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

Surface Modification of Porous Titanium Discs Using Femtosecond Laser Structuring

The failure of titanium implants is associated with two main problems that include the bone resorption and fracture of the surrounding bone tissue (stiffness incompatibility) and implant loosening (poor osseointegration). The development of porous titanium implants with low Young modulus solve the stress shielding phenomenon, while the modification of the implant surface must be implemented to promote a fast bond between the implant and bone. In this work, femtosecond laser micromachining was applied to modify the topography of the surface of Ti porous samples obtained by a space-holder technique to obtain hierarchical structures (micro and nano roughness patterns) to enhance osseointegration. Scanning electron microscopy, confocal laser microscopy, and image analysis were used for characterization of the surface morphology, roughness, and porosity before and after performing the laser treatment. Based on these results, the effect of the treatment on the mechanical behavior of the samples was estimated. In addition, a preliminary in-vitro test was performed to verify the adhesion of osteoblasts (filopodia presence) on modified titanium surface. Results revealed that laser texturing generated clusters of micro-holes and micro-columns both on the flat surface of the samples and inside the macro-pores, and periodic nanometric structures across the entire surface. The porous substrate offers suitable biomechanics (stiffness and yield strength) and bio-functional behavior (bone ingrowth and osseointegration), which improves the clinic success of titanium implants.

Effect of Surgical Installation of Dental Implants on Surface Topography and Its Influence on Osteoblast Proliferation

Surface treatment alone does not determine the final microtopography of a dental implant, which can be influenced by implant design and the surgical procedure. This study investigated the effect of surgical placement of dental implants with same surface treatments on surface roughness. Three implants (SIN) of each group with different macrogeometries (Strong, Stylus, and Tryon) were analyzed using laser interferometry and scanning electron microscopy to evaluate surface topography. All threaded regions of the implants, namely, top, flank, and valley, were analyzed individually. Relevant surface parameters (S_a, S_sk, S_ku, S_tr, and S_dq) were calculated for the different regions on each implant before (B) (n = 9) and after (A) (n = 9) placement into porcine rib bones. The behavior and proliferation of a preosteoblastic cell line MC3T3-E1 on titanium surface, cell viability, and osteopontin secretion were evaluated after 24 h, 48 h, and 96 h, also before (n = 18) and after (n = 18) implant placement into porcine ribs bone. As results, the valleys of all implants had an increase in S_a values after implant placement. By contrast, the tops of the Stylus A implant and the flanks of the Tryon A implant showed a significant decrease in mean height of the irregularities (S_a), 0.16 µm and 1.25 µm, respectively. The Stylus implant presented significantly (p < 0.05) higher asymmetry values on the distribution curve for irregularity heights (S_ku) in all regions after insertion into bone (6.99 for tops, 9.54 for flanks, and 17.64 for valleys), indicating a greater preponderance of peaks over valleys. An increase in roughness gradients (S_dq) was observed for all macrogeometries after insertion into bone. The cell culture results showed no significant difference (p > 0.05) for all macrogeometries after bone placement. In conclusion, a subtle change in implant surface roughness was detected after insertion into bone for all the macrogeometries, without significantly affecting the cellular parameters studied.

Surface microstructure of dental implants before and after insertion: an in vitro study by means of scanning probe microscopy

INTRODUCTION

The surface microstructure of dental implants affects osseointegration, which makes their accurate topographic characterization important. We defined a procedure for evaluation of implant topography before (pre-) and after (post-) in vitro implantation test in bovine bone.

MATERIALS AND METHODS

The apical morphology of ten implants was analyzed in pre- and post-conditions using atomic force microscopy or 3D profilometry. We extracted four topographical parameters (two amplitude, 1 spatial, and 1 hybrid) and assessed the differences by analysis of variance.

RESULTS AND DISCUSSION

The implant with coating (Spline Twist MP-1 HA) was damaged. The two implants with highest pre-amplitude parameters (Pitt Easy VTPS, TLR3815) maintained their character on testing. Pitt Easy PURETEX and OT-F1 were the only nondamaged implants whose amplitude parameters increased. The surface area underwent minor changes even when the texture changed (Tri-Vent, Pitt Easy PURETEX, Exp #1). The implants that ranked the lowest in all parameters before implantation were DT4013TI, Tri-Vent, OT-F1, and Exp #2. On testing, DT4013TI showed the highest decrease in values, whereas Tri-Vent showed the highest increase in surface area. All the experimental implants showed similar topographic properties both pre- and post-test.

CONCLUSION

For most implants, no major changes occurred in surface topography on implantation. The procedure applied seems promising to evaluate the degradation of implant surface on insertion.

Influence of femtosecond laser on the osteogenetic efficiency of polyetheretherketone and its composite

Objective:

This study aimed to evaluate the effect of a femtosecond laser on the osteogenetic efficiency of polyetheretherketone (PEEK) and its composite for clinical applications.

Methods:

One hundred pieces of PEEK and its composite (6 × 4 × 2 mm3) were randomly divided into four groups and treated as follows: group A1, PEEK; group A2, PEEK + femtosecond laser; group B1, PEEK composite; and group B2, PEEK composite + femtosecond. The surface morphology of the pieces of each group was observed through scanning electron microscopy. The surface roughness and wettability, which were considered as the main parameters affecting cell adhesion characteristics of implants, were measured. The animals whose mandibles were implanted with the four groups of materials were killed at the end of 6 and 12 weeks. Various characterization tests, such as Cone Beam Computed Tomography (CBCT), push-out test, microscope test, and bone implant contact , were conducted to investigate the healing effect between materials and bones.

Results:

In group B1, the nanoparticles in PEEK were uniformly distributed. In groups A2 and B2, many periodic nanostructures were observed. The surface roughness and wettability of group B2 were significantly increased compared to those of the other groups ( p < 0.05). At each time point, the number of trabecular bones, contact strength, and BIC of group B2 were higher than those of the three other groups ( p < 0.05). Compared with those of group A1, the test results of group B1 were significantly improved.

Conclusion:

Femtosecond lasers can effectively enhance the biological activity of PEEK and its composite; PEEK composite exhibits better biological activity than PEEK.

Controlled oxidative nanopatterning of microrough titanium surfaces for improving osteogenic activity

To further enhance the biological properties of acid-etched microrough titanium surfaces, titania nanotextured thin films were produced by simple chemical oxidation, without significantly altering the existing topographical and roughness features. The nanotextured layers on titanium surfaces can be controllably varied by tuning the oxidation duration time. The oxidation treatment significantly reduced water contact angles and increased the surface energy compared to the surfaces prior to oxidation. The murine bone marrow stromal cells (BMSCs) were used to evaluate the bioactivity. In comparison, oxidative nanopatterning of microrough titanium surfaces led to improved attachment and proliferation of BMSCs. The rate of osteoblastic differentiation was also represented by the increased levels of alkaline phosphatase activity and mineral deposition. These data indicated that oxidative nanopatterning enhanced the biological properties of the microrough titanium surfaces by modulating their surface chemistry and nanotopography. Based on the proven mechanical interlocking ability of microtopographies, enhancement of multiple osteoblast functions attained by this oxidative nanopatterning is expected to lead to better implant osseointegration in vivo.

Experimental investigation of the effect of surface roughness on bone-cement-implant shear bond strength

Debonding of cemented bone implants is regarded as a major contributor to complications. The relationship between shear bond strength and surface roughness has been investigated, however there are inconsistencies in the trends reported in different studies. The shear strength between poly(methyl methacrylate) bone-cement and sand blasted cobalt-chromium and titanium alloy surfaces was measured to investigate the relationship between interfacial shear strength and surface topology. Surface roughness was quantified by a power law relationship fitted to Fourier spectra as well as three traditional parameters (arithmetical average roughness (Ra), volume of interdigitation (Rr), and RMS slope (Rdq)). We found that the interfacial shear strength is directly proportional to the exponent of the surfaces power spectra (P2) and Rdq, but not to Ra and Rr. However, Rdq is shown to be critically dependent on sampling frequency, making it sensitive to measurement settings. P2 was found to be a robust measure of the surface roughness being independent of sampling frequency.

Experimental study of bone response to hydroxyapatite coating implants: bone-implant contact and removal torque test

OBJECTIVE

The objective of this study was to evaluate the early osseointegration of hydroxyapatite (HA)-coated implant.

STUDY DESIGN

Twelve adult male miniature pigs were used in this study. The removal torque of implants placed in the tibia of miniature pigs was measured. For implants placed in the mandible, histomorphometric evaluation was performed for the evaluation of the bone-implant contact (BIC) ratio.

RESULTS

After 4, 8, and 12 weeks, removal torque values were increased. Among the 3 groups, the HA-coated group showed the highest values (P < .05). At 4 and 8 weeks, the BIC ratio of HA was significantly higher than that of resorbable blast medium or sand blasted with alumina and acid etched (P < .05).

CONCLUSIONS

It was concluded that HA-coated implants are relatively favorable in early loading stages.

Microstructural and topographical characterization of different surface treatments of a surgical titanium alloy for dental implants

OBJECTIVE

To perform a topographical characterization of a titanium alloy subjected to different surface treatments using roughness evaluation, scanning electron microscopy, and atomic force microscopy.

MATERIALS AND METHODS

For each group, 6 discs of a titanium alloy had their surfaces modified by 4 treatments. All surfaces were blasted with Al2O3, cleaned, and the specimens were divided into 4 groups: G1, immersion in a standardized acid solution (SAS) (control group); G2, immersion in acetone, followed by immersion in SAS; G3, immersion in acetone, followed by immersion in SAS, followed by immersion in nitric acid; G4, immersion in acetone, followed by immersion in SAS, followed by immersion in sulfuric acid. Roughness parameters were determined with a roughness tester, and data were statistically analyzed using analysis of variance and Tukey tests (α = 5%).

RESULTS

Regarding the roughness parameters, no significant differences were found. Scanning electron microscopy and atomic force microscopy showed irregular surfaces with the presence of particles uniformly deposited on the surfaces.

CONCLUSION

A similar roughness pattern was created for all the groups. The images and topographic profiles indicated that all the groups showed high levels of roughness.

Osseointegration of titanium implants with a roughened surface containing hydride ion in a rabbit model

OBJECTIVE

The objective of this study was to investigate the effect of hydride ion on bone formation and bone-bonding strength at the early stage of implantation.

STUDY DESIGN

Implants and plates were treated in 2 ways: test implant (implant surface with hydride ion) and control implant (implant surface without hydride ion). Crystal structure of plate surfaces was analyzed by low angle x-ray diffractometry (XRD). Sixty implants (30 test implants and 30 control implants) were inserted into tibias of 10 rabbits. At 2 and 8 weeks postimplantation, tibias were retrieved and prepared for removal torque tests (RTQ) and histomorphometric evaluation, respectively.

RESULTS

TiH(2) diffractions appeared on the XRD pattern of the test surface whereas TiH(2) did not appear on the control surface. The test implants showed 51.28% and 64.63% greater RTQ values than did the control implants at 2 and 8 weeks (P = .010, .011, respectively). Histomorphometric evaluation demonstrated the test implants significantly increased bone-implant contact and peri-implant bone formation at 2 and 8 weeks.

CONCLUSION

These results suggest the presence of hydride ion in the implant surface may improve bone integration with implant surfaces at the early stage of implantation.

Effects of titanium surface topography on bone integration: a systematic review

AIM

To analyse possible effects of titanium surface topography on bone integration.

MATERIALS AND METHODS

Our analyses were centred on a PubMed search that identified 1184 publications of assumed relevance; of those, 1064 had to be disregarded because they did not accurately present in vivo data on bone response to surface topography. The remaining 120 papers were read and analysed, after removal of an additional 20 papers that mainly dealt with CaP-coated and Zr implants; 100 papers remained and formed the basis for this paper. The bone response to differently configurated surfaces was mainly evaluated by histomorphometry (bone-to-implant contact), removal torque and pushout/pullout tests.

RESULTS AND DISCUSSION

A huge number of the experimental investigations have demonstrated that the bone response was influenced by the implant surface topography; smooth (S(a)<0.5 microm) and minimally rough (S(a) 0.5-1 mum) surfaces showed less strong bone responses than rougher surfaces. Moderately rough (S(a)>1-2 microm) surfaces showed stronger bone responses than rough (S(a)>2 microm) in some studies. One limitation was that it was difficult to compare many studies because of the varying quality of surface evaluations; a surface termed 'rough' in one study was not uncommonly referred to as 'smooth' in another; many investigators falsely assumed that surface preparation per se identified the roughness of the implant; and many other studies used only qualitative techniques such as SEM. Furthermore, filtering techniques differed or only height parameters (S(a), R(a)) were reported.

CONCLUSIONS

* Surface topography influences bone response at the micrometre level. * Some indications exist that surface topography influences bone response at the nanometre level. * The majority of published papers present an inadequate surface characterization. * Measurement and evaluation techniques need to be standardized. * Not only height descriptive parameters but also spatial and hybrid ones should be used.