How Is Bone Regeneration Influenced by Polymer Membranes? Insight into the Histological and Radiological Point of View in the Literature.

The aim of this study was to analyze published works that investigate the in vivo bone regeneration capacity of polymeric membranes loaded with active substances and growth factors. This scoping review's purpose was to highlight the histological and radiological interpretation of the locally produced effects of the polymer membranes studied so far. For the selection of the articles, a search was made in the PubMed and ScienceDirect databases, according to the PRISMA algorithm, for research/clinical trial type studies.

Synthesis of Branched α-Olefins via Trimerization and Tetramerization of Ethylene.

α-Olefins are very important bulk and fine chemicals and their synthesis from ethylene, an abundantly available and inexpensive feedstock, is highly attractive. Unfortunately, the direct or on-purpose synthesis of olefins from ethylene is limited to three examples, 1-butene, 1-hexene, and 1-octene, all having a linear structure. Herein, the direct synthesis of 3-methylenepentane and 4-ethylhex-1-ene, branched trimerization, and tetramerization products of ethylene, respectively, is reported.

A Closed-Loop Recyclable Low-Density Polyethylene.

Low-density polyethylene (LDPE) is one of the most important plastics, which is produced unfortunately under extreme conditions. In addition, it consists of robust aliphatic C─C bonds which are challenging to cleave for plastic recycling. A low-pressure and -temperature (p = 2 bara, T = 70 °C) macromonomer-based synthesis of long chain branched polyethylene is reported.

The Highly Controlled and Efficient Polymerization of Ethylene.

The highly controlled and efficient polymerization of ethylene is a very attractive but challenging target. Herein we report on a Coordinative Chain Transfer Polymerization catalyst, which combines a high degree of control and very high activity in ethylene oligo- or polymerization with extremely high chain transfer agent (triethylaluminum) to catalyst ratios (catalyst economy). Our Zr catalyst is long living and temperature stable.

Elongation and branching of α-olefins by two ethylene molecules.

α-Olefins are important starting materials for the production of plastics, pharmaceuticals, and fine and bulk chemicals. However, the selective synthesis of α-olefins from ethylene, a highly abundant and inexpensive feedstock, is restricted, and thus a broadly applicable selective α-olefin synthesis using ethylene is highly desirable. Here, we report the catalytic reaction of an α-olefin with two ethylene molecules.

Degradation of low-density polyethylene to nanoplastic particles by accelerated weathering.

When plastics enter the environment, they are exposed to abiotic and biotic impacts, resulting in degradation and the formation of micro- and nanoplastic. Microplastic is ubiquitous in every environmental compartment. Nevertheless, the underlying degradation processes are not yet fully understood.

A Standardized -Force Allows the Preparation of Similar Platelet-Rich Fibrin Qualities Regardless of Rotor Angle.

Platelet-rich fibrin (PRF) is an autologous blood concentrate that supports tissue regeneration. The effect of the centrifuge rotor angle in the fabrication of PRF is still not fully elucidated. The hypothesis of this study is: When applying the same -force (relative centrifugal force [RCF]) and centrifugation time, PRF components and bioactivity are not modified using either a swing-out rotor or a fixed angle rotor.

Engaging a polylactide copolymer in oral tissue regeneration: first validation of Suprathel for guided epithelial and osseous healing.

The present study investigated the capacity of Suprathel (a copolymer membrane, so far validated for skin regeneration) to also regenerate oral tissue - mucosa and bone, by comparing this biomaterial, in a split-mouth rabbit model, to Mucoderm, a xenogeneic collagen matrix certified for keratinized oral mucosa healing. The clinical reason behind this experimental animal model was to determine whether the benefits of this advanced skin regeneration product (Suprathel) could be conveyed for future evaluation in clinical trials of oral tissue regeneration in humans. The outcomes of this study validated the use of Suprathel, a terpolymer of polylactide with trimethylene carbonate and ε-caprolactone, for stimulation of oral epithelium and alveolar bone regeneration in rabbits.

Understanding the basis of medical use of poly-lactide-based resorbable polymers and composites - a review of the clinical and metabolic impact.

This review intended to comparatively explain and present the most important medical use and biological impact of poly-lactides and lactide-based composites. The utilization and degradation of compounds based on lactic acid and polylactides is described in detail. Understanding the metabolism and degradation phenomenon and the factors that potentially influence it is key to modulating their properties as well as their characteristics driven from the fabrication procedures and the fields of use.

Prevalence of Temporomandibular Disorder Symptoms among Orthognathic Patients in Southern Germany: Retrospective Study.

This study investigated the prevalence of temporomandibular disorder (TMD) among patients before and after orthognathic surgery and assessed the effect of orthognathic surgery on each of the TMD symptoms (clicking, pain, crepitus, and MRI findings). A sample of 100 consecutive patients undergoing bimaxillary surgery for correction of craniofacial deformities (31 male and 69 female), with ages ranging between 17 and 58 years (mean age: 27.7 ± 9.

A broadly tunable synthesis of linear α-olefins.

The catalytic synthesis of linear α-olefins from ethylene is a technologically highly important reaction. A synthesis concept allowing the formation of selective products and various linear α-olefin product distributions with one catalyst system is highly desirable. Here, we describe a trimetallic catalyst system (Y-Al-Ni) consisting of a rare earth metal polymerization catalyst which can mediate coordinative chain transfer to triethylaluminum combined with a simultaneously operating nickel β-hydride elimination/transfer catalyst.

In quest of optimal drug-supported and targeted bone regeneration in the cranio facial area: a review of techniques and methods.

Craniofacial bone structures are frequently and extensively affected by trauma, tumors, bone infections and diseases, age-related degeneration and atrophy, as well as congenital malformations and developmental anomalies. Consequently, severe encumbrances are imposed on both patients and healthcare systems due to the complex and lengthy treatment duration. The search for alternative methods to bone transplantation, grafting and the use of homologous or heterologous bone thus responds to one of the most significant problems in human medicine.

Conservative treatment and implant rehabilitation of the mandible in a case of craniofacial fibrous dysplasia: a case report.

We present a case of implant rehabilitation of the mandible in a young patient affected by craniofacial fibrous dysplasia. A computed tomography scan showed involvement of the left orbital contour and left maxilla, with total involvement of the mandible. We performed conservative surgical treatment from 2004 to 2011 to reconstruct and recontour the orbital and mandible region.

SiCN nanofibers with a diameter below 100 nm synthesized via concerted block copolymer formation, microphase separation, and crosslinking.

SiCN fibers with a mean diameter of 50 nm and an aspect ratio of up to 100 are produced in a two-step process by R. Kempe and co-workers. The key step to fabricate the longitudinal and cross-sectional views of the mesofibers shown here is a concerted block-copolymer synthesis, microphase separation, and cross linking at 140 °C followed by pyrolysis at 1100 °C.

Tailored nanostructuring of end-group-functionalized high-density polyethylene synthesized by an efficient catalytic version of Ziegler's "Aufbaureaktion".

Monoguanidinato titanium complexes are efficient catalysts to make OH end-group-functionalized polyethylene (PE-OH) by a catalyzed version of Ziegler's "Aufbaureaktion". This PE-OH can be structured to mesoporous polyethylene or polyethylene nanofibers/ribbons through diblock copolymer synthesis, microphase separation, and etching of the sacrificial polylactide block.

Highly active titanium-based olefin polymerization catalysts bearing bulky aminopyridinato ligands.

A series of titanium complexes have been prepared using either salt metathesis or amine elimination reactions. Reacting the potassium salt of Ap*H {Ap*H = N-(2,6-diisopropylphenyl)-[6-(2,4,6-triisopropylphenyl)pyridin-2-yl]amine} (1) with [TiCl(4)(THF)(2)] results in the formation of a nucleophilic ring-opening product of the coordinated tetrahydrofuran (THF) ligand [Ap*TiCl(2)(OC(4)H(8)Cl)] (7). Alkylation with benzylmagnesium chloride gave rise to the corresponding benzyl complex [Ap*TiBn(2)(OC(4)H(8)Cl)] (8).

Transverse stability of 3-piece Le Fort I osteotomies.

Purpose: The transverse dentoalveolar and skeletal stability of multipiece Le Fort I osteotomies with 3 different techniques was investigated.

Materials And Methods: The records of 87 patients undergoing bimaxillary osteotomies with 3-piece Le Fort I osteotomy were evaluated. According to the surgical technique of maxillary expansion, the subjects were divided into 3 groups: unilateral palatal osteotomy (group A), bilateral palatal osteotomy (group B), and unilateral palatal osteotomy with fixation of the palatal vault with a resorbable plate (group C).

An efficient yttrium catalysed version of the "Aufbaureaktion" for the synthesis of terminal functionalised polyethylene.

The cationic lanthanoid alkyl complexes (NCN)YR(THF)(+) (R = CH(2)SiMe(3)) bearing a NCN-ligand based on N,N'-bis(2,6-diisopropylphenyl)-benzamidine (AmH), N-[6-(2,4,6-triisopropyl-phenyl)-pyridin-2-yl]-(2,6-diisopropyl)aniline (ApH) or 1,3-bis(2,6-diisopropylphenyl)-2,2-dimethylguanidine (GuaH) combined with an excess of trialkyl aluminium compounds (AlR(3); R = Et, iso-Bu, n-Oct) are efficient catalysts for the highly controlled coordinative chain transfer polymerisation (CCTP) of ethylene, a catalysed version of the "Aufbaureaktion". The aluminium terminated polyethylene (PE) can be oxidised to yield long chain alcohols which are the basis for a diverse polymer chemistry.

Stability of Le Fort I osteotomy in bimaxillary osteotomies: single-piece versus 3-piece maxilla.

Purpose: The aim of the present study was to investigate the effect of segmentation on the stability of Le Fort I osteotomies in bimaxillary procedures.

Patients And Methods: One hundred twenty patients undergoing bimaxillary osteotomies (60 single-piece maxilla, 60 3-piece maxilla) were included in the study. Cephalometric analysis was performed before surgery (T1), immediately after surgery (T2), and after a follow-up of 12 to 15 months (T3).

Changes in bone blood flow in segmental LeFort I osteotomies.

Objective: The aim of the present study was to investigate the effect of segmentation and different movements of the segments in LeFort I osteotomies on the bone blood flow (BBF).

Material And Methods: The study sample of the prospective cohort study was composed of subjects scheduled to undergo 3-piece LeFort I osteotomies and simultaneous BSSO for correction of developmental skeletal deformities. The primary predictor variables were: time (T1, before LeFort I osteotomy; T2, after LeFort I osteotomy; T3, after segmentation and fixation of the maxilla) and magnitude of maxillary movement in the sagittal, vertical, and transverse planes measured in millimeters (mm).

Factors for intraoperative blood loss in bimaxillary osteotomies.

Purpose: Autologous blood donation is not routinely recommended for all cases of orthognathic surgery. The aim of this study was to evaluate the factors for blood loss during bimaxillary osteotomies that might indicate preoperative blood donation.

Patients And Methods: In a prospective study, 127 consecutive patients undergoing bimaxillary surgery within a 14-month period were examined for hemoglobin and hematocrit reduction.

Reversible chain transfer between organoyttrium cations and aluminum: synthesis of aluminum-terminated polyethylene with extremely narrow molecular-weight distribution.

Aminopyridinato-ligand-stabilized organoyttrium cations are accessible in very good yield through alkane elimination from trialkyl yttrium complexes with sterically demanding aminopyridines, followed by abstraction of one of the two alkyl functions using ammonium borates. At 80 degrees C and in the presence of small amounts of aluminum alkyl compounds, very high ethylene polymerization activities are observed if very bulky aminopyridinato ligands are used. During these polymerizations a reversible polyethylene chain transfer is observed between the organoyttrium cations and aluminum alkyls.

Distraction osteogenesis of the mandible: evaluation of callus distraction by B-scan ultrasonography.

Introduction: Distraction osteogenesis is a new and reliable technique for lengthening of hard and soft tissue in cranio-maxillofacial surgery. Since its first applications, X-rays were often the preferred diagnostic method to monitor this treatment. Apart from adding an additional radiation dose, analysis cannot detect and follow the osteogenic process in the distraction gap on the one hand, nor can it evaluate the soft tissue around the distracted area.