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- Fretwurst, T., et al.
(author)
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Immunohistological composition of peri-implantitis affected tissue around ceramic implants-A pilot study
- 2021
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In: Journal of Periodontology. - : Wiley. - 0022-3492 .- 1943-3670. ; 92:4, s. 571-579
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Journal article (peer-reviewed)abstract
- Background: Aim of the pilot study was the histologic classification of the inflamed peri-implant soft tissue around ceramic implants (CI) in comparison with titanium implants (TI). Methods: Peri-implant tissue were retrieved from 15 patients (aged 34 to 88 years, seven males/eight females) with severe peri-implantitis (eight CI, seven TI). The peri-implant soft tissue samples were retrieved from the sites during scheduled removal of the implant and prepared for immunohistochemical analysis. Monoclonal antibodies (targeting CD3, CD20, CD138, and CD68) were used to identify T- and B-cells, plasma cells and macrophages. Quantitative assessment was performed by one histologically trained investigator. Linear mixed regression models were used. Results: A similar numerical distribution of the cell population was found in peri-implantitis around CI compared with TI. CD3 (TI, 17% to 85% versus CI, 20% to 70% of total cell number) and CD138 (TI, 1% to 73% versus CI, 12% to 69% of total cell number) were predominantly expressed. Notably, patient-individual differences of numerical cell distribution were detected. Co-localization of B- and T-lymphocytes was observed. Conclusions: Peri-implantitis around CI in comparison with TI seems to have a similar histological appearance. Differences in cellular composition of peri-implantitis lesions might also depend on the patient's specific immune status and not only on the material used.
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- Kohal, R-J, et al.
(author)
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Influence of loading and aging on the fracture strength of an injection-molded two-piece zirconia implant restored with a zirconia abutment
- 2023
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In: Clinical Oral Implants Research. - : John Wiley and Sons Inc. - 0905-7161 .- 1600-0501. ; 34:2, s. 105-115
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Journal article (peer-reviewed)abstract
- Objective: To investigate the fracture strength and potential phase transformation of an injection-molded two-piece zirconia implant restored with a zirconia abutment after loading and/or aging. Methods: Thirty-two two-piece zirconia implants (4.0 mm diameter) restored with zirconia abutments were embedded according to ISO 14801 and divided into four groups (n = 8/group): Three groups were either exclusively hydrothermally treated (group HT; 85°C), dynamically loaded (group DL; 107 cycles; 98 N), or subjected to both treatments simultaneously (group DL/HT). One group remained untreated (group 0). A sample from each group was cross-sectioned and examined by scanning electron microscopy for possible crystal phase transformation. The remaining samples were then loaded to fracture in a static loading test. A one-way ANOVA was used for statistical analyses. Results: During dynamic loading, three implants of group DL and six implants of group DL/HT fractured at a load of 98 N. The fracture strength of group DL/HT (108 ± 141 Ncm) was significantly reduced compared to the other groups (group 0: 342 ± 36 Ncm; HT: 363 ± 49 Ncm; DL: 264 ± 198 Ncm) (p <.05). Fractures from group 0 and HT occurred at both implant and abutment level, whereas implants from group DL and DL/HT fractured only at implant level. A shallow monoclinic transformation zone of approximately 2 μm was observed following hydrothermal treatment. Conclusions: Within the limitations of this study, it can be concluded that dynamic loading and the combination of loading and aging reduced the fracture strength of the implant abutment combination. Hydrothermal treatment caused a shallow transformation zone which had no influence on the fracture strength. © 2022 The Authors.
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| 4. |
- Preiss, L., et al.
(author)
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Bone healing, tissue effects and biomechanical fixation of ‘smooth’ ceramic-coated zirconia-based dental implants : An in vivo study in sheep
- 2024
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In: Open Ceramics. - : Elsevier B.V.. - 2666-5395. ; 17
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Journal article (peer-reviewed)abstract
- In this study, the effect of coating a zirconia-based ceramic oral implant with a material of the same composition to build a relatively smooth surface with three different porosity features was evaluated in vivo, at 4 and 8 weeks after implantation in sheep femoral condyles. The results showed that at 4 weeks, the three coated zirconia-based implants with smoother surface topographies behaved similarly and promoted faster bone healing compared to the results obtained in the same zirconia- or titanium-based implants, but with rougher sandblasted and acid-etched surfaces. In addition, higher pull-out strengths were estimated in the coated-ceramic sample compared to titanium sandblasted and etched one. The present work showed that zirconia coatings with smoother surfaces than those conventionally used in the market improved the early phase of bone healing, paving the way for shorter treatment times and improved patient outcomes.
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| 5. |
- Spies, B. C., et al.
(author)
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Long-term stability of an injection-molded zirconia bone-level implant : A testing protocol considering aging kinetics and dynamic fatigue
- 2017
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In: Dental Materials. - : Elsevier BV. - 0109-5641. ; 33:8, s. 954-965
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Journal article (peer-reviewed)abstract
- Objective Separately addressing the fatigue resistance (ISO 14801, evaluation of final product) and aging behavior (ISO 13356, standardized sample) of oral implants made from yttria-stabilized zirconia proved to be insufficient in verifying their long-term stability, since (1) implant processing is known to significantly influence transformation kinetics and (2) aging, up from a certain level, is liable to decrease fatigue resistance. Therefore, the aim of this investigation was to apply a new testing protocol considering environmental conditions adequately inducing aging during dynamic fatigue. Methods Zirconia implants were dynamically loaded (107 cycles), hydrothermally aged (85°, 60 days) or subjected to both treatments simultaneously. Subsequent, monoclinic intensity ratios (Xm) were obtained by locally resolved X-ray microdiffraction (μ-XRD2). Transformation propagation was monitored at cross-sections by μ-Raman spectroscopy and scanning electron microscopy (SEM). Finally, implants were statically loaded to fracture. Linear regression models (fracture load) and mixed models (Xm) were used for statistical analyses. Results All treatments resulted in increased fracture load (p ≤ 0.005), indicating the formation of transformation induced compressive stresses around surface defects during all treatment modalities. However, only hydrothermal and combinational treatment were found to increase Xm (p < 0.001). No change in Xm was observed for solely dynamically loaded samples (p ≥ 0.524). Depending on the variable observed, a monoclinic layer thickness of 1–2 μm (SEM) or 6–8 μm (Raman spectroscopy) was measured at surfaces exposed to water during treatments. Significance Hydrothermal aging was successfully induced during dynamic fatigue. Therefore, the presented setup might serve as reference protocol for ensuring pre-clinically long-term reliability of zirconia oral implants.
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