Etched implants: A comparative surface analysis of four implant systems

A new technology for the removal of corundum residues on dental implants

Surface modification is an important measure to improve dental implants. Corundum residues, which are part of current dental implant blasting, on Straumann dental implants, were found to have disappeared in recent publications. We further evaluated this new cleaning technology by evaluating the surface of four different Straumann implants using scanning electron microscopy (SEM) and energy-dispersive radiographic spectroscopy (EDX). The involved technology fits to a Straumann patent involving a dextran coating allowing easy corundum particle removal by aqueous solution.

Bone Quantification Around Chitosan-Coated Titanium Dental Implants: A Preliminary Study by Micro-CT Analysis in Jaw of a Canine Model

Surface treatments of Ti in the dental implant industry are performed with the aim of in-creasing its bioactivity and osseointegration capacity. Chitosan (Cht) is a polysaccharide that has been proposed as a promising biomaterial in tissue engineering and bone regeneration, due to its ability to stimulate the recruitment and adhesion of osteogenic progenitor cells. The aim of our preliminary study was to evaluate, by micro-computed tomography (micro-CT), the osseointegration and bone formation around Cht-coated implants and to compare them with conventional surface-etched implants (SLA type). Four im-plants (8.5 mm length × 3.5 mm Ø) per hemiarch, were inserted into the jaws of five dogs, divided into two groups: chitosan-coated implant group (ChtG) and control group (CG). Twelve weeks after surgery, euthanasia was performed, and sectioned bone blocks were obtained and scanned by micro-CT and two bone parameters were measured: bone in contact with the implant surface (BCIS) and peri-implant bone area (PIBA). For BCIS and PIBA statistically significant values were obtained for the ChtG group with respect to CG (p = 0.005; p = 0.014 and p < 0.001 and p = 0.002, respectively). The results, despite the limitations, demonstrated the usefulness of chitosan coatings. However, studies with larger sample sizes and adequate experimental models would be necessary to confirm the results.

Design and surface characterization of micropatterned silica coatings for zirconia dental implants

The use of zirconia as an alternative biomaterial for titanium implants has been increasing due to its biocompatibility, favorable aesthetic features, less potential for early plaque accumulation and mechanical properties. Despite the developed efforts, strategies to promote an effective osseointegration are still enough. In this sense and combining the silica properties to improve bone formation with the micropatterning guidance characteristics, silica coatings with micropatterns were designed and evaluated regarding their hydrophilicity and integrity through resistance to scratch and friction tests against femoral bone plates (simulating implant insertion). A combined sol-gel and soft-lithography techniques were used to produce silica coatings onto zirconia substrates and different techniques were used to characterize the micropatterned silica coatings. The results revealed that the production of lines and pillars micropatterns increases the surface roughness (Ra values) and improves the surface strength adhesion. Through the scratch test, it was possible to verify that the integrity and topography characteristics of all micropatterned coatings were not significantly affected after the friction test meaning that their function is not compromised after implant insertion. Additionally, the lines micropattern was the one that presented the highest hydrophilicity for distilled water, thus being a promising surface to promote improved osseointegration. The combined use of different surface micropatterns could potentially be used to guide bone apposition and avoiding peri-implantitis.

Innovative Surface Modification Procedures to Achieve Micro/Nano-Graded Ti-Based Biomedical Alloys and Implants

Due to the growing aging population of the world, and as a result of the increasing need for dental implants and prostheses, the use of titanium and its alloys as implant materials has spread rapidly. Although titanium and its alloys are considered the best metallic materials for biomedical applications, the need for innovative technologies is necessary due to the sensitivity of medical applications and to eliminate any potentially harmful reactions, enhancing the implant-to-bone integration and preventing infection. In this regard, the implant’s surface as the substrate for any reaction is of crucial importance, and it is accurately addressed in this review paper. For constructing this review paper, an internet search was performed on the web of science with these keywords: surface modification techniques, titanium implant, biomedical applications, surface functionalization, etc. Numerous recent papers about titanium and its alloys were selected and reviewed, except for the section on forthcoming modern implants, in which extended research was performed. This review paper aimed to briefly introduce the necessary surface characteristics for biomedical applications and the numerous surface treatment techniques. Specific emphasis was given to micro/nano-structured topographies, biocompatibility, osteogenesis, and bactericidal effects. Additionally, gradient, multi-scale, and hierarchical surfaces with multifunctional properties were discussed. Finally, special attention was paid to modern implants and forthcoming surface modification strategies such as four-dimensional printing, metamaterials, and metasurfaces. This review paper, including traditional and novel surface modification strategies, will pave the way toward designing the next generation of more efficient implants.

Physical characterization of 3 implant systems made of distinct materials with distinct surfaces

STATEMENT OF PROBLEM

Dental implants undergo various surface treatments. Studies that have characterized their surface and subsurface by using the same methods are scarce.

PURPOSE

The purpose of this study is to physically characterize the surface and subsurface of implant systems made of commercially pure (cp) titanium (Ti) grade (gr) 4 and Ti alloy gr 23 and to evaluate whether airborne-particle abrasion and acid etching is an appropriate surface treatment for Ti alloy gr 23.

MATERIAL AND METHODS

Implant groups (n=3) were as follows: TG4AO, cp Ti gr 4, treated with anodic oxidation (3.5×8 mm) (NobelReplace Conical; Nobel Biocare); TG23AE, Ti gr 23 (TiAlV ELI) airborne-particle abraded-and-etched (3.9×8 mm) (V3; MIS); and TG4AE, cp Ti gr 4, airborne-particle abraded and etched (3.3×8 mm) (BL; Institut Straumann AG). Surface roughness, surface topography, and elemental and surface composition were investigated with optical profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The presence and size of Ti hydride (TiH) needles were determined on metallographic sections. Depth profiling was obtained by time-of-flight secondary ion mass spectrometry (ToF-SIMS) to determine possible enrichment of an alloying element at the implant surface.

RESULTS

The mean arithmetic deviation roughness (S_a), of TG4AO was 0.80 μm. The S_a of TG4AO was 1.22 μm, and the S_a of TG4AO was 1.59 μm. The difference between the groups was significant (P<.001). TG23AE and TG4AE displayed a macrotexture and microtexture with pores; TG4AO showed a 3-to 12-μm canyon-like structure. The surface and subsurface compositions were as follows: for TG4AO, αTi and phosphorus-rich anatase; for TG23AE, α-Ti matrix with β-Ti grains; and for TG4AE, α-Ti and δ-TiH_2-x. TiH needles were found only on TG4AE; the Ti oxide layer of TG4AO was rough, 3-to 16-μm thick, and porous. The time-of-flight secondary ion mass spectrometry (ToF SIMS) concentration profile of TG23AE did not show enrichment of any alloying element.

CONCLUSIONS

The roughness, topography, and composition of the surfaces were different for all implants tested. Airborne-particle abrasion and subsequent etching was an appropriate treatment for Ti gr 23 alloy implants.

Laser Surface Texturing and Electropolishing of CoCr and Ti6Al4V-ELI Alloys for Biomedical Applications

The interplay between a prosthetic and tissue represents an important factor for the fixation of orthopedic implants. Laser texturing tests and electropolishing were performed on two materials used in the fabrication of medical devices, i.e., CoCr and Ti6Al4V-ELI alloys. The material surface was textured with a diode-pumped solid state (DPSS) laser and its effect on the surface quality and material modification, under different combinations of laser power and marking speed, were investigated. Our results indicate that an increment of energy per unit length causes an incremental trend in surface roughness parameters. Additionally, phase transformation on the surface of both alloys was achieved. Chemical analysis by energy dispersive X-ray spectrometer (EDX) shows the formation of (Co(Cr,Mo)) phase and the M₂₃C₆ precipitate on the CoCr surface; while quantitative analysis of the X-ray diffractometer (XRD) results demonstrates the oxidation of the Ti alloy with the formation of Ti₂O and Ti₆O from the reduction of the α-Ti phase. The behaviors were both related with an increase of the energy per unit length. Control of the final surface roughness was achieved by an electropolishing post-treatment, minimizing the as-treated values. After polishing, a reduction of surface roughness parameters was obtained in a range between 3% and 44%, while no changes in chemical composition or present phases were observed.

Characterization of a Macro- and Micro-Textured Titanium Grade 5 Alloy Surface Obtained by Etching Only without Sandblasting

Our purpose was to physically characterize the surface, and the subsurface, of a macro- and micro-textured titanium grade 5 dental implant surface obtained by etching only, without sandblasting. The topography, surface roughness, as well as the surface structure and subsurface distribution of elements, were determined by scanning electronic microscopy (SEM), non-contact profilometry, X-ray diffraction (XRD), and a concentration profile performed by Auger electron spectroscopy (AES). The hydrogen concentration in the implants was measured; the ability to generate nanostructures when stored in deionized water was also investigated. Under SEM, the surface resembled a sandblasted and etched titanium surface with its typical macro- and micro-texture; roughness was moderate with average roughness (Sa) 1.29 µm. No titanium hydride was found at the implant surface and no enrichment of any alloying element was identified at the surface and subsurface. Hydrogen concentration was 79 ppm, within the normative tolerance (<130 ppm). After storage in water for 6 months, densely packed finger-like nanostructures were observed. The clinical advantage of this textured titanium alloy surface is that it displays the typical macro- and micro-features of a moderately rough sandblasted and etched (SLA) titanium surface without leaving behind any foreign sandblasting material.

[Factors affecting osteointegration and the use of early functional load to reduce the duration of treatment in dental implantation]

The article presents literature data on the impact of the surface and shape of dental implants and early functional load with aesthetic and functional rehabilitation on osteointegration and stability of implants at various implantation terms.

Raman spectroscopy of bone composition during healing of subcritical calvarial defects

Subcritical calvarial defects heal spontaneously and optical methods can study the healing without mechanically perturbing the bone. In this study, 1mm defects were created on the skulls (in vivo) of Sprague-Dawley rats (n = 14). After 7 (n = 7) and 14 days (n = 7) of healing, the subjects were sacrificed and additional defects were similarly created (control). Raman spectroscopy (785nm) was performed at the two time points and defect types. Spectra were quantified by the mineral/matrix ratio, carbonate/phosphate ratio and crystallinity. Mineral/matrix of in vivo defects is lower than that of controls by ~34% after 7 days and ~21% after 14 days. Carbonate/phosphate is 8% and 5% higher while crystallinity is 7% and 3% lower, respectively. Optical profiling shows that the surface roughness increases 1.2% from controls to in vivo after 7 days, then decreases 13% after 14 days. Overall, the results show maturation of mineral crystals during healing and agree with microscopic assessment.

The Effects of Acid Etching on the Nanomorphological Surface Characteristics and Activation Energy of Titanium Medical Materials

The purpose of this study was to characterize the etching mechanism, namely, the etching rate and the activation energy, of a titanium dental implant in concentrated acid and to construct the relation between the activation energy and the nanoscale surface topographies. A commercially-pure titanium (CP Ti) and Ti-6Al-4V ELI surface were tested by shot blasting (pressure, grain size, blasting distance, blasting angle, and time) and acid etching to study its topographical, weight loss, surface roughness, and activation energy. An Arrhenius equation was applied to derive the activation energy for the dissolution of CP Ti/Ti-6Al-4V ELI in sulfuric acid (H₂SO₄) and hydrochloric acid (HCl) at different temperatures. In addition, white-light interferometry was applied to measure the surface nanomorphology of the implant to obtain 2D or 3D roughness parameters (Sa, Sq, and St). The nanopore size that formed after etching was approximately 100–500 nm. The surface roughness of CP Ti and Ti-6Al-4V ELI decreased as the activation energy decreased but weight loss increased. Ti-6Al-4V ELI has a higher level of activation energy than Ti in HCl, which results in lower surface roughness after acid etching. This study also indicates that etching using a concentrated hydrochloric acid provided superior surface modification effects in titanium compared with H₂SO₄.

Protein adsorption on a laser-modified titanium implant surface

PURPOSE

The aim of this study was to investigate the earlier phase of the osseointegration of a laser-treated implant surface in terms of human protein adsorption.

MATERIALS AND METHODS

Titanium surfaces were divided into machined (M), sandblasted (SB), and laser-treated (LT). The LT surfaces were created with an Nd diode-pumped laser in Q-switching, whereas the SB were treated with Al2O3. An x-ray photoelectron spectroscopy (XPS) analysis of titanium surface was performed. Titanium discs were used for albumin and fibronectin adsorption evaluation through fluorescence intensity. Fibronectin evaluation was also made with Western Blot analysis on experimental implants.

RESULTS

LT discs appeared to trigger a higher albumin and fibronectin adsorption with a regular pattern. The mean count of albumin adsorption was 0.29 and 3.8 for SB and LT, respectively (P = 0.016), whereas fibronectin values were 0.67 and 4.9 for (SB) and (LT) titanium (P = 0.02). XPS analysis showed that titanium, oxygen, carbon, and nitrogen were found on all 3 surfaces.

CONCLUSION

Laser-engineered porous titanium surface seems to promote, in vitro, the adsorption of albumin and fibronectin more than sandblasted (SB) or machined (M) implants.

Topographic characterisation of dental implants for commercial use

BACKGROUND

To characterize the surface topography of several dental implants for commercial use.

MATERIAL AND METHODS

Dental implants analyzed were Certain (Biomet 3i), Tissue Level (Straumann), Interna (BTI), MG-InHex (MozoGrau), SPI (Alphabio) and Hikelt (Bioner). Surface topography was ascertained using a confocal microscope with white light. Roughness parameters obtained were: Ra, Rq, Rv, Rp, Rt, Rsk and Rku. The results were analysed using single-factor ANOVA and Student-Neuman-Keuls (p<0.05) tests.

RESULTS

Certain and Hikelt obtained the highest Ra and Rq scores, followed by Tissue Level. Interna and SPI obtained lower scores, and MG-InHex obtained the lowest score. Rv scores followed the same trend. Certain obtained the highest Rp score, followed by SPI and Hikelt, then Interna and Tissue Level. MG-InHex obtained the lowest scores. Certain obtained the highest Rt score, followed by Interna and Hikelt, then SPI and Tissue Level. The lowest scores were for MG-InHex. Rsk was negative (punctured surface) in the MG-InHex, SPI and Tissue Level systems, and positive (pointed surface) in the other systems. Rku was higher than 3 (Leptokurtic) in Tissue Level, Interna, MG-InHex and SPI, and lower than 3 (Platykurtic) in Certain and Hikelt.

CONCLUSIONS

The type of implant determines surface topography, and there are differences in the roughness parameters of the various makes of implants for clinical use.

Chemical and Topographic Analysis of Eight commercially Available Dental Implants

BACKGROUND

Surface characterization of dental implants allows us to better understand the effects of the implant on the host biological response. In this study, we analyzed and compared these characteristics among implants commercially available in South Africa.

MATERIALS AND METHODS

Eight implants from different manufacturers were chosen for analysis (Touareg, ICE, (R)Evolutions, Uniti, AnyRidge, MIS, Ivory-QSI, Southern), using scanning electron microscopy (SEM), interferometry, and energy dispersive X-ray spectroscopy to study the surface chemical composition and morphology.

RESULTS

The results indicate that variations in manufacturer processes result in implant surfaces that are distinctly different from one another. Most implants presented a moderately rough surface with sandblasted-only implant surfaces having a lower mean value of Sa when compared with sandblasted and acid-etched surfaces. Carbon contamination was detected on all the implants and that of aluminum on five implant surfaces. Ca and P were detected on the surface of Touareg implants, indicating the manufacturer's attempt to enhance osseointegration.

CONCLUSION

The surface of the implants showed a range of chemical, physical properties, and surface topographies.

CLINICAL SIGNIFICANCE

The results indicate that implant surface treatment is not standardized. This may have clinical implications. Further clinical research is required.

Differentiation, apoptosis, and GM-CSF receptor expression of human gingival fibroblasts on a titanium surface treated by a dual acid-etched procedure

OBJECTIVES

Analysis of the effects of titanium surface properties on the biological behavior of human gingival fibroblasts (HGFs).

MATERIALS AND METHODS

HGFs were in vitro cultured on a titanium surface modified by a dual acid-etched procedure and on a control machined surface. Cell adhesion, proliferation, apoptosis, production of certain extracellular matrix (ECM) proteins, and expression of granulocyte macrophage-colony stimulating factor receptor (GM-CSFR) were investigated using in each experiment a total of 18 samples for each titanium surface.

RESULTS

Cell attachment at 3 h of culture was statistically significantly higher on the etched surface. HGF growth increased on both surfaces during the entire experimental period and at day 14 of culture cell proliferation was statistically significantly higher on the treated surface than on the control. No statistically significant differences in percentage of apoptosis events were observed between the surfaces. ECM protein production increased progressively over time on both surfaces. A statistically significant deposition was observed at day 7 and 14 for collagen I and only at day 14 for fibronectin and tenascin, when compared to the baseline. GM-CSFR registered a positive expression on both surfaces, statistically significant at day 14 on the etched surface in comparison with the machined one.

CONCLUSIONS

Data showed that titanium surface microtopography modulates in vitro cell response and phenotypical expression of HGFs. The etched surface promoted a higher cell proliferation and differentiation improving the biological behavior of HGFs.

CLINICAL RELEVANCE

Results suggest a possible beneficial effect of surface etching modification on peri-implant biological integration and soft tissue healing which is critical for the formation of a biological seal around the neck of dental implants.

Surface Topographical Changes of a Failing Acid-Etched Long-Term in Function Retrieved Dental Implant

The aim of the present study was to report the main topographical and chemical changes of a failing 18-year in function retrieved acid-etching implant in the micro- and nanoscales. A partially edentulous 45 year old rehabilitated with a dental implant at 18 years of age exhibited mobility. After careful examination, a 3.25 × 13-mm press-fit dental implant was retrieved. Scanning electron microscope (SEM) analysis was carried out to study topographical changes of the retrieved implant compared with an unused implant with similar topographical characteristics. Moreover, X-ray photoelectron spectroscopy (XPS) analysis was used to study the surface composition of the retrieved failing implant. Clear changes related to the dual dioxide layer are present as visible in ≥×500 magnification. In addition, it was found that, for the retrieved implant, the surface composition consisted mainly of Ti2p, O1s, C1s, and Al2p. Also, a meaningful decrease of N and C was noticed, whereas the peaks of Ti2p, Al2p, and O1s increased when analyzing deeper (up to ×2000s) in the sample. It was shown that the superficial surface of a retrieved press-fit dual acid-etched implant 18 years after placement is impaired. However, the causes and consequences for these changes cannot be determined.

Positive Biomechanical Effects of Titanium Oxide for Sandblasting Implant Surface as an Alternative to Aluminium Oxide

The aim of this study was to evaluate the physico-chemical properties and the in vivo host response of a surface sandblasted with particles of titanium oxide (TiO2) followed by acid etching as an alternative to aluminium oxide. Thirty titanium disks manufactured in the same conditions as the implants and 24 conventional cylindrical implants were used. Half of the implants had a machined surface (Gcon) while in the other half; the surface was treated with particles of TiO2 followed by acid etching (Gexp). Surface characterization was assessed by scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), profilometry, and wettability. For the in vivo test, 12 implants of each group were implanted in the tibia of 6 rabbits, and were reverse torque tested after periods of 30 or 60 days after implantation. Following torque, SEM was utilized to assess residual bone-implant contact. The surface characterization by SEM showed a very homogeneous surface with uniform irregularities for Gexp and a small amount of residues of the blasting procedure, while Gcon presented a surface with minimal irregularities from the machining tools. Wettability test showed decreased contact angle for the Gcon relative to the Gexp. The Gexp removal torque at 30 and 60 days was 28.7%, and 33.2% higher relative to the Gcon, respectively. Blasting the surface with particles of TiO2 represents an adequate option for the surface treatment of dental implants, with minimal risk of contamination by the residual debris from the blasting procedure.

Acid etching and plasma sterilization fail to improve osseointegration of grit blasted titanium implants

Interaction between implant surface and surrounding bone influences implant fixation. We attempted to improve the bone-implant interaction by 1) adding surface micro scale topography by acid etching, and 2) removing surface-adherent pro-inflammatory agents by plasma cleaning. Implant fixation was evaluated by implant osseointegration and biomechanical fixation.

The study consisted of two paired animal sub-studies where 10 skeletally mature Labrador dogs were used. Grit blasted titanium alloy implants were inserted press fit in each proximal tibia. In the first study grit blasted implants were compared with acid etched grit blasted implants. In the second study grit blasted implants were compared with acid etched grit blasted implants that were further treated with plasma sterilization. Implant performance was evaluated by histomorphometrical investigation (tissue-to-implant contact, peri-implant tissue density) and mechanical push-out testing after four weeks observation time.

Neither acid etching nor plasma sterilization of the grit blasted implants enhanced osseointegration or mechanical fixation in this press-fit canine implant model in a statistically significant manner.

Surface characterization analysis of failed dental implants using scanning electron microscopy

OBJECTIVE

To investigate the failure of 15 dental implants (Paragon/Zimmer) in relation to their surface quality.

MATERIALS AND METHODS

The study comprised of 15 dental implants (7 mm D Advent Implant, 3.9 mm D apex design implant), which were followed from surgery to completion of prosthetic restorations. The implants were placed during a 6-year period from 2003-2009 in non-smoking patients (male; 7, females; 5). There were eight upper and seven lower implants. Surface characterization after immersion in SBF of these failed implants was investigated using SEM and EDS compared to that of an unused implant of the same brand.

RESULTS

Results revealed that, following immersion in SBF, the implant surfaces showed new components like Ca(+), Na(+) and Cl(-), but in trace quantities.

CONCLUSIONS

After SEM observation and EDS analysis, it was concluded that the apatite layer formation could not be verified.

Fracture surface analysis to understand the failure mechanisms of collagen degraded bone

Fracture surface analysis is a powerful technique to investigate bone failure mechanisms. Previously, emu tibiae were endocortically treated with 1 M potassium hydroxide (KOH) solution for 14 days. This treatment caused in situ collagen degradation rather than removal, with no differences in geometrical parameters, but with significant changes in mechanical properties. KOH-treated tibiae showed significant decreases in failure stress and increased failure strain and toughness. The fracture surfaces of untreated and 14-day KOH-treated failed specimens were examined to further identify differences in the failure process to explain the previously observed increase in toughness. Areas of 'tension,' 'compression,' and 'transition' were identified using digital images of the fracture surfaces. Within these areas, the degree of 'roughness' and 'smoothness' was identified and estimated, using an optical profiler and SEM images. The fracture surfaces of 14-day KOH-treated bones showed a significantly higher 'roughness' compared to untreated bones. Furthermore, additional toughening mechanisms, which are important features for dissipating energy during the failure process, were observed in KOH-treated samples, but were absent in untreated samples. These results indicate that the significant increase in toughness of KOH treated bones is the result of structural alterations that enhance the ability of the microstructure to dissipate energy during the failure process, thereby slowing crack propagation. Fracture surface analysis has helped explain why KOH-treated bones have increased toughness compared to untreated bones, namely via toughening mechanisms on the compressive failure side.

Altered cell motility and attachment with titanium surface modifications

BACKGROUND

Titanium implants are widely used in dentistry to replace lost teeth. Various surface modifications have been used to improve implant retention and osseointegration. This study is designed to compare the ability of three titanium surfaces to promote cell attachment and cell motility of cells relevant to periodontal tissues.

METHODS

Three clinically relevant surfaces were tested: 1) machined titanium; 2) a titanium surface roughened through acid etching (dual thermal-etched titanium [DTET]); and 3) a titanium surface roughened with nanometer-scale calcium phosphate deposition (nanoscale calcium phosphate-impregnated titanium [NCPIT]). Cell attachment and migration were examined for four cell types: rat osteosarcoma cells, human osteoblasts, and gingival and periodontal ligament (PDL) fibroblasts.

RESULTS

All four cell types attached to each of the three titanium surfaces equally by 2 hours, and the PDL and gingival fibroblasts generally displayed less attachment than the osteosarcoma cells and osteoblasts. The cells displayed differential motility and long-term attachment to each of the titanium surfaces. Osteosarcoma cells displayed preferential motility on NCPIT, whereas PDL fibroblasts were more motile on machined titanium, and gingival fibroblasts moved more rapidly on both DTET and NCPIT. Osteoblasts displayed little motility on any of the titanium surfaces and lost viability on NCPIT after 24 hours. Gingival fibroblasts lost attachment to machined titanium.

CONCLUSIONS

Periodontal cells displayed differential motility and long-term attachment to titanium surfaces. Selective modification of titanium surface properties in various regions of an implant may be useful in guiding specific cell populations to specific locations where they might best aid in osseointegration and soft tissue remodeling.

Bone remodeling induced by dental implants of functionally graded materials

Functionally graded material (FGM) had been developed as a potential implant material to replace titanium for its improved capability of initial osseointegration. The idea behind FGM dental implant is that its properties can be tailored in accordance with the biomechanical needs at different regions adapting to its hosting bony tissues, therefore creating an improved overall integration and stability in the entire restoration. However, there have been very few reports available so far on predicting bone remodeling induced by FGM dental implants. This article aims to evaluate bone remodeling when replacing the titanium with a hydroxyapatite/collagen (HAP/Col) FGM model. A finite element model was constructed in the buccal-lingual section of a dental implant-bone structure generated from in vivo CT scan images. The remodeling simulation was performed over a 4 year healing period. Comparisons were made between the titanium implant and various FGM implants of this model. The FGM implants showed an improved bone remodeling outcome. The study is expected to provide a basis for future development of FGM implants.

XPS, AES and SEM analysis of recent dental implants

Today, surface chemistry modifications of titanium implants have become a development strategy for dental implants. The present study investigated the chemistry and morphology of commercially available dental implants (Nobel biocare TiUnite, Astra AB OsseoSpeed, 3i Osseotite, ITI-SLA). X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy were employed for the analysis of surface chemistry. The morphology was investigated by scanning electron microscopy. The present study demonstrated the major differences of surface properties, mainly dependent on the surface treatment used. The blasting and acid etching technique for the OsseoSpeed, Osseotite and SLA surfaces generally showed mainly TiO(2), but a varying surface morphology. In contrast, the electrochemical oxidation process for TiUnite implants not only produces microporous surface (pore size: 0.5-3.0microm), but also changes surface chemistry due to incorporation of anions of the used electrolyte. As a result, TiUnite implants contain more than 7at.% of P in oxide layer and higher amounts of hydroxides compared to the other implants in XPS analysis. F in OsseoSpeed implants was detected at 0.3% before as well as after sputter cleaning.

Corrosion resistance and biocompatibility of a new porous surface for titanium implants

Alterations of the commercially pure titanium (cpTi) surface may be undertaken to improve its biological properties. The aim of this study was to investigate the biocompatibility of cpTi when submitted to a new, porous titanium, surface treatment (porous Ti). Five types of surface treatments, namely sintered microspheres porous titanium (porous Ti), titanium plasma spray (TPS), hydroxyapatite (HA), sandblasted and acid etched (SBAE), and resorbable blast medium, sandblasted with hydroxyapatite (RBM) were made. In the experimental methods, the corrosion potentials were measured over time, and then a linear sweep voltammetric analysis measured the polarization resistances and corrosion currents. For biocompatibility evaluation, MG63 osteoblast-like cells were used. Cell morphology, cell proliferation, total protein content, and alkaline phosphatase (ALP) activity were evaluated after 2 h, and after 2, 4 and 7 d. Porous Ti and SBAE showed a better corrosion resistance, with a weak corrosion current and a high polarization resistance, than the other surfaces. Cell attachment, cell morphology, cell proliferation, and ALP synthesis were influenced by the surface treatments, with a significant increase observed of the activity of osteoblast cells on the porous coating (porous Ti). Based on these results, it is suggested that the porous Ti surface has a significantly better biocompatibility than the other surface treatments and an excellent electrochemical performance.

The use of fractography to supplement analysis of bone mechanical properties in different strains of mice

Fractography has not been fully developed as a useful technique in assessing failure mechanisms of bone. While fracture surfaces of osteonal bone have been explored, this may not apply to conventional mechanical testing of mouse bone. Thus, the focus of this work was to develop and evaluate the efficacy of a fractography protocol for use in supplementing the interpretation of failure mechanisms in mouse bone. Micro-computed tomography and three-point bending were performed on femora of two groups of 6-month-old mice (C57BL/6 and a mixed strain background of 129SV/C57BL6). SEM images of fracture surfaces were collected, and areas of "tension", "compression" and "transition" were identified. Percent areas of roughness were identified and estimated within areas of "tension" and "compression" and subsequently compared to surface roughness measurements generated from an optical profiler. Porosity parameters were determined on the tensile side. Linear regression analysis was performed to evaluate correlations between certain parameters. Results show that 129 mice exhibit significantly increased bone mineral density (BMD), number of "large" pores, failure strength, elastic modulus and energy to failure compared to B6 mice (p<0.001). Both 129 and B6 mice exhibit significantly (p<0.01) more percent areas of tension (49+/-1%, 42+/-2%; respectively) compared to compression (26+/-2%, 31+/-1%; respectively). In terms of "roughness", B6 mice exhibit significantly less "rough" areas (30+/-4%) compared to "smooth" areas (70+/-4%) on the tensile side only (p<0.001). Qualitatively, 129 mice demonstrate more evidence of bone toughening through fiber bridging and loosely connected fiber bundles. The number of large pores is positively correlated with failure strength (p=0.004), elastic modulus (p=0.002) and energy to failure (p=0.041). Percent area of tensile surfaces is positively correlated with failure strength (p<0.001), elastic modulus (p=0.016) and BMD (p=0.037). Percent area of rough compressive surfaces is positively correlated with energy to failure (p=0.039). Evaluation of fracture surfaces has helped to explain why 129 mice have increased mechanical properties compared to B6 mice, namely via toughening mechanisms on the compressive side of failure. Several correlations exist between fractography parameters and mechanical behavior, supporting the utility of fractography with skeletal mouse models.

Effects of a novel calcium titanate coating on the osseointegration of blasted endosseous implants in rabbit tibiae

OBJECTIVE

The purpose of this study was to investigate the effects of a nanostructured calcium coating on the surfaces of blasted Ti implants on peri-implant bone formation in the rabbit tibiae.

MATERIAL AND METHODS

Threaded implants (3.75 mm in diameter, 6 mm in length) were roughened by hydroxyapatite (HA) blasting (control; blasted implants). The implants were then hydrothermally treated in a Ca-containing solution for 24 h to prepare Ca-incorporated Ti surfaces (experimental; blasted/Ca implants). Surface characterizations were performed by scanning electron microscopy and stylus profilometry before and after Ca coating. Forty-two implants (21 control and 21 experimental) were placed in the proximal tibiae of seven New Zealand White rabbits. Each rabbit received six implants. To evaluate the effects of the nanostructured Ca coating on the peri-implant bone-healing response, removal torque tests and histomorphometric analyses were performed 6 weeks after surgery.

RESULTS

The Ca coating did not significantly change the surface properties produced by blasting at the micron level. Histologically, active bone apposition was observed in the blasted/Ca implants in the marrow space. Compared with the blasted implants, the blasted/Ca implants showed significantly increased bone-to-implant contact over the total implant length (P<0.01) and greater mean removal torque values (P<0.05).

DISCUSSION AND CONCLUSION

The nanostructured, Ca-incorporated surface significantly enhanced the peri-implant bone-healing response of HA-blasted Ti implants. It may be concluded that the use of nanostructured, Ca-coated surfaces may have synergic effects in enhancing osseointegration of blasted Ti implants due to their micron-scaled surface properties and biologically active surface chemistry.

Interfacial shear strength of titanium implants in bone is significantly improved by surface topographies with high pit density and microroughness

Surface structure of implants influences bone response and interfacial shear strength between implants and bone. The aim of this study was to find topographical parameters that correlate with the interfacial shear strength. Two groups of sand-blasted titanium screws were implanted in 17 sheep tibia, each for 2-52 weeks: (A) acid pickled with HF/HNO(3); (B) acid etched with HCl/H(2)SO(4). Screw removal torque was measured and surface topography of both implant groups was studied by scanning electron microscopy, optical profilometry, and scanning probe microscopy. The roughness as well as the surface area of type A surface was higher in the scan region of 100 microm, but the microroughness and surface area of type B surface was higher in the scan region of 10 microm. A significantly higher removal torque (interfacial shear strength) of the surface treatment type B (412 +/- 60 Ncm) compared to surface treatment type A (157 +/- 33 Ncm) was found after 52 weeks of implantation in sheep due to differences in microroughness of both types of screws. It was also shown that the specification of the parameters Delta(a), R(a) and R(q) was not sufficient to characterize the properties of the implant surfaces. The analysis of R(q) parameter over wavelengths was required to characterize the size, shape and distribution of the implant surface structures.

Histologic Evaluation of 3 Retrieved Immediately Loaded Implants After a 4-Month Period

OBJECTIVE

To perform a histologic and histomorphometric analysis of the peri-implant tissue reactions and bone-titanium interface in 3 immediately loaded (provisional loaded) titanium implants retrieved from a man after a loading period of 4 months.

MATERIALS & METHODS

A 35-year-old patient with a maxillary partial edentulism did not want to wear a provisional removable prosthesis during the healing period. It was decided to insert 3 definitive implants and use 3 provisional implants for the transitional period. The provisional implants were loaded the same day with a resin prosthesis in occlusal contact. During the second surgical phase, after 4 months, the provisional prosthesis was removed, and the provisional implants were retrieved with a trephine bur. Before retrieval, all implants appeared to be clinically osseointegrated. The specimens were processed for observation under light microscopy.

RESULTS

At low magnification, it was possible to observe that bone trabeculae were present around the implant. Areas of bone remodeling and haversian systems were present near the implant surface. Under polarized-light microscopy, it was possible to observe that in the coronal aspect of the thread, the lamellar bone showed lamellae that tended to run parallel to the implant surface, while in the inferior aspect of the thread, the bone lamellae ran perpendicular to the implant surface.

CONCLUSIONS

Histologic data pertaining to these 3 immediately loaded implants, and retrieved after a 4-month loading period, show that immediate loading did not produce untoward effects on peri-implant bone healing.

The effects of implant surface roughness and surgical technique on implant fixation in an in vitro model

OBJECTIVES

The aim of the present study was to determine the relationship between implant surface parameters, surgical approach and initial implant fixation.

MATERIAL AND METHODS

Sixty tapered, conical, screw-shaped implants with machined or etched surface topography were implanted into the explanted femoral condyle of goats. The implant sites were prepared either by a conventional technique, by undersized preparation, or by the osteotome technique. Peak insertion & removal torque, bone-to-implant contacts (BIC) and morphological bone appearance were assessed by scanning electron microscope (SEM) and micro-computer tomography. (micro-CT).

RESULTS

Insertion and removal torque values were significantly higher for etched implants inserted with the undersized technique (115.2 +/- 31.1, 102.9 +/- 36.4 N cm) respectively. Also, the average BIC value was higher for the etched implants placed with the undersized technique (87.5 +/- 5.6), which was statistically significant compared with machined and etched implants inserted by conventional technique.

CONCLUSION

In conclusion, this study shows that the surgical technique has a decisive effect on implant fixation (represented in this study by installation torque value/removal torque value and histomorphometric evaluation) in trabecular bone. Nevertheless, additional in vivo studies have to be done to prove the importance of surgical protocol for the final implant-bone response.

Bone Response to Submerged, Unloaded Implants Inserted in Poor Bone Sites: A Histological and Histomorphometrical Study of 8 Titanium Implants Retrieved From Man

An important parameter that influences the long-term success of oral implants is the bone quality of the implant bed. Posterior areas of the jaws have been avoided in implant dentistry because of their poor bone quality, higher chewing forces, and presumed higher implant failure rates. Several researchers have deemed soft bone implant sites to be a great potential risk situation, and most failures have been found in sites where the bone density was already low. The inferior success rates in the posterior maxilla have been attributed to a lower bone density and a lesser bone-implant interface. The aim of the present study was a histological and histomorphometrical analysis of the bone response to submerged implants inserted in posterior areas of the human jaws and retrieved, for different causes, after healing periods varying from 6 weeks to 12 months. Eight submerged implants that had been retrieved for different causes after different healing periods were evaluated in the present study. All implants were submerged and unloaded. Three implants had been removed for inadequate patient adaptation, 2 for inability of the implant to meet changed prosthetic needs, 1 for not optimal position from esthetic and hygiene aspects, and the last 2 for pain and dysesthesia. All the implants were retrieved with a 5-mm trephine bur. Newly formed peri-implant bone was found in all implants even after shorter healing periods. The bone-implant contact percentage varied from 30% to 96%. In conclusion, some surfaces have an improved characteristic of contact osteogenesis in soft bone, with coverage of the implant surface with a bone layer as a base for intensive bone formation and remodeling. We documented osseointegration of implants with a rough surface even after an insertion period of less than 2 months, both in the mandible and in the maxilla. From these results, we tentatively extrapolate that these implants might be carefully loaded after 2 months of healing, even when inserted in soft bone. A higher removal torque value might lead to a more predictable use of shorter implants, to a support of a prosthesis with fewer implants, or to shorter healing periods.