wear debris-induced osteolysis remains a major clinical problem and the greatest limitation for total joint arthroplasty. Based on our knowledge of osteoclast involvement in this process and the requirements of receptor activator of NF-kappaB (RANK) signaling in osteoclastogenesis and bone resorption, we investigated the efficacy of RANK blockade in preventing and ameliorating titanium (Ti)-induced osteolysis in a mouse calvaria model. Compared with placebo controls we found that all doses of RANK:Fc above 1 mg/kg intraperitoneally (ip) per 48 h significantly inhibited osteoclastogenesis and bone resorption in response to Ti implanted locally. Complete inhibition occurred at 10 mg/kg ip per 48 h, yielding results that were statistically equivalent to data obtained with Ti-treated RANK-/- mice. We also evaluated the effects of a single injection of RANK:Fc on day 5 on established osteolysis and found that Ti-treated were still depleted for multinucleated tartrate-resistant acid phosphatase-positive (TRAP+) cells 16 days later. More importantly, this osteoclast depletion did not affect bone formation because the bone lost from the osteolysis on day 5 was restored by day 21. An assessment of the quantity and quality of the newly formed bone in these calvariae by calcein labeling and infrared (IR) microscopy, respectively, showed no significant negative effect of RANK:Fc treatment. These studies indicate that osteoclast depletion via RANK blockade is an effective method to prevent and reverse wear debris-induced osteolysis without jeopardizing osteogenesis.

Acid Phosphatase↗

PubMed1997

Effects of guided bone regeneration around commercially pure titanium and hydroxyapatite-coated dental implants. II. Histologic analysis.

The purpose of this study was to determine which treatment of a large osseous defect adjacent to an endosseous dental implant would produce the greatest regeneration of bone and degree of osseointegration: barrier membrane therapy plus demineralized freeze-dried bone allograft (DFDBA), membrane therapy alone, or no treatment. The current study histologically assessed changes in bone within the healed peri-implant osseous defect. In a split-mouth design, 6 implants were placed in edentulous mandibular ridges of 10 mongrel dogs after preparation of 6 cylindrical mid-crestal defects, 5 mm in depth, and 9.525 mm in diameter. An implant site was then prepared in the center of each defect to a depth of 5 mm beyond the apical extent of the defect. One mandibular quadrant received three commercially pure titanium (Ti) screw implants (3.75 x 10 mm), while the contralateral side received three hydroxyapatite (HA) coated root-form implants (3.3 x 10 mm). Consequently, the coronal 5 mm of each implant was surrounded by a circumferential defect approximately 3 mm wide and 5 mm deep. The three dental implants in each quadrant received either DFDBA (canine source) and an expanded polytetrafluoroethylene membrane (ePTFE), ePTFE membrane alone, or no treatment which served as the control. Clinically, the greatest increase in ridge height and width was seen with DFDBA/ePTFE. Histologically, statistically significant differences in defect osseointegration were seen between treatment groups (P < 0.0001: DFDBA/ePTFE > ePTFE alone > control). HA-coated implants had significantly greater osseointegration within the defect than Ti implants (P < 0.0001). Average trabeculation of newly formed bone in the defect after healing was significantly greater for HA-coated implants than for titanium (P < 0.0001), while the effect on trabeculation between treatments was not significantly different (P = 0.14). Finally, there were significantly less residual allograft particles in defect areas adjacent to HA-coated implants than Ti implants (P = 0.0355). The use of HA-coated implants in large size defects with DFDBA and ePTFE membranes produced significantly more osseointegration histologically than other treatment options and more than Ti implants with the same treatment combinations. The results of this study indicate that, although the implants appeared osseointegrated clinically after 4 months of healing, histologic data suggest that selection of both the implant type and the treatment modality is important in obtaining optimum osseointegration in large size defects.

Alveolar Bone Loss↗

PubMedDate not supplied

Osseointegrated dental implants as alternative therapy to bridge construction or orthodontics in young patients: seven years of clinical experience.

Young patients often require fixed bridgework or orthodontic therapy in cases of traumatic tooth loss or congenitally missing teeth. Dental implants represent an alternative to the more conventional treatment methods. We report positive experience over a seven-year period with 42 titanium Ha-Ti implants in 34 patients aged 9 to 18 years. Fourteen implants were placed into prepared tooth sockets immediately after traumatic luxation of anterior teeth in 12 patients aged 9 to 18 years (median age 16). An additional 22 patients (median age 15.5, range 11 to 18) also received implants (N = 28), but these were placed only after healing of extraction sites, or as substitutes for congenitally missing teeth. Implants remained in situ for an average of 7.7 months before loading. During the healing period, three implants were lost due to additional trauma and one became infected. The 38 remaining implants osseointegrated and since have been loaded for five to 79 months in successful function. There was no difference between immediate and delayed implants in clinical success. These experiences demonstrate that appropriate, versatile, osseointegrated implants can provide a successful treatment method for young patients, without damaging adjacent teeth.

Adolescent↗

PubMed1997

Osseointegration of dental implants in rabbit bone with low mineral density.

PURPOSE: The purposes of this study were to establish an experimental animal model with bone of low mineral density, and to then investigate the reaction of the bone-implant interface in these experimental animals. MATERIALS AND METHODS: To prepare the experimental model, rabbits were ovariectomized and fed a 0.15% low-calcium diet. The bone mineral density (BMD) of the tibia was periodically measured by dual-energy X-ray absorptiometry. Approximately 1 month after the introduction of the low-calcium diet, when BMD had decreased to about 12% less than that of control rabbits, a titanium implant (TI) was inserted into the tibia of each rabbit. At 2, 4, 8, and 12 weeks after the insertion of the TI, the rabbits were killed, and the reaction of the bone tissue surrounding the TI was examined both histologically and radiographically. RESULTS: The combined ovariectomy and low-calcium diet produced rabbits having bone with low mineral density, and the histologic features of the tibia in these rabbits were consistent with those in human osteoporotic bone. In control rabbits, new bone formation surrounding the TI was evident 2 weeks after its insertion, and the TI surface was almost completely covered with new bone after 8 weeks. In contrast, new bone formation in the experimental rabbits was delayed, but considerable direct bone contact with the TI was observed after 12 weeks. CONCLUSION: These results suggest that osteoporotic bone may affect the healing period of bone tissue after the insertion of dental implants, but that osseointegration of dental implants may be obtained even in osteoporotic bone.

Animals↗

PubMed2001

Influence of age and gender on peri-implant osteogenesis. Age and gender on peri-implant osteogenesis.

Among the local and systemic factors affecting bone repair, great interest is focused on age and gender. The aim of this work was to perform a histomorphometric evaluation of peri-implant bone healing response in male and female rats aged 1 and 3 months. Forty Wistar rats were i.p. anesthetized with xylazine and ketamine. A c.p. Ti implant (Implant Vel, Buenos Aires-Argentina) was placed in the right tibia following the method described by Cabrini et al. (Implant Dent 1993; 2:264-267). Group I: (GI, n = 10) female rats aged 1 month; Group II: (GII, n = 10) female rats aged 3 months; Group III: (GIII, n = 10) male rats aged 1 month; Group IV: (GIV, n = 10) male rats aged 3 months. All the animals were killed by ether overdose 30 days post-implantation. The tibiae were resected, radiographed and embedded in methyl-methacrylate. Ground sections perpendicular to the longer axis of the tibia were obtained and stained with toluidine blue. Percentage of osseointegration and peri-implant bone tissue volume were evaluated. No differences in peri-implant bone tissue histology were observed among groups. No statistically significant differences in peri-implant bone volume and percentage of osseointegration were observed between GII (adult females) and GIV (adult males). Peri-implant bone volume and percentage of osseointegration were markedly greater in GIV (adult males) than in GIII (young males) (14 +/- 1 mm2 and 8 +/- 2 mm2) p < 0.01 and (49 +/- 6% and 24 +/- 9%) p < 0.01 respectively. Using this experimental model, differences in peri-implant osteogenesis (bone volume and percentage of osseointegration) associated to gender were only observed in the young rats, and differences associated to age were found between the groups of males.

Age Factors↗

PubMedDate not supplied

Long-term bone response to titanium implants coated with thin radiofrequent magnetron-sputtered hydroxyapatite in rabbits.

PURPOSE: The present study was designed to investigate the long-term bone response around machined screw-type uncoated and calcium phosphate (CaP) -coated commercially pure titanium implants. MATERIALS AND METHODS: Using a magnetron sputtering technique, implants with a CaP coating similar in composition and CaP ratio to hydroxyapatite were produced. Heat treatment was subsequently used to increase the crystallinity of the coatings. Four types of coatings (0.1 and 2.0 microm amorphous and 0.1 and 2.0 microm crystalline) were manufactured; uncoated implants served as a control. Three hundred twenty implants (64 of each type) were randomly placed in the tibial cortical and trabecular femoral bones of 40 rabbits. The rabbits were sacrificed 9 months after implant placement. RESULTS: Histomorphometric evaluation carried out on ground sections revealed that the crystalline CaP coatings achieved the highest bone-implant contact in both tibiae and femora compared with amorphous CaP-coated and uncoated titanium. DISCUSSION: The present study suggests that submicron crystalline hydroxyapatite coating adds bioactive properties to titanium oral implants. CONCLUSION: An ultra-thin, 0.1-microm crystalline CaP coating can elicit and maintain an improved long-term bone response compared to amorphous coated or uncoated Ti implants, without any adverse tissue reactions.

Analysis of Variance↗

PubMed1998

Measurement and control of interface strength of RF magnetron-sputtered Ca-PO coating on Ti-6Al-4V substrates using a laser spallation technique.

In previous studies, an RF magnetron sputter technique was developed for the production of thin calcium phosphate coating. Several deposition parameters were found to influence the growth rate and the stoichiometry of the coatings. For instance, deposition with additional oxygen pressure decreased the Ca to P ratio of the coatings to 1.67. For application of these coatings on actual Ti implants, it is important to know their adhesive tensile strength with the implant surface and how it varies with the deposition parameters. Motivated by these goals, the aim of this study was to measure the adhesive tensile strength of these coatings with Ti substrates and to study its variation with the deposition parameters. Since most mechanical characterization methods are incapable of providing a direct measure of the interface's fundamental strength, a novel laser spallation experiment was used to accomplish this task. In this experiment, a compressive stress pulse is generated on the back side of a substrate by impinging a 3-ns long Nd:YAG laser pulse. The stress pulse propagates through the substrate and is reflected into a tensile stress wave from the free surface of the coating deposited on its front surface. The returning tensile pulse pries off the coating if its amplitude is high enough. The peak interface tensile stress is computed by using the optically recorded free surface displacement of the coating. Because interface decohesion is accomplished at a strain rate of almost 10(7) s-1, all inelastic processes essentially are suppressed and the measured value essentially is the intrinsic tensile strength of the interface. Tensile strength values in the range of 500-900 MPa were recorded for the interfaces between sputter-deposited calcium-phosphate coatings and Ti substrates. To confirm the locus of failure, the spalled spots were examined using SEM and EDS. The variation in the measured values was related to the changes in the deposition conditions.

Alloys↗

PubMed1995

Oral bacterial attachment to titanium surfaces: a scanning electron microscopy study.

Despite the wide use of dental implants, the understanding of the mechanism(s) of bacterial attachment to implant surfaces and of the factors that affect such attachment is limited. In this study, the attachment of oral bacteria--including Streptococcus sanguis, Actinomyces viscosus, and Porphyromonas gingivalis--to titanium (Ti) discs with different surface morphology (smooth, grooved, or rough) was examined by scanning electron microscopy (SEM). The most bacterial attachment was observed on the rough BSA-coated Ti surfaces. The smooth surfaces promoted poor attachment for S. sanguis and A. viscosus. However, P. gingivalis attached equally well to both the smooth and grooved coated Ti surfaces, based on direct cell quantitation and examination with SEM. Cell-surface fimbriae (which may play a role in adhesion) of both A. viscosus and P. gingivalis observed were associated with the Ti surfaces. Ti implant surface characteristics appeared to influence oral bacterial attachment in vitro. The in vitro attachment system has proven its usefulness for future bacterial attachment studies with model implant surfaces.

Actinomyces viscosus↗

PubMed2005

Varying Ti-6Al-4V surface roughness induces different early morphologic and molecular responses in MG63 osteoblast-like cells.

Osteoblast response to Ti implants depends not only on the chemistry of the implant but also on the physical properties of the implant surface, such as microtopography and roughness. This study was undertaken to examine early changes in cell morphology and gene expression during the early phase of osteoblast interaction with titanium alloy (Ti-6Al-4V) surfaces of two different roughnesses. MG63 osteoblast-like cells were cultured for 2, 6, 24, and 72 h on smooth (Ra=0.18+/-0.03 microm) and rough (Ra=2.95+/-0.23 microm) Ti-6Al-4V surfaces. Changes in cell proliferation were assessed by measuring cell number after 72 h in culture. Morphological characteristics were observed by scanning electron microscopy after 2, 6, and 24 h of culture. Changes in gene expression for extracellular signal-regulated kinase 2 (Erk2), type I collagen (alpha2[I] collagen), phospholipase C-gamma2 (Plc-gamma2), and beta-actin were measured by RT-PCR after 6 and 24 h in culture. Cell number was significantly higher on the smooth surface. In scanning electron micrographs, cells on smooth Ti-6Al-4V were spherical and raised up from the surface after 2 h in culture. In contrast, cells on the rough surface adopted an irregular, elongated shape that spanned across pits in the surface. At 24 h, cells on the smooth surface had flattened, become elongate, and covered the surface. In contrast, cells on the rough surface appeared more differentiated in shape and the margins of the cells were irregular, with many processes extending out, following the contour of the surface. Of the genes examined, only Erk2 and beta-actin showed a change in expression with surface roughness. Both genes were upregulated (p<0.05) on the rough surface at 6 h. These results indicate that Ti-6Al-4V surface roughness affects osteoblast proliferation, morphology, and gene expression, and that these effects can be measured after periods as short as 2-6 h.

Alloys↗

PubMed1998

Laminin-5 coating enhances epithelial cell attachment, spreading, and hemidesmosome assembly on Ti-6A1-4V implant material in vitro.

Enhancement of epithelial cell attachment to laminin-5-coated titanium alloy (Ti-6Al-4V) implant material was evaluated in vitro. Protein analysis showed that Ti-6Al-4V has a high affinity for laminin-5 and adsorbed significantly more laminin-5 than laminin-1. DNA analysis showed that laminin-5 enhanced attachment of normal human epidermal keratinocytes (NHEK) to Ti-6Al-4V significantly more than did laminin-1 or uncoated controls. The effect of passivation on laminin-5 adsorption and activity on Ti-6Al-4V also was evaluated. Passivation had no significant effect on the amount of protein adsorbed; however, AFM, ESCA, and ToF-SIMS analyses suggested that passivation affects the conformation of adsorbed laminin-5. Although laminin-5 coating significantly enhanced rapid attachment of epithelial cells to both passivated and unpassivated Ti-6Al-4V, surface area measurements showed that cells spread on laminin-5-coated passivated Ti-6Al-4V covered a significantly larger surface area than cells spread on laminin-5-coated unpassivated samples. TEM analysis showed that cells formed significantly more hemidesmosomes on the surface of laminin-5 coated passivated than on the surface of laminin-5 coated unpassivated titanium alloy. The enhancement of rapid cell attachment, spreading, and hemidesmosome assembly on laminin-5-coated passivated samples may reflect better integration between epithelial cells and titanium alloy and thus may be predictive of long-term implant stability.

Cell Adhesion↗

PubMed2005

Fixation of revision implants is improved by a surgical technique to crack the sclerotic bone rim.

Revision joint replacement has poorer outcomes compared with primary joint replacement, and these poor outcomes have been associated with poorer fixation. We investigated a surgical technique done during the revision operation to improve access from the marrow space to the implant interface by locally cracking the sclerotic bone rim that forms during aseptic loosening. Sixteen implants were inserted bilaterally by distal femur articulation of the knee joint of eight dogs, using our controlled experimental model that replicates the revision setting (sclerotic bone rim, dense fibrous tissue, macrophages, elevated cytokines) by pistoning a loaded 6.0-mm implant 500 microm into the distal femur with particulate PE. At 8 weeks, one of two revision procedures was done. Both revision procedures included complete removal of the membrane, scraping, lavaging, and inserting a revision plasma-spray Ti implant. The crack revision procedure also used a splined tool to circumferentially locally perforate the sclerotic bone rim before insertion of an identical revision implant. Superior fixation was achieved with the cracking procedure in this experimental model. Revision implants inserted with the rim cracking procedure had a significantly higher pushout strength (fivefold median increase) and energy to failure (sixfold median increase), compared with the control revision procedure. Additional evaluation is needed of local perforation of sclerotic bone rim as a simple bone-sparing means to improve revision implant fixation and thereby increase revision implant longevity.

Animals↗

PubMed2004

The effects of patient age on human osteoblasts' response to Ti-6Al-4V implants in vitro.

Osseointegrated implants are a common therapy for the elderly population as lifespan increases. Understanding the effects of age and sex on osseointegration is important for successful implant therapy. Therefore, the response of primary human osteoblasts (HOB) to implant materials was studied. HOBs were obtained by outgrowth of cells from bone from orthopaedic procedures and categorized as Young (Y), <15; Middle (M), 30-50; and Old (O), >60 years old. Initially the HOB phenotype was determined on tissue culture plastic. Alkaline phosphatase (ALP) staining and activity were significantly increased in HOBs from older patients. Message levels of type I collagen (COL), bone sialoprotein (BSP) and ALP were significantly higher (from 2.3- to 3.8-fold) in Y subjects compared to M and O patients at 2 weeks. Studies of the response of HOBs to implant materials were undertaken using Ti-6Al-4V disks prepared in a manner similar to orthopaedic implants. A 1.4-fold (p<0.05) increase in cell attachment was found in HOBs from Y compared with O in female subjects but not in male subjects. Cell proliferation at 24 h was not significantly different by age or sex, nor was DNA content different at 2 and 4 weeks. Mineralization in HOB-implant cultures was 2.3-fold higher in Y than in O, and 1.7-fold higher in Y compared to M HOBs from female but not male subjects at 4 weeks. Northern blot and RT-PCR analysis at 2 weeks of culture showed significantly higher levels (1.6-2.3-fold) of COL, BSP, and osteocalcin (OC) mRNAs in Y HOBs compared to M and O HOBs from female subjects. We conclude that human osteoblasts from older female patients have a decreased ability to form bone on implants.

Adult↗

PubMed2000

Sealing effect of hydroxyapatite coating: a 12-month study in canines.

This study addresses the clinical problems regarding access of wear debris to the bone-implant interface and the possible dissemination of polyethylene (PE) particles to distant organs. We inserted two implants into each knee of 7 dogs allowing access of joint fluid to the bone-implant interface with a 0.75 mm initial gap around the implant. Hydroxyapatite (HA)-coated and non-coated (Ti) titanium alloy implants were randomly allocated to each distal femoral condyle. PE particles were repeatedly injected into the right knee joint 3 weeks after surgery for a period of 49 weeks, while only vehicle was injected into the left knee joint. We found huge amounts of PE particles mainly in the bone-implant interface around Ti implants. Infiltration of mononuclear inflammatory cells was present around 3 of 7 Ti implants in relation to PE particles. HA implants had approximately 70% bone ongrowth. In contrast, no bone ongrowth was seen on any Ti implants, all being surrounded by a fibrous membrane. The number of PE particles was evaluated semi-quantitatively. More PE particles were found around Ti implants than with HA implants (p < 0.002). Specimens from iliac lymph nodes, liver, spleen and lung were examined and showed dissemination of PE particles only in regional lymph nodes.

Animals↗