Glimepiride Loaded Poly(D,L-lactide-co-glycolide) Microspheres Improve Osseointegration of Dental Implants in Type 2 Diabetic Rats

The patients with type 2 diabetes mellitus (T2DM) have high dental implant failure frequency. This study explores the function of glimepiride local delivery on dental implant osseointegration in diabetes animal. Glimepiride loaded PLGA microspheres were loaded on the surface of the dental implant, and transplanted into ten Goto-Kakizaki (GK) rats. Blood sugar level and Implant Stability Quotient (ISQ) were measured every week after surgery. Histological, osseointegration rate and bone-implant contact (BIC) rate analysis were performed to evaluate dental osseointegration. The results showed that Glimepiride loaded Poly-lactide-co-glycolide (PLGA) microspheres have sustained-release curve. The glimepiride group exhibited greater ISQ than the control group. The BIC rate of the control and glimepiride group was 44.60%±1.95% and 59.80%±1.79%, respectively. This study demonstrated that the glimepiride group has a significantly greater osseointegration rate than that of the control group. Thus, Glimepiride could provide an alternative drug release microspheres for enhance the dental implant osseointegration in diabetes patients.

A Review of Strategies to Improve Biomechanical Fixation in the Cervical Spine

Study Design Systematic review. Objectives Review the surgical techniques and construct options aimed at improving the biomechanical strength of cervical constructs. Methods A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A search of the MEDLINE, Embase, and Cochrane Library databases was performed to identify all studies examining biomechanical strategies utilized in the osteoporotic cervical spine. Screening was performed in duplicate for all stages of the review process. Results An initial search returned 3887 articles. After deletion of duplications and review of abstracts and full text, 39 articles met inclusion criteria. Overall, the surgical techniques reviewed aimed at obtaining rigid fixation in the setting of poor bone quality, or dispersing the forces at the bone-implant interface. We identified 6 key techniques to improve biomechanical fixation. These include bicortical fixation, appropriate screw selection (size and trajectory), PMMA augmentation, load sharing techniques, consideration of ancillary fixation around the occipitocervical junction, and supplementing the construct with post-operative collar or halo. Conclusion The summation of the literature highlights a framework of modalities available to surgeons to improve biomechanical fixation in the cervical spine. While these may improve construct strength in the setting of osteoporosis, there is a paucity of evidence available to make recommendations in this patient population.

Engineering immunomodulatory and osteoinductive implant surfaces via mussel adhesion-mediated ion coordination and molecular clicking

Immune response and new tissue formation are important aspects of tissue repair. However, only a single aspect is generally considered in previous biomedical interventions, and the synergistic effect is unclear. Here, a dual-effect coating with immobilized immunomodulatory metal ions (e.g., Zn2+) and osteoinductive growth factors (e.g., BMP-2 peptide) is designed via mussel adhesion-mediated ion coordination and molecular clicking strategy. Compared to the bare TiO2 group, Zn2+ can increase M2 macrophage recruitment by up to 92.5% in vivo and upregulate the expression of M2 cytokine IL-10 by 84.5%; while the dual-effect of Zn2+ and BMP-2 peptide can increase M2 macrophages recruitment by up to 124.7% in vivo and upregulate the expression of M2 cytokine IL-10 by 171%. These benefits eventually significantly enhance bone-implant mechanical fixation (203.3 N) and new bone ingrowth (82.1%) compared to the bare TiO2 (98.6 N and 45.1%, respectively). Taken together, the dual-effect coating can be utilized to synergistically modulate the osteoimmune microenvironment at the bone-implant interface, enhancing bone regeneration for successful implantation.

CHARACTERIZATION OF 3D-PRINTING FILAMENT WITH EXTRUDER MELTING TEMPERATURE VARIATION FOR BONE IMPLANT FROM KUPANG SHELL

<p><em>The number of bone damage in Indonesia continues to increase. Bone implant is one of the medical treatment methods performed on bone damage. Organic and non-organic materials can be used as bone implants. Non-organic materials are stronger, but not biocompatible, while organic materials are biocompatible, but brittle. The addition of polycaprolactone polymer (PCL) can increase the mechanical strength of 3D printing bone implant filaments. Extruder melting temperature is one of the factors that affect the quality of PCL-HAp filaments for bone implants. Studies related to temperature variations in PCL-HAp materials have not been widely studied. Therefore, it is necessary to characterize 3D printing filaments with variations in the melting temperature of the extruder as bone implants from mussel shells with temperature variables of 65^oC, 75^oC, and 85^oC. From this study, the optimum point was found at the melting extruder temperature of 75^oC with the results of a diameter of 1.810 and mechanical strength which showed an increase in tensile strength and Young's modulus of PCL-HAp composite in all variables compared to pure PCL. The SEM test showed a rough surface on the filaments that could increase the proliferation and adhesion of good cells for the growth of bone tissue.</em></p>

Microstructure and Mechanical Properties of Inverse Nanocomposite Made from Polylactide and Hydroxyapatite Nanoparticles

Polymer nanocomposites have been extensively researched for a variety of applications, including medical osteoregenerative implants. However, no satisfactory solution has yet been found for regeneration of big, and so-called critical, bone losses. The requirement is to create a resorbable material which is characterised by optimum porosity, sufficient strength, and elastic modulus matching that of the bone, thus stimulating tissue regrowth. Inverse nanocomposites, where the ceramic content is larger than the polymer content, are a recent development. Due to their high ceramic content, they may offer the required properties for bone implants, currently not met by polymer nanocomposites with a small number of nanoparticles. This paper presents inverse nanocomposites composed of bioresorbable nano crystalline hydroxyapatite (HAP NPs) and polylactide (PLLA), produced by cryomilling and a warm isostatic pressing method. The following compositions were studied: 25%, 50%, and 75% of HAP NPs by volume. The mechanical properties and structure of these composites were examined. It was discovered that 50% volume content was optimal as far as compressive strength and porosity are concerned. The inverse nanocomposite with 50% nanoceramics volume displayed a compressive strength of 99 ± 4 MPa, a contact angle of 50°, and 25% porosity, which make this material a candidate for further studies as a bioresorbable bone implant.

Reversal of Osseointegration as a Novel Perspective for the Removal of Failed Dental Implants: A Review of Five Patented Methods

Osseointegration is the basis of successful dental implantology and the foundation of cementless arthroplasty and the osseointegrated percutaneous prosthetic system. Osseointegration has been considered irreversible thus far. However, controlled heating or cooling of dental implants could selectively damage the bone at the bone–implant interface, causing the reversal of osseointegration or “osseodisintegration”. This review compares five methods for implant removal, published as patent documents between 2010 and 2018, which have not yet been discussed in the scientific literature. We describe these methods and evaluate their potential for reversing osseointegration. The five methods have several technical and methodological similarities: all methods include a handpiece, a connecting device for coronal access, and a controlling device, as well as the application of mechanical and/or thermal energy. The proposed method of quantifying the temperature with a sensor as the sole means for regulating the process seems inadequate. A database used in one of the methods, however, allows a more precise correlation between a selected implant and the energy needed for its removal, thus avoiding unnecessary trauma to the patient. A flapless, microinvasive, and bone-conserving approach for removing failed dental implants, facilitating successful reimplantation, would benefit dental implantology. These methods could be adapted to cementless medical implants and osseointegrated percutaneous prosthetics. However, for some of the methods discussed herein, further research may be necessary.

The Effect of Design Parameters on Mechanical Characteristics of Porous CoCrMo Scaffold Manufactured by Additive Manufacturing

Metallic orthopedic implants to replace or generate lost bones caused by traumatic road traffic injuries often failed prematurely after surgery. Bone resorption caused by stress shielding of metallic implants became a main concern as it can potentially lead to bone implant failure. Metallic scaffold designed in porous structures fabricated using additive manufacturing (AM) are widely used as bone implant, since the elastic modulus of the scaffolds can easily tailored according to the bone properties, and the large surfaces are beneficial to cell in-growth. The microarchitecture of scaffold can control their mechanical and biological properties, but it is found that there is lack of systematic approach to select a cell topology with full perspective requirements of bone implant. This paper presents a systematic approach of design space mapping for two CoCrMo unit cell shapes namely square and diamond to understand the relationship between geometrical parameters with additive manufacturing limitation, mechanical and bone ingrowth requirements. The compressive response of the components was simulated by finite element analysis and the influence of design parameters on the scaffold behaviour was compared theoretically with Gibson and Ashby model. The FEA give prediction for effective elastic modulus of 3 GPa to 4.8 GPa for diamond type and range of 6 GPa to 29 GPa for square type. Experimental results showed accurate prediction of compression elastic modulus with average error of 13% for diamond type and 35% for square type respectively. The significance of the methodology and the results showed that different design parameters of the structures can play a major role in the mechanical behaviour of the metallic scaffold.

Sustained Release of Vitamin D3 Enhanced Osseointegration Capacity: An Experimental Sheep Study

This study aimed to investigate the effect of sustained-release vitamin D loaded in poly-lactic acid (PLA) nanoparticles and applied to grafting materials around titanium (ti) dental implants. A total of 48 implants were inserted into the standardized bone defects created in the iliac crest of 6 sheep, divided into 4 different experimental sites (empty control, autografted, xenografted, and autograft + xenografted). Vitamin D3, which was encapsulated by PLA nanoparticles, was prepared and applied in half of the defects and left to heal for 3 and 6 weeks. New bone formation (NBF%) and bone-implant contact (BIC%) values were evaluated by histologic and histomorphometric analyses (P < 0.05). Nanoparticles with a yield of 80.30% ± 2.14% and high encapsulation efficiency of 72.99% ± 2.20% were achieved. In all sections, osseointegration was observed, with no signs of inflammation, necrosis, or foreign body reaction. NBF% and BIC% were significantly higher in vitamin D3–loaded groups (P < 0.001). In both healing periods, the highest NBF% and BIC% have been recorded in the autograft + xenograft groups. (For the respective third and sixth weeks: the NBF% was 49.63 ± 1.53 and 74.25 ± 0.96, and BIC% was 54.26 ± 0.66 and 82.59 ± 2.09, respectively; P < 0.001). Sustained-release of vitamin D loaded into the PLA system demonstrated high biocompatibility, favorable sustained release of vitamin D3, and improved NBF% and BIC% around ti implants placed in box-shaped sheep iliac crest defects. Further investigations are required for their clinical applicability.