Influence of zirconia implant surface topography on first bone implant contact within a prospective cohort study

Hyperbranched Poly-l-Lysine Modified Titanium Surface With Enhanced Osseointegration, Bacteriostasis, and Anti-Inflammatory Properties for Implant Application: An Experimental In Vivo Study

OBJECTIVES

This study aimed to explore multiple effects of hyperbranched poly-l-lysine (HBPL) titanium (Ti) surfaces on osseointegration, bacteriostasis, and anti-inflammation across three different animal models.

METHODS

Ti surfaces were covalently modified with HBPL, with uncoated surfaces as controls. Characterization included scanning electron microscopy (SEM) and surface chemistry and elemental analysis (EDX). Ti and Ti-HBPL implants were placed in conventional canine edentulous sites, post-operative infection canine edentulous sites, and diabetic rat tibias. Implants from canine edentulous models were analyzed using micro-CT and histomorphometry to assess osseointegration at 8 weeks. Post-operative infection beagles were used to evaluate antibacterial efficacy through clinical parameters and bacterial cultures at 1 week. In diabetic rats, micro-CT and histomorphometry were performed at 8 weeks.

RESULTS

HBPL was uniformly grafted on Ti-HBPL surfaces. Ti-HBPL surfaces showed higher bone volume/total volume (BV/TV, p < 0.001), bone-implant contact (BIC%, p < 0.001), and trabecular number (Tb.N, p < 0.01) in beagles. Besides, it displayed higher BIC% (p < 0.001) and bone area fraction occupancy (BAFO%, p < 0.01) in hard tissue sections. In an infected model, Ti-HBPL surfaces exhibited lower bleeding on probing (BOP, p < 0.001), and plaque index (DI, p < 0.01), with reduced bacterial colony formation (p < 0.001) compared to the control group. In diabetic rats, Ti-HBPL surfaces showed an increase in BV/TV (p < 0.01) and Tb.N (p < 0.001), downregulated TNF-α and IL-1β (p < 0.01), and upregulated IL-10 (p < 0.01) and osteocalcin (OCN) expression (p < 0.01).

CONCLUSIONS

HBPL-Ti surfaces demonstrated enhanced osseointegration, bacteriostasis, and anti-inflammatory effects in vivo.

Clinical, radiographic and patient-reported outcomes of zirconia and titanium implants in the posterior zone after 1 year of loading-A randomized controlled trial

OBJECTIVE

To assess the clinical, radiographic and patient-reported outcomes (PROMs) of posterior zirconia and titanium implants at 1 year of implant loading.

MATERIALS AND METHODS

Forty-two patients with two adjacent missing teeth were enrolled in a randomized controlled trial with a within-subject controlled design. Each patient received one zirconia (Zr) and one titanium (Ti) implant, with the mesial and distal positions randomized. The implant restoration consisted of multiple layered zirconia, with the buccal aspect veneered. In group Zr, the restoration was intraorally cemented onto the one-piece Zr implant, whereas in group Ti, the restoration was extraorally cemented onto the titanium base abutment and intraorally screw-retained onto the Ti implant. Examinations were performed following restoration delivery at baseline (BL) and at 1 year. Measurements included clinical parameters, radiographic outcomes (MBL) and PROMs.

RESULTS

Bleeding on probing showed an increase from BL to 1 year (34 ± 30% for Zr; 25 ± 21% for Ti). MBL remained stable with minimal changes from BL to 1 year, measuring 0.1 ± 0.4 mm (mean ± SD) for Zr and -0.1 ± 0.7 mm for Ti. Veneering fractures were the most frequent technical complication and amounted to 17.5% in group Zr and 5% in group Ti (p = .100). Patients preferred Zr implants for their soft tissue color, with a significant difference in perception between patients and clinicians (p < .017).

CONCLUSION

The study showed that both Zr and Ti implants had similar clinical outcomes, despite a high prevalence of mucositis and a few technical complications. Both implant types demonstrated stable marginal bone levels and similar patient-reported outcome measures.

Nanoscale osseointegration of zirconia evaluated from the interfacial structure between ceria-stabilized tetragonal zirconia and cell-induced hydroxyapatite

BACKGROUND

The osseointegration of zirconia implants has been evaluated based on their implant fixture bonding with the alveolar bone at the optical microscopic level. Achieving nano-level bonding between zirconia and bone apatite is crucial for superior osseointegration; however, only a few studies have investigated nanoscale bonding. This review outlines zirconia osseointegration, including surface modification, and presents an evaluation of nanoscale zirconia-apatite bonding and its structure.

HIGHLIGHT

Assuming osseointegration, the cells produced calcium salts on a ceria-stabilized zirconia substrate. We analyzed the interface between calcium salts and zirconia substrates using transmission electron microscopy and found that 1) the cell-induced calcium salts were bone-like apatite and 2) direct nanoscale bonding was observed between the bone-like apatite and zirconia crystals without any special modifications of the zirconia surface.

CONCLUSION

Structural affinity exists between bone apatite and zirconia crystals. Apatite formation can be induced by the zirconia surface. Zirconia bonds directly with apatite, indicating superior osseointegration in vivo.

Optimized Gingiva Cell Behavior on Dental Zirconia as a Result of Atmospheric Argon Plasma Activation

Several physico-chemical modifications have been developed to improve cell contact with prosthetic oral implant surfaces. The activation with non-thermal plasmas was one option. Previous studies found that gingiva fibroblasts on laser-microstructured ceramics were hindered in their migration into cavities. However, after argon (Ar) plasma activation, the cells concentrated in and around the niches. The change in surface properties of zirconia and, subsequently, the effect on cell behavior is unclear. In this study, polished zirconia discs were activated by atmospheric pressure Ar plasma using the kINPen^®09 jet for 1 min. Surfaces were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and water contact angle. In vitro studies with human gingival fibroblasts (HGF-1) focused on spreading, actin cytoskeleton organization, and calcium ion signaling within 24 h. After Ar plasma activation, surfaces were more hydrophilic. XPS revealed decreased carbon and increased oxygen, zirconia, and yttrium content after Ar plasma. The Ar plasma activation boosted the spreading (2 h), and HGF-1 cells formed strong actin filaments with pronounced lamellipodia. Interestingly, the cells' calcium ion signaling was also promoted. Therefore, argon plasma activation of zirconia seems to be a valuable tool to bioactivate the surface for optimal surface occupation by cells and active cell signaling.

Effect of Hydrogen Peroxide on the Surface and Attractiveness of Various Zirconia Implant Materials on Human Osteoblasts: An In Vitro Study

The aim of this in vitro study was to investigate the effect of hydrogen peroxide (H₂O₂) on the surface properties of various zirconia-based dental implant materials and the response of human alveolar bone osteoblasts. For this purpose, discs of two zirconia-based materials with smooth and roughened surfaces were immersed in 20% H₂O₂ for two hours. Scanning electron and atomic force microscopy showed no topographic changes after H₂O₂-treatment. Contact angle measurements (1), X-ray photoelectron spectroscopy (2) and X-ray diffraction (3) indicated that H₂O₂-treated surfaces (1) increased in hydrophilicity (p < 0.05) and (2) on three surfaces the carbon content decreased (33-60%), while (3) the monoclinic phase increased on all surfaces. Immunofluorescence analysis of the cell area and DNA-quantification and alkaline phosphatase activity revealed no effect of H₂O₂-treatment on cell behavior. Proliferation activity was significantly higher on three of the four untreated surfaces, especially on the smooth surfaces (p < 0.05). Within the limitations of this study, it can be concluded that exposure of zirconia surfaces to 20% H₂O₂ for 2 h increases the wettability of the surfaces, but also seems to increase the monoclinic phase, especially on roughened surfaces, which can be considered detrimental to material stability. Moreover, the H₂O₂-treatment has no influence on osteoblast behavior.

Results at the 1-Year Follow-Up of a Prospective Cohort Study with Short, Zirconia Implants

The objective of this study was to clinically and radiologically evaluate the performance of a short (8 mm), 1-piece, zirconia implant after an observation period of 1 year in function. A total of 47 patients with 1 missing tooth in the position of a premolar or molar were recruited. Short (8 mm), 1-piece, zirconia implants were placed and loaded after a healing period of 2 to 4 months with monolithic crowns made of 3 different materials. Implants were followed up for one year and clinically and radiologically assessed. A total of 46 implants were placed. One was excluded since no primary stability was achieved at implant placement. At the 1-year follow-up, mean marginal bone loss 1 year after loading was 0.05 ± 0.47 mm. None of the implants showed marginal bone loss greater than 1 mm or clinical signs of peri-implantitis. A total of 2 implants were lost during the healing phase and another after loading, resulting in a survival rate of 93% after 1 year. All lost implants showed a sudden increased mobility with no previous signs of marginal bone loss or peri-implant infection. The short, 8 mm, zirconia implants showed stable marginal bone levels over the short observation period of 1 year. Although they revealed slightly lower survival rates, they can be suggested for the use in sites with reduced vertical bone. Scientific data are very limited, and long-term data are not yet available, and therefore, they are needed.

Surface Structure of Zirconia Implants: An Integrative Review Comparing Clinical Results with Preclinical and In Vitro Data

Background: The purpose of this review was to analyze and correlate the findings for zirconia implants in clinical, preclinical and in vitro cell studies in relation to surface structure. Methods: Electronic searches were conducted to identify clinical, preclinical and in vitro cell studies on zirconia implant surfaces. The primary outcomes were mean bone loss (MBL) for clinical studies, bone-to-implant contact (BIC) and removal torque (RT) for preclinical studies and cell spreading, cell proliferation and gene expression for cell studies. The secondary outcomes included comparisons of data found for those surfaces that were investigated in all three study types. Results: From 986 screened titles, 40 studies were included for data extraction. In clinical studies, only micro-structured surfaces were investigated. The lowest MBL was reported for sandblasted and subsequently etched surfaces, followed by a sinter and slurry treatment and sandblasted surfaces. For BIC, no clear preference of one surface structure was observable, while RT was slightly higher for micro-structured than smooth surfaces. All cell studies showed that cell spreading and cytoskeletal formation were enhanced on smooth compared with micro-structured surfaces. Conclusions: No correlation was observed for the effect of surface structure of zirconia implants within the results of clinical, preclinical and in vitro cell studies, underlining the need for standardized procedures for human, animal and in vitro studies.

Fabrication and Characterization of PCL/HA Filament as a 3D Printing Material Using Thermal Extrusion Technology for Bone Tissue Engineering

The most common three-dimensional (3D) printing method is material extrusion, where a pre-made filament is deposited layer-by-layer. In recent years, low-cost polycaprolactone (PCL) material has increasingly been used in 3D printing, exhibiting a sufficiently high quality for consideration in cranio-maxillofacial reconstructions. To increase osteoconductivity, prefabricated filaments for bone repair based on PCL can be supplemented with hydroxyapatite (HA). However, few reports on PCL/HA composite filaments for material extrusion applications have been documented. In this study, solvent-free fabrication for PCL/HA composite filaments (HA 0%, 5%, 10%, 15%, 20%, and 25% weight/weight PCL) was addressed, and parameters for scaffold fabrication in a desktop 3D printer were confirmed. Filaments and scaffold fabrication temperatures rose with increased HA content. The pore size and porosity of the six groups’ scaffolds were similar to each other, and all had highly interconnected structures. Six groups’ scaffolds were evaluated by measuring the compressive strength, elastic modulus, water contact angle, and morphology. A higher amount of HA increased surface roughness and hydrophilicity compared to PCL scaffolds. The increase in HA content improved the compressive strength and elastic modulus. The obtained data provide the basis for the biological evaluation and future clinical applications of PCL/HA material.