Supposedly identical microplastic particles substantially differ in their material properties influencing particle-cell interactions and cellular responses.

Microplastics and its putative adverse effects on environmental and human health increasingly gain scientific and public attention. Systematic studies on the effects of microplastics are currently hampered by using rather poorly characterised particles, leading to contradictory results for the same particle type. Here, surface properties and chemical composition of two commercially available nominally identical polystyrene microparticles, frequently used in effect studies, were characterised. We show distinct differences in monomer content, ζ-potentials and surface charge densities. Cells exposed to particles showing a lower ζ-potential and a higher monomer content displayed a higher number of particle-cell-interactions and consequently a decrease in cell metabolism and proliferation, especially at higher particle concentrations. Our study emphasises that no general statements can be made about the effects of microplastics, not even for the same polymer type in the same size class, unless the physicochemical properties are well characterised.

Effect of bimaxillary orthognathic surgery on dysfunction of the temporomandibular joint: a retrospective study of 500 consecutive cases.

We investigated the effect of bimaxillary orthognathic surgery on symptoms in the temporomandibular joint (TMJ) and predictive factors for postoperative dysfunction. A total of 500 patients with different craniofacial deformities who were having bimaxillary orthognathic surgery were assessed for overjet, overbite, maximal mouth opening, maximal protrusion, maximal lateral movement to both sides, and symptoms of TMJ dysfunction (pain on palpation, clicking, or crepitus) before operation and one year postoperatively. The panoramic radiographs taken on the same dates were assessed for reduction in the height of the ramus. Other variables were age, sex, segmentation of the maxilla, and additional genioplasty. Changes in the symptoms of dysfunction were investigated with the McNemar test. Measurements of the maximum mandibular movements taken preoperatively and postoperatively were compared using the paired t test. Multivariate logistic regression was used to assess the influence of the variables on symptoms preoperatively and postoperatively. The effect of occlusal stability (overjet and overbite) on postoperative symptoms in the TMJ was investigated with the unpaired t test. Women and class II patients had significantly more pain on palpation preoperatively, and a significant reduction in pain on palpation and clicking after operation. Predictive factors were preoperative crepitus for postoperative pain, and preoperative clicking for postoperative clicking. Patients with and without symptoms showed no significant differences in overjet and overbite postoperatively. Condylar resorption was found in 29 patients (5.8 %), and only 14 of them had symptoms in the TMJ. In patients with no preoperative symptoms or radiological abnormalities of the condyle, condylar resorption was rare (0.8 %). Orthognathic surgery has a beneficial effect on dysfunction of the TMJ as it reduces pain and clicking considerably. Patients should be informed, however, that TMJ disorders could still develop even if they had no symptoms preoperatively.

The effect of distraction rate on bone histological and histomorphometrical properties in an ovine mandible model.

UNLABELLED: Lengthening the mandible by distraction osteogenesis (DO) is nowadays a well-recognized technique in maxillofacial surgery. This study compared two different distraction rates and evaluated histological and histomorphometrical properties of the distracted bone in an experimental ovine mandible model with the goal of elaborating a universally accepted distraction protocol. STUDY DESIGN: Tissue blocks of regenerated bone were harvested from twelve young adult sheep. DO was performed on the mandibular midline after five days of latency period. The sheep were divided into two groups. The first group underwent activation of 0.8 mm÷day during 12 days resulting in 9.6 mm of new bone while the second group followed a geometric rate pattern of 0.2 mm - three days, 0.4 mm - three days, 0.8 mm - three days and 1.6 mm - three days resulting in 9 mm of new bone. The regenerated bone was histologically and histomorphometrically analyzed after 30, 45 and 60 days of consolidation. The relative osteoid volume (OV÷TTV) was significantly increased in the geometric rate distraction group (p=0.015) comparing with linear distraction group while the relative bone volume (BV÷TTV) was significantly increased in the linear distraction group (p=0.019) compared to the geometric distraction group.

The influence of expansion on intraoperative bone blood flow in multisegmental maxillary osteotomies: an experimental study.

The aim of the presented study was to investigate the effect of maxillary expansion in multisegmental Le Fort I osteotomies on bone blood flow. Five sheep underwent a three-piece total maxillary osteotomy. Bone blood flow was measured intraoperatively by laser Doppler flowmetry in the premaxilla, the lateral segments and the mandible before osteotomy, after osteotomy and segmentation as well as after 4mm, 8mm and 12mm expansion with a Hyrax screw. A significant reduction in blood flow was seen after osteotomy and segmentation with a factor of 3.10 and between 4mm and 8mm expansion with a factor of 1.81. No significant differences could be found between 0mm and 4mm widening or between 8mm and 12mm widening. These results suggest that expansion of more than 4mm in multisegmental osteotomies enhances the risk of avascular sequelae. As greater maxillary widening has been carried out in many cases without avascular complications, further research on additional factors, influencing the recovery of perfusion, is needed.

Intraoperative blood loss in bimaxillary orthognathic surgery with multisegmental Le Fort I osteotomies and additional procedures.

Autologous blood donation is not currently recommended by most authors for routine bimaxillary osteotomies. There are few data about bimaxillary procedures with multisegmental maxillary osteotomies. Our aim was to investigate the effect of additional osteotomies and iliac crest grafts on operative blood loss. A total of 225 consecutive patients having bimaxillary multisegmental osteotomies during a three-year period (January 2006-January 2009) were examined to see if their haemoglobin concentration and packed cell volume were reduced. The influence of iliac crest grafts, additional osteotomies (genioplasty, malar osteotomy, iliac crest graft, anterior mandibular segmental osteotomy), operating time, age, and sex were assessed. Neither age nor sex influenced blood loss, whereas operating time correlated significantly with reductions in haemoglobin concentration and packed cell volume. Blood loss was significantly higher in the group who had additional procedures (p 0.001 for haemoglobin concentration and packed cell volume) than in the group who had no additional procedures, whereas there were no significant differences among the three subgroups who had additional procedures (additional osteotomies, iliac crest grafts, or both procedures). Four patients who had additional procedures required transfusion, whereas no blood was given in the group who had no additional procedures. Because the transfusion rate was so low, we could make no general recommendation for preoperative blood donation in such cases.

Accuracy of maxillary positioning in bimaxillary surgery.

The aim of the study was to investigate the accuracy of a modified pin system for the vertical control of maxillary repositioning in bimaxillary osteotomies. The preoperative cephalograms of 239 consecutive patients who were to have bimaxillary osteotomies were superimposed on the postoperative films. Planned and observed vertical and horizontal movements of the upper incisor were analysed statistically. The mean deviations of -0.07 mm (95% confidence intervals (CIs) -0.17 to 0.04 mm) for the vertical movement and 0.12 mm (95% CI -0.06 to 0.30 mm) for the horizontal movement did not differ significantly from zero. Comparison of the two variances between intrusion and extrusion of the maxilla did not differ significantly either (p=0.51). These results suggest that the modified pin system for vertical control combined with interocclusal splints provides accurate vertical positioning of the anterior maxilla in orthognathic surgery.

Improved limits on nu(e) emission from mu+ decay.

We investigated mu(+) decays at rest produced at the ISIS beam stop target. Lepton flavor (LF) conservation has been tested by searching for nu(e) via the detection reaction p(nu(e),e(+))n. No nu(e) signal from LF violating mu(+) decays was identified. We extract upper limits of the branching ratio (BR) for the LF violating decay mu(+)-->e(+)+nu(e)+nu(-) compared to the standard model (SM) mu(+)-->e(+)+nu(e)+nu(mu) decay: BR<0.9(1.7) x 10(-3) (90% C.L.) depending on the spectral distribution of nu(e) characterized by the Michel parameter rho=0.75(0.0). These results improve earlier limits by one order of magnitude and restrict extensions of the SM in which nu(e) emission from mu(+) decay is allowed with considerable strength. The decay mu(+)-->e(+)+nu(e)+nu(mu) often proposed as a potential source for the nu(e) signal observed in the LSND experiment can be excluded.

Vertical distraction of a free vascularized fibula flap in a reconstructed hemimandible: case report.

The authors report a case of vertical distraction osteogenesis of a free revascularized fibula flap used to reconstruct an hemimandible lost as a result of a gunshot injury. The reconstruction procedure and the distraction protocol are described; clinical and radiological results are presented. The vertical discrepancy between the fibula and the native right hemimandible was corrected.