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At least 1,423 records · Page 79Linked to original sources
PubMed1994

Titanium implant insertion into dog alveolar ridges augmented by allogenic material.

The purpose of this investigation was to evaluate whether titanium endosseous implants would osseointegrate in dog alveolar ridges augmented by allogenic material. In 8 dogs en bloc resection, including 2 pre-molars, was performed bilaterally in the maxilla and the mandible. After a healing period of 6 weeks allogenic, demineralized and lyophilized dentin or bone was implanted subperiosteally. Titanium implants were installed 5.5 months later in some of the regions. Light and fluorescence microscopic evaluation revealed fibrous encapsulation of the implanted allogenic material, no osteoinduction and only minimal osteoconduction, few multinuclear giant cells and a sparse inflammatory reaction. The titanium implants healed mainly by fibrous encapsulation.

Alveolar Process↗
PubMed1996

Maintenance of implants: an in vitro study of titanium implant surface modifications subsequent to the application of different prophylaxis procedures.

The aim of the present study was to evaluate surface alterations on titanium implant necks subsequent to different prophylaxis procedures. Fifty ITI implants were utilized. Forty implants were treated with 10 different prophylaxis procedures (ultrasonic scaler, plastic tip ultrasonic scaler, stainless steel curette, titanium curette, teflon curette, air powered system, abrasive rubber cups, polishing rubber cup and brush), and 10 implants were left as untreated controls. Surface alterations were studied on an area of 1 mm x 0.9 mm and quantified using optical microscopic, SEM and laser prophylometer analysis. The use of laser prophylometer provided an objective criterion for evaluation, expressing implant neck surface alterations in numeric values in terms of two roughness indexes, Ra and Rz. The results showed that, in comparison with the controls (Ra = 0.50; Rz = 3.98) the procedures investigated could be divided into 3 main groups: 1) Methods which altered the implant neck surface producing increased roughness (Ra = 0.68-2.08; Rz = 4.68-11.92); 2) Methods which left the implant neck surface unaltered (Ra = 0.44-0.57; Rz = 0.42-3.46); 3) Methods resulting in a smoothening of the implant neck surface (Ra = 0.36; Rz = 2.15). Group 1 included procedures that should be avoided. However, it appeared safe to apply the procedures of groups 2 and 3. To confirm these results, it will be necessary to evaluate the plaque- and calculus-removing efficacy from titanium neck implant surfaces in vivo.

Air↗
PubMed1998

The effect of hyperbaric oxygen treatment on bone tissue reactions to c.p. titanium implants placed in free autogenous bone grafts. A histomorphometric study in the rabbit mandible.

This study aimed to investigate the effect of hyperbaric oxygen (HBO) therapy on the tissue reactions to commercially pure (c.p.) titanium implants placed in free autogenous bone graft by a 1-stage procedure. Eighty c.p. titanium implants were placed in the bone grafted from iliac crest to bilateral mandible of 40 Japanese white rabbits without tapping. Twenty rabbits underwent daily a HBO treatment for 60 min under 2.4 ATA during 20 consecutive days and the other untreated 20 rabbits served as controls. The implants with surrounding bone tissue were retrieved 20, 30, 60, 90 and 120 days after surgery, fixated, dehydrated and embedded in resin. About 20 microns thick ground sections were prepared prior to microscopical observations. The bone area and the bone-to-implant contact inside the threads were calculated separately in the grafted bone and in the host bone for each implant. After 30 and up to 120 days, the HBO treated group showed more bone-to-implant contacts in the grafted bone as compared to the non-HBO treated group. In the host bone there were no differences observed between HBO and non-HBO treated groups. This study indicated that HBO treatment was beneficial for the tissue incorporation of c.p. titanium implants when placed immediately in free autogenous bone grafts.

Animals↗
PubMed1997

Morphological and dimensional changes after barrier removal in bone formed beyond the skeletal borders at titanium implants. A kinetic study in the rabbit tibia.

The aim of the present experimental investigation was to study the morphological and dimensional changes of bone, augmented at titanium implants by a membrane technique, taking place after membrane removal. In 12 rabbits, screw-shaped titanium implants were inserted in the tibial metaphyses in such a way that 5 threads became uncovered with bone. Surgery was performed on 2 occasions in order to retrieve specimens with different follow-up times. An e-PTFE barrier and a titanium device were used to provide space for bone formation. In 1 tibia of each rabbit, the membranes and spacers were removed after 8 weeks of healing, and the implants followed for 16 more weeks. Impressions were taken at day 0 and after 8 and 24 weeks of healing and plaster models were produced. In the contralateral tibiae, implants were inserted either 16 or 8 weeks prior to sacrifice. Measurements were made on the plaster models in 3 dimensions at 35 points around each implant in a coordinate measuring machine. Specimens taken 8, 16 and 24 weeks after insertion were analysed by means of light microscopical morphometry. The coordinate measurements showed that, in mean, 1.92 mm of bone had been formed during the first 8 weeks. A statistically significant loss of the height of the newly formed bone (0.70 mm) and thereby reduction of bone volume was found 24 weeks postoperatively. The volume decrease of the newly formed bone was more pronounced beside the implants than over the implant body. The histology showed that woven bone had been formed at the implants after 8 weeks. Further bone formation and remodelling and a net increase of mineralized bone were seen. The degree of bone-implant contact and bone area in the threads increased with time. The present study showed that coordinate measurements on plaster models, obtained from the experimental areas, in combination with histology, form a useful technique to study long-term changes of augmented bone. It was found that bone formed by a barrier membrane technique, decreased in volume during a 16-week follow-up period after barrier removal. Less dimensional changes were observed for the bone formed over the implant body, indicating that a solid surface may have a stabilizing effect on the augmented bone.

Animals↗
PubMed1998

Attachment and proliferation of human oral fibroblasts to titanium surfaces blasted with TiO2 particles. A scanning electron microscopic and histomorphometric analysis.

The purpose of this study was to determine the effect of c.p. titanium surfaces blasted with TiO2 particles on the biological responses of human gingival fibroblasts (HGF). Fibroblast morphology and attachment were investigated on turned (control) titanium surfaces and those blasted with 45 microns (standard), 45-63 microns, and 63-90 microns TiO2 particles. The specimens were analyzed using a confocal laser scanner and SEM. The cell profile areas were measured using a semiautomatic interactive image analyser. The figures were expressed as percent of attachment. The turned samples had the smoothest surfaces and the roughest were those blasted with 63-90 microns. All TiO2 blasted specimens had homogeneous surfaces. Cells appeared to flatten, spread and form cellular bridges with the adjacent cells. Fibroblasts on the turned titanium surfaces appeared to follow the direction of the fine irregularities on the surface but tended to spread haphazardly on the blasted surfaces. The attachment assays showed no significant difference in the percentage of fibroblast cell attachment on the standard surfaces compared to the turned surfaces. Both surfaces blasted with 45-63 microns or 63-90 microns had significantly (P < 0.05) lower percentages of cell attachment than the control. The surfaces blasted with 63-90 microns particles had the lowest rate of cell attachment. A significant correlation (P < 0.01) was found between the degree of particle size and attachment of fibroblasts after 1-72 h. It is concluded that surface micro-texture influences the attachment and growth of HGF: surfaces blasted with 45 microns TiO2 do not inhibit fibroblast attachment and smooth or finely grooved surfaces could be conducive to cellular attachment.

Air Abrasion, Dental↗
PubMed1999

Implant placement and simultaneous ridge augmentation using autogenous bone and a micro titanium mesh: a prospective clinical study with 20 implants.

This prospective clinical study evaluated bone regeneration around 20 dental implants placed in 15 patients (mean age 39.7 years). Peri-implant bone defects were augmented with autogenous bone grafts harvested intraorally from the mandible (chin or retromolar area). Augmented sites were covered with an individually trimmed micro titanium mesh which was rigidly affixed with microscrews to the residual jaw bone. Height of implant exposure (mean 6.5 mm), i.e. dehiscencies (80%) or fenestrations (20%), and graft height (mean 6.2 mm) were measured in an apico-coronal direction using a periodontal probe. At re-entry (mean interval 6.6 months) the titanium mesh and microscrews were removed and bone regeneration assessed. The mean height of the integrated bone graft was 5.8 mm corresponding to a mean bone fill of 93.5%. The overall postop healing course was excellent with only one site developing a soft tissue dehiscence with subsequent mesh exposure (complication rate 5%). This study demonstrated that a micro titanium mesh in combination with autogenous bone grafts is effective for treatment of peri-implant bone defects.

Adolescent↗
PubMed2002

Evaluation of stability of titanium and hydroxyapatite-coated osseointegrated dental implants: a pilot study.

An endosseous implant is described as osseointegrated when it is immobile in function. Objective measures of stability testing have been described. The Periotest is a commercially available device that is used for this purpose. This study was designed to measure stability of endosseous implants placed in the mandible. Implants were placed in the mandibular canine or first premolar area to support an overdenture prosthesis. Stability was evaluated through the use of a Periotest device at the time of implant placement and following one year of functional loading. Implant designs were either a screw-shaped titanium alloy or a hydroxyapatite-coated cylinder. A total of 54 implants were placed, 37 were titanium screw-shaped implants, while the remaining 17 were hydroxyapatite cylinders. Initial measurements of stability showed no difference due to implant type. Following one year of functional loading, titanium screw-shaped implants were more stable than hydroxyapatite implants (P < 0.05). The difference in implant rigidity following a period of functional loading may be an indication of a difference in osseointegration between the two implants used in this study.

Aged↗
PubMed2002

Bone formation in transforming growth factor beta-I-loaded titanium fiber mesh implants.

The osteoconductive properties of porous titanium (Ti) fiber mesh with or without a calcium phosphate (Ca-P) coating and osteoinductive properties of noncoated Ti fiber mesh loaded with recombinant human Transforming Growth Factor beta-1 (rhTGF-beta1) were investigated in a rabbit non-critical size cranial defect model. Nine Ca-P-coated and 18 non-coated porous titanium implants, half of them loaded with rhTGF-beta1, were bilaterally placed in the cranium of 18 New Zealand White rabbits. At 8 weeks postoperative, the rabbits were sacrificed and the skulls with the implants were retrieved. Histological analysis demonstrated that in the TGF-beta1-loaded implants, bone had been formed throughout the implant, up to its center, whereas in the non-loaded implants only partial ingrowth of bone was observed. Bone formation had a trabecular appearance together with bone marrow-like tissue. No difference in ingrowth could be observed between the non-TGF-beta1-loaded non-coated implants and the Ca-P-coated ones. All histological findings were confirmed by image analysis: 97% ingrowth was seen in the rhTGF-beta1-loaded implants, while only 57% and 54% ingrowth was observed in the non-loaded Ca-P-coated and non-coated implants, respectively. Bone surface area and bone fill were significantly higher in the rhTGF-beta1-loaded implants (1.37 mm2 and 36%, respectively) than in the non-loaded implants (0.57 mm2 and 26%). No statistical difference was found for any parameter between the Ca-P-coated and noncoated implants. Quadruple fluorochrome labeling showed that in the Ti and Ti-CaP implants mainly bone guidance had occurred from the former defect edge, while in the Ti-TGF-beta1 implants bone formation had mainly started in the center of a pore and proceeded in a centrifugal manner. Our results show that: (1) the combination of Timesh with TGF-beta1 can induce orthotopic bone formation; (2) Ti-fiber mesh has good osteoconductive properties; (3) a thin Ca-P coating, as applied in this study, does not seem to further enhance the bone-conducting properties of a titanium scaffold material.

Animals↗
PubMed2003

Evaluation of the interface between bone and titanium surfaces being blasted by aluminium oxide or bioceramic particles.

The surface structure, in particular the surface roughness, and the surface chemistry of titanium implants influence their anchoring in bone. The aim of this study was to analyse metal-bone contact (MBC) after modification of the implant surface, using different materials for blasting. The surface modification of titanium was produced by blasting it with particles made of Al2O3 or bioceramics. The biological effects were then investigated experimentally using 27 rabbits, analysed after 7, 28 and 84 days after the implantation of titanium cylinders treated accordingly. The MBC showed a tendency for more bone after bioceramics were used as a blasting material, compared to Al2O3.

Aluminum Oxide↗
PubMed2003

Effects of occlusiveness of a titanium cap on bone generation beyond the skeletal envelope in the rabbit calvarium.

We evaluate the effects of occlusiveness of a titanium cap on bone generation beyond the skeletal envelope. In eight rabbits, the calvarial bone was exposed and a circular groove was prepared with a trephine drill. After marrow penetration, a standardized hemispherical titanium cap, either with or without small holes (1.5 mm in diameter), was then placed into the bone and covered by a cutaneous flap. After 1 month or 3 months of healing, the animals were euthanized and examined histologically. The percentage area of newly generated tissue consisting of mineralized bone and marrow spaces in each section was calculated relative to the area bounded by the hemispherical shape of the titanium cap and the parent bone; this latter volume was taken to be 100%. Furthermore, the cross-sectional areas of generated mineralized bone expressed as percentages of the total tissue area generated within each space were determined. In the 1-month specimens, there was no statistically significant difference between the two caps in the amount of tissue generated, 54.7%+/-12.2% with holes vs. 60.4%+/-8.8% without holes (p=0.225). However, in the 3-month specimens, we observed a significant difference between the caps (55.9%+/-7.4% with holes vs. 89.9%+/-6.5% without holes, P<0.05). Also, there was a statistically significant difference between 1- and 3-month specimens in the amount of tissue generated under the cap without holes (60.4%+/-8.8% vs. 89.9%+/-6.5%, P<0.05). Although there was no significant difference in the relative amount of mineralized bone generated between the caps with holes and those without holes in the 1-month specimens (27.7%+/-4.8% vs. 30.8%+/-6.4%, P=0.225), there was a statistically significant difference between the two caps in the 3-month specimens (24.3%+/-4.1% with holes vs. 34.0%+/-8.6% without holes, P<0.05). A substantial ingrowth of fibrous connective tissue through the holes appeared to prevent further new tissue generation in a defined area adjacent to the bone surface. We concluded that total occlusiveness, sufficient stiffness of the cap, as well as the passage of time will allow predictable mineralized bone augmentation to occur in spaces beyond the skeletal envelope.

Animals↗
PubMed2003

FGF-4 and titanium implants: a pilot study in rabbit bone.

AIM: To evaluate the effect of a local single injection of amino-terminally truncated recombinant human fibroblast growth factor-4 (rhFGF-4s) on titanium implant incorporation in a rabbit bone. MATERIAL AND METHODS: Thirty-six threaded titanium implants were inserted into the femur and tibia of six rabbits. Three weeks prior to implant insertion 10 microg of FGF-4 in an altelocollagen carrier or the carrier alone was injected into the intended implant sites. Biomechanical evaluation by (i) resonance frequency analysis and (ii) peak removal torque measurements was performed after 6 weeks. The implants with surrounding tissue were processed to undecalcified ground sections followed by light-microscopic quantifications of the bone in threaded area and the apical parts of the implants. RESULTS: A general trend, however not statistically significant, with higher mean values obtained in the above-mentioned tests was found. The FGF-4-treated implants revealed a significantly increased bone area in the apical part of the implants compared to the corresponding control implants. CONCLUSION: A local single injection of rhFGF-4 may stimulate bone formation around titanium implants in bone. However, further research is required to confirm these results, understand the mechanisms of FGF, and establish optimal dose and delivery methods.

Animals↗
PubMed2003

Effects of hydroxyapatite-coated and commercially pure titanium oral implant surfaces on compound nerve action potentials.

The aim of this study was to investigate the effects of hydroxyapatite-coated and commercially pure titanium oral implants on nerve conduction. Isolated rat sciatic nerves were placed between two suction electrodes in a bath containing a tyrode solution. The implants were brought into intimate contact with the nerves and evoked compound action potentials (cAPs) were recorded before and after contact with the implants. The commercially pure titanium implants did not cause any change in cAPs. A gradual reduction in cAPs was observed for hydroxyapatite-coated implants. However, this reduction was < 50% after an application time of 120 min. Recovery of the cAPs in this group was recorded after approximately 60 min. We conclude that, although intimate contact with hydroxyapatite-coated implants leads to a reduction in cAPs in nerves in vitro, neither this surface nor a commercially pure titanium surface leads to irreversible neurotoxic effects.

Action Potentials↗
PubMed2000

Humoral immunity host factors in subjects with failing or successful titanium dental implants.

BACKGROUND: Treatment with titanium dental implants is in general successful. However, an unknown number of implants do not integrate and are removed either by exfoliation or at the time of second stage surgery. It would be of importance to identify subjects at risk and predict early implant failure. METHODS: In a retrospective study serum IgG antibody titers and avidity in sera from 40 subjects who had experienced titanium dental implant treatments with non-osseo-integration as the outcome (NOTI) and in sera from 40 age and gender matched control subjects who had received successful titanium dental implants (SOTI) were studied. Serum IgG titers to whole cell Actinomyces viscosus, Bacteroides forsythus, Porphyromonas gingivalis, Staphylococcus aureus, and Streptococcus intermedius sonicated antigen preparations were studied by ELISA. RESULTS: Serum IgG antibody titers to S. aureus were significantly higher in subjects with SOTI than in NOTI (p<0.001) suggesting that higher titers indicate protection against implant failure as a result of S. aureus infection. Statistically significant higher serum IgG antibody avidity to P. gingivalis and B. forsythus were found in subjects with SOTI than in subjects with NOTI (p<0.01 and p<0.001, respectively). Statistical analysis failed to demonstrate antibody titer or avidity differences to the other pathogens studied. The likelihood that SOTI was associated with a high OD reading for S. aureus was 13.1:1 (p<0.001). Whether subjects were edentulous or not, or if they had lost teeth because of periodontitis or caries did not seem to matter. CONCLUSION: Serum IgG antibodies relative to B. forsythus, P. gingivalis and S. aureus may be associated with the outcome of implant procedures and explain why early implant failures occur.

Adult↗
PubMed2001

Adhesive bonding of titanium nitride-plated stainless steel for magnetic attachments.

The purpose of this study was to evaluate adhesive bonding of resin to titanium nitride ion-plated stainless steel in order for magnetic attachments to survive in the oral environment. Two primers, Cesead II Opaque Primer (CPII) and Metal Primer II (MPII), and one bonding agent, Super-Bond C&B (SB), were used. The surfaces of stainless steel disks were ground and then plated with titanium nitride. After the primer and SB resin were applied, a self-curing resin was bonded to the metal surfaces. Shear bond strengths were determined after 24 h of water storage and after 2,000 thermocycles. Titanium nitride ion-plated stainless steel showed bond strength comparable to the non-plated material. After thermocycling, all specimens of the group no primer/no SB were debonded. The bond strengths of groups CPII/no SB, MPII/no SB and no primer/SB were significantly lower bond strengths than groups CPII/SB and MPII/SB. An appropriate combination of primer and bonding agent should be selected when bonding a magnetic attachment to the denture base.

Adhesiveness↗
PubMed2001

In vitro kinetic evaluation of titanium alloy biodegradation.

The present controlled in vitro experiment evaluated the dissolution kinetics of titanium (Ti), aluminum (Al) and vanadium (V). Titanium alloy (Ti90Al6V4) dental implants were inserted in 1.8 ml sterile tubes, containing equal volumes of NaCl 0.9% (w/v) and human serum. Metallic elements released by the atomic process of corrosion were measured at pH 7.2 and 37 C by atomic absorption spectrophotometer at 1, 3, 6, 9, 15, 21, 27, 33, 42, 51, 60, 69, 78, 87 and 96 days. Ti dissolution averaged 16+/-5 ng/cm2/day and 1565 ng/cm2 over the experimental period. Al dissolution was stable at 9+/-5 ng/cm2/day and averaged 945 ng/cm2 over the 96-day period. V dissolution was stable at 0.15+/-0.18 ng/cm2/day after the sixth day of incubation and averaged 42 ng/cm2 over the 96-day period. Major disparities in atomic dissolution were detected among implants. No local or systemic reaction to titanium has been documented. In contrast, 4% toxic V and 6% Al may suffice to elicit local and systemic reactions or inhibit cellular proliferation and differentiation.

Alloys↗
PubMed1994

Titanium-containing mesoporous molecular sieves for catalytic oxidation of aromatic compounds.

Titanium silicalite is an effective molecular-sieve catalyst for the selective oxidation of alkanes, the hydroxylation of phenol and the epoxidation of alkenes in the presence of H2O2 (refs 1-3). The range of organic compounds that can be oxidized is greatly limited, however, by the relatively small pore size (about 0.6 nm) of the host framework. Large-pore (mesoporous) silica-based molecular sieves have been prepared recently by Kresge et al. and Kuroda et al.; the former used a templating approach in which the formation of an inorganic mesoporous structure is assisted by self-organization of surfactants, and the latter involved topochemical rearrangement of a layered silica precursor. Here we describe the use of the templating approach to synthesize mesoporous silica-based molecular sieves partly substituted with titanium--large-pore analogues of titanium silicalite. We find that these materials show selective catalytic activity towards the oxidation of 2,6-di-tert-butyl phenol to the corresponding quinone and the conversion of benzene to phenol.

Amines↗
PubMed2001

Influence of pH and ionic strength on adhesion of a wild strain of Pseudomonas sp. to titanium.

The adherence of an environmental strain of Pseudomonas sp. to titanium was evaluated modifying the pH (2 to 8) and ionic strength (0.1 and 0.6 M NaCl) of the electrolyte solution. Results were analyzed considering the participation of the different interfacial forces under the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. At 0.1 M, maximal bacterial adhesion was at pH 6, in agreement with the point of zero charge of the titanium surface. Similar adhesion values were observed at both sides of this point despite the opposite electrostatic condition of the surface oxide. At 0.6 M an absence of bacterial adhesion was observed throughout the pH range tested. The changes in bacterial adhesion are in agreement with the changes in the number of reinforced H-bond-forming sites on the titanium surface calculated using a simple model for the ionization of OH group adsorbed to the surface.

Adsorption↗
PubMed2005

New anilinotropone-based titanium complexes: synthesis, characterization and application as catalysts for olefin polymerization.

New titanium(IV) dichloride complexes containing 2-anilinotropone ligands have been synthesized and characterized. Bis(ligand)titanium dichloride complexes 1 and 2 were synthesized from reaction of TiCl4(THF)2 with 2 equivalents of the corresponding sodium salts of 2-(2,6-diisopropylanilino)tropone (L1) and 2-(2,3,4,5,6-pentafluoroanilino)tropone (L2), respectively. The mixed cyclopentadienyl-anilinotropone compound 3 was synthesized by reaction of the lithium salt of with CpTiCl3. The Cp-mixed micro-O bimetallic complex 4 was also isolated as a by-product owing to the adventitious presence of moisture. The molecular structures 1-4 of have been determined by single-crystal X-ray diffraction studies. Complexes 1 and 2 are isostructural and exhibit a C2-symmetric octahedral geometry, with a trans(N,N), cis(O,O) arrangement in complex 1, but with a trans(O,O), cis(N,N) arrangement in complex 2. The Cp-mixed complex 3 has a distorted square-pyramidal structure with the Cp ligand in the apical position. Bimetallic complex 4 shows a similar coordination geometry for the five-coordinate titanium atom and a pseudo-tetrahedral coordination for the second metallic centre. All new complexes, when activated with methylaluminoxane, are active in the polymerization of ethylene and propene.

Alkenes↗