Studies of Elemental Analysis and Structure on Implantable Metal Alloys

It is obvious that all the elements in a metallic prosthesis implanted in the human body may have beneficial or detrimental effects on the tissue-prosthesis interference. For this reason, the precise knowledge of the chemical composition and structure of an implantable metallic material becomes a major requirement for estimating the medical prosthesis behavior and minimizing the risk of rejection of the implant by the human body. This paper presents an elemental and structural analysis of some potentially biocompatible materials, such as AISI 316 and Co-Cr-Mo alloys.

Influence of the Elastic Modulus on the Osseointegration of Dental Implants

The load transfer from metallic prosthesis to tissue plays an important role in the success of a designed device. From a mechanical behavior point of view, the load transfer will be favored when the elastic modulus between the metallic implant and the bone tissue are similar. Titanium and Ti-6Al-4V are the most commonly used metals and alloys in the field of dental implants, although they present high elastic moduli and hence trigger bone resorption. We propose the use of low-modulus β-type titanium alloys that can improve the growth of new bone surrounding the implant. We designed dental implants with identical morphology and micro-roughness composed of: Ti-15Zr, Ti-19.1Nb-8.8Zr, Ti-41.2Nb-6.1Zr, and Ti-25Hf-25Ta. The commercially pure Ti cp and Ti-6Al-4V were used as control samples. The alloys were initially mechanically characterized with a tensile test using a universal testing machine. The results showed the lowest elastic modulus for the Ti-25Hf-25Ta alloy. We implanted a total of six implants in the mandible (3) and maxilla (3) for each titanium alloy in six minipigs and evaluated their bone index contact (i.e., the percentage of new bone in contact with the metal—BIC%) after 3 and 6 weeks of implantation. The results showed higher BIC% for the dental implants with lowest elastic modulus, showing the importance of decreasing the elastic modulus of alloys for the successful osseointegration of dental implants.

Modular endoprosthetic implant for maximizing residual limb length: A case report

Background: For transfemoral amputations, the residual femoral length is critically important to prosthetic function. The aim of this report is to describe a novel method of extending femoral length and to assess its stability over time. Case Description and Methods: A 57-year-old woman with recurrent parosteal osteosarcoma was treated with above-knee amputation. A portion of the distal femoral endoprosthesis, which included uncemented fixation with a Compress® stem, was retained in an effort to extend the short femoral remnant and maximize stump length. Findings: At 3 years follow-up, the Compress stem remained well-fixed, and there was no soft tissue breakdown over the implant. The patient ambulated with a prosthetic limb and no external support. Outcomes and Conclusion: To the best of our knowledge, this is the first report of using the Compress device as a means to maintain stable fixation and extend residual femoral length following above-knee amputation. Clinical relevance Extension of residual bone length in amputated limbs can help improve prosthetic fitting and function. The Compress device may be useful in this application as a means of secure fixation for a modular metallic prosthesis.

Stress Analysis on Single Cobalt/Chrome Prosthesis With a 15-mm Cantilever Placed Over 10/13/15-mm–length Implants: A Simulated Photoelastic Model Study

The aim of study was to assess the stress around 10/13/15-mm implants in the mandibular area with a 15-mm cantilevered acrylic-resin–coated prostheses following the application force, using the photoelasticity method. Three photoelastic mandibular models were created containing 10-, 13-, and 15-mm implants in length and 3.75 mm in diameter. The implants had bore internal hex connections and were placed parallel to the intermental region. Abutments with 1-mm high cuffs were placed over the implants, and a single cobalt/chrome metallic prosthesis with a 15-mm cantilever, coated with thermoplastic acrylic resin, was placed on top. Loads of 1.0 and 3.0 bars were applied, and the images were photographed and assessed by photoelasticity method. The greatest stress levels were observed for the 10-mm implants. The stress pattern was the same regardless of implant length; only the magnitude of the stress along the implant body revealed changes. Increased implant length played a role in reducing stress on the investigated area of the model, and the 15-mm implants exhibited the best performance in regard to stress distribution. The highest stress levels were found in the implants closest to the cantilever and the central implant. The longest implants were more favorable in regard to the stress distribution on the peri-implant support structures in the 15-mm cantilevered prosthesis under loads.

Innovative Magnetic Nanoparticles Approaches for Bone and Osteochondral Tissue Engineering

The necessity of new clinical approaches regarding musculoskeletal system regeneration is evident. Nowadays different strategies such as autografts, allografts also used in synergy with cell therapy are already used in clinical treatments for moderate defects, but they face significant limitations due to limited supply, and risk of immune rejection. Currently, the treatments of extended osteochondral and bone defects involve invasive permanent metallic prosthesis, challenging reconstructive procedures and long rehabilitation period. Despite that, the gold standard seems to be far to obtain.