Osseointegration: a reality

Guided bone regeneration in implant dentistry: Basic principle, progress over 35 years, and recent research activities

Bone augmentation procedures are frequent today in implant patients, since an implant should be circumferentially anchored in bone at completion of bone healing to have a good long-term stability. The best documented surgical technique to achieve this goal is guided bone regeneration (GBR) utilizing barrier membranes in combination with bone fillers. This clinical review paper reflects 35 years of development and progress with GBR. In the 1990s, GBR was developed by defining the indications for GBR, examining various barrier membranes, bone grafts, and bone substitutes. Complications were identified and reduced by modifications of the surgical technique. Today, the selection criteria for various surgical approaches are much better understood, in particular, in post-extraction implant placement. In the majority of patients, biodegradable collagen membranes are used, mainly for horizontal bone augmentation, whereas bioinert PTFE membranes are preferred for vertical ridge augmentation. The leading surgeons are using a composite graft with autogenous bone chips to accelerate bone formation, in combination with a low-substitution bone filer to better maintain the augmented bone volume over time. In addition, major efforts have been made since the millenium change to reduce surgical trauma and patient morbidity as much as possible. At the end, some open questions related to GBR are discussed.

Fit and forget: The future of dental implant therapy via nanotechnology

Unlike orthopedic implants, dental implants require the orchestration of both osseointegration at the bone-implant interface and soft-tissue integration at the transmucosal region in a complex oral micro-environment with ubiquitous pathogenic bacteria. This represents a very challenging environment for early acceptance and long-term survival of dental implants, especially in compromised patient conditions, including aged, smoking and diabetic patients. Enabling advanced local therapy from the surface of titanium-based dental implants via novel nano-engineering strategies is emerging. This includes anodized nano-engineered implants eluting growth factors, antibiotics, therapeutic nanoparticles and biopolymers to achieve maximum localized therapeutic action. An important criterion is balancing bioactivity enhancement and therapy (like bactericidal efficacy) without causing cytotoxicity. Critical research gaps still need to be addressed to enable the clinical translation of these therapeutic dental implants. This review informs the latest developments, challenges and future directions in this domain to enable the successful fabrication of clinically-translatable therapeutic dental implants that would allow for long-term success, even in compromised patient conditions.

Biological Activity and Thrombogenic Properties of Oxide Nanotubes on the Ti-13Nb-13Zr Biomedical Alloy

The success of implant treatment is dependent on the osseointegration of the implant. The main goal of this work was to improve the biofunctionality of the Ti-13Nb-13Zr implant alloy by the production of oxide nanotubes (ONTs) layers for better anchoring in the bone and use as an intelligent carrier in drug delivery systems. Anodization of the Ti-13Nb-13Zr alloy was carried out in 0.5% HF, 1 M (NH₄)₂SO₄ + 2% NH₄F, and 1 M ethylene glycol + 4 wt.% NH₄F electrolytes. Physicochemical characteristics of ONTs were performed by high-resolution electron microscopy (HREM), X-ray photoelectron spectroscopy (XPS), and scanning Kelvin probe (SKP). Water contact angle studies were conducted using the sitting airdrop method. In vitro biological properties and release kinetics of ibuprofen were investigated. The results of TEM and XPS studies confirmed the formation of the single-walled ONTs of three generations on the bi-phase (α + β) Ti-13Nb-13Zr alloy. The ONTs were composed of oxides of the alloying elements. The proposed surface modification method ensured good hemolytic properties, no cytotoxity for L-929 mouse cells, good adhesion, increased surface wettability, and improved athrombogenic properties of the Ti-13Nb-13Zr alloy. Nanotubular surfaces allowed ibuprofen to be released from the polymer matrix according to the Gallagher-Corrigan model.

The Sympathetic Nervous System in Dental Implantology

The sympathetic nervous system plays a vital role in various regulatory mechanisms. These include the well-known fight-or-flight response but also, for example, the processing of external stressors. In addition to many other tissues, the sympathetic nervous system influences bone metabolism. This effect could be highly relevant concerning osseointegration, which is responsible for the long-term success of dental implants. Accordingly, this review aims to summarize the current literature on this topic and to reveal future research perspectives. One in vitro study showed differences in mRNA expression of adrenoceptors cultured on implant surfaces. In vivo, sympathectomy impaired osseointegration in mice, while electrical stimulation of the sympathetic nerves promoted it. As expected, the beta-blocker propranolol improves histological implant parameters and micro-CT measurements. Overall, the present data are considered heterogeneous. However, the available publications reveal the potential for future research and development in dental implantology, which helps to introduce new therapeutic strategies and identify risk factors for dental implant failure.

Gene-activated titanium implants for gene delivery to enhance osseointegration

Osseointegration is the direct and intimate contact between mineralized tissue and titanium implant at the bone-implant interface. Early establishment and stable maintenance of osseointegration is the key to long-term implant success. However, in patients with compromised conditions such as osteoporosis and patients beginning early load-bearing activities such as walking, lower osseointegration around titanium implants is often observed, which might result in implant early failure. Gene-activated implants show an exciting prospect of combining gene delivery and biomedical implants to solve the problems of poor osseointegration formation, overcoming the shortcomings of protein therapy, including rapid degradation and overdose adverse effects. The conception of gene-activated titanium implants is based on "gene-activated matrix" (GAM), which means scaffolds using non-viral vectors for in situ gene delivery to achieve a long-term and efficient transfection of target cells. Current preclinical studies in animal models have shown that plasmid DNA (pDNA), microRNA (miRNA), and small interference RNA (siRNA) functionalized titanium implants can enhance osseointegration with safety and efficiency, leading to the expectation of applying this technique in dental and orthopedic clinical scenarios. This review aims to comprehensively summarize fabrication strategies, current applications, and futural outlooks of gene-activated implants, emphasizing nucleic acid targets, non-viral vectors, implant surface modification techniques, nucleic acid/vector complexes loading strategies.

Electrochemical deposition of lithium coating on titanium implant with enhanced early stage osseointegration

Recently, a large number of studies have reported that lithium (Li) displayed a positive effect on osteogenesis. However, only a few studies have investigated the Li-incorporated surfaces through electrochemical deposition. In this study, electrochemical deposition was conducted on a CHI600E electrochemical workstation. The characterization of electrochemical deposition (ECD) and ECD-Li surfaces were detected by field-emission scanning electron microscopy with energy-dispersive spectrometer. rBMSCs were cultured on two surfaces for subsequent adhesion, proliferation and live/dead assay. To evaluate the effects of Li-incorporated implants by electrochemical deposition on osseointegration in vivo, teeth extraction of two premolars and one first molar in bilateral mandible were performed on six male beagle dogs. After 3 months, ZDI and ZDI-Li implants were inserted into the bilateral mandible of each beagle dog. Micro Computed Tomography (Micro-CT) and hard tissue sectioning analysis were carried out to evaluate the osseointegration at 4- and 8-weeks post-implantation. Results showed that ECD-Li surface promoted adhesion and proliferation of BMSCs in the early stage. More importantly, through micro-CT analysis, the values of bone volume/total volume (BV/TV) (0.374 ± 0.015), bone-implant contact (BIC) (0.831 ± 0.025), and Tb.Th (0.412 ± 0.007) in ZDI-Li group was significantly higher than those of ZDI group (0.302 ± 0.009, 0.700 ± 0.023, 0.353 ± 0.001, p < .01) at 4 weeks. Similarly, ZDI-Li group manifested more bone contact with the implant surfaces at 4 weeks based on hard tissue sectioning analysis, whereas no significant difference was detected between two groups at 8 weeks. Therefore, incorporating Li into implant surface through ECD could enhance early osseointegration in vivo.

Osseointegration of Zirconia Implants after UV-Light or Cold Atmospheric Plasma Surface Treatment In Vivo

The influence of UV light and non-thermal plasma on the osseointegration of yttria-stabilized zirconia implants (Y-TZP) comparing the two methods is unclear. The aim of this study was to show the influence of these methods on the osseointegration of dental zirconia implants in an animal model. A total of 54 implants were either untreated, treated with UV light (UV), or non-thermal oxygen plasma for 12 min and inserted into the parietal bones of six domestic pigs. The animals were sacrificed after a healing interval of two, four, and nine weeks. The degree of osseointegration was determined using histomorphometric determination of bone-to-implant contact values (BIC) and the bone-to-implant contact values within the retentive parts of the implants (BAFO). BIC values decreased in all groups after four weeks of healing and re-increased after nine weeks in all groups. BAFO increased significantly over time in all groups. However, there were no statistically significant differences in BIC and BAFO values between the control group and the test groups and over time. Clinical studies may follow to confirm the influence of cold plasma and UV light on the healing and survival of zirconia implants.

Secondary stability achieved in dental implants with a calcium-coated sandblasted, large-grit, acid-etched (SLA) surface and a chemically modified SLA surface placed without mechanical engagement: A preclinical study

OBJECTIVES

To assess the osseointegration of calcium-coated (CS) and chemically modified, sandblasted, large-grit, acid-etched (MS) dental implants with a lack of primary mechanical stability.

MATERIALS AND METHODS

Eighteen implants in CS and MS groups each were loosely placed in the mandible of six mongrel dogs and allowed to heal for 2, 4 and 8 weeks. Implant stability quotient (ISQ) and implant stability test (IST) values recorded periodically and bone-to-implant contact (BIC) and the number of Haversian canals per 1 mm² measured histologically were statistically analysed (p < .05).

RESULTS

All CS and MS implants placed survived. Compared with immediately after installation, ISQ and IST values in both groups increased significantly to over 76 at 2 weeks (p < .0083) and remained stable thereafter. BIC was significantly greater at 8 weeks (61.3 ± 13.6% in CS group; 57.6 ± 5.9% in MS group) compared to 2 and 4 weeks in both groups (p < .017). There were no significant intergroup differences in ISQ, IST or BIC at different time points. Significantly more Haversian canals were observed in group CS (6.2 ± 1.0/mm² ) compared with group MS at 4 weeks (3.7 ± 1.8 /mm² ; p < .05), while intergroup difference was not significant at 8 weeks.

CONCLUSION

Both CS and MS implants inserted without primary stability obtained osseointegration within 2 weeks, and lamellar bone adjacent to the implants was first observed at 8 weeks. The formation of primary osteons was more active at 4 weeks in group CS than in group MS.

A Parametric Study on a Dental Implant Geometry Influence on Bone Remodelling through a Numerical Algorithm

To ensure the long-term success of a dental implant, it is imperative to understand how chewing loads are transferred through the implant prosthetic components to the surrounding bone tissue. The stress distribution depends on several factors, such as load type, bone–implant interface, shape and materials of the fixture and quality and quantity of the bone. These aspects are of fundamental importance to ensure implant stability and to evaluate the remodelling capacity of the bone tissue to adapt to its biomechanical environment. A bone remodelling algorithm was formulated by the authors and implemented by means of finite element simulations on four different implants with several design characteristics. Internal bone microstructure and density, apposition/resorption of tissue and implant stability were evaluated over a period of 12 months, showing the influence of the geometry on bone tissue evolution over time. Bone remodelling algorithms may be a useful aid for clinicians to prevent possible implant failures and define an adequate implant prosthetic rehabilitation for each patient. In this work, for the first time, external bone remodelling was numerically predicted over time.

The early loading of different surface-modified implants: a randomized clinical trial

BACKGROUND

Various surface treatment options have been adopted with the aim to improve osseointegration, reducing the overall treatment time. Implant stability of early loaded implants with different modified surfaces was compared in the present study.

METHODS

Patients were selected from the Department of Oro-Maxillofacial Surgery and Stomatology at Semmelweis University. Patients randomly received SA (alumina sandblasted and acid-etched), NH (bioabsorbable apatite nanocoating) or SLA (large-grit sandblasted and acid-etched) surface implants. Outcome measures were: implant success, implant stability, and periodontal parameters. The implant stability was measured at the time of implant placement (primary stability) and six weeks after (prothesis delivery, secondary stability). Osstell and Periotest were applied to take all the measurements. The primary and secondary stability were compared in the three study groups Finally the periimplant probing depth appearing after three months of loading was checked on 6 points around to the implant-supported prostheses. Shapiro-Wilk and Mann-Whitney tests were used for the comparison between the study groups.

RESULTS

A total of 75 implants with different length and diameter were inserted into various positions. One implant failed spontaneously at the fourth week after implant placement. The survival rate was 98,7%. Comparing the primary and secondary stability values, the data were significantly improved in every groups. The difference was the highest in the NH group, however, this difference was not significant compared to the two other groups. Good periodontal parameters were experienced in all the tested implants, independently by the groups.

CONCLUSIONS

With the limitation of the present study, all the implants showed improved stability six weeks after implant placement. A trend of higher result was found for the NH group. Further studies with longer follow-up are needed to confirm this preliminary results.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN13181677; the date of registration: 04/03/2021. Retrospectively registered.

The Bone Buttress Theory: The Effect of the Mechanical Loading of Bone on the Osseointegration of Dental Implants

Simple Summary

The bone, as a vertebrate support tissue, is capable of adapting its structure and function to the mechanical demands resulting from the loads that are produced during the performance of its activity. This regulatory action also occurs during the healing processes of a fracture. The purpose of this study was to determine to what extent a dynamic load was capable of modulating the bone healing response around a titanium implant. The study was carried out on experimental rabbits, to which dental implants were placed in the tibiae and there were two test groups, one in which they did not undergo exercise during healing period and another that ran daily during this process on a treadmill. The trail results showed an improvement in the osseointegration process of the implant in the group in which it was subjected to load. The importance of these results is that it opens the door to a better understanding of the mechanisms that can modulate bone healing, especially around dental implants, supporting implant loading protocols that are based on efficiency.

Abstract

Objectives: To determine the effect of mechanical loading of bone on the stability and histomorphometric variables of the osseointegration of dental implants using an experimental test in an animal model. Materials and Methods: A total of 4 human implants were placed in both tibiae of 10 New Zealand rabbits (n = 40). A 6-week osseointegration was considered, and the rabbits were randomly assigned to two groups: Group A (Test group) included 5 rabbits that ran on a treadmill for 20 min daily during the osseointegration period; Group B (Controls) included the other 5 that were housed conventionally. The monitored variables were related to the primary and secondary stability of the dental implants (implant stability quotient—ISQ), vertical bone growth, bone to implant contact (BIC), area of regenerated bone and the percentage of immature matrix. Results: The results of the study show a greater vertical bone growth (Group A 1.26 ± 0.48 mm, Group B 0.32 ± 0.47 mm, p < 0.001), higher ISQ values (Group A 11.25 ± 6.10 ISQ, 15.73%; Group B 5.80 ± 5.97 ISQ, 7.99%, p = 0.006) and a higher BIC (Group A 19.37%, Group B 23.60%, p = 0.0058) for implants in the test group, with statistically significant differences. A higher percentage of immature bone matrix was observed for implants in the control group (20.68 ± 9.53) than those in the test group (15.38 ± 8.84) (p = 0.108). A larger area of regenerated bone was also observed for the test implants (Group A 280.50 ± 125.40 mm², Group B 228.00 ± 141.40 mm²), but it was not statistically significant (p = 0.121). Conclusions: The mechanical loading of bone improves the stability and the histomorphometric variables of the osseointegration of dental implants.

Novel technique using cold atmospheric plasma coupled with air-polishing for the treatment of titanium discs grown with biofilm: An in-vitro study

OBJECTIVES

The aim of the present study was to assess the decontamination efficacy and titanium surface alterations of erythritol based air abrasion (AA) and cold atmospheric plasma (CAP) targeting a human complex biofilm.

METHODS

Saliva collected from a peri-implantitis patient was used to develop in vitro human biofilm over titanium discs with machined (group A) and moderately rough (group B) surface. The discs were treated with AA, experimental CAP or a combination of both treatments (COM). The amount of biofilm on the discs was measured by crystal violet (CV). Surface features and roughness before and after treatment were assessed by SEM and laser profilometry, respectively. The data were statistically analyzed using Kruskal Wallis followed by Dunn's multiple comparison test after being checked for normality by Shapiro-Wilk test.

RESULTS

All the discs in group A performed better to treatments compared to group B. In both groups, CV data showed significantly lower amount of biofilm after AA treatment compared to CAP (p<0.05). Cleaning efficacy revealed relevant decontamination of both the surfaces following AA and COM treatments and almost complete biofilm removal after AA application on group A (99.92%). SEM analysis demonstrated no post-treatment alterations on the discs and laser profilometry did not show statistically significant changes in S_a and S_dr values.

SIGNIFICANCE

Decontamination with AA delivering erythritol with or without CAP is highly effective in biofilm removal from different titanium surfaces. All the tested treatments, including CAP showed no noticeable alterations of the titanium discs surface features. Further in vivo studies are necessary to understand the potential of CAP technology in implant surface decontamination.

In vitro evaluation of NaOCl-mediated functionalization of biologically aged titanium surfaces

The aim of this study was to evaluate the NaOCl-mediated biofunctionalization of titanium surfaces. Titanium disks stored for 2 weeks were immersed in 5% NaOCl solution for 24 h. A disk immersed in distilled water for 24 h was used as a control. X-ray photoelectron spectrometer assay of the titanium surface after NaOCl treatment demonstrated that organic contaminants containing carbon and nitrogen were removed and the number of hydroxyl groups increased. The NaOCl treatment substantially converted the titanium surface to superhydrophilic status (θ<5°), which resulted in an increased number of attached cells and enhanced cell spreading on the NaOCl-treated surfaces. These results indicate that biofunctionalization of the biologically degraded titanium surfaces can be achieved by chemical surface treatment with 5% NaOCl. The mechanism for desorption of strongly adsorbed organic molecules with polar groups such as amino and aldehyde groups from titanium surfaces by ClO^- was elucidated.

Oral Implants: The Paradigm Shift in Restorative Dentistry

The discovery of the phenomenon "osseointegration," or functional ankylosis, has led to the development of oral implants with high clinical performance. Consequently, the placement of titanium implants has changed the paradigms of restorative dentistry. Implants are used to prevent placing reconstructions anchored on natural teeth when these are vital and intact. Furthermore, implants are suitable to improve subjective chewing function and to replace missing and strategically important abutments. The osseointegration process is characterized by a predictable sequence of healing events that encompass the formation of woven bone, parallel fibers, and lamellar bone and result in fully functional bone that will remodel throughout life. While the osseointegration facilitates the use of implants as prosthetic abutments, it has to be kept in mind that the peri-implant soft tissue may be subject to biological complications. This, in turn, may result in an infectious process that will jeopardize the osseointegration. Consequently, the monitoring of the peri-implant tissues is an important aspect, and early intervention in situations with peri-implant mucositis is mandatory for the prevention of peri-implantitis. Hence, it is evident that oral implants need lifelong maintenance care if their longevity is to be assured.

Novel Yttria-Stabilized Zirconium Oxide and Lithium Disilicate Coatings on Titanium Alloy Substrate for Implant Abutments and Biomedical Application

This study aimed to create novel bioceramic coatings on a titanium alloy and evaluate their surface properties in comparison with conventional prosthetic materials. The highly polished titanium alloy Ti6Al4V (Ti) was used as a substrate for yttria-stabilized zirconium oxide (3YSZ) and lithium disilicate (LS2) coatings. They were generated using sol-gel strategies. In comparison, highly polished surfaces of Ti, yttria-stabilized zirconium oxide (ZrO2), polyether ether ketone (PEEK) composite, and poly(methyl methacrylate) (PMMA) were utilized. Novel coatings were characterized by an X-ray diffractometer (XRD) and scanning electron microscope (SEM). The roughness by atomic force microscope (AFM), water contact angle (WCA), and surface free energy (SFE) were determined. Additionally, biocompatibility and human gingival fibroblast (HGF) adhesion processes (using a confocal laser scanning microscope (CLSM)) were observed. The deposition of 3YSZ and LS2 coatings changed the physicochemical properties of the Ti. Both coatings were biocompatible, while Ti-3YSZ demonstrated the most significant cell area of 2630 μm2 (p ≤ 0.05) and the significantly highest, 66.75 ± 4.91, focal adhesions (FAs) per cell after 24 h (p ≤ 0.05). By contrast, PEEK and PMMA demonstrated the highest roughness and WCA and the lowest results for cellular response. Thus, Ti-3YSZ and Ti-LS2 surfaces might be promising for biomedical applications.

Copper-enriched diamond-like carbon coatings promote regeneration at the bone-implant interface

There have been several attempts to design innovative biomaterials as surface coatings to enhance the biological performance of biomedical implants. The objective of this study was to design multifunctional Cu/a-C:H thin coating depositing on the Ti-6Al-4V alloy (TC4) via magnetron sputtering in the presence of Ar and CH4 for applications in bone implants. Moreover, the impact of Cu amount and sp2/sp3 ratio on the interior stress, corrosion behavior, mechanical properties, and tribological performance and biocompatibility of the resulting biomaterial was discussed. X-ray photoelectron spectroscopy (XPS) revealed that the sp2/sp3 portion of the coating was enhanced for samples having higher Cu contents. The intensity of the interior stress of the Cu/a-C:H thin bio-films decreased by increase of Cu content as well as the sp2/sp3 ratio. By contrast, the values of Young's modulus, the H3/E2 ratio, and hardness exhibited no significant difference with enhancing Cu content and sp2/sp3 ratio. However, there was an optimum Cu content (36.8 wt.%) and sp2/sp3 ratio (4.7) that it is feasible to get Cu/a-C:H coating with higher hardness and tribological properties. Electrochemical impedance spectroscopy test results depicted significant improvement of Ti-6Al-4V alloy corrosion resistance by deposition of Cu/a-C:H thin coating at an optimum Ar/CH4 ratio. Furthermore, Cu/a-C:H thin coating with higher Cu contents showed better antibacterial properties and higher angiogenesis and osteogenesis activities. The coated samples inhibited the growth of bacteria as compared to the uncoated sample (p < 0.05). In addition, such coating composition can stimulate angiogenesis, osteogenesis and control host response, thereby increasing the success rate of implants. Moreover, Cu/a-C:H thin films encouraged development of blood vessels on the surface of titanium alloy when the density of grown blood vessels was increased with enhancing the Cu amount of the films. It is speculated that such coating can be a promising candidate for enhancing the osseointegration features.

Role and influence of growth factors on early osseointegration in animal jaw bone: A meta-analysis

Aim:

Growth factors (GFs) are polypeptides, which are intricately involved in the regulation of bone formation, preservation, and regeneration through gene expression. However, the role of these bioactive agents in osseointegration of dental implants has not been substantially proven. The objective of this systematic review (SR) and meta-analysis was to explore the effect of GFs on early osseointegration of dental implants in animal jaws. An attempt to decipher an adjunctive role of GFs in modulating predictable bone growth in peri-implant areas was done.

Materials and Methods:

An electronic and manual search of different databases was performed. Only randomized controlled trials (RCTs) were included and reviewed. The risk of bias (ROB) of the selected studies was assessed using the SR Centre for Laboratory Animal Experimentation (Cochrane) tool. A meta-analysis was also performed to evaluate the different study characteristics quantitatively.

Statistical Analysis used:

The total Weighted mean difference was evaluated using the Rev-Manv5.3 algorithm. Chi-square test and I² test were done to assess the heterogeneity between the studies.

Results:

Seven RCTs were included in the study. These were associated with a high ROB. The total weighted mean difference (WMD) of the percentage of bone–implant contact was 3.25% (95% confidence interval [CI] = 1.49%–6.03%; P = 0.001; I² = 91%) between groups with and without exogenous application of GFs. The total WMD of the percentage of newly formed bone area was 4.48% (95% CI = 2.31%–5.90%; P < 0.00001, I² = 84%). A high level of heterogeneity (P < 0.001 for Chi-square test; I²>50 %) among comparable studies was observed.

Conclusion:

The ancillary application of external GFs exhibited evidence of early osseointegration, resulting in more predictable and faster results. However, a careful discernment of conclusions drawn from this SR is a must before conducting any human trials.

Donor-site Morbidity after Retromolar Bone Harvesting Using a Standardised Press Fit Cylinder Protocol

Precise fitting and immobilisation of bone transplants at the recipient site is of utmost importance for the healing process. With the help of the standardised Osseo Transfer System, the recipient site is adjusted to the graft, rather than vice versa as it is typically done. The aim of this study was to analyse donor-site morbidity after harvesting cylindrical bone grafts from the retromolar region using the Osseo Transfer System. The patient satisfaction with the surgical procedures was also evaluated. All patients treated with this standardised reconstruction method between 2006 and 2013 at the Department of Cranio-Maxillofacial Surgery, University Hospital Giessen, were included in this study. Complications were recorded and evaluated. Bone graft success and patient satisfaction were documented with a questionnaire, and then confirmed by clinical and radiological follow-up examinations. Fifty-four patients were treated and 64 harvested cylindrical autologous bone grafts were transplanted. In all cases, dental implants could be inserted after bone healing. One patient lost an implant, associated with failure of the bone graft. Six patients who were examined continued to show neurological disorders in locally limited areas. No complete or long-term damage of the inferior alveolar nerve occurred. More than 94% (n = 52) of the patients were 'very satisfied' or 'satisfied' with the results and would recommend this surgical treatment to other patients. The standardised Osseo Transfer was an effective treatment option for small and mid-sized alveolar ridge augmentations. A low donor-site morbidity rate and a high transplant success rate were verified. The Osseo Transfer System demonstrated to be a reliable surgical technique without major complications. We highly recommend this surgical augmentation procedure as a surgical treatment for local bone defects.

Enhanced Osseointegration of Titanium Alloy Implants with Laser Microgrooved Surfaces and Graphene Oxide Coating

Rapid and effective osseointegration, as a critical factor in affecting the success rate of titanium (Ti) implants in orthopedic applications, is significantly affected by their surface microstructure and chemical composition. In this work, surface microgrooved Ti-6Al-4V alloys with graphene oxide coating (Ti-G-GO) were fabricated by a combination of laser processing and chemical assembly techniques. The osteogenic capability in vitro and new bone formation in vivo of the implants were systematically investigated, and biomechanical pull-out tests of the screws were also performed. First, in vitro studies indicated that the optimal microgroove width of the titanium alloy surface was 45 μm (Ti-G), and the optimum GO concentration was 1 mg/mL. Furthermore, the effects of the surface microstructure and GO coating on the in vitro bioactivity were investigated through culturing bone marrow mesenchymal stem cells (BMSCs) on the surface of titanium alloy plates. The results showed that the BMSCs cultured on the Ti-G-GO group exhibited the best adhesion, proliferation, and differentiation, compared with that on the Ti-G and Ti groups. Micro-computed tomography evaluation, histological analysis, and pull-out testing demonstrated that both Ti-G and Ti-G-GO implants had the higher osseointegration than the untreated Ti implant. Moreover, the osteogenic capability of the Ti-G-GO group appeared to be superior to that of the Ti-G group, which could be attributed to the improvement of surface wettability and apatite formation by the GO coatings. These results suggest that the combination of the microgroove structure and GO coatings exhibits considerable potential for enhancing the surface bioactivation of materials, and the combination modification is expected to be used on engineered titanium alloy surfaces to enhance osseointegration for orthopedic applications.

Covalent Attachment of P15 Peptide to Ti Alloy Surface Modified with Polymer to Enhance Osseointegration of Implants

Titanium (Ti) and its alloys are used in orthopedic and dental implants due to their excellent physical properties and biocompatibility. Although Ti exhibits superior osteoconductive properties compared to those of polymer-based implants, improved bone-on growth properties are required for enhanced surgical outcomes and improved recovery surgical interventions. Herein, we demonstrate a novel surface modification strategy to enhance the osteoconductivity of Ti surfaces through the grafting-from procedure of a reactive copolymer via surface-initiated atom transfer radical polymerization (SI-ATRP). Then, postpolymerization conjugation of the P15 peptide, an osteoblast binding motif, was successfully carried out. Subsequent in vitro studies revealed that the surface modification promoted osteoblast attachment on the Ti discs at 6 and 24 h. Moreover, mineral matrix deposition by osteoblasts was greater for the surface-modified Ti than for plain Ti and P15 randomly absorbed onto the Ti surface. These results suggest that the strategy for postpolymerization incorporation of P15 onto a Ti surface with a polymer interface may provide improved osseointegration outcomes, leading to enhanced quality of life for patients.

Excessive occlusal load on chemically modified and moderately rough titanium implants restored with cantilever reconstructions. An experimental study in dogs

OBJECTIVE

To evaluate the outcomes of excessively loaded implants.

MATERIAL AND METHODS

In five dogs, all mandibular premolars were extracted. After 3 months, six implants (three SLA® and three SLActive®) were placed (S). After 4 weeks, implants were restored: one single crown with stable occlusal contacts (SC), one crown and a cantilever unit with excessive occlusal contacts (OL), and a non-loaded implant (NL). Bleeding-on-probing (BoP), attachment level (AL), mucosal margin (GM) were assessed. Resonance frequency analysis (RFA) was assessed weekly. Standardized X-rays were taken at S, 4 and 24 weeks.

RESULTS

Similar findings were observed for SLA® and SLActive® implants regarding PlI, GI, GM, AL, and BL. No significant differences were detected between baseline and 24-weeks or between treatment modalities for all clinical parameters (p > .05). Six months after loading, RFA values were significantly greater than at implant placement. No significant differences between treatment modalities were found. Linear radiographic measurements yielded similar results between SLA® and SLActive® implants. SLA® OL implants yielded a statistically significant gain on peri-implant bone density over all other groups (p = .012). Radiographic results were confirmed by descriptive histology. Technically, loosened occlusal screws occurred in 13.3% (SC = 3.3%; OL = 10%), while abutment fractures totalized 23.3% (SC = 6.6%; OL = 16.6%).

CONCLUSIONS

Excessive occlusal load applied to implants (SLA® or SLActive®) restored with cantilevers did not cause loss of osseointegration or significant changes in their clinical, radiographic, or histologic outcomes. Early excessive occlusal load on SLA® implants promoted a gain in peri-implant bone density. Excessively loaded implants showed more technical complications.

Early loading of splinted implants in posterior mandible: Three-year results of a prospective multicenter study

OBJECTIVE

To evaluate the clinical outcomes of an early loading protocol of splinted implants with a fluoride-modified nanostructure surface and a tapered apex design for the therapy of posterior partial edentulism of mandible.

MATERIALS AND METHODS

One hundred and seven implants were placed in the mandible of 45 subjects at three centres in China. A minimum of two and a maximum of three implants were placed in an edentulous region using a one-stage protocol. Each subject received a screw-retained, splinted and fixed permanent prosthesis 6-8 weeks after surgery. Marginal bone level (MBL) change, implant survival and soft tissue health were assessed at 6, 12, 24 and 36 months after loading. A total of 92 implants from 40 subjects were recalled and investigated in this clinical trial.

RESULTS

After three-year loading, the survival rate of implant was 100%. On a subject level, there was a mean (±SD) marginal bone gain of 0.23 ± 0.48 mm at 36-month recall and the change in MBL was statistically significant (p = .00061) compared with time of loading. On an implant level, the change in MBL was statistically significant (p = .03914, p = .01494, p = .00000) at 12, 24 and 36 months of loading compared with time of loading.

CONCLUSION

Three-year data indicate that early loading protocol of splinted implants with a fluoride-modified nanostructure surface and a tapered apex design is feasible and safe for the therapy of partial edentulism in posterior mandible, which may contribute to bone gain when the suitable occlusal load and oral hygiene maintenance are kept.

Immediate Loading of Unsplinted Implant Retained Mandibular Overdenture: A Randomized Controlled Clinical Study

This clinical study aimed to clinically and radiographically compare the implant survival rate and peri-implant tissue response between immediate and delayed loading protocols for unsplinted implant retained mandibular overdentures. Twenty patients were enrolled to participate in this study. Each subject was randomly assigned to 1 of 2 treatment groups: test group patients' implants (n = 10), which were immediately loaded, and control group patients' implants (n = 10), which were conventionally loaded. Locator abutments were torqued to 15 Ncm at delivery. Attachments were picked up intraorally immediately after implant placement for the test group and at 3 months for the control group, and 3-lb retention inserts were placed. Marginal bone levels based on cone beam computed tomography fixed reference points were recorded at baseline and 12 months. Modified plaque index, gingival index, and implant stability quotients were recorded at baseline, 3 months, and 12 months. After 12 months, implant survival rate was 100% in both groups. Marginal bone levels, keratinized mucosa, modified plaque index, and gingival index were significantly different among the groups at 3- and 12-month intervals, whereas no significant differences were found in implant stability quotients between the groups. The fact that implant survival rate was 100% in both treatment groups suggests that, within the limitations of this study, immediate loading protocol for unsplinted implant retained mandibular complete overdenture is as predictable, safe, and successful as the delayed loading protocol. Implementing the immediate loading protocol for mandibular implant retained overdentures could shorten treatment time, which could lead to better patient's satisfaction.

Bioinspired polydopamine and polyphenol tannic acid functionalized titanium suppress osteoclast differentiation: a facile and efficient strategy to regulate osteoclast activity at bone-implant interface

Osseointegration of metallic implants in porous osteoporotic bone remains a challenge. Surface modification of implants to reduce peri-implant osteoclastic bone resorption was explored in the study. Bioinspired polydopamine (pDOP) and polyphenol tannic acid (pTAN) are nature-derived universal coating systems that have emerged either as a sole coating or ad-layer for biomolecular conjugation on different biomaterials. The effects pDOP and pTAN on osteoclast development have not been reported before. In this study, osteoclast development was investigated on titanium (Ti) substrates coated with pDOP (Ti-pDOP) and pTAN (Ti-pTAN). The results showed that Ti-pDOP and Ti-pTAN coating reduced tartrate-resistant acid phosphatase activity and osteoclast cell number as compared with pristine Ti. Intriguingly, the reduction was higher on Ti-pTAN than on Ti-pDOP. Economical and biocompatible tannic acid serves as a superior coating in decreasing osteoclast activity when compared with that of pDOP coating and could be used to modulate osteoclast activity at bone-implant interfaces.

Bone healing dynamics associated with 3 implants with different surfaces: histologic and histomorphometric analyses in dogs

Purpose

This study evaluated differences in bone healing and remodeling among 3 implants with different surfaces: sandblasting and large-grit acid etching (SLA; IS-III Active^®), SLA with hydroxyapatite nanocoating (IS-III Bioactive^®), and SLA stored in sodium chloride solution (SLActive^®).

Methods

The mandibular second, third, and fourth premolars of 9 dogs were extracted. After 4 weeks, 9 dogs with edentulous alveolar ridges underwent surgical placement of 3 implants bilaterally and were allowed to heal for 2, 4, or 12 weeks. Histologic and histomorphometric analyses were performed on 54 stained slides based on the following parameters: vertical marginal bone loss at the buccal and lingual aspects of the implant (b-MBL and l-MBL, respectively), mineralized bone-to-implant contact (mBIC), osteoid-to-implant contact (OIC), total bone-to-implant contact (tBIC), mineralized bone area fraction occupied (mBAFO), osteoid area fraction occupied (OAFO), and total bone area fraction occupied (tBAFO) in the threads of the region of interest. Two-way analysis of variance (3 types of implant surface×3 healing time periods) and additional analyses for simple effects were performed.

Results

Statistically significant differences were observed across the implant surfaces for OIC, mBIC, tBIC, OAFO, and tBAFO. Statistically significant differences were observed over time for l-MBL, mBIC, tBIC, mBAFO, and tBAFO. In addition, an interaction effect between the implant surface and the healing time period was observed for mBIC, tBIC, and mBAFO.

Conclusions

Our results suggest that implant surface wettability facilitates bone healing dynamics, which could be attributed to the improvement of early osseointegration. In addition, osteoblasts might become more activated with the use of HA-coated surface implants than with hydrophobic surface implants in the remodeling phase.

The functional loading of implants increases their stability: A retrospective clinical study

PURPOSE

To assess the difference in the evolution of implant stability values, determined by resonance frequency analysis (RFA), between two groups of implants subjected to two different loading protocols: immediate and delayed.

MATERIALS AND METHODS

A retrospective clinical study was conducted, including a total of 93 implants placed in 38 patients. All implants corresponded to one of two models of the Klockner Implant System (Essential Cone and Vega) and were divided into two groups according to the loading protocol adopted: delayed loading in group A (>10 weeks) and immediate loading in group B (<48 hours). Implant stability was measured four times throughout the study period with a Penguin RFA device: implant placement (T0), definitive loading (T1), 6 months after loading (T2), and 12 months after loading (T3).

RESULTS

Implant stability quotient (ISQ) values showed a statistically significant increase in both groups after loading. In group A, the greatest increase in stability occurred between T1 and T2, whereas in group B, the greatest increase occurred between T0 and T1, coinciding in both cases with the period in which the implants were subjected to prosthetic loading.

CONCLUSIONS

The functional loading of implants increases their stability, as measured in ISQ values by RFA. Increases in ISQ values are greater during the months immediately following loading, which shows that immediate or early loading protocols are not only possible but can also be beneficial.

The Effect of Smoking Behavior on Alveolar Bone Marrow Mesenchymal Stem Cells of Clinical Implant Patient

Objective

The hazardous effects of smoking on the alveolar bone healing after implant surgery and nicotine on the biofunction of human alveolar bone marrow mesenchymal stem cells (hABMMSCs) were reported. There was little direct evidence regarding the specific detrimental effects of the smoking on hABMMSCs. The aim of this study was to test the influence of smoking behavior on hABMMSCs and the osseointegration situation after implant surgery.

Methods

hABMMSCs from 6 dental implant patients randomly (3 smokers and 3 nonsmokers) were compared. The cell viability, colony forming unit, and cell cycle were performed to assay proliferation capacity. The Oil Red O staining, Alizarin Red staining, alkaline phosphatase staining and activity, adipogenic and osteogenic gene expressions in vitro, and bone formation ectopically in vivo were performed under proper inductions, respectively, to assay multilineage differentiation. Besides the implant stability quotient and marginal bone loss were checked in both groups.

Results

Smoking hABMMSCs showed lower proliferation in vitro and poorer bone regeneration capacity in vivo. Moreover, smokers performed worse on bone healing after implant surgery.

Conclusions

Our results suggested smoking had the detrimental genetic effect on proliferation and osteogenesis of hABMMSCs and the decreased biofunction of hABMMSCs was positively related with bone healing.

Clinical Significance

The present study provided direct evidence about hazardous effects of smoking behavior on hABMMSCs. Smoking decreased the osteogenesis and proliferation of hABMMSCs in vivo and in vitro, and smoking was positively related with osseointegration reduction. Prevention of smoking behavior may promote biofunction of hABMMSCs and successful rate of dental implant.

Clinical Assessment of Dental Implant Stability During Follow-Up: What Is Actually Measured, and Perspectives

The optimization of loading protocols following dental implant insertion requires setting up patient-specific protocols, customized according to the actual implant osseointegration, measured through quantitative, objective methods. Various devices for the assessment of implant stability as an indirect measure of implant osseointegration have been developed. They are analyzed here, introducing the respective physical models, outlining major advantages and critical aspects, and reporting their clinical performance. A careful discussion of underlying hypotheses is finally reported, as is a suggestion for further development of instrumentation and signal analysis.

Chronological Age as Factor Influencing the Dental Implant Osseointegration in the Jaw Bone

The objectives of this study were to evaluate osseointegration of dental implant in the jaw bone in the young and elderly population and comparing the results to assess indicators and risk factors as age for the success or failure of dental implants. A retrospective study of 107 implants (Impladent, LASAK, Czech Republic) was prepared. The patients at implants surgery were divided in three groups. The patients were followed-up for a 7-year period. We evaluated osseointegration from long term point of view as a change of marginal bone levels close to dental implant. Marginal bone levels were recorded and analysed with regard to different patient- and implant-related factors. An influence of chronological age on change of marginal bone levels during 6-year retrospective study vas evaluated. The study examined 47 patient charts and 107 implants from the Second Faculty of Medicine, Charles University and University Hospital Motol. We proved that young healthy patients with long bridges or Branemarks have the same progression of marginal bone levels changes. The chronological age hasn't therefore direct influence on the osseointegration from long term point of view. But we found that the length of dental suprastrucure-prosthetic construction negatively influences marginal bone changes, though these results weren't statistically significant. More extensive dental implant suprastrucure undergoes smaller osseointegration. On the other hand the length of dental suprastrucure (prosthetic construction) negatively influences dental osseointegration in both groups of patient.

A Novel Image Probing System for Precise Quantification of Angiogenesis

The rapid development of clinical diagnostic imaging technology, in tandem with medical and angiogenesis research, has led to some major advances in healthcare. The chorioallantoic membrane assay is commonly used for studying normal angiogenesis as well as putative angiogenic and antiangiogenic substances. Despite the progress, it is generally recognized that a major problem is the lack of a suitable quantitative bioassay for angiogenesis. Image probing is a novel solution to this problem, which, together with its associated discipline of evaluating angiogenesis, is showing great potential not only for accurate measurement of even very small blood vessels but also for detailed three-dimensional quantification of blood vessels and surface characterization. This technique could be a helpful tool for quantification in angiogenesis research.

Osseointegration of titanium, titanium alloy and zirconia dental implants: current knowledge and open questions

Bone healing around dental implants follows the pattern and sequence of intramembraneous osteogenesis with formation of woven bone first of all followed later by formation of parallel-fibered and lamellar bone. Bone apposition onto the implant surface starts earlier in trabecular bone than in compact bone. While the first new bone may be found on the implant surface around 1 week after installation, bone remodeling starts at between 6 and 12 weeks and continues throughout life. Bone remodeling also involves the bone-implant interface, thus transiently exposing portions of the implant surface. Surface modifications creating micro-rough implant surfaces accelerate the osseointegration process of titanium implants, as demonstrated in numerous animal experiments. Sandblasting followed by acid-etching may currently be regarded as the gold standard technique to create micro-rough surfaces. Chemical surface modifications, resulting in higher hydrophilicity, further increase the speed of osseointegration of titanium and titanium-zirconium implants in both animals and humans. Surface modifications of zirconia and alumina-toughened zirconia implants also have an influence on the speed of osseointegration, and some implant types reach high bone-to-implant contact values in animals. Although often discussed independently of each other, surface characteristics, such as topography and chemistry, are virtually inseparable. Contemporary, well-documented implant systems with micro-rough implant surfaces, placed by properly trained and experienced clinicians, demonstrate high long-term survival rates. Nevertheless, implant failures do occur. A low percentage of implants are diagnosed with peri-implantitis after 10 years in function. In addition, a low number of implants seem to be lost for primarily reasons other than biofilm-induced infection. Patient factors, such as medications interfering with the immune system and bone cells, may be an element contributing to continuous bone loss and should therefore be monitored and studied in greater detail.

Osteocyte morphology and orientation in relation to strain in the jaw bone

Bone mass is important for dental implant success and is regulated by mechanoresponsive osteocytes. We aimed to investigate the relationship between the levels and orientation of tensile strain and morphology and orientation of osteocytes at different dental implant positions in the maxillary bone. Bone biopsies were retrieved from eight patients who underwent maxillary sinus-floor elevation with β-tricalcium phosphate prior to implant placement. Gap versus free-ending locations were compared using 1) a three-dimensional finite-element model of the maxilla to predict the tensile strain magnitude and direction and 2) histology and histomorphometric analyses. The finite-element model predicted larger, differently directed tensile strains in the gap versus free-ending locations. The mean percentage of mineralised residual native-tissue volume, osteocyte number (mean ± standard deviations: 97 ± 40/region-of-interest), and osteocyte shape (~90% elongated, ~10% round) were similar for both locations. However, the osteocyte surface area was 1.5-times larger in the gap than in the free-ending locations, and the elongated osteocytes in these locations were more cranially caudally oriented. In conclusion, significant differences in the osteocyte surface area and orientation seem to exist locally in the maxillary bone, which may be related to the tensile strain magnitude and orientation. This might reflect local differences in the osteocyte mechanosensitivity and bone quality, suggesting differences in dental implant success based on the location in the maxilla.

Collagen-Coated Poly(lactide-co-glycolide)/Hydroxyapatite Scaffold Incorporated with DGEA Peptide for Synergistic Repair of Skull Defect

The treatment of large-area bone defects remains a challenge; however, various strategies have been developed to improve the performances of scaffolds in bone tissue engineering. In this study, poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) scaffold was coated with Asp-Gly-Glu-Ala (DGEA)-incorporated collagen for the repair of rat skull defect. Our results indicated that the mechanical strength and hydrophilicity of the PLGA/HA scaffold were clearly improved and conducive to cell adhesion and proliferation. The collagen-coated scaffold with DGEA significantly promoted the repair of skull defect. These findings indicated that a combination of collagen coating and DGEA improved scaffold properties for bone regeneration, thereby providing a new potential strategy for scaffold design.

Osseointegration as Treatment for a Knee Disarticulation Because of a Congenital Femoral Deficiency: A Case Report

CASE

A 25-year-old woman underwent osseointegration surgery as treatment for an amputation that had been performed because of congenital femoral deficiency. The undersized custom-designed implant for the congenitally hypoplastic femur subsequently loosened, causing substantial pain and loss of function. The patient underwent revision surgery with a larger standard-sized osseointegration implant, and experienced no additional complications.

CONCLUSION

This case demonstrates the possibility of stimulating a hypertrophic response in underdeveloped bone, which allows the subsequent insertion of a larger implant with greater stability. Similar procedures can be considered for the treatment of patients who had amputations because of congenital deficiencies, in order to produce improved outcomes and reduce the risk of additional complications.

Oral fibroblasts modulate the macrophage response to bacterial challenge

Tissue damage in chronic periodontal disease is driven by the host response to a dysbiotic microbiota, and not by bacteria directly. Among chronic inflammatory diseases of the oral cavity, inflammation and tissue damage around dental implants (peri-implantitis) is emerging as a major clinical challenge, since it is more severe and less responsive to treatment compared to inflammation around natural teeth. We tested whether oral fibroblasts from the periodontal ligament (PDLF), which are present around natural teeth but not around dental implants, actively regulate inflammatory responses to bacterial stimulation. We show that human PDLF down-regulate TNF-α post-transcriptionally in macrophages stimulated with the oral pathogen Porphyromonas gingivalis. Cell contact and secretion of IL-6 and IL-10 contribute to the modulation of inflammatory cytokine production. Although fibroblasts decreased TNF-α secretion, they enhanced the ability of macrophages to phagocytose bacteria. Surprisingly, donor matched oral fibroblasts from gingival tissues, or fibroblasts from peri-implant inflamed tissues were at least as active as PDLF in regulating macrophage responses to bacteria. In addition, priming fibroblasts with inflammatory mediators enhanced PDLF regulatory activity. A further understanding of the spectrum of fibroblast activities in inflammatory lesions is important in order to design ways to control inflammatory tissue damage.

Preserving the Bone Profile in Anterior Maxilla using an Equine Cortical Bone Membrane and an Equine Enzyme-treated Bone Graft: A Case Report with 5-year Follow-up

AIM

This study aimed to report a well-succeeded use of equine enzyme-deantigenic cortical membrane and bone granules for guided bone regeneration (GBR) in the esthetic zone concomitant with implant placement.

BACKGROUND

In the anterior maxilla, where patients typically have the highest expectations for implant-supported restorations, bone resorption in the wake of tooth loss often leads to a lack of soft tissue support and ultimately to unsatisfactory esthetic results. Buccal bone augmentation at the time of implant placement has thus become common. This is usually accomplished following GBR principles and employing membranes made from various materials to serve as a barrier between the soft tissue and graft material. One of the more recently introduced membrane materials is made from thin, flexible equine cortical bone, i.e., rendered nonantigenic in an enzymatic process that preserves native bone collagen.

CASE REPORT

This report describes the treatment of a patient who received an equine enzyme-deantigenic graft and membrane in conjunction with placement of an implant in the right maxillary lateral incisor site.

CONCLUSION

After 5 years of follow-up, the patient was very satisfied with her appearance. A cone-beam computed tomography scan showed that the peri-implant bone levels and ridge thickness had been maintained, and the cortical layer in the pristine ridge had also undergone remodeling.

CLINICAL SIGNIFICANCE

Guided bone regeneration with the concomitant use of enzyme-deantigenic membrane and graft is a valuable and suitable option for effective implant-supported prosthetic rehabilitation in the esthetic zone.

Wound healing in immediately loaded implants

The orthopedic field has accumulated ample evidence that bone formation is related to functional loading and in general to physical activity. However, despite evidence that immediately loaded implants can be predictably successful, many clinicians still use the classical (delayed loading) treatment protocol. This paper examines the effects of loading on dental implants and discusses the advantages of immediate loading. The role of loading on augmented alveolar ridges is also addressed and provides evidence that early bone resorption may be controlled when bone is functionally loaded. Similar data are emerging for advanced augmentation techniques in order to control crestal bone loss.

Temporal sequence of hard and soft tissue healing around titanium dental implants

The objective of the present review was to summarize the evidence available on the temporal sequence of hard and soft tissue healing around titanium dental implants in animal models and in humans. A search was undertaken to find animal and human studies reporting on the temporal dynamics of hard and soft tissue integration of titanium dental implants. Moreover, the influence of implant surface roughness and chemistry on the molecular mechanisms associated with osseointegration was also investigated. The findings indicated that the integration of titanium dental implants into hard and soft tissue represents the result of a complex cascade of biological events initiated by the surgical intervention. Implant placement into alveolar bone induces a cascade of healing events starting with clot formation and continuing with the maturation of bone in contact with the implant surface. From a genetic point of view, osseointegration is associated with a decrease in inflammation and an increase in osteogenesis-, angiogenesis- and neurogenesis-associated gene expression during the early stages of wound healing. The attachment and maturation of the soft tissue complex (i.e. epithelium and connective tissue) to implants becomes established 6-8 weeks following surgery. Based on the findings of the present review it can be concluded that improved understanding of the mechanisms associated with osseointegration will provide leads and targets for strategies aimed at enhancing the clinical performance of titanium dental implants.

Are Cementoblasts a Subpopulation of Osteoblasts or a Unique Phenotype?

Experimental studies have shown a great potential for periodontal regeneration. The limitations of periodontal regeneration largely depend on the regenerative potential at the root surface. Cellular intrinsic fiber cementum (CIFC), so-called bone-like tissue, may form instead of the desired acellular extrinsic fiber cementum (AEFC), and the interfacial tissue bonding may be weak. The periodontal ligament harbors progenitor cells that can differentiate into periodontal ligament fibroblasts, osteoblasts, and cementoblasts, but their precise location is unknown. It is also not known whether osteoblasts and cementoblasts arise from a common precursor cell line, or whether distinct precursor cell lines exist. Thus, there is limited knowledge about how cell diversity evolves in the space between the developing root and the alveolar bone. This review supports the hypothesis that AEFC is a unique tissue, while CIFC and bone share some similarities. Morphologically, functionally, and biochemically, however, CIFC is distinctly different from any bone type. There are several lines of evidence to propose that cementoblasts that produce both AEFC and CIFC are unique phenotypes that are unrelated to osteoblasts. Cementum attachment protein appears to be cementum-specific, and the expression of two proteoglycans, fibromodulin and lumican, appears to be stronger in CIFC than in bone. A theory is presented that may help explain how cell diversity evolves in the periodontal ligament. It proposes that Hertwig’s epithelial root sheath and cells derived from it play an essential role in the development and maintenance of the periodontium. The role of enamel matrix proteins in cementoblast and osteoblast differentiation and their potential use for tissue engineering are discussed.

The Prosthetic Influence and Biomechanics on Peri-Implant Strain: a Systematic Literature Review of Finite Element Studies

Objectives

To systematically review risks of mechanical impact on peri-implant strain and prosthetic influence on stability across finite element studies.

Material and Methods

An online literature search was performed on MEDLINE and EMBASE databases published between 2011 and 2016. Following keywords tiered screening and selection of the title, abstract and full-text were performed. Studies of finite element analysis (FEA) were considered for inclusion that were written in English and revealed stress concentrations or strain at peri-implant bone level.

Results

There were included 20 FEA studies in total. Data were organized according to the following topics: bone layers, type of bone, osseointegration level, bone level, design of implant, diameter and length of implant, implant-abutment connection, type of supra-construction, loading axis, measurement units. The stress or strain at implant-bone contact was measured over all studies and numerical values estimated. Risks of overloading were accented as non-axial loading, misfits, cantilevers and the stability of peri-implant bone was related with the usage of platform switch connection of abutment.

Conclusions

Peri-implant area could be affected by non-axial loading, cantilever prosthetic elements, crown/implant ratio, type of implant-abutment connection, misfits, properties of restoration materials and antagonistic tooth. The heterogeneity of finite element analysis studies limits systematization of data. Results of these studies are comparable with other findings of in vitro, in vivo, prospective and retrospective studies.

Osteointegration of a modular metal-polyethylene surface gliding finger implant: a case report

INTRODUCTION

Primary press fit and secondary osteointegration is a precondition for component anchoring in articular surface replacements, also in the case of proximal interphalangeal (PIP) joint. Nevertheless, many existing prostheses for the PIP joint have failed to show sufficient osteointegration. CapFlex-PIP(©) implant is a modular metal-polyethylene surface replacement for the PIP joint consisting of a proximal and distal component each having a titanium pore backside, which allows secondary osteointegration at the bone-implant interface. To evaluate osseous integration of this implant, we report a histological analysis of an explantation of a CapFlex-PIP(©) finger implant.

CASE PRESENTATION

We present a case of a removed CapFlex-PIP(©) implant due to a soft tissue complication in an 84-year-old woman. The patient received bisphosphonate medication as treatment for osteoporosis. For the histological analysis, the bone-implant contact (BIC) was measured on all stained sections using a Zeiss Axioplan microscope. The summated BIC was 40.7 % for the proximal component and 46.5 % for the distal component of the implant. Histology showed that the implant was in direct contact with the bone at various locations, with no signs of wear or degradation.

CONCLUSIONS

This case demonstrates successful osteointegration of the CapFlex-PIP(©) implant. Both components of the investigated implant show osseous integration to an extent which is comparable to that of other load-bearing and articulating implants at different locations in the human body.

In Vitro Bioactivity Study of RGD-Coated Titanium Alloy Prothesis for Revision Total Hip Arthroplasty

Total hip arthroplasty (THA) is a common procedure for the treatment of end-stage hip joint disease, and the demand for revision THA will double by 2026. Ti6Al4V (Titanium, 6% Aluminum, and 4% Vanadium) is a kind of alloy commonly used to make hip prothesis. To promote the osseointegration between the prothesis and host bone is very important for the revision THA. The peptide Arg-Gly-Asp (RGD) could increase cell attachment and has been used in the vascular tissue engineering. In this study, we combined the RGD with Ti6Al4V alloy using the covalent cross-linking method to fabricate the functional Ti6Al4V alloy (FTA). The distribution of RGD oligopeptide on the FTA was even and homogeneous. The FTA scaffolds could promote mouse osteoblasts adhesion and spreading. Furthermore, the result of RT-qPCR indicated that the FTA scaffolds were more beneficial to osteogenesis, which may be due to the improvement of osteoblast adhesion by the RGD oligopeptide coated on FTA. Overall, the FTA scaffolds developed herein pave the road for designing and building more efficient prothesis for osseointegration between the host bone and prothesis in revision THA.

Impact of Dental Implant Surface Modifications on Osseointegration

Objective. The aim of this paper is to review different surface modifications of dental implants and their effect on osseointegration. Common marketed as well as experimental surface modifications are discussed. Discussion. The major challenge for contemporary dental implantologists is to provide oral rehabilitation to patients with healthy bone conditions asking for rapid loading protocols or to patients with quantitatively or qualitatively compromised bone. These charging conditions require advances in implant surface design. The elucidation of bone healing physiology has driven investigators to engineer implant surfaces that closely mimic natural bone characteristics. This paper provides a comprehensive overview of surface modifications that beneficially alter the topography, hydrophilicity, and outer coating of dental implants in order to enhance osseointegration in healthy as well as in compromised bone. In the first part, this paper discusses dental implants that have been successfully used for a number of years focusing on sandblasting, acid-etching, and hydrophilic surface textures. Hereafter, new techniques like Discrete Crystalline Deposition, laser ablation, and surface coatings with proteins, drugs, or growth factors are presented. Conclusion. Major advancements have been made in developing novel surfaces of dental implants. These innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions.