Peri-implant and systemic release of metallic elements following insertion of a mandibular modular endoprosthesis in Macaca fascicularis

Analytical Problems with Preparation of Paraspinal Tissues from Patients with Spinal Fusion for Analysis of Titanium

Preparation of paraspinal tissue of patients with implants for elemental analysis is a challenge because it contains titanium in the ionic form, as well as metallic debris. Most literature reports focus on dissolving the tissue, but the impact of digestion conditions on metallic debris of Ti has not been investigated. In our work, various digestion conditions, including systems, compositions of oxidising mixture, and time, were tested aiming (i) to digest the tissue without digestion of metallic titanium to quantify soluble Ti and (ii) to digest metallic titanium debris to asses total Ti content in tissue. The experiments were performed in a closed mode using a microwave-assisted system and a carbon heating block. Our study revealed that total digestion of titanium was impossible in the tested conditions and the maximal level of digested titanium was below 70%. The mineralisation with the use of concentrated nitric acid was optimal to prepare paraspinal samples to analyse the soluble titanium form because metallic titanium passivated and did not migrate to the solution. The elaborated conditions were applied to determine titanium ion in the periimplant tissue of patients with three different titanium-based surgical systems, including traditional growing rod (TGR), guided growth systems (GGS), and vertical expandable prosthesis titanium rib (VEPTR).

Evaluation of serum metal ion levels in dental implant patients: A prospective study

Introduction:

Titanium is the most commonly used bio-inert implant material. Nevertheless, there is a possibility of systemic release of metal ions, which could have clinical implications like implant failure and toxicity. This prospective study focuses on the evaluation of serum metal ion levels in patients receiving dental implants. The aim of the study is to evaluate the release of titanium, aluminium, and vanadium from dental implants by comparing the preoperative and postoperative serum levels of these ions.

Methodology:

Serum samples were collected from 30 patients undergoing dental implant placement preoperatively and postoperatively at intervals of 6 weeks, 3, 6, and 12 months. These samples were analyzed for titanium, aluminium, and vanadium levels using Inductively Coupled Plasma Optical Emission Spectrometry. The difference in preoperative and postoperative serum levels was measured and statistically analyzed using the paired t-test.

Results:

There was a slight difference in the postoperative levels of titanium and aluminium (2.30 and 4.07 mg/dl) as compared to the preoperative levels (2.28 and 2.30 mg/dl), which was statistically insignificant (P > 0.5). The serum levels of vanadium were too insignificant to be detected by the instrument (<0.0088 mg/dl).

Discussion:

Mild increase in the titanium and aluminium levels in blood serum was noted. These metallic ion levels might increase significantly due to which further clinical research with larger sample sizes and a long-term follow-up period is required to evaluate the clinical effects of metallic ion release from dental implants. There is no significant difference in the serum metal ion levels before and after the implant placement, although a little increase is observed in the aluminium ion levels after the implant placement.

Removal of dental alloys and titanium attenuates trace metals and biological effects on liver and kidney

To determine whether the potential effects on liver and kidney caused by dental alloys could be reduced or terminated by the removal of nickel-chromium (Ni-Cr) alloy, cobalt-chromium (Co-Cr) alloy, and commercially pure titanium (CP-Ti), they were placed in the cheek pouches of Syrian hamsters according to ISO 10993-10. Then, the peak/plateau and end times of trace metals in the blood were determined with or without the removal of the dental alloys. Based on these time points, the trace metals and their effects on liver and kidney were examined. We found that trace metals released from these dental alloys and titanium were accumulated transiently in the blood, liver, and kidney but had no effect on the histopathology of the liver or kidney. Although the functions of the liver and kidney were compromised, the function of these tissues seemed to be clinically acceptable compared to those in control Syrian hamsters. In addition, the apoptotic effect on renal cells was terminated by removing the Ni-Cr and Co-Cr alloys, and that on hepatocytes was also eliminated by removing the Ni-Cr alloy. In contrast, the effect of the Co-Cr alloy on hepatocytes was temporary and recovered by itself. Taken together, Ni- and Co-based dental alloys and titanium have no effect on the histopathology or function of liver and kidney. Moreover, Ni-Cr and Co-Cr alloys induce transient trace metal accumulation and apoptotic effects in liver and kidney, which can be reduced or terminated by the removal of the alloys, while CP-Ti shows favorable biocompatibility.

Release of titanium after insertion of dental implants with different surface characteristics - an ex vivo animal study

In the present study, amount of titanium (Ti) released into the surrounding bone during placement of implants with different surface structure was investigated. Quantification of Ti released during insertion from three different implants was performed in this ex vivo study. Jaw bone from pigs was used as model for installation of the implants and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) was used for analysis of the released Ti. Implant surface were examined with scanning electron microscopy (SEM), before and after the placement into the bone. Ti was abraded to the surrounding bone upon insertion of a dental implant and the surface roughness of the implant increased the amount of Ti found. Diameter and total area of the implant were of less importance for the Ti released to the bone. No visible damages to the implant surfaces could be identified in SEM after placement.

Titanium: a review on exposure, release, penetration, allergy, epidemiology, and clinical reactivity

Exposure to titanium (Ti) from implants and from personal care products as nanoparticles (NPs) is common. This article reviews exposure sources, ion release, skin penetration, allergenic effects, and diagnostic possibilities. We conclude that human exposure to Ti mainly derives from dental and medical implants, personal care products, and foods. Despite being considered to be highly biocompatible relative to other metals, Ti is released in the presence of biological fluids and tissue, especially under certain circumstances, which seem to be more likely with regard to dental implants. Although most of the studies reviewed have important limitations, Ti seems not to penetrate a competent skin barrier, either as pure Ti, alloy, or as Ti oxide NPs. However, there are some indications of Ti penetration through the oral mucosa. We conclude that patch testing with the available Ti preparations for detection of type IV hypersensitivity is currently inadequate for Ti. Although several other methods for contact allergy detection have been suggested, including lymphocyte stimulation tests, none has yet been generally accepted, and the diagnosis of Ti allergy is therefore still based primarily on clinical evaluation. Reports on clinical allergy and adverse events have rarely been published. Whether this is because of unawareness of possible adverse reactions to this specific metal, difficulties in detection methods, or the metal actually being relatively safe to use, is still unresolved.

A Pig Model for the Histomorphometric Evaluation of Hard Tissue Around Dental Implants

This study aimed to evaluate the frontal bone of Swiss Domestic pigs as an animal model for the histologic-histomorphometric examination of bony tissue around dental implants. We inserted SLA surface implants 4.1 mm in diameter and 10 mm in length into the frontal bones of 9 Swiss-Domestic pigs. Histologic and histomorphometric studies were conducted on the undecalcified sections. Histologic examinations showed that the specimens contain a sufficient amount of bone to provide homogenous bone coverage for standard diameter dental implant placement. The mean bone to implant contact was 61.9% ± 8.7%. Other histomorphometric parameters revealed the regular trabecular architecture at this site. Pigs' frontal bone appears to be a suitable animal model in short-term dental implant studies because it provides a sufficient amount of bone and favorable bone microarchitecture.

Comparison of morphological changes in efferent lymph nodes after implantation of resorbable and non-resorbable implants in rabbits

Background

Magnesium alloys as biodegradable implant materials received much interest in recent years. It is known that products of implant degradation can induce several types of immune response. Hence, the aim of this study was to examine the morphological changes of efferent lymph nodes after implantation of different resorbable magnesium alloys (MgCa0.8, LAE442) in comparison to commercially available resorbable (PLA) and non-resorbable (titanium) implant materials as well as control groups without implant material.

Methods

The different implant materials were inserted intramedullary into the rabbit tibia. After postoperative observation periods of three and six months, popliteal lymph nodes were examined histologically and immunhistologically and compared to lymph nodes of sham operated animals and animals without surgery. Haematoxylin and eosin staining was performed for cell differentiation. Mouse anti-CD79α and rat anti-CD3 monoclonal primary antibodies were used for B- and T-lymphocyte detection, mouse anti-CD68 primary antibodies for macrophage detection. Evaluation of all sections was performed applying a semi quantitative score.

Results

The histological evaluation demonstrated low and moderate levels of morphological changes for both magnesium alloys (LAE442 and MgCa0.8). Higher than moderate values were reached for titanium in sinus histiocytosis and histiocytic apoptosis (3 months) and for PLA in histiocytic apoptosis (3 and 6 months). The immune response to all investigated implants had a non-specific character and predominantly was a foreign-body reaction. LAE442 provoked the lowest changes which might be due to a lower degradation rate in comparison to MgCa0.8. Therewith it is a promising candidate for implants with low immunogenic potential.

Conclusion

Both examined magnesium alloys did not cause significantly increased morphological changes in efferent lymph nodes in comparison to the widely used implant materials titanium and PLA. LAE442 induced even lower immunological reactions. Therewith MgCa0.8 and especially LAE442 are appropriate candidates for biomedical use.