The Dilemma of Reconstructive Material Choice for Orbital Floor Fracture: A Narrative Review

The aim of this study is to present a narrative review of the properties of materials currently used for orbital floor reconstruction. Orbital floor fractures, due to their complex anatomy, physiology, and aesthetic concerns, pose complexities regarding management. Since the 1950s, a myriad of materials has been used to reconstruct orbital floor fractures. This narrative review synthesises the findings of literature retrieved from search of PubMed, Web of Science, and Google Scholar databases. This narrative review was conducted of 66 studies on reconstructive materials. Ideal material properties are that they are resorbable, osteoconductive, resistant to infection, minimally reactive, do not induce capsule formation, allow for bony ingrowth, are cheap, and readily available. Autologous implants provide reliable, lifelong, and biocompatible material choices. Allogenic materials pose a threat of catastrophic disease transmission. Newer alloplastic materials have gained popularity. Consideration must be made when deliberating the use of permanent alloplastic materials that are a foreign body with potential body interactions, or the use of resorbable alloplastic materials failing to provide adequate support for orbital contents. It is vital that surgeons have an appropriate knowledge of materials so that they are used appropriately and reduce the risks of complications.

Basic Biomechanics for Craniofacial Surgeons: The Responses of Alloplastic Materials and Living Tissues to Mechanical Forces

Many terms such as twist, compress, bend, and stretch, describe how materials behave when subjected to mechanical stresses. Subjective adjectives to describe the property of materials such as hard or brittle are imprecise and impedes proper understanding of important principles needed in planning and performing surgical treatments. The viability of tissue and time dependent variables effect healing and compound the issue. Some parameters are time dependent (strain rate), while others are nearly independent of time (Young’s modulus). The craniofacial skeleton and enveloping soft tissues are viscoelastic composite materials which undergo time-dependent changes upon loading. The ability to remodel and respond to environmental changes makes them “smart,” reenforcing where needed and removing where not required based on a set of predetermined upper and lower thresholds. This mini review has 7 sections on engineering principles that underpin craniofacial surgery: (1) The general concept of mechanics: load, force, stress, strain, compression, tension, shear, stress-strain curves and values derived from them such as Young’s modulus, fatigue damage, and load- shearing. (2) Material properties of bone and suture and structural engineering of the craniofacial skeleton in normal and pathological conditions. (3) Fixation using wires, screws, and plates: anatomy and function of screws and plates, locking plates, lag screws, internal and external fixators. (4) Biomechanics of distraction osteogenesis and the effects of radiation. (5) Finite element analysis and other computational biomechanical tools. (6) Virtual surgical planning, cutting guides, and intra-operative navigation. (7) Tissue engineering: design goals, criteria, and constraints. An appreciation and understanding of these biomechanical principles will help craniofacial surgeons to facilitate intrinsic optimization and better treat complex morphological problems, helping one achieve the most favorable and durable results. The biological responses to mechanical stress are extremely important as well, but due to space constraints, they will be the subject of a separate dedicated review.

Effects of Pentagonal Pore Sizes in the Zinc Hydroxyapatite Parietal-Temporal Implant

To reconstruct the fractured skull, affected patients are advised to undergo cranioplasty, which is a surgical procedure to repair the cranial defect by implanting materials such as autologous bone grafts or synthetic alloplastic materials. The use of synthetic alloplastic materials such as hydroxyapatite (HA) has been widely accepted due to their biocompatibility and suitability for larger cranial defects. The zinc hydroxyapatite (ZnHA) material is favourable as HA mimics 60% of the actual human bone, whereas zinc helps to improve its biomechanical properties. The purpose of this study is to construct the ZnHA cranial implant with different pore sizes of 600, 900, and 1200 µm in pentagonal shapes and to study its mechanical performance. At the end of the research, it was found that the implant with a pore size of 900 µm is the most appropriate implant to be utilized without affecting its mechanical performance. Aspects such as the deformation and von Mises stress are discussed to assist on the development of the ZnHA cranial implant. Keywords — Biomechanical analysis, cranial implant, finite element analysis, pore size, zinc hydroxyapatite

Reconstruction of the Mandibular Condyle

The mandibular condyle is an integral structure in the temporomandibular joint (TMJ) serving not only as the hinge point for mandibular opening, but also facilitating mandibular growth and contributing to facial aesthetics. Significant compromise of the TMJ can be debilitating functionally, psychologically, and aesthetically. Reconstruction of the mandibular condyle is rarely straightforward. Multiple considerations must be accounted for when preparing for condylar reconstruction such as ensuring eradication of all chronically diseased or infected bone, proving clear oncologic margins following tumor resection, or achieving stability of the surrounding architecture in the setting of a traumatic injury. Today, there is not one single gold-standard reconstructive method or material; ongoing investigation and innovation continue to improve and transform condylar reconstruction. Herein, we review methods of condylar reconstruction focusing on autologous and alloplastic materials, surgical techniques, and recent technological advances.

Increased Elasticity Modulus of Polymeric Materials Is a Source of Surface Alterations in the Human Body

The introduction of alloplastic materials (meshes) in hernia surgery has improved patient outcome by a radical reduction of hernia recurrence rate, but discussion about the biocompatibility of these implanted materials continues since observations of surface alterations of polypropylene and other alloplastic materials were published. This study intends to investigate if additives supplemented to alloplastic mesh materials merge into the solution and become analyzable. Four polypropylene and one polyester alloplastic material were incubated in different media for three weeks: distilled water, saline solution, urea solution, formalin, and hydrogen peroxide. No swelling or other changes were observed. Infrared spectroscopy scanning of incubated alloplastic materials and NMR studies of extracted solutions were performed to investigate loss of plasticizers. The surface of the mesh materials did not show any alterations independent of the incubation medium. FT-IR spectra before and after incubation did not show any differences. NMR spectra showed leaching of different plasticizers (PEG, sterically hindered phenols, thioester), of which there was more for polypropylene less for polyester. This could be the reason for the loss of elasticity of the alloplastic materials with consecutive physically induced surface alterations. A mixture of chemical reactions (oxidative stress with additive leaching from polymer fiber) in connection with physical alterations (increased elasticity modulus by loss of plasticizers) seem to be a source of these PP and PE alterations.

Quo Vadis Urogynecology 2020 – Innovative Treatment Concepts for Urinary Incontinence and Pelvic Organ Prolapse

The current treatment for urinary incontinence and pelvic organ prolapse includes a wide range of innovative options for conservative and surgical therapies. Initial treatment for pelvic floor dysfunction consists of individualized topical estrogen therapy and professional training in passive and active pelvic floor exercises with biofeedback, vibration plates, and a number of vaginal devices. The method of choice for the surgical repair of stress urinary incontinence consists of placement of a suburethral sling. A number of different methods are available for the surgical treatment of pelvic organ prolapse using either a vaginal or an abdominal/endoscopic approach and autologous tissue or alloplastic materials for reconstruction. This makes it possible to achieve optimal reconstruction both in younger women, many of them affected by postpartum trauma, and in older women later in their lives. Treatment includes assessing the patientʼs state of health and anesthetic risk profile. It is important to determine a realistically achievable patient preference after explaining the individualized concept and presenting the alternative surgical options.

Current and advanced nanomaterials in dentistry as regeneration agents: an update

: In modern dentistry, nanomaterials have strengthened their foothold among tissue engineering strategies for treating bone and dental defects due to a variety of reasons, including trauma and tumors. Besides their finest physiochemical features, the biomimetic characteristics of nanomaterials promote cell growth and stimulate tissue regeneration. The single units of these chemical substances are small-sized particles, usually between 1 to 100 nm, in an unbound state. This unbound state allows particles to constitute aggregates with one or more external dimensions and provide a high surface area. Nanomaterials have brought advances in regenerative dentistry from the laboratory to clinical practice. They are particularly used for creating novel biomimetic nanostructures for cell regeneration, targeted treatment, diagnostics, imaging, and the production of dental materials. In regenerative dentistry, nanostructured matrices and scaffolds help control cell differentiation better. Nanomaterials recapitulate the natural dental architecture and structure and form functional tissues better compared to the conventional autologous and allogenic tissues or alloplastic materials. The reason is that novel nanostructures provide an improved platform for supporting and regulating cell proliferation, differentiation, and migration. In restorative dentistry, nanomaterials are widely used in constructing nanocomposite resins, bonding agents, endodontic sealants, coating materials, and bioceramics. They are also used for making daily dental hygiene products such as mouth rinses. The present article classifies nanostructures and nanocarriers in addition to reviewing their design and applications for bone and dental regeneration.