Accelerated Healing Period with Hydrophilic Implant Placed in Sheep Tibia

Analysis of peri-implant bone tissue between hydrophilic and rough implant surfaces in spontaneously hypertensive rats treated with losartan

OBJECTIVES

to evaluate the morphological and functional characteristics of the peri-implant bone tissue that was formed during the healing process by the placement implants using two different surface treatments: hydrophilic Acqua™ (ACQ) and rough NeoPoros™ (NEO), in spontaneously hypertensive (SHR) and normotensive rats (Wistar) whether or not treated with losartan.

METHODOLOGY

In total, 96 male rats (48 Wistar and 48 SHR) were divided into eight subgroups: absolute control rough (COA NEO), absolute control hydrophilic (COA ACQ), losartan control rough (COL NEO), losartan control hydrophilic (COL ACQ), SHR absolute rough (SHR NEO), SHR absolute hydrophilic (SHR ACQ), SHR losartan rough (SHRL NEO), and SHR losartan hydrophilic (SHRL ACQ). The rats medicated with losartan received daily doses of the medication. NeoPoros™ and Acqua™ implants were installed in the tibiae of the rats. After 14 and 42 days of the surgery, the fluorochromes calcein and alizarin were injected in the rats. The animals were euthanized 67 days after treatment. The collected samples were analyzed by immunohistochemistry, biomechanics, microcomputerized tomography, and laser confocal scanning microscopy analysis.

RESULTS

The osteocalcin (OC) and vascular endothelium growth factor (VEGF) proteins had moderate expression in the SHRL ACQ subgroup. The same subgroup also had the highest implant removal torque. Regarding microarchitectural characteristics, a greater number of trabeculae was noted in the control animals that were treated with losartan. In the bone mineralization activity, it was observed that the Acqua™ surface triggered higher values of MAR (mineral apposition rate) in the COA, COL, and SHRL groups (p<0.05).

CONCLUSION

the two implant surface types showed similar responses regarding the characteristics of the peri-implant bone tissue, even though the ACQ surface seems to improve the early stages of osseointegration.

Evaluation of hydrophilic surface osseointegration in low-density bone: Preclinical study in rabbits

The aim of this study was to evaluate the osseointegration of a hydrophilic surface (blasting + acid etching + immersion in isotonic solution) in comparison with that of a control surface (blasting + acid etching) using an experimental model of low-density bone. To perform the study, 24 rabbits were submitted to the installation of 4 implants in the iliac bone bilaterally: 2 implants with a control surface and 2 implants with a hydrophilic surface. The rabbits were euthanized at 2, 4, and 8 weeks after implant installation. After euthanasia, one implant from each surface was used to perform the removal torque analysis, and the other implant was used for the execution of non-decalcified histological sections and evaluation of the bone implant contact (% BIC) as well as the fraction of bone tissue area between the implant threads (% BBT). The implants with a hydrophilic surface presented higher %BIC (42.92 ± 2.85% vs. 29.49 ± 10.27%) and % BBT (34.32 ± 8.52% vs. 23.20 ± 6.75%) (p < 0.05) in the 2-week period. Furthermore, the hydrophilic surface presented higher removal torque in the 8-week period (76.13 ± 16.00 Ncm2 vs. 52.77 ± 13.49 Ncm2) (p<0.05). Implants with a hydrophilic surface exhibited acceleration in the process of osseointegration, culminating in greater secondary stability in low-density bone than in implants with a control surface.

In vivo osseointegration evaluation of implants coated with nanostructured hydroxyapatite in low density bone

OBJECTIVE

This in vivo study, aimed to biomechanically, histomorphometrically and histologically evaluate an implant surface coated with nanostructured hydroxyapatite using the wet chemical process (biomimetic deposition of calcium phosphate coating) when compared to a dual acid-etching surface.

MATERIAL AND METHODS

Ten sheep (2-4 years old) received 20 implants, 10 with nanostructured hydroxyapatite coating (HAnano), and 10 with dual acid-etching surface (DAA). The surfaces were characterized with scanning electron microscopy and energy dispersive spectroscopy; insertion torque values and resonance frequency analysis were measured to evaluate the primary stability of the implants. Bone-implant contact (BIC) and bone area fraction occupancy (BAFo) were evaluated 14 and 28 days after implant installation.

RESULTS

The HAnano and DAA groups showed no significant difference in insertion torque and resonance frequency analysis. The BIC and BAFo values increased significantly (p<0.05) over the experimental periods in both groups. This event was also observed in BIC value of HAnano group. The HAnano surface showed superior results compared to DAA after 28 days (BAFo, p = 0.007; BIC, p = 0.01).

CONCLUSION

The results suggest that the HAnano surface favors bone formation when compared to the DAA surface after 28 days in low-density bone in sheep.

Osseointegration of a New, Ultrahydrophilic and Nanostructured Dental Implant Surface: A Comparative In Vivo Study

This study compared the osseointegration of acid-etched, ultrahydrophilic, micro- and nanostructured implant surfaces (ANU) with non-ultra-hydrophilic, microstructured (SA) and non-ultrahydrophilic, micro- and nanostructured implant surfaces (AN) in vivo. Fifty-four implants (n = 18 per group) were bilaterally inserted into the proximal tibia of New Zealand rabbits (n = 27). After 1, 2, and 4 weeks, bone-implant contact (BIC, %) in the cortical (cBIC) and spongious bone (sBIC), bone chamber ingrowth (BChI, %), and the supra-crestal, subperiosteal amount of newly formed bone, called percentage of linear bone fill (PLF, %), were analyzed. After one week, cBIC was significantly higher for AN and ANU when compared to SA (p = 0.01 and p = 0.005). PLF was significantly increased for ANU when compared to AN and SA (p = 0.022 and p = 0.025). After 2 weeks, cBIC was significantly higher in SA when compared to AN (p = 0.039) and after 4 weeks, no significant differences in any of the measured parameters were found anymore. Ultrahydrophilic implants initially improved osseointegration when compared to their non-ultrahydrophilic counterparts. In accordance, ultrahydrophilic implants might be appropriate in cases with a necessity for an accelerated and improved osseointegration, such as in critical size alveolar defects or an affected bone turnover.

Long-term antibacterial properties of a nanostructured titanium alloy surface: An in vitro study

The demand for joint replacement and other orthopedic surgeries involving titanium implants is continuously increasing; however, 1%-2% of surgeries result in costly and devastating implant associated infections (IAIs). Pseudomonas aeruginosa and Staphylococcus aureus are two common pathogens known to colonise implants, leading to serious complications. Bioinspired surfaces with spike-like nanotopography have previously been shown to kill bacteria upon contact; however, the longer-term potential of such surfaces to prevent or delay biofilm formation is unclear. Hence, we monitored biofilm formation on control and nanostructured titanium disc surfaces over 21 days following inoculation with Pseudomonas aeruginosa and Staphylococcus aureus. We found a consistent 2-log or higher reduction in live bacteria throughout the time course for both bacteria. The biovolume on nanostructured discs was also significantly lower than control discs at all time points for both bacteria. Analysis of the biovolume revealed that for the nanostructured surface, bacteria was killed not just on the surface, but at locations above the surface. Interestingly, pockets of bacterial regrowth on top of the biomass occurred in both bacterial species, however this was more pronounced for S. aureus cultures after 21 days. We found that the nanostructured surface showed antibacterial properties throughout this longitudinal study. To our knowledge this is the first in vitro study to show reduction in the viability of bacterial colonisation on a nanostructured surface over a clinically relevant time frame, providing potential to reduce the likelihood of implant associated infections.

Pre-Clinical Models in Implant Dentistry: Past, Present, Future

Biomedical research seeks to generate experimental results for translation to clinical settings. In order to improve the transition from bench to bedside, researchers must draw justifiable conclusions based on data from an appropriate model. Animal testing, as a prerequisite to human clinical exposure, is performed in a range of species, from laboratory mice to larger animals (such as dogs or non-human primates). Minipigs appear to be the animal of choice for studying bone surgery around intraoral dental implants. Dog models, well-known in the field of dental implant research, tend now to be used for studies conducted under compromised oral conditions (biofilm). Regarding small animal models, research studies mostly use rodents, with interest in rabbit models declining. Mouse models remain a reference for genetic studies. On the other hand, over the last decade, scientific advances and government guidelines have led to the replacement, reduction, and refinement of the use of all animal models in dental implant research. In new development strategies, some in vivo experiments are being progressively replaced by in vitro or biomaterial approaches. In this review, we summarize the key information on the animal models currently available for dental implant research and highlight (i) the pros and cons of each type, (ii) new levels of decisional procedures regarding study objectives, and (iii) the outlook for animal research, discussing possible non-animal options.

Nature-Inspired Nanoflower Structures on Titanium Surface via Alkali Treatment for Biomedical Applications

Titanium based metallic biomaterials for orthopedic implant applications are often associated with biocompatibility problems which can be ameliorated via proper surface modification strategies. Improving the hydrophilic nature of the titanium surface offers an effective strategy to sort out such limitations by intensifying the cellular activity. Development of titania as well as titanate layers on the titanium surface via alkali treatment represents an effective strategy to improve the hydrophilicity of native titanium surface. Inspired from nature, in the present work, we report the formation of three-dimensional (3D) hierarchical nanoflowers resembling Gomphrena globosa flowers developed on commercially pure titanium (cp-Ti) surface via a facile alkali treatment technique. X-ray diffraction studies evidenced anatase and rutile phases of TiO2 confirming the development of titania on the surface. In addition to the TiO2 phase, presence of titanate (Na2Ti3O7) has also been observed as alkali treatment was conducted in NaOH solution. The hydrophilicity of the Ti surface has been enhanced after the alkali treatment as evidenced from wettability studies using static contact angle measurements. This increase in hydrophilicity is due to the enrichment of the surface by TiO2 and titanate and increased roughness of nanoflower surface based on classical Wenzel law. In addition, the alkali-treated surface demonstrated an increased polar surface energy beneficial for biocompatible surfaces.

Comparative Study of Physicochemical Properties and Biocompatibility (L929 and MG63 Cells) of TiN Coatings Obtained by Plasma Nitriding and Thin Film Deposition

Ti6Al4V is one of the most lightweight, mechanically resistant, and appropriate for biologically induced corrosion alloys. However, surface properties often must be tuned for fitting into biomedical applications, and therefore, surface modification is of paramount importance to carry on its use. This work compares the interaction between two different cell lines (L929 fibroblasts and osteoblast-like MG63) and medical grade Ti6Al4V after surface modification by plasma nitriding or thin film deposition. We studied the adhesion of these two cell lines, exploring which trends are consistent for cell behavior, correlating with osseointegration and in vivo conditions. Modified surfaces were analyzed through several physicochemical characterization techniques. Plasma nitriding led to a more pronounced increase in surface roughness, a thicker aluminum-free layer, made up of diverse titanium nitride phases, whereas thin film deposition resulted in a single-phase pure titanium nitride layer that leveled the ridged topography. The selective adhesion of osteoblast-like cells over fibroblasts was observed in nitrided samples but not in thin film deposited films, indicating that the competitive cellular behavior is more pronounced in plasma nitrided surfaces. The obtained coatings presented an appropriate performance for its use in biomedical-aimed applications, including the possibility of a higher success rate in osseointegration of implants.

Osseodensification enables bone healing chambers with improved low-density bone site primary stability: an in vivo study

Primary implant stability is a prerequisite for successful implant osseointegration. The osseodensification technique (OD) is a non-subtractive drilling technique that preserves the bone tissue, increases osteotomy wall density, and improves the primary stability. This study aimed to investigate the hypothesis that OD, through a wider osteotomy, produces healing chambers (HCs) at the implant-bone interface without impacting low-density bone primary stability. Twenty implants (3.5 × 10 mm) with a nanohydroxyapatite (nHA) surface were inserted in the ilium of ten sheep. Implant beds were prepared as follows: (i) 2.7-mm-wide using subtractive conventional drilling (SCD) technique (n = 10); (ii) 3.8-mm-wide using an OD bur system (n = 10). The sheep were randomized to two groups, with samples collected at either 14-(n = 5) or 28-days (n = 5) post-surgery and processed for histological and histomorphometric evaluation of bone-implant contact (BIC) and bone area fraction occupancy (BAFO). No significant group differences were found with respect to final insertion torque and implant stability quotient (p > 0.050). BIC values were higher for SCD after 14 and 28 days (p < 0.050); however, BAFO values were similar (p > 0.050). It was possible to conclude that the OD technique allowed a wider implant bed preparation without prejudice on primary stability and bone remodeling.

Osseointegration of different implant surfaces in areas grafted with deproteinized bovine bone associated or not with fresh bone marrow-Preclinical study in rabbits

OBJECTIVES

To assess the influence of two different implant surfaces on osseointegration in maxillary sinuses of rabbits previously grafted with deproteinized bovine bone (DBB) associated or not with fresh bone marrow (BM).

MATERIAL AND METHODS

Sixteen New Zealand albino rabbits (males, 3.5/4.5 kg and 9-12 months old) were randomly divided into two groups with 8 rabbits each, according to the type of association of biomaterials used to fill the animals' maxillary sinuses: DBB (Deproteinized Bovine Bone) and DBB/BM (Deproteinized bovine bone associated with fresh autologous bone marrow). Ninety (90) days following the grafting procedure, the animals received implants in the area with two different microstructures (SA-Sandblasting + acid attack and SA-H-Sandblasting + acid attack + immersion in 0.9% sodium chloride isotonic solution). All rabbits were euthanized 90 days after implant placement. The microtomographic analysis was performed to verify the number of mineralized tissues around the implants throughout their length (%BV/TV), while the histomorphometric analysis was performed to verify the percentage of bone-implant contact around the implants throughout their length (%BIC).

RESULTS

We observed no differences in the quantity for %BV/TV (DBB-SA:33.25 ± 19.67; DBB-SA-H:35.15 ± 22.17; DBB/BM-SA:39.71 ± 24.21; DBB/BM-SA-H:36.40 ± 23.07) and %BIC (DBB-SA:58.94 ± 24.37; DBB-SA-H:52.52 ± 24.36; DBB/BM-SA: 61.66 ± 14.60; DBB/BM-SA-H: 64.06 ± 23.30) between the groups assessed.

CONCLUSIONS

The addition of BM and the type of surface did not influence the osseointegration of implants installed in areas grafted with sintered deproteinized bovine bone at high temperatures in the late period assessed.

Impact of a Hydrophilic Dental Implant Surface on Osseointegration: Biomechanical Results in Rabbit

This study aimed to evaluate the effect of surface hydrophilicity on the biomechanical aspects of osseointegration of dental implants in the tibia and femur of rabbits. Forty-eight mature female New Zealand White rabbits were included, and 96 commercially pure, Grade 4, titanium dental implants (control group), and 96 implants of same macro geometry with the hydrophilic surface (test group) were used in this study. One osteotomy was performed in each tibia and femur on both sides of the rabbit, and four implants were placed in each rabbit. Control and test groups were randomly allocated on the left and right sides. During surgery, insertion torque (ITQ) value of the complete implant placement was recorded. After healing periods of 0, 2, 4, and 8 weeks after surgery, implant stability quotient (ISQ) value, and removal torque (RTQ) values were measured. No statistical difference was observed for ITQ, for ISQ and for RTQ between the control group and test group in tibia/femur for all time periods. The effect of hydrophilic properties on moderately roughened surfaces has no impact in terms of biomechanical outcomes (ISQ values and RTQ values) after a healing period of 2 to 8 weeks in rabbit tibias /femurs.

Does implant surface hydrophilicity influence the maintenance of surface integrity after insertion into low-density artificial bone?

OBJECTIVE

To evaluate the influence of hydrophilicity on the surface integrity of implants after insertion in low-density artificial bone and to determine the distribution of titanium (Ti) particles along the bone bed.

METHODS

Forty-eight dental implants with different designs (Titamax Ex, Facility, Alvim, and Drive) and surface treatments (Neoporos® and Aqua™) were inserted into artificial bone blocks with density compatible with bone type III-IV. Hydrophobic Neoporos® surfaces were obtained by sandblasting and acid etching while hydrophilic Aqua™ surfaces were obtained by sandblasting, acid etching, and storage in an isotonic 0.9% NaCl solution. The surface integrity was evaluated by Scanning Electron Microscope (SEM) and the surface roughness parameters (Sa, Sp, Ssk, Sdr, Spk, Sk, and Svk) and surface area were measured with Laser Scanning Confocal Microscopy before and after installation. Bone beds were inspected with Digital Microscopy and micro X-Ray Fluorescence (μ-XRF) to analyze the metallic element distribution along the bone bed.

RESULTS

Acqua™ implants had higher initial Sa and a pronounced reduction of Sa and Sp during insertion, compared to NeoPoros® implants. After insertion, Sa and Sp of Acqua™ and NeoPoros® implants equalized, differing only between designs of Acqua™ implants. Surface damage was observed after insertion, mainly in the apical region. Facility implants that are made of TiG5 released fewer debris particles, while the highest Ti intensity was detected in the cervical region of the Titamax Ex Acqua™ and Drive Acqua™ implants.

SIGNIFICANCE

Physicochemical modifications to achieve surface hydrophilicity created a rougher surface that was more susceptible to surface alterations, resulting in more Ti particle release into the bone bed during surgical insertion. The higher Ti intensities detected in the cervical region of bone beds may be related to peri-implantitis and marginal bone resorption.

The Influence of Nanostructured Hydroxyapatite Surface in the Early Stages of Osseointegration: A Multiparameter Animal Study in Low-Density Bone

Background and Objective

The success rates of dental implants in low-density bone have been reported as a challenge, especially for early or immediate loading in the maxilla posterior area. Nanoscale architecture affects the roughness, surface area, surface energy of the implant and can enhance osseointegration. This study aimed to evaluate the implant-surface topography and biomechanical, histomorphometric, and histological bone responses to a new nanostructured hydroxyapatite surface placed in the iliac crest of sheep.

Methods

Ten female sheep (2–4 years) received 30 implants (n=10/group): HAnano^® coated (Epikut Plus^®, S.I.N. Implant System, Sao Paulo, SP, Brazil), SLActive (BLX^®, Straumann, Basel, Switzerland), and TiUnite (NobelActive^®, Nobel Biocare, Göteborg, Sweden) surfaces. Scanning electron microscopy with energy-dispersive spectroscopy evaluated the implant surface topography, the insertion torque value, and resonance frequency analysis evaluated the primary stability, bone-implant contact, and bone-area fraction occupancy were evaluated after 14 and 28 days after implant placement.

Results

The surface morphology was considerably comparable between the implant groups’; however, the TiUnite^® group presented a remarkable different surface. The SLActive^® and TiUnite^® groups presented an insertion torque average of 74 (±8.9) N/cm that was similar to that of HAnano^® 72 (±8.3) N/cm (p >0.05). The resonance frequency evaluated with Osstell^®/SmartPeg^® or Penguin^®/MulTipeg^® showed similar results when assessing implants from the same group. BIC and BAFO significantly increased (p<0.05) throughout the experimental periods to all groups, but BIC and BAFO values were similar among the implants at the same time point. After 4 weeks, bone-implant contact was higher than 80% of the total length analyzed. New bone occupies around 60% of analyzed area around the implants.

Conclusion

HAnano^® coated surface promoted comparable osseointegration as SLActive and TiUnite in the sheep model. The three tested surfaces showed comparable osseointegration at the early stages of low-density bone repair in the sheep model.

De Aza P. Can changes in implant macrogeometry accelerate the osseointegration process?: An in vivo experimental biomechanical and histological evaluations

OBJECTIVES

The propose was to compare this new implant macrogeometry with a control implant with a conventional macrogeometry.

MATERIALS AND METHODS

Eighty-six conical implants were divided in two groups (n = 43 per group): group control (group CON) that were used conical implants with a conventional macrogeometry and, group test (group TEST) that were used implants with the new macrogeometry. The new implant macrogeometry show several circular healing cambers between the threads, distributed in the implant body. Three implants of each group were used to scanning electronic microscopy (SEM) analysis and, other eighty samples (n = 40 per group) were inserted the tibia of ten rabbit (n = 2 per tibia), determined by randomization. The animals were sacrificed (n = 5 per time) at 3-weeks (Time 1) and at 4-weeks after the implantations (Time 2). The biomechanical evaluation proposed was the measurement of the implant stability quotient (ISQ) and the removal torque values (RTv). The microscopical analysis was a histomorphometric measurement of the bone to implant contact (%BIC) and the SEM evaluation of the bone adhered on the removed implants.

RESULTS

The results showed that the implants of the group TEST produced a significant enhancement in the osseointegration in comparison with the group CON. The ISQ and RTv tests showed superior values for the group TEST in the both measured times (3- and 4-weeks), with significant differences (p < 0.05). More residual bone in quantity and quality was observed in the samples of the group TEST on the surface of the removed implants. Moreover, the %BIC demonstrated an important increasing for the group TEST in both times, with statistical differences (in Time 1 p = 0.0103 and in Time 2 p < 0.0003).

CONCLUSIONS

Then, we can conclude that the alterations in the implant macrogeometry promote several benefits on the osseointegration process.

Bone tissue formation around two titanium implant surfaces placed in bone defects filled with bone substitute material or blood clot: A pilot study

OBJECTIVES

The objective of this study was to evaluate the peri-implant bone tissue formation around titanium implants with different surface treatments, placed in bone defects filled or not with bone substitute material (BSM).

MATERIALS AND METHODS

Ten animals were divided into two groups according to implant surface treatment. In each tibia, a bone defect was created followed by the placement of one implant. On the left tibia, the defect was filled with blood clot (BC), and on the right tibia, the defect was filled with biphasic hydroxyapatite/β-tricalcium-phosphate (HA/TCP) generating four subgroups: BC-N: blood clot and porous surface; BC-A: blood clot and porous-hydrophilic surface; HA/TCP-N: BSM and porous surface; HA/TCP-A: BSM and porous-hydrophilic surface. The animals were submitted to euthanasia 60 days after implant installation. After light-curing resin inclusion, the blocks containing the implant and the bone tissue were stained and evaluated by means of histomorphometry to assess the percentages of bone implant contact (% BIC). Data was normally distributed and the group differences were examined using the parametric tests of Two-Way ANOVA.

RESULTS

The BC-A group presented the higher mean value of BIC (46.43%). The HA/TCP-A group presented the higher mean value of BIC. The porous-hydrophilic surfaces presented better results of BIC when compared to the porous surface in both conditions of defect filling. No statistically significant differences were found among all groups (95% confidence interval and P < .05).

CONCLUSION

According to histomorphometric analysis, after 60-days in a rabbit model, hydrophilic and hydrophobic surfaces have the same behavior in the presence or absence of HA/TCP.

Review on titanium and titanium based alloys as biomaterials for orthopaedic applications

Variety of implant materials have been employed in various disciplines of medical science depending on the requirement of a particular application. Metals, alloys, ceramics, and polymers are the commonly used biomaterials. The main focus of this study is to review the various structural and microstructural properties of titanium and titanium based alloys used as orthopaedic implants. Orthopaedic implants need to possess certain important qualities to ensure their safe and effective use. These properties like the biocompatibility, relevant mechanical properties, high corrosion and wear resistance and osseointegration are summarized in this review. Various attempts to improve upon these properties like different processing routes, surface modifications have also been inculcated in the paper to provide an insight into the extent of research and effort that has been put into developing a highly superior titanium orthopaedic implant.