A comparison of endosseous dental implant surfaces

Clinical Performance of 170 Frictional Morse Taper Implants: 2 Years Follow-Up

This study evaluated the clinical survival rates of 170 Morse taper implants through clinical and mechanical parameters in different therapeutic approaches such as single crowns, fixed partial prostheses, and fixed full-arch prostheses. Patients referred to the Center on Education and Research on Dental Implants from May 2017 to July 2018 with the indication for dental implant therapy, aged >18 years, without periodontal disease, recent evidence of inflammatory activity or other oral disorders, current pregnancy, uncontrolled diabetes mellitus or heavy smoking habit were included in this study. After 12 weeks of healing since the implants were placed in the mandible and after 16 weeks following implants placed in the maxilla, patients returned to the Center for prosthetic rehabilitation. After implant therapy, all patients underwent periodical, clinical, and prosthetic examinations every 6 months. Prosthetic restorations involved 109 fixed reconstructions in function. Few prosthetic complications were reported (6.55%). Twenty implants were rehabilitated with cemented prostheses; from those, 1 crown suffered a loss in retention/decementation. Of the 148 implants rehabilitated with screwed-retained prostheses, 6.76% suffered prosthetic screw loosening. The cumulative implant survival rate was 98.2%. When peri-implant tissue health was evaluated, the keratinized mucosa band appeared related to peri-implant tissue stability. Thus, Morse taper implants represented a successful procedure for implant rehabilitation, with a high cumulative implant survival rate, low prevalence of biological and prosthetic complications, and good stability of peri-implant tissues over the assessed period.

Comparative study of hydroxyapatite synthesized using Schiff base and wet chemical precipitation methods

Hydroxyapatite (HAp) exists as an inorganic and crystalline composition present in bones and dental enamel, and hence can be utilized as a direct element or as part of the composition of biomaterials and implants for dental and orthopaedic applications. Listed below are a few synthesis techniques for HAp that are listed in the literature: solid-state and mechano-chemical methods (dry methods), wet chemical precipitation and sol-gel methods (wet methods), and combustion and pyrolysis methods (high-temperature processes). Nevertheless, there are new and more productive techniques that result in HAp with a regulated morphology, such as the Schiff base method, which, on reaction with calcium and phosphate precursors, forms chelating complexes to produce HAp nuclei. This research paper presents the comparison in characteristics between HAp synthesized using Schiff base (HAp-SB), wet chemical precipitation (HAp-WC) methods, and commercial HAp (HAp-CM) in their powdered and pelleted form. The average size of HAp-WC particles in the spherical form was found to be 603 nm ± 176, HAp-SB were found to have rod-like morphology, which is very similar to human bone-like HAp, with an average length and width of 1522 nm ± 759 and 400 nm ± 112, respectively, and HAp-CM were found to have spherical morphology with dimensions of 52 nm ± 25. Biological studies show that cell viability of HAp-SB pellet (202.01% ± 8.16) seemed to have higher cell proliferation properties than HAp-WC pellet (145.7% ± 5.11) and HAp-CM pellet (71.53% ± 3.61) due to its higher aspect ratio, and hence higher surface area for the cells to adhere. In a detailed study, it is observed that both techniques had their advantages, and there were no significant disadvantages observed.

Surface modification of titanium implants with Mg-containing coatings to promote osseointegration

Titanium (Ti) and Ti alloys are commonly used in dental implants, which have good biocompatibility, mechanical strength, processability, and corrosion resistance. However, the surface inertia of Ti implants leads to delayed integration of Ti and new bone, as well as problems such as aseptic loosening and inadequate osseointegration. Magnesium (Mg) ions can promote bone regeneration, and many studies have used Mg-containing materials to modify the Ti implant surface. This systematic review summarizes the methods, effects, and clinical applications of surface modification of Ti implants with Mg-containing coatings. Database collection was completed on Janury 1, 2023, and a total of 29 relevant studies were ultimately included. Mg can be compounded with different materials and coated to the surface of Ti implants using different methods. In vitro and in vivo experiments have shown that Mg-containing coatings promote cell adhesion and osteogenic differentiation. On the one hand, the surface roughness of implants increases with the addition of Mg-containing coatings, which is thought to have an impact on the osseointegration of the implant. On the other hand, Mg ions promote cell attachment through binding interactions between the integrin family and FAK-related signaling pathways. And Mg ions could induce osseointegration by activating PI3K, Notch, ERK/c-Fos, BMP-4-related signaling pathways and TRPM7 protein channels. Overall, Mg-based coatings show great potential for the surface modification of Ti implants to promote osseointegration. STATEMENT OF SIGNIFICANCE: The inertia surface of titanium (Ti) implants leads to delayed osseointegration. Magnesium (Mg) ions, known for promoting bone regeneration, have been extensively studied to modify the surface of Ti implants. However, no consensus has been reached on the appropriate processing methods, surface roughness and effective concentration of Mg-containing coatings for osseointegration. This systematic review focus on the surface modification of Ti implants with Mg-containing compounds, highlighting the effects of Mg-containing coatings on the surface properties of Ti implants and its associated mechanisms. Besides, we also provide an outlook on future directions to promote the clinical application of Mg-modified implants.

Clinical outcome of narrow diameter dental implants: a 3-year retrospective study

BACKGROUND

This study aimed to analyze the clinical outcome and complications of narrow-diameter dental implants (NDIs) (diameter ≤3.5 mm).

METHODS

The 274 NDIs that met the selection criteria from 2013 to 2018 were included in the retrospective study, and the survival rates (SVR) were compared. Mechanical complications included screw loosening and fractures of the implant components, such as the implant fixture, abutment, and prosthesis. In addition, marginal bone loss (MBL) was measured immediately after surgery and 1 year after loading.

RESULTS

The 3-year cumulative SVR was 92.4%. Nineteen fixtures failed during the follow-up. The failure rate was significantly higher (OR=4.573, p<0.05) in smokers and was significantly higher in osteoporosis patients (OR=3.420, p<0.05). The vertical and horizontal values of MBL were 0.33±0.32 mm and 0.18±0.17 mm, respectively. Mechanical complications included screw loosening (5.5%) and porcelain fracture (2.2%), but no fractures of the fixture or components were observed. The choice of titanium and zirconium (TiZr) alloy implant was significantly more frequent in the posterior region. Bone graft was significantly more frequently done in the anterior region.

CONCLUSIONS

According to the high SVR and stability of NDIs, the findings of the study suggest that NDIs may be a replacement for regular diameter dental implants (RDIs) and the use of TiZr alloy could extend the indication of NDIs. In the esthetic area, contour augmentation may be a reason for increasing the frequency of bone grafts.

In vitro and in vivo evaluation of surface functionalization of titanium with H2 O2 hydrothermal treatment and FGF-2

The goals of the study were to investigate the effects on bone bioactivity of a titanium dioxide layer formed by hydrothermal oxidation of a titanium surface with hydrogen peroxide (H₂ O₂ ) and loading with fibroblast growth factor-2 (FGF-2) in vitro and in vivo. Ti-6Al-4V discs were hydrothermally oxidized with H₂ O₂ and then loaded with FGF-2. After cytotoxicity testing, Ti-6Al-4V mini-implants were subjected to the same treatment, and their osteogenic potential was evaluated histologically in a rat model. H₂ O₂ hydrothermal oxidation resulted in a dense porous network structure and hydrophilic changes, which improved retention of FGF-2. Morphologically, the cell density was higher, cell elongation was more pronounced, and the cell adhesion area was significantly higher in FGF-2-loaded cells than in those without FGF-2. In a cell proliferation assay using mouse osteoblast-like cells, absorbance tended to increase over time, especially in the FGF-2 group after 7 and 14 days, and in a bone differentiation assay based on ALP activity, there was a significant increase in the FGF-2 group after 14 days. In the rat model, H₂ O₂ hydrothermal oxidation and FGF-2 loading both resulted in more laminar bone tissue in the bone marrow around the mini-implant. These results suggest that titanium surface functionalization by H₂ O₂ hydrothermal oxidation and FGF-2 may promote initial cell adhesion, proliferation, and osteodifferentiation, and enhance bone bioactivity. These effects all contribute to early bonding of an implant with the surrounding bone.

Histomorphometric and biomechanical evaluation of the osseointegration around micro- and nano-level boron-nitride coated titanium dental implants

INTRODUCTION

Titanium dental implants has been coated with different materials such as polymers and biomimetic agents, bone morphogenetic protein, calcium phosphate to enhance surface properties of the titanium implants for osseointegration. The aim of this study was to evaluate the bone tissue healing around Boron Nitride-coated (BN-coated) titanium implants histomorphometrically and biomechanically and also observe the effect of different coating thicknesses on osseointegration.

MATERIALS AND METHODS

BN was coated on dental titanium implants with two different coating thicknesses by using RF magnetron sputtering system. Totally fifty-four implants were inserted into the tibias' of 12 New Zealand rabbits bilaterally under general anesthesia. All animals were sacrificed after 4-weeks. Bone-implant contact (BIC) and new bone area/total area ratios (BATA) were calculated. Also, the removal torque (RT) test was performed.

RESULTS

The highest new bone area in the medullary cavity was around the nano-BN-coated surface with 15.70%. In micro-BN-coated surface and control group, this ratio was determined as 10.48% and 8.23%, respectively. The BIC ratios in upper-side of implants and cortical-associated BIC ratios in lower-side were found significantly higher in control and micro-BN-coated group than nano-BN-coated group (p < 0.05). Similar BIC values were observed between control and micro-BN-coated groups (p > 0.05). BATA values did not show statistically significant differences between all three groups (p > 0.05). The RT values measured in all groups were found comparable and no statistically significant differences were found (p > 0.05).

CONCLUSION

No inflammatory reaction developed around any implant. Relatively more new bone formation around nano-BN-coated titanium implants indicates the promising osseoinductive effect of BN coating. BN-coated implants showed similar biomechanical and histomorphometrical outcomes to that of the conventional titanium implants through a 4-week evaluation period.

Effects of Different Titanium Surface Treatments on Adhesion, Proliferation and Differentiation of Bone Cells: An In Vitro Study

The objective of this study was to evaluate the impacts of different sandblasting procedures in acid etching of Ti6Al4V surfaces on osteoblast cell behavior, regarding various physicochemical and topographical parameters. Furthermore, differences in osteoblast cell behavior between cpTi and Ti6Al4V SA surfaces were evaluated. Sandblasting and subsequent acid etching of cpTi and Ti6Al4V discs was performed with Al2O3 grains of different sizes and with varying blasting pressures. The micro- and nano-roughness of the experimental SA surfaces were analyzed via confocal, atomic force and scanning electron microscopy. Surface free energy and friction coefficients were determined. hFOB 1.19 cells were seeded to evaluate adhesion, proliferation and osteoblastic differentiation for up to 12 d via crystal violet assays, MTT assays, ALP activity assays and Alizarin Red staining assays. Differences in blasting procedures had significant impacts on surface macro- and micro-topography. The crystal violet assay revealed a significant inverse relationship between blasting grain size and hFOB cell growth after 7 days. This trend was also visible in the Alizarin Red assays staining after 12 d: there was significantly higher biomineralization visible in the group that was sandblasted with smaller grains (F180) when compared to standard-grain-size groups (F70). SA samples treated with reduced blasting pressure exhibited lower hFOB adhesion and growth capabilities at initial (2 h) and later time points for up to 7 days, when compared to the standard SA surface, even though micro-roughness and other relevant surface parameters were similar. Overall, etched-only surfaces consistently exhibited equivalent or higher adhesion, proliferation and differentiation capabilities when compared to all other sandblasted and etched surfaces. No differences were found between cpTi and Ti6Al4V SA surfaces. Subtle modifications in the blasting protocol for Ti6Al4V SA surfaces significantly affect the proliferative and differentiation behavior of human osteoblasts. Surface roughness parameters are not sufficient to predict osteoblast behavior on etched Ti6Al4V surfaces.

In-Vitro Phenotypic Response of Human Osteoblasts to Different Degrees of Titanium Surface Roughness

Objectives: This study aimed to investigate human osteoblast (HOB) responses towards different degrees of titanium (Ti) implant surface roughness. Methods: Four degrees of Ti surface roughness were investigated on a micrometer roughness scale: smooth (S: 0.08−0.1 µm), minimally rough (MM: 0.3−0.5 µm), moderately rough (MR: 1.2−1.4 µm), and rough (R: 3.3−3.7 µm). HOB cells were cultured, expanded, and maintained according to the supplier’s protocol. Cell proliferation and cytotoxicity were assessed at day 1, 3, 5, and 10 using alamarBlue and lactate dehydrogenase colorimetric assays. Data were analyzed with one-way ANOVA, two-way ANOVA, and Tukey’s post hoc test (p = 0.05 for all tests). Results: There was no significant difference in the cell proliferation or cytotoxicity of the HOB cells in contact with the different degrees of Ti surface roughness. There was, however, a significant time effect on cell proliferation (p < 0.0001) with different exposure durations for each roughness degree. Furthermore, a positive correlation (non-significant) between proliferation and cytotoxicity was observed for all investigated degrees of surface roughness. Conclusion: All investigated roughness degrees showed comparable HOB proliferation, with the MR surface presenting the highest percentage, followed by the R, MM, ad S, surfaces, respectively. The S surface showed the highest cytotoxic effect on HOBs; however, it did not reach the cytotoxic level suggested by the ISO for any medical device to be considered cytotoxic.

Twelve Month Evaluation of a Novel Mineral Organic Adhesive Material Used to Stabilize Dental Implants Placed in Oversized Osteotomies in Vivo in an Animal Model

OBJECTIVES

To evaluate long-term in vivo stability of dental implants stabilized at time of placement in oversized osteotomies with a novel, self-setting, mineral-organic bone adhesive.

MATERIALS/METHODS

Canine (26) mandibular teeth were removed, and 3 oversized osteotomies prepared bilaterally. Implants were placed with either adhesive, particulate xenograft or with blood clot filling the implant/osteotomy gaps. Removal torque and histology were assessed.

RESULTS

The adhesive provided significant and clinically relevant immediate implant stability of 22.2N-cm (95%CI 5.3; 39.0) which continued throughout the early postoperative course and persisted through the nine- (155N-cm 95%CI 113; 197) and twelve-month (171N-cm 95%CI 134.2; 209.4) time points. This is in comparison to the blood clot of 1.4N-cm (95%CI 0.7; 2.1), 128.6N-cm (95%CI 66.8; 190.4), and 140.7N-cm (95%CI 78.8; 202.5) and particulate xenograft, 1.3N-cm (95%CI 0.6; 2.0), 132.1N-cm (95%CI 94.5; 169.7), and 101.5 (95%CI 59.5; 143.5) respectively. Histological examination shows the adhesive establishes intimate contact with the implant and bony walls and is replaced with new bone without compromising stability. Soft tissue does not penetrate the adhesive and marginal bone/biomaterial level is maintained. Control sites filled with xenograft or blood clot heal with reduced bone levels and, in some cases, xenograft particles were encapsulated in connective tissue.

CONCLUSIONS

Implants placed in oversized osteotomies and lacking primary stability can be stabilized at placement with a novel, highly osteoconductive and resorbable adhesive. Gradual replacement of the biomaterial allows osseointegration without loss of stability through 12 months of follow-up. This novel adhesive has the potential to stabilize implants placed in sites with inadequate bony support.

Clinical Considerations in Orthodontically Forced Eruption for Restorative Purposes

For restorations on teeth involving invasion of the supracrestal tissue attachment (biological width), as well as for lack of ferrule effect, crown lengthening is required for long-term periodontal health and success of the restoration. In the same fashion, site development is often necessary prior to implant placement in order to provide optimal peri-implant soft and hard tissue architecture conducive to future esthetics and function. Orthodontic extrusion, also known as forced eruption, has been developed and employed clinically to serve the purposes of increasing the clinical crown length, correcting the periodontal defect, and developing the implant site. In order to provide comprehensive guidance on the clinical usage of this technique and maximize the outcome for patients who receive the dental restoration, the currently available literatures were summarized and discussed in the current review. Compared to traditional crown lengthening surgery, forced eruption holds advantages of preserving supporting bone, providing improved esthetics, limiting the involvement of adjacent teeth, and decreasing the negative impact on crown-to-root ratio compared to the traditional resective approach. As a non-invasive and natural technique capable of increasing the available volume of bone and soft tissue, forced eruption is also an attractive and promising option for implant site development. Both fixed and removable appliances can be used to achieve the desired extrusion, but patient compliance is a primary limiting factor for the utilization of removable appliances. In summary, forced eruption is a valuable treatment adjunct for patients requiring crown lengthening or implant restorations. Nonetheless, comprehensive evaluation and treatment planning are required for appropriate case selection based upon the known indications and contraindications for each purpose; major contraindications include inflammation, ankylosis, hypercementosis, vertical root fracture, and root proximity. Further studies are necessary to elucidate the long-term stability of orthodontically extruded teeth and the supporting bone and soft tissue that followed them.

One-year outcomes of dental implants with a hybrid surface macro-design placed in patients with history of periodontitis: A randomized clinical trial

AIM

To evaluate the radiological, clinical, and microbiological outcomes of implants with a hybrid surface macro-design in patients with a history of periodontitis.

MATERIAL AND METHODS

The study was designed as a 12-month, parallel-arm, randomized controlled trial where patients with a history of treated periodontitis in need of dental implants for single-unit or short-span prosthesis were randomly allocated to a test [implants with a machined titanium surface in the coronal collar (hybrid; HS)] or a control group [conventional implants with moderately rough surface up to the implant shoulder (RS)]. Patients were followed at 3, 6, and 12 months after loading with assessment of radiological, clinical, and microbiological outcomes, as well as patient-related outcome measures (PROMs).

RESULTS

Forty patients were randomly assigned to either the RS group (n = 20) or the HS (n = 20) group. At 1 year, the mean marginal bone level changes were 0.22 [standard deviation (SD) 0.36] mm for the HS group and 0.22 (SD 0.29) mm for the RS group, with no significant differences between them (p = .961). Similarly, no significant differences in clinical, microbiological, or PROMs were observed between groups.

CONCLUSIONS

HS implants demonstrated radiographic, clinical, and microbiological characteristics equal to RS implants in patients with a history of periodontitis.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (identifier NCT05010382).

De novo bone formation around implants with a surface based on a monolayer of multi-phosphonate molecules. An experimental in vivo investigation

OBJECTIVES

The purpose of this experimental in vivo investigation was to evaluate the influence of modifying the implant surface by adding a monolayer of multi-phosphonate molecules on the de novo bone formation and osseointegration.

MATERIAL AND METHODS

The study was designed as an animal preclinical trial with intra-animal control and two healing periods, 2 and 8 weeks, to compare implants with an identical macro-design but with two different surfaces. Eight female Beagle dogs participated in the study. Control implants had a moderately rough surface combining sandblasting and acid etching; test implants had an additional monophosphonate layer covalently bonded to titanium. Histologic and radiographic (micro-CT) outcome variables were evaluated.

RESULTS

The first bone-to-implant contact (fBIC) was located more coronally for the test implants at the first (0.065 mm (95% CI = -0.82, 0.60)) and second healing milestones (0.17 mm (95% CI = -0.9, 0.55)). Most coronal BIC of the test implants displayed a higher percentage of osseointegration, +6.33% and +13.38% after 2 and 8 weeks, respectively; however, the differences were not statistically significant. The micro-CT examination did not show any BIC difference.

CONCLUSIONS

The monophosphonate layer coating demonstrated clinical, histological, and radiographic results similar to the control surface.

The Oxidative Response of Human Monocytes to Surface Modified Commercially Pure Titanium

Cellular responses to implanted biomaterials are key to understanding osseointegration. The aim of this investigation was to determine the in vitro priming and activation of the respiratory burst activity of monocytes in response to surface-modified titanium. Human peripheral blood monocytes of healthy blood donors were separated, then incubated with surface-modified grade 2 commercially pure titanium (CPT) disks with a range of known surface energies and surface roughness for 30- or 60-min. Secondary stimulation by phorbol 12-myrisate 13-acetate (PMA) following the priming phase, and luminol-enhanced-chemiluminescence (LCL) was used to monitor oxygen-dependent activity. Comparison among groups was made by incubation time using one-way ANOVA. One sample from each group for each phase of the experiment was viewed under scanning electron microscopy (SEM) and qualitative comparisons made. The results indicate that titanium is capable of priming peripheral blood monocytes following 60-min incubation. In contrast, 30 min incubation time lead to reduced LCL on secondary stimulation as compared to cells alone. At both time intervals, the disk with the lowest surface energy produced significantly less LCL compared to other samples. SEM examination revealed differences in surface morphology at different time points but not between differently surface-modified disks. These results are consistent with the hypothesis that the titanium surface characteristics influenced the monocyte activity, which may be important in regulating the healing response to these materials.

Effect of previous implant failure on the prognosis of subsequent implants: A retrospective study

OBJECTIVES

To compare the long-term survival of dental implants placed in patients with and without a history of implant failure.

MATERIAL AND METHODS

Within a retrospective analysis, an experimental group was selected consisting of 59 patients with 137 implants placed after previous failure. The control group included 1,072 patients with 2,664 implants without previous failure. Kaplan-Meier curves were used to describe the group-specific long-term implant survival. Mixed-effects Cox regression models were applied to examine the effects of patient- and site-specific risk factors. To take multiple implants into account, a random intercept model was applied.

RESULTS

During the observation period of up to 15 years, 11 implants (8%) failed in the experimental group and 74 implants (2.5%) in the control group (p < .001). Five-year cumulative survival was 96.8% (95% CI 0.96-0.98) in the control group and 91.5% (95% CI 0.86-0.97) in the experimental group. The variables group assignment and simultaneous augmentation had a significant effect on survival, but this effect was lost in the random intercept model. The effect of implant location remained, whereby the risk of failure was five times lower for mandible implants, irrespective of group (p = .013; 95% CI 0.103-0.767; HR: 0.281).

CONCLUSIONS

Long-term implant survival was lower in the experimental group than in the control group. The effect of previous failure was negligible. However, a patient-specific "clustering effect" was observed. Irrespective of previous implant failure, the risk of long-term failure is two times higher for maxillary implants than for mandibular implants.

Microscopic Characterization of Bioactivate Implant Surfaces: Increasing Wettability Using Salts and Dry Technology

The surface topography of dental implants plays an important role in cell-surface interaction promoting cell adhesion, proliferation and differentiation influencing osseointegration. A hydrophilic implant leads to the absorption of water molecules and subsequently promotes the adhesion of cells to the implant binding protein. Dried salts on the implant surfaces allow one to store the implant surfaces in a dry environment while preserving their hydrophilic characteristics. This process has been identified as “dry technology”. The aim of the present study is to describe from a micrometric and nanometric point of view the characteristics of this new bioactivated surface obtained using salts dried on the surface. Topographic analysis, energy-dispersive X-ray spectroscopy, and contact angle characterization were performed on the samples of a sandblasted and dual acid-etched surface (ABT), a nanosurface (Nano) deriving from the former but with the adding of salts air dried and a nanosurface with salts dissolved with distilled water (Nano H₂O). The analysis revealed promising results for nanostructured surfaces with increased wettability and a more articulated surface nanotopography than the traditional ABT surface. In conclusion, this study validates a new promising ultra-hydrophilic nano surface obtained by sandblasting, double acid etching and surface salt deposition using dry technology.

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.

Implant Material Sciences

In the past, the only way to replace missing teeth was to have a removable appliance. However, these days, dental implants are commonly being used to replace missing teeth. The dental implants are improving as a result of new technological and scientific advances. Different materials have been used in the past for dental implants such as lead, stainless steel, and gold. Currently, the focus is on using Roxolid, surface-modified titanium implants, and zirconia. These materials have superior esthetic and functional characteristics for dental implants.

Evaluation of cervical peri-implant optical density in longitudinal control of immediate implants in the anterior maxilla region

OBJECTIVE

This research aimed to longitudinally evaluate the optical density of peri-implant alveolar bone. The data acquired from study participants previously treated with 37 osseointegrated implants were analyzed utilizing the radiographic subtraction technique.

METHODS AND MATERIALS

The radiographic follow-ups were performed five times: at the implantation of the prostheses and after 15, 90, 180 and 360 days. Intraoral radiographs were obtained by the paralleling technique using individualized Hanshin-type positioners to guarantee the standardization of the images. The obtained digital images were aligned and equalized before they were submitted to the radiographic subtraction procedure.

RESULTS

A significant difference was found between the distal region of Group I (patients treated with osseointegrated implants who required extraction of the dental element) and the 360 day follow-up and the distal region of Group II (patients with healed alveolar sockets) in all follow-up analyses (p < 0.05). We did not observe a significant difference between the groups analyzed and other follow-ups concerning the subcrestal and middle third regions for both the mesial and distal variables (p > 0.05). There was a statistically significant difference in the distal sites [χ2 = 5,745,, p = 0.03], showing a significant association between time and the presence of bone resorption. This association was not shown on the mesial surface (p = 0.16).

CONCLUSION

We concluded that there was no statistically significant difference between groups I and II. Using this technique, we were able to quantitatively and qualitatively evaluate the changes in the proximal sites on the digital radiographic images for the analyzed data. Digital subtraction technology to measure peri-implant bone density is an accurate and reproducible technique for quantifying peri-implant bone reactions to different therapeutic modalities.

Investigating the Response of Human Neutrophils to Hydrophilic and Hydrophobic Micro-Rough Titanium Surfaces

Various treatments have been used to change both the topography and chemistry of titanium surfaces, aiming to enhance tissue response and reduce healing times of endosseous implants. Most studies to date focused on bone healing around dental implants occurring later during the healing cascade. However, the impact of the initial inflammatory response in the surgical wound site on the success and healing time of dental implants is crucial for implant integration and success, yet it is still poorly understood. The purpose of this study was to investigate the effect of titanium surface hydrophilicity on the response of human neutrophils by monitoring oxygen radical production, which was measured as chemiluminescence activity. Materials and Methods: Neutrophils were isolated from human donors’ blood buffy coats using the double sucrose gradient method. Neutrophils were exposed to both hydrophilic and hydrophobic titanium surfaces with identical topographies in the presence and absence of human serum. This resulted in six experimental groups including two different implant surfaces, with and without exposure to human serum, and two control groups including an active control with cells alone and a passive control with no cells. Two samples from each group were fixed and analyzed by SEM. Comparisons between surface treatments for differences in chemiluminescence values were performed using analysis of variance ANOVA. Results and Conclusion: In the absence of exposure to serum, there was no significant difference noted between the reaction of neutrophils to hydrophilic and hydrophobic surfaces. However, there was a significant reduction in the mean and active chemiluminescence activity of neutrophils to serum-coated hydrophilic titanium surfaces than to serum-coated hydrophobic titanium surfaces. This suggests that surface hydrophilicity promotes enhanced adsorption of serum proteins, which leads to decreased provocation of initial immune cells and reduction of local oxygen radical production during wound healing. This can help explain the faster osseointegration demonstrated by hydrophilic titanium implants.

Implant Soft-Tissue Attachment Using 3D Oral Mucosal Models-A Pilot Study

PURPOSE

The aim of this study was to investigate soft-tissue attachment to different metal, ceramic, and polymer implant surfaces using an inflamed, three-dimensional (3D), tissue-engineered, human oral mucosal model, as well as multiple-endpoint qualitative and quantitative biological approaches.

METHODS

Normal human oral fibroblasts, OKF6/TERT-2 keratinocytes and THP-1 monocytes were cultured, and full-thickness, 3D oral mucosal models were engineered inside tissue culture inserts. Sand-blasted and acid-etched (SLA) and machined (M) titanium-zirconium alloy (TiZr; commercially known as Roxolid; Institut Straumann AG, Switzerland), ceramic (ZrO2), and polyether ether ketone (PEEK) rods (Ø 4 mm × 8 mm) were inserted into the center of tissue-engineered oral mucosa following a Ø 4mm punch biopsy. Inflammation was simulated with addition of the lipopolysaccharide (LPS) of Escherichia coli (E. coli) and tumor necrosis factor (TNF)-alpha to the culture medium. Implant soft-tissue attachment was assessed using histology, an implant pull-test with PrestoBlue assay, and scanning electron microscopy (SEM).

RESULTS

Inflamed, full-thickness, 3D human oral mucosal models with inserted implants were successfully engineered and histologically characterized. The implant pull-test with PrestoBlue assay showed higher viability of the tissue that remained attached to the TiZr-SLA surface compared to the other test groups. This difference was statistically significant (p < 0.05). SEM analysis showed evidence of epithelial cell attachment on different implant surfaces.

CONCLUSIONS

The inflamed, 3D, oral mucosal model has the potential to be used as a suitable in vitro test system for visualization and quantification of implant soft-tissue attachment. The results of our study indicate greater soft tissue attachment to TiZr-SLA compared to TiZr-M, ceramic, and PEEK surfaces.

Regulation of mesenchymal stem cell differentiation on microstructured titanium surfaces by semaphorin 3A

Peri-implant bone formation depends on the ability of mesenchymal stem cells (MSCs) to colonize implant surfaces and differentiate into osteoblasts, but the precise mechanisms controlling this process remain unclear. In vitro, MSCs undergo osteoblastic differentiation on microstructured titanium (Ti) surfaces in the absence of exogenous media supplements and produce factors that promote osteogenesis while regulating osteoclast activity, including semaphorins. The goal of this study was to evaluate the role of semaphorin 3A (Sema3A) on surface-mediated osteoblastic differentiation and determine the hierarchy of this signaling cascade. Human MSCs were cultured on 15 mm grade 2 smooth (pretreatment, PT), hydrophobic-microrough (sand blasted/acid etched, SLA), hydrophilic-microrough Ti (mSLA) (Institut Straumann AG, Basel, Switzerland), or tissue culture polystyrene (TCPS). Expression of SEMA3A family proteins increased after 7 days of culture, and the increased expression in response to microstructured Ti was dependent on recognition of the surface by integrin α2β1. Exogenous Sema3A increased differentiation whereas differentiation was decreased in cells treated with a Sema3A antibody. Furthermore, Sema3A influenced the production of osteoprotegerin and osteopontin suggesting it as an important local regulator of bone remodeling. Inhibition of Wnt3A and Wnt5A revealed that activation of Sema3A occurs downstream of Wnt5A and may facilitate the translocation of β-catenin bypassing the canonical Wnt3A initiating signal associated with osteoblastic differentiation. Furthermore, chemical inhibition of calmodulin (CaM), Ca²⁺/calmodulin-dependent protein kinase (CaMKII), phospholipase A₂ (PLA2), protein kinase C (PKC), and BMP receptors suggest that Sema3A could serve as a feedback mechanism for both Wnt5A and BMP2. Here, we show novel roles for Sema3A family proteins in the surface-dependent modulation of MSCs as well as important interactions with pathways known to be associated with osteoblastic differentiation. Moreover, their effects on bone remodeling markers have significant implications for peri-implant bone remodeling and downstream modulation of osteoclastic activity. These results suggest that Sema3A aids in peri-implant bone formation through regulation on multiple stages of osseointegration, making it a potential target to promote osseointegration in patients with compromised bone remodeling.

Descriptive retrospective study analyzing relevant factors related to dental implant failure

Background

The objective of this retrospective descriptive study was to analyze the characteristics of incident reports provided by dentists while using a specific brand of dental implants.

Material and Methods

The study was carried out in collaboration with Oxtein Iberia S.L.®, with the company providing access to the incident database in order to evaluate the characteristics of incidents from January 2014 to December 2017 (a total of 917 over four years). The data sheet recorded different variables during each of the stages of implant treatment, from initial implant placement to subsequent prosthetic rehabilitation. These variables included age, sex, systemic pathologies, smoking habits, bone quality, implant type, prosthesis type, and type of load applied, among others. SPSS Statistics was used to perform statistical analysis of the qualitative variables (univariate logistic regressions, χ2 test, Haberman's adjusted standardized residuals).

Results

The total study sample consisted of 44,415 implants shipped from Oxtein® warehouses on the dates indicated, of which 917 implants (2.1%) were flagged due to reports of lack of primary stability, failed osseointegration, or implant failure within one year of placement. When analyzing incident reports, it was observed that 61.6% of incidents occurred in male patients, compared to 38.4% in female patients. The average age of patients in the reported cases was 56.12 ± 12.15 years. A statistically significant correlation was discovered between incidents of implant failure and tobacco use, diabetes, heart disease, poor oral hygiene, previous infection, poor bone quality, and bruxism (p < 0.05). A (statistically significant) higher rate of incidents was also observed in tapered, internal connection, Grade IV titanium, narrow, and short implants.

Conclusions

Analysis of these implants reveals a higher rate of complication in short, tapered, internal connection and narrow-diameter implants. These data can help and encourage clinicians to use the utmost surgical precautions when placing these implants.

Key words:Pharmacovigilance, Dental implant, Dental implant failure.

Predominant surface property of an anodized titanium that enhances the cell response

The aim of this study is to evaluate the predominant material property that enhances the biocompatibility of an anodized titanium (Ti) implant. A Ti surface was anodized in an H₃PO₄ electrolyte with various voltages. Then, the cell responses involving attachment, proliferation, and differentiation were evaluated. Anodization using various voltages formed TiO₂ layers with various surface morphologies. All the anodized surfaces showed enhanced cell responses; however, the performance differences depending on the surface morphologies were minimal. In addition, enhanced cell responses were not observed on the thermally oxidized Ti surface, although a TiO₂ layer was formed; therefore, the beneficial effect was derived from the TiO₂ layer fabricated via anodization. Based on these findings, the topmost surface structure of the TiO₂ layer predominantly influenced the cell behaviors because this property governed the important surface functions, such as hydrophilicity.

Improvement of Quality of Life with Implant-Supported Mandibular Overdentures and the Effect of Implant Type and Surgical Procedure on Bone and Soft Tissue Stability: A Three-Year Prospective Split-Mouth Trial

In fully edentulous patients, the support of a lower dental prosthesis by two implants could improve the chewing ability, retention, and stability of the prosthesis. Despite high success rates of dental implants, complications, such as peri-implantitis, do occur. The latter is a consequence of crestal bone loss and might be related to the implant surface and peri-implant soft tissue thickness. The aim of this paper is to describe the effect of implant surface roughness and soft tissue thickness on crestal bone remodeling, peri-implant health, and patient-centered outcomes. The mandibular overdenture supported by two implants is used as a split-mouth model to scrutinize these aims. The first study compared implants placed equicrestal to implants placed biologically (i.e., dependent on site-specific soft tissue thickness). The second clinical trial compared implants with a minimally to a moderately rough implant neck. Both studies reported an improvement in oral health-related quality of life and a stable peri-implant health after three years follow-up. Only equicrestal implant placement yielded significantly higher implant surface exposure, due to the establishment of the biologic width. Within the limitations of this study, it can be concluded that an implant supported mandibular overdenture significantly improves the quality of life, with limited biologic complications and high survival rates of the implants.

Survival of dental implants at sites after implant failure: A systematic review

STATEMENT OF PROBLEM

Despite an overall high survival rate for dental implants, the effectiveness of implant retreatment remains unclear.

PURPOSE

The purpose of this systematic review was to examine the survival rate of implants placed at sites which had an implant failure and to investigate factors that might affect outcomes after retreatment.

MATERIAL AND METHODS

A search of electronic databases limited to English language articles was conducted using the following MeSH terms: "dental implants," "dental implantation," or "dental restoration failure," combined with "retreatment," "replacement," or "reoperation." A hand search of selected journals was also performed. Of the retrieved 668 publications, 8 retrospective clinical studies met the inclusion criteria, providing the survival outcome for 673 implants in 557 patients after retreatment. Implant- and patient-related characteristics related to implant failures were assessed.

RESULTS

The weighted mean survival rate for implants after retreatment was 86.3%, with follow-up ranging from less than 1 year to over 5 years. The survival rates of smooth-surfaced and rough-surfaced implants were compared in 217 retreated implants, revealing a significantly higher survival rate for rough-surfaced implants than for smooth-surfaced implants (90% versus 68.7%). Insufficient data were available to evaluate the effect of patient- or treatment-related characteristics on the survival of implants after retreatment.

CONCLUSIONS

The survival rate of retreated implants is lower than that generally reported after initial implant placement. Higher survival rates were reported with rough-surfaced implants than with smooth-surfaced implants in retreatment. An overall implant survival rate of 86.3% after retreatment suggests that most initial implant failures are likely attributable to modifiable risk factors, such as implant architecture, anatomic site, infection, and occlusal overload.

Effect of dental implant surface roughness in patients with a history of periodontal disease: a systematic review and meta-analysis

BACKGROUND

To review the literature on the effect of dental implant surface roughness in patients with a history of periodontal disease. The present review addresses the following focus question: Is there a difference for implant survival, mean marginal bone loss, and the incidence of bleeding on probing in periodontally compromised patients receiving a machined dental implant or rough surface dental implant?

METHODS

Electronic and manual literature searches were conducted on PubMed/MEDLINE and the Cochrane Library on studies published until May 2018 to collect information about the effect of machined, moderately rough, and rough dental implant surfaces in patients with a history of periodontal disease. The outcome variables implant survival, mean marginal bone level, and the incidence of peri-implantitis and bleeding on probing were evaluated. Meta-analysis was performed to obtain an accurate estimation of the overall, cumulative results.

RESULTS

Out of 2411 articles, six studies were included in this systematic review. The meta-analysis of the implant survival and implant mean marginal bone loss revealed a risk ratio of 2.92 (CI 95% 0.45, 18.86) for implant failure and a total mean difference of - 0.09 (CI 95% - 0.31, 0.14) for implant mean marginal bone loss measured in a total group of 215 implants, both not statistically significant.

CONCLUSIONS

Due to lack of long-term data (> 5 years), the heterogeneity and variability in study designs and lack of reporting on confounding factors, definitive conclusions on differences in implant survival, and mean marginal bone loss between machined and moderate rough implants in periodontally compromised patients cannot be drawn. Future well-designed long-term randomized controlled trials are necessary to reveal that machined surfaces are superior to moderately rough and rough surfaces in patients with a history of periodontal disease.

Surface modification of ultrafine-grained titanium: Influence on mechanical properties, cytocompatibility, and osseointegration potential

OBJECTIVE

The main objective of this study was to demonstrate that dental implants made from ultrafine-grain titanium (UFG-Ti) can be created that replicate state of the art surfaces of standard coarse-grain titanium (Ti), showing excellent cytocompatibility and osseointegration potential while also providing improved mechanical properties.

MATERIAL AND METHODS

UFG-Ti was prepared by continuous equal channel angular processing (ECAP), and surfaces were treated by sandblasting and acid etching. Mechanical properties (tensile and fatigue strength), wettability, and roughness parameters were evaluated. Human trabecular bone-derived osteoblast precursor cells (HBCs) were cultured on all samples to examine cytocompatibility and mineralization after 4 and 28 days, respectively. Biomechanical pull-out measurements were performed in a rabbit in vivo model 4 weeks after implantation.

RESULTS

Both yield and tensile strength as well as fatigue endurance were higher for UFG-Ti compared to Ti by 40%, 45%, and 34%, respectively. Fatigue endurance was slightly reduced following surface treatment. Existing surface treatment protocols could be applied to UFG-Ti and resulted in similar roughness and wettability as for standard Ti. Cell attachment and spreading were comparable on all samples, but mineralization was higher for the surfaces with hydrophilic treatment with no significant difference between UFG-Ti and Ti. Pull-out tests revealed that osseointegration of surface-treated UFG-Ti was found to be similar to that of surface-treated Ti.

CONCLUSION

It could be demonstrated that existing surface treatments for Ti can be translated to UFG-Ti and, furthermore, that dental implants made from surface-treated UFG-Ti exhibit superior mechanical properties while maintaining cytocompatibility and osseointegration potential.

Relationship Between Crestal Bone Levels and Crown-to-Implant Ratio of Ultra-Short Implants With a Microrough Surface: A Prospective Study With 48 Months of Follow-Up

The aim of this cohort study was to investigate the relationship between crestal bone levels and crown-to-implant ratio of ultra-short implants, after functional loading. Sixty patients with single or partial edentulism and alveolar bone atrophy were enrolled and treated between December 2009 and January 2016. Without using bone-grafting procedures, patients were rehabilitated with ultra-short implants characterized by a microrough surface and a 6-mm length. Clinical and anatomical crown-to-implant (C/I) ratios and crestal bone levels (CBL) were measured after a follow-up period ranging from 12 to 72 months; all peri-implant and prosthetic parameters were recorded. The data collected were statistically analyzed ( P = .05). A total of 47 patients with 66 ultra-short implants were completely followed up according to described protocol. The mean follow-up was 48.5 ± 19.1 months. The mean anatomical C/I ratio was 2.2, while the mean clinical C/I ratio was 2.6 ± 0.6 at baseline and 2.8 ± 0.6 at the last follow-up appointment. Mean CBL as calculated at the baseline was 0.7 ± 0.5 mm, while at the last appointment it measured 1.0 ± 0.5 mm. The overall implant-based success rate was 96.9%, and the mean peri-implant bone loss (PBL) was 0.3 ± 0.3 mm. No statistically significant relationship was found between anatomical or clinical C/I ratio and PBL. Ultra-short implants appear to offer a predictable solution for implant-prosthetic rehabilitation in patients with edentulism and bone atrophy. A high percentage of implants were successful, with minimal crestal bone loss. The high C/I ratio did not appear to influence either peri-implant bone loss or prosthetic complication rates.

Incidence and Determinants of Dental Implant Failure: A Review of Electronic Health Records in a U.S. Dental School

The aim of this study was to use electronic health care records (EHRs) to examine retrospectively the incidence of and attributes associated with dental implant failures necessitating implant removal in a large cohort of patients treated in the student clinics of a U.S. dental school over three and a half years. EHRs were searched for all patients who received dental implants between July 1, 2011, and December 31, 2014. Characteristics of patients and implants that were actively removed due to irrevocable failure of any etiology ("failure cohort") during this period were compared to those of all other patients who received dental implants during the same time frame ("reference cohort"). Differences in the frequency distribution of various characteristics between the failure and reference cohorts were compared. Of a total 6,129 implants placed in 2,127 patients during the study period, 179 implants (2.9%) in 120 patients (5.6%) were removed. In the multivariate analysis, presence of a removable (OR=2.86) or fixed temporary prosthesis (OR=3.71) was statistically significantly associated with increased risk for implant failure. In contrast, antibiotic coverage (pre- and post-surgery OR=0.16; post-surgery only OR=0.38) and implants of certain manufacturers were associated with lower risk of implant failure. In this sizeable cohort of patients receiving care in dental student clinics, the review of EHRs facilitated identification of multiple variables associated with implant failure resulting in removal; however, these findings do not suggest causative relationships. The adopted analytical approach can enhance quality assurance measures and may contribute to the identification of true risk factors for dental implant failure.

Clinical Outcome of Hydroxyapatite Coated, Bioactive Glass Coated, and Machined Ti6Al4V Threaded Dental Implant in Human Jaws: A Short-Term Comparative Study

INTRODUCTION

Growing aspect of endosseous implant research is focused on surface modification of dental implants for the purpose of improving osseointegration. The aim of this study was to evaluate and compare the clinical outcome (ie, osseointegration) of hydroxyapatite coated, bioactive glass coated and machined titanium alloy threaded dental implants in human jaw bone after implantation.

MATERIALS AND METHODS

One hundred twenty-six implants (45 hydroxyapatite coated, 41 bioactive glass coated, and 40 machined titanium implants) have been placed in incisor areas of 62 adult patients. Outcome was assessed up to 12 months after prosthetic rehabilitation using different clinical and radiological parameters. Surface roughness of failed implants was analyzed by laser profilometer.

DISCUSSION

Hydroxyapatite and bioactive glass coating materials were nontoxic and biocompatible. Least marginal bone loss in radiograph, significantly higher (P < 0.05) interface radiodensity, and less interfacial gaps were observed in computed tomography with bioactive glass coated implants at anterior maxilla compared to other 2 types.

CONCLUSION

Bioactive glass coated implants are equally safe and effective as hydroxyapatite coated and machined titanium implants in achieving osseointegration; therefore, can be effectively used as an alternative coating material for dental implants.

Immediate Dental Implant Placements Using Osteotome Technique: A Case Report and Literature Review

This clinical case describes the effect of the osteotome technique on the osseointegration of a mandibular dental implant in a 42-year-old female patient with dento-alveolar bony defects and to review the literature regarding immediate implant placement using osteotome technique. The amount of bone expansion at the alveolar ridge and the marginal bone resorption from the time of implant placement to one year after the implant's functional loading were recorded clinically. The esthetic outcome for the restored implant (the gingival margin) was achieved one years after the implant's functional loading. The surgical and prosthetic sites for the implant showed no postoperative complications, and no infection or wound dehiscence was recorded during the follow-up period. The osteotome technique is good for the purpose for which it was introduced, and its advantages with immediate implant placement include reduced surgical trauma and a shorter treatment time.

Pre-treatment of titanium alloy with platelet-rich plasma enhances human osteoblast responses

Osseointegration, the histological direct bone-to-implant contact, is the ultimate goal of implant healing and the first prerequisite for long-term success of endosseous implants. It is well-known that metal implants with rough surfaces achieve better osseointegration than those with smooth surfaces in vivo. The implantation of metal materials into bone is always accompanied by bleeding. The implant surface is initially coated with blood and these initial events could determine subsequent osseointegration. However, there is little concordance between in vitro results and in vivo findings regarding the effect of surface roughness on osseointegration. Here, we show that the osteoblast response to metal surfaces pre-treated with platelets and plasma proteins elucidates the superior osseointegration of rough surfaced implants in vivo. We found that osteoblast attachment, proliferation, and osteoblastic differentiation were significantly higher on a rough titanium surface pre-treated with platelet-rich plasma (PRP) than on the same surface without pretreatment. Furthermore, we found that the three-dimensional fibrillar network formed on the rough surface of the titanium by PRP pre-treatment might enhance osteoblast responses. Our results demonstrate why osseointegration is found to be most active on metal implants with a rough surface in vivo. We anticipate that our assay would be a useful tool for mimicking the in vivo model of osseointegration. Because cellular responses to the titanium implant that are pre-treated with platelet and plasma proteins on their surfaces after the biomimetic process in vitro, may be more similar to the events that occur in vivo.

Soft and hard tissue changes around laser microtexture single tooth implants--a clinical and radiographic evaluation

PURPOSE

To investigate the periodontal parameters that affect the soft and hard tissues around Laser microtextured single tooth implants at 18 months after loading.

METHODS

Twenty Laser Lok implants were placed in 20 single missing tooth sites using a 2-stage protocol. Clinical Parameters included Plaque Index (PI), Gingival Index (GI), Probing Pocket Depth (PPD), Bleeding on Probing (BOP), and Crestal Bone Loss (CBL). Clinical and radiographic evaluation was done at loading, 12 months and 18 months after loading. The data collected were analyzed statistically.

RESULTS

The PI and GI during the entire follow-up period were well controlled. Eighty-six percent of implant sites were free of BOP at loading and 87% of sites were free of BOP at 18 months. A significant increase in PPD was not observed. The mean CBL was 0.59 mm at the time of loading, 0.80 mm at 12 months, and 1.06 mm at 18 months.

CONCLUSION

The Laser Lok implants showed minimal CBL at 18 months than the commonly accepted 1.5 to 2.0 mm. The periimplant soft tissue stability was maintained throughout the study.

Stress distribution patterns of implant supported overdentures-analog versus finite element analysis: A comparative in-vitro study

Aims and Objectives:

The aim of this study was to asses & compare the load transfer characteristics of Ball/O-ring and Bar/Clip attachment systems in implant supported overdentures using analog and finite element analysis models.

Methodology:

For the analog part of the study, castable bar was used for the bar and clip attachment and a metallic housing with a rubber O-ring component was used for the ball/O-ring attachment. The stress on the implant surface was measured using the strain-gauge technique. For the finite element analysis, the model were fabricated and load applications were done in a similar manner as in analog study.

Results:

The difference between both the attachment systems was found to be statistically significant (P<0.001).

Conclusion:

Ball/O-ring attachment system transmitted lesser amount of stresses to the implants on the non-loading side, as compared to the Bar-Clip attachment system. When overall stress distribution is compared, the Bar-Clip attachment seems to perform better than the Ball/O-ring attachment, because the force was distributed better.

Novel Osteogenic Ti-6Al-4V Device For Restoration Of Dental Function In Patients With Large Bone Deficiencies: Design, Development And Implementation

Custom devices supporting bone regeneration and implant placement are needed for edentulous patients with large mandibular deficiencies where endosteal implantation is not possible. We developed a novel subperiosteal titanium-aluminum-vanadium bone onlay device produced by additive manufacturing (AM) and post-fabrication osteogenic micro-/nano-scale surface texture modification. Human osteoblasts produced osteogenic and angiogenic factors when grown on laser-sintered nano-/micro-textured surfaces compared to smooth surfaces. Surface-processed constructs caused higher bone-to-implant contact, vertical bone growth into disk pores (microCT and histomorphometry), and mechanical pull-out force at 5 and 10 w on rat calvaria compared to non surface-modified constructs, even when pre-treating the bone to stimulate osteogenesis. Surface-modified wrap-implants placed around rabbit tibias osseointegrated by 6 w. Finally, patient-specific constructs designed to support dental implants produced via AM and surface-processing were implanted on edentulous mandibular bone. 3 and 8 month post-operative images showed new bone formation and osseointegration of the device and indicated stability of the dental implants.

A meta-analysis on the effect of implant characteristics on the survival of the wide-diameter implant

The purposes of the study are to study the implant survival of the wide-diameter implant and to analyze if the length, the implant surface, or the placement location has any effect on its survival. Electronic databases were searched from inception to Dec 2014. Studies included in the review had implants placed in areas of adequate bone width and had clear inclusion and exclusion criteria for patient selection. Immediately placed and immediately loaded implants were excluded. A meta-analysis was done using the “random effects” model on the included studies. And, a meta-regression was used to evaluate the effects of location, length, and surface on the implant survival. Of the six studies selected, three evaluated surface-treated implants and three machined implants. The overall pooled survival rate of the wide implant is 96.3 %. The meta-regression showed that when using a wide implant, neither its surface nor its length nor its position in the maxilla or mandible adversely affected its survival (P > 0.05). This meta-analysis concluded that the location, length, and surface of the wide-diameter implant did not affect its survival and therefore suggested that when the conditions of the implant site corresponded to the inclusion criteria of our meta-analysis, choosing a wide-diameter implant in the posterior mandible or maxilla, where implant length may be limited by the nerve or the sinus, the use of a short implant regardless of its surface would not affect its survival.

Macrophages, Foreign Body Giant Cells and Their Response to Implantable Biomaterials

All biomaterials, when implanted in vivo, elicit cellular and tissue responses. These responses include the inflammatory and wound healing responses, foreign body reactions, and fibrous encapsulation of the implanted materials. Macrophages are myeloid immune cells that are tactically situated throughout the tissues, where they ingest and degrade dead cells and foreign materials in addition to orchestrating inflammatory processes. Macrophages and their fused morphologic variants, the multinucleated giant cells, which include the foreign body giant cells (FBGCs) are the dominant early responders to biomaterial implantation and remain at biomaterial-tissue interfaces for the lifetime of the device. An essential aspect of macrophage function in the body is to mediate degradation of bio-resorbable materials including bone through extracellular degradation and phagocytosis. Biomaterial surface properties play a crucial role in modulating the foreign body reaction in the first couple of weeks following implantation. The foreign body reaction may impact biocompatibility of implantation devices and may considerably impact short- and long-term success in tissue engineering and regenerative medicine, necessitating a clear understanding of the foreign body reaction to different implantation materials. The focus of this review article is on the interactions of macrophages and foreign body giant cells with biomaterial surfaces, and the physical, chemical and morphological characteristics of biomaterial surfaces that play a role in regulating the foreign body response. Events in the foreign body response include protein adsorption, adhesion of monocytes/macrophages, fusion to form FBGCs, and the consequent modification of the biomaterial surface. The effect of physico-chemical cues on macrophages is not well known and there is a complex interplay between biomaterial properties and those that result from interactions with the local environment. By having a better understanding of the role of macrophages in the tissue healing processes, especially in events that follow biomaterial implantation, we can design novel biomaterials-based tissue-engineered constructs that elicit a favorable immune response upon implantation and perform for their intended applications.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL RELEVANCE

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

Key local and surgical factors related to implant failure

The concept of osseointegration has revolutionized the treatment options for the replacement of missing teeth in both partially and completely edentulous patients. Dental implants are widely used because clinical practice and studies have documented its successful outcomes. However, implants can occasionally fail, and such failures can be classified as early or late. Measures that can aid in the early recognition of failing osseointegrated implants are needed, as are measures that can facilitate appropriate treatment methods aimed at saving failing implants by determining the probable etiologic factors. This article summarizes our current understanding of the local factors that can be linked to implant failure.

Characterization and evaluation of curcumin loaded guar gum/polyhydroxyalkanoates blend films for wound healing applications

Schematic representation of the blockage of UV rays and controlled release of curcumin on a wound.

Novel zirconia surface treatments for enhanced osseointegration: laboratory characterization

Purpose. The aim of this study was to evaluate three novel surface treatments intended to improve osseointegration of zirconia implants: selective infiltration etching treatment (SIE), fusion sputtering (FS), and low pressure particle abrasion (LPPA). The effects of surface treatments on roughness, topography, hardness, and porosity of implants were also assessed. Materials and Methods. 45 zirconia discs (19 mm in diameter × 3 mm in thickness) received 3 different surface treatments: selective infiltration etching, low pressure particle abrasion with 30 µm alumina, and fusion sputtering while nontreated surface served as control. Surface roughness was evaluated quantitatively using profilometery, porosity was evaluated using mercury prosimetry, and Vickers microhardness was used to assess surface hardness. Surface topography was analyzed using scanning and atomic force microscopy (α = 0.05). Results. There were significant differences between all groups regarding surface roughness (F = 1678, P < 0.001), porosity (F = 3278, P < 0.001), and hardness (F = 1106.158, P < 0.001). Scanning and atomic force microscopy revealed a nanoporous surface characteristic of SIE, and FS resulted in the creation of surface microbeads, while LPPA resulted in limited abrasion of the surface. Conclusion. Within the limitations of the study, changes in surface characteristics and topography of zirconia implants have been observed after different surface treatment approaches. Thus possibilities for enhanced osseointegration could be additionally offered.

Maintaining the pluripotency of mouse embryonic stem cells on gold nanoparticle layers with nanoscale but not microscale surface roughness

Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction.

In vitro and in vivo performance of bioactive Ti6Al4V/TiC/HA implants fabricated by a rapid microwave sintering technique

Failure of the bone-implant interface in a joint prosthesis is a main cause of implant loosening. The introduction of a bioactive substance, hydroxyapatite (HA), to a metallic bone-implant may enhance its fixation on human bone by encouraging direct bone bonding. Ti6Al4V/TiC/HA composites with a reproducible porous structure (porosity of 27% and pore size of 6-89 μm) were successfully fabricated by a rapid microwave sintering technique. This method allows the biocomposites to be fabricated in a short period of time under ambient conditions. Ti6Al4V/TiC/HA composites exhibited a compressive strength of 93 MPa, compressive modulus of 2.9 GPa and microhardness of 556 HV which are close to those of the human cortical bone. The in vitro preosteoblast MC3T3-E1 cells cultured on the Ti6Al4V/TiC/HA composite showed that the composite surface could provide a biocompatible environment for cell adhesion, proliferation and differentiation without any cytotoxic effects. This is among the first attempts to study the in vivo performance of load-bearing Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites in a live rabbit. The results indicated that the Ti6Al4V/TiC/HA composite had a better bone-implant interface compared with the Ti6Al4V/TiC implant. Based on the microstructural features, the mechanical properties, and the in vitro and in vivo test results from this study, the Ti6Al4V/TiC/HA composites have the potential to be employed in load-bearing orthopedic applications.

The seven-year cumulative survival rate of Osstem implants

OBJECTIVES

This study was performed to analyze the cumulative survival rate of Osstem implants (Osstem Implant Co., Ltd.) over a seven-year period.

MATERIALS AND METHODS

A total of 105 patients who had 467 Osstem implants that were placed at the Section of Dentistry, Seoul National University Bundang Hospital (Seongnam, Korea) from June 2003 through December 2005 were analyzed. The life table method and a cross-tabulation analysis were performed to evaluate the cumulative survival rate. The log rank test was used to evaluate the survival curve. The influence that the prognostic factors had on the survival rate was determined with a Cox proportional hazard model based on logistic regression analysis [corrected].

RESULTS

The seven-year cumulative survival rate of Osstem implants was 95.37%. The Cox proportional hazard model revealed that the following factors had a significant influence on survival rate; increased diameter, reduced prosthetic loading period and performance of bone grafting.

CONCLUSION

The osstem implants showed satisfactory results over the seven-year study period.

Survival of 352 titanium implants placed in 181 patients: a 4-year multicenter field study

PURPOSE

The aim of this retrospective chart review was to evaluate the four-year survival rate of a titanium implant system.

METHODS

A total of 352 sand-blasted, thermally acid-etched titanium implants were inserted into 181 partially or completely edentulous patients. Their cumulative survival rate was evaluated retrospectively. Associated factors, such as the implant distribution and treatment type were included in the evaluation.

RESULTS

The implants were equally distributed between the maxilla (52.3%) and the mandible (47.7%). 48 implants (13.6%) were placed in the anterior region and 304 implants (86.4%) in the posterior region. The majority of the implants were inserted into bone of type II and III quality (89.8%) and volume (quantity B and C, 87.2%). Most of the implants (70.7%) were restored as single crowns; 28.7% supported a bridge construction and 0.6% a full denture. Only one implant failed, resulting in a four-year cumulative survival rate of 99.7%.

CONCLUSIONS

The implant system showed an excellent four-year survival rate. It proved to be a safe and predictable means for restoration of the dentition in partially or completely edentulous patients.

External mechanical microstimuli modulate the osseointegration of titanium implants in rat tibiae

Purpose. To assess the effect of external mechanical microstimuli of controlled magnitude on the microarchitecture of the peri-implant bone beds in rat tibiae. Materials and Methods. Tibiae of forty rats were fitted with two transcutaneous titanium cylinders. After healing, the implants were loaded to 1 to 3 N, five days/week for four weeks. These force levels translated into intraosseous strains of 700 ± 200 με, 1400 ± 400 με, and 2100 ± 600 με. After sacrifice, the implants' pullout strength was assessed. Second, the bone's microarchitecture was analyzed by microcomputed tomography (μCT) in three discrete regions of interest (ROIs). Third, the effect of loading on bone material properties was determined by nanoindentation. Results. The trabecular BV/TV significantly increased in an ROI of 0.98 mm away from the test implant in the 1 N versus the 3 N group with an opposite trend for cortical thickness. Pull-out strength significantly increased in the 2 N relatively to the nonstimulated group. Higher values of E-modulus and hardness were observed in the trabecular bone of the 2 N group. Conclusion. The in vivo mechanical loading of implants induces load-dependent modifications in bone microarchitecture and bone material properties in rat tibiae. In pull-out strength measurements, implant osseointegration was maximized at 2 N (1400 ± 400 με).