Nanosilver/DCOIT-containing surface coating effectively and constantly reduces microbial load in emergency room surfaces

BACKGROUND

Colonization of near-patient surfaces in hospitals plays an important role as a source of healthcare-associated infections. Routine disinfection methods only result in short-term elimination of pathogens.

AIM

To investigate the efficiency of a newly developed antimicrobial coating containing nanosilver in long-term reduction of bacterial burden in hospital surfaces to close the gap between routine disinfection cycles.

METHODS

In this prospective, double-blinded trial, frequently touched surfaces of a routinely used treatment room in an emergency unit of a level-I hospital were treated with a surface coating (nanosilver/DCOIT-coated surface, NCS) containing nanosilver particles and another organic biocidal agent (4,5-dichloro-2-octyl-4-isothiazolin-3-one, DCOIT), whereas surfaces of another room were treated with a coating missing both the nanosilver- and DCOIT-containing ingredient and served as control. Bacterial contamination of the surfaces was examined using contact plates and liquid-based swabs daily for a total trial duration of 90 days. After incubation, total microbial counts and species were assessed.

FINDINGS

In a total of 2880 antimicrobial samples, a significant reduction of the overall bacterial load was observed in the NCS room (median: 0.31 cfu/cm²; interquartile range: 0.00-1.13) compared with the control coated surfaces (0.69 cfu/cm²; 0.06-2.00; P < 0.001). The nanosilver- and DCOIT-containing surface coating reduced the relative risk of a critical bacterial load (defined as >5 cfu/cm²) by 60% (odds ratio 0.38, P < 0.001). No significant difference in species distribution was detected between NCS and control group.

CONCLUSION

Nanosilver-/DCOIT-containing surface coating has shown efficiency for sustainable reduction of bacterial load of frequently touched surfaces in a clinical setting.

New quantitative automated model to simulate bacterial dissemination in human tissue during irrigation of contaminated wounds

This study presents a simple and cost-effective model using microparticles to simulate the bacterial distribution pattern in soft tissue after low- and high-pressure irrigation. Silica coated iron microparticles [comparable diameter (1 µm) and weight (0.8333 pg) to Staphylococcus aureus] were applied to the surface of twenty fresh human muscle tissue samples in two amputated lower legs. Particle dissemination into deep tissue layers as an undesired side effect was investigated in four measuring fields as positive control (PC) as well as after performing pulsatile high-pressure (HP, 8 measuring fields) and low-pressure flushing (LP, 8 measuring fields). Five biopsies were taken out of each measuring field to get a total number of 100 biopsies. After histological and digital image processing, the specimens were analysed, and all incomplete sections were excluded. A special detection algorithm was parameterised using the open source bioimage analysis software QuPath. The application of this detection algorithm enabled automated counting and detection of the particles with a sensitivity of 95 % compared to manual counts. Statistical analysis revealed significant differences (p < 0.05) in our three different sample groups: HP (M = 1608, S = 302), LP (M = 2176, SD = 609) and PC (M = 4011, SD = 686). While both HP and LP flushing techniques are able to reduce the number of bacteria, a higher effectiveness is shown for HP irrigation. Nevertheless, a challenge for the validity of the study is the use of dead tissue and therefore a possible negative influence of high-pressure irrigation on tissue healing and further dispersion of particles cannot be evaluated.

Probing stress relaxation behavior in glassy methacrylate networks containing thio-carbamate additives

The incorporation of thiourethane prepolymer (TU) into either the organic phase or as a surface treatment for filler particles in composites reduces polymerization stress and improves fracture toughness. The aim of this study was to gain insight into the influence of the inclusion of thiourethanes on the resulting network of methacrylate-based materials polymerized via free-radical mechanisms. Dynamic mechanical analysis was used to elucidate network parameters and potential stress relaxation behavior of these networks. TU oligomers were synthesized using a combination of trimethylol-tris-3-mercaptopropionate and dicyclohexylmethane 4,4'-diisocyanate and added into composite formulations at 20 wt% replacing part of the organic matrix and/or as TU-silanes used to functionalize filler particles (TU-matrix, TU-Sil or TU-matrix/sil). Materials not containing any form of TU were used as the control (in those cases, 3-(trimethoxysilyl)propyl methacrylate was used as the silane agent). Filler was added at 50 wt%. Degree of conversion was evaluated by near-IR spectroscopy, mechanical properties by 3-point bending and rotational rheometry. Dynamic mechanical analysis was used to obtain network parameters (glass transition temperature (Tg), storage modulus, cross-link density, and breadth of tan delta a proxy for network homogeneity - temperature sweep experiments) and to evaluate the potential for network relaxation (stress relaxation). TU-containing formulations showed 10% higher DC than the control. The time to reach storage/loss modulus crossover in the rheometer experiments was significantly longer for TU-matrix and TU-matrix/sil in comparison with the control (21.6, 27.9, and 5.1 s, respectively). TU-matrix and TU-matrix/sil presented significant lower Tg than the control (151.5, 153.8, and 161.3 °C, respectively). There were no statistical differences among the groups in terms of shear modulus, cross-link density, breadth of tan delta, flexural strength/modulus, and toughness. For at least one group (TU-matrix/sil), the relaxation time was four times faster than for the control at 105 °C. The addition of TU additives into dental polymers resulted in a stark reduction in the stress relaxation time. This behavior, in tandem with the network characterization and mechanical properties seems to indicate the TU networks undergo a variety of reversible associative and dissociative chemical reactions which facilitate enhanced stress relief.

Thiourethane filler functionalization for dental resin composites: Concentration-dependent effects on toughening, stress reduction and depth of cure

OBJECTIVES

The aim of this study was to modify the surface of fillers used in dental composites by the synthesis of two novel thiourethane oligomeric silanes, used to functionalize the silica-containing inorganic particles. Several thiourethane silane concentrations were tested during the silanization process to systematically assess the effect of silane coverage on experimental composite conversion, polymerization stress and fracture toughness.

MATERIALS AND METHODS

Two different thiourethane silanes were synthesized based either on 1,6-hexanediol-diissocynate (HDDI), or 1,3-bis(1-isocyanato-1-methylethyl) benzene (BDI). Conventional 3-(Trimethoxysilyl)propyl methacrylate was used as the control. Glass fillers were silanized with 1, 2 or 4 wt% of each thiourethane silane, then evaluated by thermogravimetrical analysis. Photopolymerizable resin composites were prepared with Bis-GMA/UDMA/TEGDMA and 50 wt% silanized glass filler. Polymerization kinetics and degree of conversion were tested using Near-IR. Bioman was used to test polymerization stress. Data were analyzed with two-way ANOVA/Tukey's test (α = 5%).

RESULTS

The mass of silane coupled to the filler increased with the concentrations of thiourethane in the silanizing solution, as expected. Thiourethane-containing groups exhibited significantly higher degree of conversion compared to control groups, except for BDI 4%. HDDI 4%, BDI 2% and BDI 4% showed significantly lower polymerization stress than control groups. HDDI 4% exhibited significantly higher fracture toughness.

CONCLUSIONS AND CLINICAL SIGNIFICANCE

Novel filler functionalization with thiourethane silanes may be a promising alternative for improving dental composites properties by significantly increasing the degree of conversion, fracture toughness and reducing the polymerization stress.

Trimers Conjugated to Fibrin Hydrogels Promote Salivary Gland Function

New strategies for tissue engineering have great potential for restoring and revitalizing impaired tissues and organs, including the use of smart hydrogels that can be modified to enhance organization and functionality of the salivary glands. For instance, monomers of laminin-111 peptides chemically conjugated to fibrin hydrogel (L_1pM-FH) promote cell cluster formation in vitro and salivary gland regeneration in vivo when compared with fibrin hydrogel (FH) alone; however, L_1pM-FH produce only weak expression of acinar differentiation markers in vivo (e.g., aquaporin-5 and transmembrane protein 16). Since previous studies demonstrated that a greater impact can be achieved when trimeric forms were used as compared with monomeric or dimeric forms, we investigated the extent to which trimers of laminin-111 chemically conjugated to FH (L_1pT-FH) can increase the expression of acinar differentiation markers and elevate saliva secretion. In vitro studies using Par-C10 acinar cells demonstrated that when compared with L_1pM-FH, L_1pT-FH induced similar levels of acinar-like cell clustering, polarization, lumen formation, and calcium signaling. To assess the performance of the trimeric complex in vivo, we compared the ability of L_1pM-FH and L_1pT-FH to increase acinar differentiation markers and restore saliva flow rate in a salivary gland wound model of C57BL/6 mice. Our results show that L_1pT-FH applied to wounded mice significantly improved the expression of the acinar differentiation markers and saliva secretion when compared with the monomeric form. Together, these positive effects of L_1pT-FH warrant its future testing in additional models of hyposalivation with the ultimate goal of applying this technology in humans.

Effect of different composite modulation protocols on the conversion and polymerization stress profile of bulk-filled resin restorations

OBJECTIVE

The aim of this in vitro study was to test the effect of different composite modulation protocols (pre-heating, light-curing time and oligomer addition) for bulk filling techniques on resin polymerization stress, intra-pulpal temperature change and degree of conversion.

METHODS

Class I cavities (4mm depth×5mm diameter) were prepared in 48 extracted third molars and divided in 6 groups. Restorations were completed with a single increment, according to the following groups: (1) Filtek Z250XT (room temperature - activated for 20s); (2) Filtek Z250XT (at room temperature - activated for 40s); (3) Filtek Z250XT (pre-heated at 68°C - activated for 20s); (4) Filtek Z250XT (pre-heated at 68°C - activated for 40s); (5) Filtek BulkFill (at room temperature - activated for 20s); (6) Filtek Z250XT (modified by the addition of a thio-urethane oligomer at room temperature - activated for 40s). Acoustic emission test was used as a real-time polymerization stress (PS) assessment. The intra-pulpal temperature change was recorded with a thermocouple and bottom/top degree of conversion (DC) measured by Raman spectroscopy. Data were analyzed with one-way ANOVA/Tukey's test (α=5%).

RESULTS

Pre-heating the resin composite did not influence the intra-pulpal temperature (p=0.077). The thio-urethane-containing composite exhibited significantly less PS, due to a lower number of acoustic events. Groups with pre-heated composites did not result in significantly different PS. Filtek BulkFill and the thio-urethane experimental composite presented significantly higher DC.

SIGNIFICANCE

Resin composite pre-heating was not able to reduce polymerization stress in direct restorations. However, thio-urethane addition to a resin composite could reduce the polymerization stress while improving the DC.

Effect of the photoinitiator system on the polymerization of secondary methacrylamides of systematically varied structure for dental adhesive applications

OBJECTIVE

The aim of this study was to investigate the influence of the photoinitiator system on the polymerization kinetics of methacrylamide-based monomers as alternatives to methacrylates in adhesives dental-based materials.

METHODS

In total, 16 groups were tested. Monofunctional monomers (2-hydroxyethyl methacrylate) - HEMA; (2-hydroxy-1-ethyl methacrylate) -2EMATE, (2-hydroxyethyl methacrylamide) - HEMAM; and (N-(1-hydroxybutan-2-yl) methacrylamide) -2EM; were combined with bifunctional monomers containing the same polymerizing moieties as the monofunctional counterparts (HEMA-BDI; 2EMATE-BDI; HEMAM-BDI; and 2EM-BDI) at 50/50 M ratios. BHT was used as inhibitor (0.1 wt%) and the photoinitiators used were: CQ + EDMAB (0.2/0.8), BAPO (0.2), IVOCERIN (0.2), and DMPA (0.2), in wt%. The polymerization kinetics were monitored using Near-IR spectroscopy (∼6165 cm-1) in real-time while the specimens were photoactivated with a mercury arc lamp (Acticure 2; 320-500 nm, 300 mW/cm2) for 5 min, and maximum rate of polymerization (Rpmax, in %.s-̄1), degree of conversion at Rpmax (DC@Rpmax, in %), and the final degree of conversion (Final DC, in %) were calculated (n = 3). Initial viscosity was measured with an oscillating rheometer (n = 3). Data were analyzed using Two-way ANOVA for the polymerization kinetics and one-way ANOVA for the viscosity. Multiple comparisons were made using the Tukey's test (∝ = 0.05).

RESULTS

There was statistically significant interaction between monomer and photoinitiator (p < 0.001). For the methacrylates groups, the highest Rpmax was observed for HEMA + DMPA and 2EMATE + BAPO. For methacrylamides groups, the highest Rpmax were observed for HEMAM and 2EM, both with DMPA. Final DC was higher for the methacrylate groups, in comparison with methacrylamide groups, independent of the photoinitiators. However, for the methacrylamide groups, the association with BAPO led to the lowest values of DC. In terms of DC@Rpmax, methacrylate-based systems showed significantly higher values than methacrylamide formulations. DMPA and Ivocerin led to higher values than CQ/EDMAB and BAPO in methacrylamide-based compounds. BAPO systems showed de lowest values for both HEMA and HEMAM formulations. For the viscosity (Pa.s), only 2EM had higher values (1.60 ± 0.15) in comparison with all monomers. In conclusion, polymerization kinetics was affected by the photoinitiators for both monomers. Viscosity was significantly increased with the use of secondary methacrylamide.

SIGNIFICANCE

this work demonstrated the feasibility of using newly-synthesized methacrylamide monomers in conjunction with a series of initiator systems already used in commercial materials.

Effect of the addition of thiourethane oligomers on the sol⿿gel composition of BisGMA/TEGDMA polymer networks

OBJECTIVES

Thiourethane oligomers have been shown to increase the fracture toughness and reduce the polymerization stress of methacrylate-based materials. However, network formation has not been elucidated in these materials yet. The aim of this study was to evaluate how the addition of a thiourethane oligomer (TU) influences the sol/gel composition and network structure of methacrylate-based materials using dynamic mechanical analysis and extraction methods.

MATERIALS AND METHODS

BisGMA/TEGDMA at systematically varied mass ratios (20/80 to 80/20wt%) were mixed with pre-polymerized thiourethane oligomers at 0 (control) or 20wt%, synthesized by combining pentaerythritol tetra-3-mercaptopropionate with dicyclohexylmethane 4,4⿲-Diisocyanate, at 1:2 isocyanate:thiol. 0.1wt% of 2,2-Dimethoxy-2-phenylacetophenone was added as the photoinitiator and 0.3wt% of 2,6-di-tert-butyl-4-methylphenol was added as a free radical inhibitor. Disk specimens (0.8ÿ10mm in diameter, n=3) were photoactivated at 270mW/ (320⿿500nm) for 1min. The degree of conversion (DC) was measured in near-IR (˿6165cm⿿1). Specimens were immersed in two different solvents (water for 7 days or dicholoromethane for 48h). Water sorption (WS) and solubility (SL) were obtained according to ISO 4049. The leachates for both solutions were analyzed with 1H-NMR (400MHz, CDCL3). Bar specimens (1ÿ3ÿ25mm, photocured and then post-processed at 180°C for 8h to DC>95%) were subjected to dynamic mechanical analysis (⿿30 to 230°C) to obtain glass transition temperature (Tg), tan delta curves and crosslinking density (ν). Data was analyzed with two-way ANOVA/Tukey⿿s test (95%).

RESULTS

In general, the presence of TU increased the overall conversion. The WS was similar for all groups, but the SL decreased by 2-fold with the addition of the TU oligomer for all compositions, except BisGMA/TEGDMA 80/20. The BisGMA concentration of the leachates increased with increasing BisGMA in the initial mixture, and with the presence of thiourethane. This compositional drift of the gel with the presence of TU was attributed to the preferential dissolution of TEGDMA into the TU network. Tg and ν decreased with the addition of TU, as expected. The addition of TU produced more homogeneous networks, as evidenced by narrower breadth of the tan delta curve.

CONCLUSION

The addition of TU affected the composition of the sol/gel in crosslinked networks, which were more homogeneous and presented 2-fold less potentially toxic leachates than the methacrylate controls.

CLINICAL SIGNIFICANCE

The addition of TU may produce less cytotoxic materials based on the increased conversion and reduced amount of unreacted extractables from its network after water storage.

New Resins for Dental Composites

Restorative composites have evolved significantly since they were first introduced in the early 1960s, with most of the development concentrating on the filler technology. This has led to improved mechanical properties, notably wear resistance, and has expanded the use of composites to larger posterior restorations. On the organic matrix side, concerns over the polymerization stress and the potential damage to the bonded interface have dominated research in the past 20 y, with many "low-shrinkage" composites being launched commercially. The lack of clinical correlation between the use of these materials and improved restoration outcomes has shifted the focus more recently to improving materials' resistance to degradation in the oral environment, caused by aqueous solvents and salivary enzymes, as well as biofilm development. Antimicrobial and ester-free monomers have been developed in the recent past, and evidence is mounting for their potential benefit. This article reviews literature on the newest materials currently on the market and provides an outlook for the future developments needed to improve restoration longevity past the average 10 y.

Timing of anterior cruciate ligament reconstruction within the first year after trauma and its influence on treatment of cartilage and meniscus pathology

PURPOSE

Anterior cruciate ligament (ACL) ruptures are often associated with primary meniscal and cartilage lesions. Late reconstruction of ACL-deficient knees may increase the risk of developing secondary meniscal and cartilage lesions; hence, the timing of ACL repair is of the utmost importance. Because meniscus outcome is also a potential predictor for osteoarthritis (OA), this study compared ACL repair within the first 6 months after injury to that of surgery conducted 7-12 months after injury with regard to the incidence of meniscal and cartilage lesions.

METHODS

This prospective cross-sectional study included all complete isolated primary ACL ruptures treated in our institution within 1 year after trauma over a 12-month period. Exclusion criteria were revision ACL, complex ligament injuries, previous knee surgery, and missing injury data. Cartilage lesions were classified according to the score established by the International Cartilage Repair Society (ICRS score) and meniscal tears according to their treatment options.

RESULTS

Two hundred and thirty-three of 730 patients (162 men, 71 women) with ACL repair met the inclusion criteria. 86.3 % of surgical interventions were conducted within 6 months and 13.7 % after 6 months of trauma. Severe cartilage lesions grade III-IV did not significantly differ between the different time points of ACL repair (<6 months 39.9 %; >6 months 31.3 %; p = n.s.). Medial meniscus lesions received significantly higher meniscal repair in early compared to delayed ACL repair. Significantly higher rate of meniscal repair of the medial meniscus was seen in cases of early ACL repair compared to delayed (<6 months 77.2 %, >6 months 46.7; p = 0.022). The rate of medial meniscal repair in early ACL repair was significantly higher for women (89.5-0 %; p = 0.002), however, not for men (73.3-53.8 %; p = n.s.). No differences were found for lateral meniscal lesions, with regard to neither the different time points (p = n.s.) nor the sex (p = n.s.).

CONCLUSIONS

Because of the significantly higher rate of prognostically advantageous meniscal repair, the recommendation for an ACL reconstruction within 6 months after trauma was made to preserve the meniscus and reduce the risk of developing OA.

LEVEL OF EVIDENCE

Prospective cross-sectional cohort study, Level II.

Clinical/Photographic/Scanning Electron Microscopy Analysis of Pit and Fissure Sealants After 22 Years: A Case Series

Pit and fissure sealant is a clinical technique adopted to prevent caries lesion development. Ionomeric and/or resin-based materials are commonly used for this purpose. This article presents a case series of sealed teeth with 22-year follow-up evaluated by clinical, photographic, and microscopic analysis. In 1992, sixteen patients (9-14 years of age) had at least three teeth sealed with one of the following materials: resin-modified glass ionomer cement (RMGIC, Vitrebond or Fuji II LC) or polyacid-modified resin composite (PMRC, VariGlass VLC), totaling 86 sealed permanent teeth. After 22 years, 10 patients were recalled, representing 41 teeth. The retention of sealants was assessed by three methods: clinical analysis by visual inspection; photography; and scanning electron microscope (SEM) images and classified as retained (pits and fissures filled by sealant material); partially retained (pits and fissures partially filled by sealant material); or totally lost (no material was found in pits and fissures). The SEM images provided a higher number of retained sealants when compared with the clinical and photographic evaluations. Also, no totally lost scores were found with SEM analysis, regardless of the sealing material. No caries lesions were found. A fully or partially retained sealant in pits and fissures was capable of preventing caries lesions after 22 years within the patient pool analyzed.

Effect of Insufficient Light Exposure on Polymerization Kinetics of Conventional and Self-adhesive Dual-cure Resin Cements

Objectives: The purpose of this study was to investigate the influence of insufficient light exposure on the polymerization of conventional and self-adhesive dual-cure resin cements under ceramic restorations.

Methods: Two conventional dual-cure resin cements (Rely-X ARC, Duolink) and two self-adhesive resin cements (Rely-X U200, Maxcem Elite) were polymerized under different curing modes (dual-cure or self-cure), curing times (20 and 120 seconds), and thickness of a ceramic overlay (2 and 4 mm). Polymerization kinetics was measured by Fourier transform infrared spectroscopy for the initial 10 minutes and after 24 hours. Data were analyzed using mixed model analysis of variance (ANOVA), one-way ANOVA/Student-Newman-Keuls post hoc test, and paired t-test (α=0.05).

Results: When light-curing time was set to 20 seconds, the presence of the ceramic block significantly affected the degree of conversion (DC) of all resin cements. Especially, the DC of the groups with 20 seconds of light-curing time under 4 mm of ceramic thickness was even lower than that of the self-cured groups at 24 hours after polymerization (p&lt;0.05). However, when light-curing time was set to 120 seconds, a similar DC compared with the group with direct light exposure (p&gt;0.05) was achieved in all dual-cure groups except Maxcem Elite, at 24 hours after polymerization.

Conclusions: For both conventional and self-adhesive dual-cure resin cements, insufficient light exposure (20 seconds of light-curing time) through thick ceramic restoration (4 mm thick) resulted in a DC even lower than that of self-curing alone.

Posterolateral fusion in acute traumatic thoracolumbar fractures: a comparison of demineralized bone matrix and autologous bone graft

INTRODUCTION Alternative fusion expanders are in clinical use for instrumented posterolateral fusion (PLF) to avoid donor site morbidity in autologous bone graft (ABG) harvesting. Purpose of this study was to evaluate demineralized bone matrix (DBM) in PLF as alternative to the gold standard of ABG in acute traumatic vertebral body fractures of the thoracolumbar spine. MATERIAL AND METHODS We retrospectively identified 101 patients with acute traumatic vertebral body fractures of the thoracic and lumbar spine who were treated with instrumented PLF in our level one trauma center between 2005 and 2011. Patients with a primary paraplegia, osteodepriving disease or loss to follow-up had been excluded. Until August 2008, autologous bone graft harvested from the posterior iliac crest was used in PLF (control group n = 46). Starting September 2008, DBM was used as fusion expander in PLF (study group n = 16). Clinical and radiological evaluation was performed with a minimum followup of 18 months to assess the clinical and radiological outcome. RESULTS We found a fusion rate of 94% in patients undergoing PLF with the use of DBM and 100% with the use of ABG. There was one major complication of deep infection in the DBM group and two cases of superficial wound infection in the ABG group. We discovered a trend of reduced operating time with the use of DBM. CONCLUSIONS DBM leads to a similar fusion rate as the use of ABG in patients undergoing PLF for acute traumatic vertebral body fractures of the thoracic and lumbar spine. DBM is associated with reduced operating time.

LEVEL OF EVIDENCE III

case-control study Key words: demineralized bone matrix instrumented posterolateral fusion, acute traumatic vertebral body fracture, thoracolumbar spine, autologous bone graft.

Thio-urethanes improve properties of dual-cured composite cements

This study aims at modifying dual-cure composite cements by adding thio-urethane oligomers to improve mechanical properties, especially fracture toughness, and reduce polymerization stress. Thiol-functionalized oligomers were synthesized by combining 1,3-bis(1-isocyanato-1-methylethyl)benzene with trimethylol-tris-3-mercaptopropionate, at 1:2 isocyanate:thiol. Oligomer was added at 0, 10 or 20 wt% to BisGMA-UDMA-TEGDMA (5:3:2, with 25 wt% silanated inorganic fillers) or to one commercial composite cement (Relyx Ultimate, 3M Espe). Near-IR was used to measure methacrylate conversion after photoactivation (700 mW/cm(2) × 60s) and after 72 h. Flexural strength and modulus, toughness, and fracture toughness were evaluated in three-point bending. Polymerization stress was measured with the Bioman. The microtensile bond strength of an indirect composite and a glass ceramic to dentin was also evaluated. Results were analyzed with analysis of variance and Tukey's test (α = 0.05). For BisGMA-UDMA-TEGDMA cements, conversion values were not affected by the addition of thio-urethanes. Flexural strength/modulus increased significantly for both oligomer concentrations, with a 3-fold increase in toughness at 20 wt%. Fracture toughness increased over 2-fold for the thio-urethane modified groups. Contraction stress was reduced by 40% to 50% with the addition of thio-urethanes. The addition of thio-urethane to the commercial cement led to similar flexural strength, toughness, and conversion at 72h compared to the control. Flexural modulus decreased for the 20 wt% group, due to the dilution of the overall filler volume, which also led to decreased stress. However, fracture toughness increased by up to 50%. The microtensile bond strength increased for the experimental composite cement with 20 wt% thio-urethane bonding for both an indirect composite and a glass ceramic. Novel dual-cured composite cements containing thio-urethanes showed increased toughness, fracture toughness and bond strength to dentin while demonstrating reduced contraction stress. All of these benefits are derived without compromising the methacrylate conversion of the resin component. The modification does not require changing the operatory technique.

Contrast enhanced ultrasound (CEUS) and time intensity curve (TIC) analysis in compartment syndrome: first results

OBJECTIVE

Purpose of this study was to monitor changes of microcirculation in acute compartment syndrome using contrast enhanced ultrasound (CEUS) and to assess the modified perfusion with a special quantification software.

METHODS

8 patients with trauma of the lower limb or the upper extremity were enrolled after acute compartment syndrome was diagnosed clinically and by intracompartmental pressure measurement. The qualitative analysis of the corresponding compartment was assessed using B-scan mode and CEUS simultaneously. CEUS was performed using a multifrequence probe (6-9 MHz, LOGIQ E9 GE) after a i.v. bolus injection of 2 × 2.4 ml contrast agent (SonoVue(®), Bracco, Italy). Digital raw data were stored as cine loops up to 2 minutes. Retrospectively semiquantitative perfusion analysis was performed using time intensity curve analysis and the quantification software QONTRAST(®).

RESULTS

6 out of 8 patients had to be operated due to clinical symptoms and to a pressure perfusion gradient lower than 30 mm Hg. 2 out of 8 were treated conservatively. In all patients haematomas were seen in B-scan mode. No necrosis could be detected. In the TIC analysis low levels of time to peak (20.0 ± 12.1) and area under the curve (118.4 ± 87.8) were observed in acute compartment syndrome. Similarly results have been obtained using the perfusions parameter PEAK (11.1 ± 5.7), time to PEAK (14.7 ± 9.7), regional blood volume (257.1 ± 192.6), and regional blood flow (12.1 ± 6.5) in QONTRAST(®) perfusion software.

CONCLUSION

CEUS may be capable of differing between acute compartment syndrome and imminent compartment syndrome.

Osteocutaneous free flaps: a critical analysis of quantitative evaluation of bone microcirculation with contrast-enhanced high resolution ultrasound (hrCEUS) and TIC analysis

PURPOSE

Osteocutaneous free flaps (OFF) are widely used to reconstruct large bone defects in trauma and cancer surgery. Currently no monitoring method is available to detect blood circulation around and inside the bone after transplantation. Therefore we used for the first time contrast-enhanced high-resolution ultrasound (hrCEUS) to gain evidence for the microcirculation of the transplanted bone.

MATERIALS AND METHODS

15 patients transplanted with OFF because of large bone defects at different sites were examined postoperatively with hrCEUS with a high resolution linear probe (6-9 MHz, LOGIQ E9/GE) and a bolus injection of 2.4 ml of contrast agent (SonoVue®, Bracco, Italy). Operation and examination were performed by either an experienced plastic surgeon or an experienced ultrasound examiner. Microcirculation of the periost and bone was analyzed in different regions of interest (ROIs) and quantitative microcirculation analysis was performed using time intension curve analysis (TIC). We further analyzed clinical outcome of the patients in respect to revision-surgery, necrosis of the OFF and flap survival as well as viability on standard x-rays 2 months after surgery.

RESULTS

The most representative parameter by TIC analysis of hrCEUS were the area under the curve (AUC) and the time to peak (Ttop). The AUC of the periost and central part of the bone showed a high correlation (Pearson's r = 0.831). Mean AUC for the periost was 163.92 dB ± 49.44 and for the central part of the bone 70.42 dB ± 25.33. The Ttop of the periosteal ROI was 33.04 sec. ± 6.71 and the bone ROI 41.01 sec. ± 9.24. There was a high correlation of the Ttop of the periost and bone (Pearson's r = 0.937). One revision had to be performed due to haematoma and microcirculation defect of the distal part of the transplanted bone graft which was detected early by hrCEUS and the distal part of the avital bone could be removed timely.

CONCLUSION

For the first time we could show that hrCEUS is a reliable method to evaluate the viability of OFF. The AUC and Ttop seem to be a valuable parameter to detect the microcirculation around and inside the bone transplant.

Improved dental adhesive formulations based on reactive nanogel additives

Current challenges in adhesive dentistry include over-hydrophilic bonding formulations, which facilitate water percolation through the hybrid layer and result in unreliable bonded interfaces. This study introduces nanogel-modified adhesives as a way to control the material's hydrophobic character without changing the basic monomer formulation (keeping water-chasing capacity and operatory techniques unaltered). Nanogel additives of varied hydrophobicity were synthesized in solution, rendering 10- to 100-nm-sized particles. A model BisGMA/HEMA solvated adhesive was prepared (control), to which reactive nanogels were added. The increase in adhesive viscosity did not impair solvent removal by air-thinning. The degree of conversion in the adhesive was similar between control and nanogel-modified materials, while the bulk dry and, particularly, the wet mechanical properties were significantly improved through nanogel-based network reinforcement and reduced water solubility. As preliminary validation of this approach, short-term micro-tensile bond strengths to acid-etched and primed dentin were significantly enhanced by nanogel inclusion in the adhesive resins.

Factors affecting photopolymerization stress in dental composites

Polymerization stress development results from the complex interplay of volumetric shrinkage, reaction kinetics, and viscoelastic properties. The objective of this study was to examine the relationships among volumetric shrinkage, degree of conversion, rate of polymerization (RP(max)), and stress development for 2 model bis-GMA-based composites. Three irradiances were used--220, 400, or 600 mW/cm(2)--with exposure times adjusted to deliver the same radiant energy. Volumetric shrinkage was determined with a mercury dilatometer, degree of conversion and RP(max) by differential scanning calorimetry (DSC), and polymerization stress with a low-compliance device (Sakaguchi et al., 2004b). Results indicated that polymerization reaction rate and shrinkage were not correlated. Irradiance was directly related to polymerization reaction rate and to stress development. The group with the highest stress/degree of conversion exhibited the lowest RP(max), so it can be assumed, within the limitations of this study, that the conversion was most closely related to stress development.

Contraction stress determinants in dimethacrylate composites

The influence of composite organic content on polymerization stress development remains unclear. It was hypothesized that stress was directly related to differences in degree of conversion, volumetric shrinkage, elastic modulus, and maximum rate of polymerization encountered in composites containing different BisGMA (bisphenylglycidyl dimethacrylate) concentrations and TEGDMA (triethylene glycol dimethacrylate) and/or BisEMA (ethoxylated bisphenol-A dimethacrylate) as co-monomers. Stress was determined in a tensilometer. Volumetric shrinkage was measured with a mercury dilatometer. Elastic modulus was obtained by flexural test. We used fragments of flexural specimens to determine degree of conversion by FT-Raman spectroscopy. Reaction rate was determined by differential scanning calorimetry. Composites with lower BisGMA content and those containing TEGDMA showed higher stress, conversion, shrinkage, and elastic modulus. Polymerization rate did not vary significantly, except for the lower value of the 66% TEGDMA composite. We used linear regressions to evaluate the association between polymerization stress and conversion (R(2)=0.905), shrinkage (R(2)=0.825), and modulus (R(2)=0.623).

Hepatitis C in Austria 1993-2000: reporting bias distort HCV epidemiology in Austria

From 1993 to 2000 in Austria, the notification system registered 2232 cases of hepatitis C whereas 10 607 hospital cases were reported in the hospital discharge register (HDR). These differences can be explained by under-reporting due to lax reporting behaviour and stigma associated with this disease. The distribution of HCV infection varied geographically. The notification data showed the highest incidence rates in Tyrol, while HDR data showed highest hospitalisation rates in Vienna and Lower Austria. This study highlights the urgent need for a clear case definition at the national level and an electronic reporting system.

Malaria in Austria 1990-2000

In Austria, between 1990 and 2000, 924 travel related malaria cases were reported (mean = 84/year). No significant decreasing or increasing trends were observed. P. falciparum (n=517; 55.9%) accounted for the highest number of cases followed by P. vivax or ovale (n=321; 34.7%) and P. malariae (n=29; 2.2%). Most infections were contracted in highly endemic malaria regions (n=686; 74.2%) and most cases were reported from the largest counties: Vienna (n=336, 36.4%), Styria (n=156, 16.8%), and Lower Austria (n=151, 16.3%). Overall, 12 deaths occurred, most were caused by P. falciparum (n=9, 75%; case fatality rate: 1.9%). Data on chemoprophylaxis was available for 752 cases (81.4%) but only half of them (n=367, 48.8%) gave detailed information on the drug used. Data on compliance were obtained for only 45.4% of the cases, with only about 60% of patients completing the full course of prophylaxis.

Tuberculosis in Austria 1995–99: geographical distribution and trends

A descriptive analysis of routine surveillance data on tuberculosis (TB) from 1995 to 1999 was performed in Austria. The federal states of Vienna and Upper Austria showed the highest yearly incidences for all five years. In general, however, a decrease of the yearly incidence was observed for all federal states except for Carinthia (where there was a small increase of 3.2 %). In the cities of Vienna, Linz, Wels, Salzburg, Klagenfurt and St-Pölten, as well as in the regions of Eastern Tyrol, Southern Carinthia, and Southern Burgenland, the incidence was above average (&gt;19 cases/100 000 for each). The number of cases per year and per district reported by the statutory reporting system were clearly in excess of those reported by hospitals. The comparison of the two datasets, however, showed a highly significant regional correlation of age standardised morbidity rates at district level. The findings are prone to reporting bias and might not reflect the real TB situation. The responsible health authorities should therefore consider the results as a 'working hypothesis’ in order to review the reporting behaviour at district level.

Tuberculosis in Austria 1995-99: geographical distribution and trends

A descriptive analysis of routine surveillance data on tuberculosis (TB) from 1995 to 1999 was performed in Austria. The federal states of Vienna and Upper Austria showed the highest yearly incidences for all five years. In general, however, a decrease of the yearly incidence was observed for all federal states except for Carinthia (where there was a small increase of 3.2 %). In the cities of Vienna, Linz, Wels, Salzburg, Klagenfurt and St-Pölten, as well as in the regions of Eastern Tyrol, Southern Carinthia, and Southern Burgenland, the incidence was above average (>19 cases/100,000 for each). The number of cases per year and per district reported by the statutory reporting system were clearly in excess of those reported by hospitals. The comparison of the two datasets, however, showed a highly significant regional correlation of age standardised morbidity rates at district level. The findings are prone to reporting bias and might not reflect the real TB situation. The responsible health authorities should therefore consider the results as a 'working hypothesis in order to review the reporting behaviour at district level.

Centromere and telomere redistribution precedes homologue pairing and terminal synapsis initiation during prophase I of cattle spermatogenesis

Alterations in nuclear topology associated with meiotic chromosome pairing were studied in premeiotic cells and spermatocytes I of adult bovine males. To this end, we performed FISH with chromosome, pericentromeric satellite-DNA and telomere-specific probes in combination with immunostaining of synaptonemal complex proteins (SCP3, SCP1) on testis tissue sections. Nuclei of premeiotic cells (spermatogonia) exhibited a scattered telomere distribution while pericentromeres formed a few intranuclear clusters. We observed that the chromosome pairing process in cattle prophase I is preceded by repositioning of centromeres and telomeres to the nuclear periphery during preleptotene. Clustering of chromosome ends (bouquet formation) was observed during the transition from leptonema to zygonema and coincided with pairing of a sub-centromeric marker of bovine chromosomes 7. Dissolution of bouquet topology during zygonema left perinuclear telomeres scattered over the nuclear periphery at pachynema. SCP3 staining in frozen tissue sections revealed the appearance of this axial element protein in intranuclear aggregates during preleptotene, followed by extensive axial element formation during leptotene. Synapsis as revealed by SCP1 staining initiated peripherally at earliest zygotene, at this stage nuclei still contained numerous SCP3 clusters. Our observations reveal prominent non-homologous satellite-DNA associations in spermatogonia and indicate the conservation of topological features of the meiotic chromosome pairing process among mammals. The comparison of telomere dynamics in mouse and cattle prophase I suggests that a larger number of chromosomes prolongs the duration of the bouquet stage.

[Injury pattern and overuse stress syndrome in young sport climbers]

The rapidly growing interest in sports climbing in recent years among young climbers raises the question about the risk of injuries and overstrain syndromes in this group. This paper investigates injuries and overstrain syndromes of 99 adolescent climbers aged between 8 and 19 years. The authors interviewed climbers from Austria, Germany and Switzerland. Besides the type and pattern of injuries and overstrain syndromes, the level and duration of climbing, intensity of training and gender were recorded as potential risk factors. 47 climbers were asked about setting up fingers on small holds, which is considered a main reason for epiphyseal injuries of fingers in the literature. Injuries and overstrain syndromes, as well as their frequency and pattern are reported and classified. Descriptive data analysis and statistical models are used to assess the influence of risk factors. Among the potential risk factors only the climbing level has a significant influence on the risk of injuries and overstrain syndromes (p = 0.0427). Furthermore the risk of injuries and overstrain syndromes in the area of the fingers is significantly higher for climbers who reported setting up fingers on small holds (OR = 8.24, p = 0.0022). Finally we found a higher frequency of injuries and overstrain syndromes in lower extremities (43% of all injury and overstrain occurrences) and a lower frequency of injuries and overstrain syndromes in general (43% of all the climbers under investigation) compared to other studies. As a result special guidelines for training and competition are given. In order to increase the accuracy of the reports and to investigate long-term effects we recommend a study with clinical assessment and a longer period of observation.

Spatial analysis of Percutaneous Transluminal Coronary Angioplasty (PTCA) in Austria

STUDY OBJECTIVES

To investigate the geographical distribution of Percutaneous Transluminal Coronary Angioplasty (PTCA) and morbidity for coronary heart disease, angina pectoris and myocardial infarction by spatial analysis of the standardized morbidity rates (SMR) on district level. To identify clusters by Moran's I Statistic and the Regional Spatial Autocorrelation Coefficient (RSAC) of Munasinghe and Morris. To investigate demand factor morbidity and supply factor health care infrastructure on the district level as reasons for geographical disparity. To describe characteristics of the cluster population and intervention centres.

STUDY DESIGN

Retrospective record linkage study.

SETTING

All hospitals and cardiological centres in Austria (n = 150) which performed the Minimum Basic Data Set (MBDS).

PATIENTS

All Austrian residents who were diagnosed for myocardial infarction, coronary heart disease or angina pectoris in 1995 (n = 87,174).

MEASUREMENTS AND MAIN RESULTS

One 'positive' PTCA cluster (all SMRs > or =0.96) and one 'negative' PTCA cluster (all SMRs < or =0.59) were identified. They differed significantly in morbidity rate, intervention rate and available cardiological beds. The tendency to inverse relation between PTCA utilization and morbidity in the 'negative' cluster supported the thesis of 'inverse care law'. Austrianwide no significant correlation was found between the SMR of PTCA-application and both demand factor and supply factors. Nevertheless, differences between the clusters concerning number and capacity of intervention centres and density of specialists pointed to supply factors as reasons for geographical disparity. The ongoing trend of steady expansion of existing intervention centres and establishment of new ones will reduce the extent of geographical variation in future.

Effects of morbidity, age, gender and region on percutaneous transluminal coronary angioplasty (PTCA) utilisation

OBJECTIVES

To investigate changes in the use of PTCA application in respect to morbidity, gender, region and age, and to investigate the morbidity as related to geographical variation.

STUDY DESIGN

Retrospective record linkage study.

SETTING

All hospitals and cardiological centres (n = 156) which performed the Minimum Basic Data Set (MBDS).

PATIENTS

All Austrian residents who were diagnosed for myocardial infarction, coronary heart disease or angina pectoris in 1993-1995 (1993: n = 73.077; 1994: n = 80.173; 1995: n = 84.896).

MEASUREMENTS AND MAIN RESULTS

The intervention rate (IR = PTCA/indication) increased from 0.03-0.04 (33%) between 1993 and 1995 with differences in genders (males: 24%, females: 27.7%) and regions (Vorarlberg: -7.5%, Burgenland: 65.3%). Male morbidity started to increase at about 60 y and female morbidity at about 70 y. Morbidity as a demand factor did not correlate with PTCA application. The intervention rate was significantly lower for females in Austria in general (P < 0.001) as it was in every Federal State (P < 0.001). This pattern was constant during 1993-1995 with the highest difference in Salzburg and the lowest in Styria. Austrian men were about three times more likely to have received PTCA application than women (crude Odds Ratio = 2.8, 95% CI = 2.6-3, P-value < 0.001). Logistic regression modelling revealed age as main confounder (adjusted Odds Ratio = 1.36, 95% CI = 1.31-1.42, P < 0.001). The > or = 5% intervention rate peak was between 30-75 y for males and between 30-65 y for females whereas morbidity of > or = 1% started for males at about 50 y and for females at about 60 y. Marked geographical differences of the intervention rate were observed (Upper Austria, Salzburg IR = 0.07, Styria IR = 0.02) but could not be explained by the demand factor morbidity (Pearson's correlation coefficients 1993: 0.039, P = 0.71; 1994: 0.155, P = 0.133; 1995: 0.087, P = 0.399).

CONCLUSIONS

The highest intervention rates were in the age groups with the lowest morbidity. Women received significantly fewer interventions than men by age and region. The demographic strata with lowest use rate were women aged 64 y and more. Marked geographical differences of PTCA application were stated but could not be explained by the demand factor morbidity. Further studies on supply factors as well as on economic and social factors are needed in order to develop public health strategies to guarantee equal utilisation rates for the whole Austrian population.

[Hospitalization of young women after selected cardiovascular and thromboembolic incidents in Austria 1993 and 1994]

The aim of this study is to describe the hospitalization and regional distribution of selected cardiovascular and thrombo-embolic events (cardiac infarction, cerebral strokes, deep vein thromboses, pulmonary embolism) of young women in Austria in the years 1993 and 1994, and to collect basic epidemiologic data for the study of the side effects of oral contraceptives. The calculated hospitalization rates are based on the Austrian hospitals' discharge records of 1993 and 1994. The persons concerned are women aged between 15 and 44 who live in Austria. The results of the study reveal that--in 1993--of the above mentioned group 51 out of 100,000 inhabitants were hospitalized because of the selected cardiovascular and thromboembolic events: 4/100,000 had a cardiac infarction, 5/100,000 had a stroke, 17/100,000 had a pulmonary embolism, and 27/100,000 suffered a deep vein thrombosis. In 1994 the counted cases per 100,000 inhabitants were 48, out of which 4/100,000 where cardiac infarcts, 5/100,000 strokes, 16/100,000 pulmonary embolism, and 25/100,000 deep vein thromboses.

Systemic hematological effects of granulocyte colony-stimulating factor produced by irradiated gene-transfected fibroblasts

Although long-term expression of therapeutic molecules is necessary for the treatment of permanent deficiencies, short-term expression of therapeutic molecules inducing local or systemic effects is preferable in clinical situations where temporary substitution is the goal. One such clinical setting is the administration of hematopoietic growth factors in cancer chemotherapy-induced myelosuppression. Several plasmid vectors containing the human granulocyte colony-stimulating factor (G-CSF) gene under transcriptional control of different regulatory elements were constructed. In vitro production of G-CSF by nonvirally transfected murine fibroblast clones initially increased after lethal irradiation and was detectable for at least 12 days. We also demonstrate that a single injection of irradiated G-CSF-secreting fibroblasts leads to accelerated hematopoietic recovery and mobilization of committed peripheral blood progenitor cells equivalent to that achieved by twice daily s.c. administration of high doses of recombinant human G-CSF. Using dicistronic vectors, high levels of G-CSF secretion were also obtained in human fibroblasts.

Involving health care workers in screening for alcohol problems

OBJECTIVES

(1) Examine physician and nursing staff compliance with conducting an alcohol screening interview; (2) Compare compliance with the interview with usual physician and nurse assessment of drinking; (3) Examine reasons why drinking information might not be collected.

DESIGN

Residents and nurses were taught how to use an alcohol screening interview and were told by the director of residency training or by the Vice-President for Nursing to administer it to all admitted patients. Data on interviewed patients were compared with medical record data on a randomly selected series of 80 patients who were not interviewed.

SETTING

Teaching hospital in an urban/suburban community.

PATIENTS/PARTICIPANTS

Residents on internal medicine and family practice services; surgical nurses.

MEASUREMENTS AND MAIN RESULTS

Compliance with conducting the interview was low (14.7% of residents' admissions; 13.53% of nurses' admissions). Review of the medical records indicated that some alcohol-related information was recorded in most patients' medical records (physicians recorded information on 94% of patients on the teaching services, nurses on the surgical unit recorded alcohol-related information on 71% of patients). Surgeons and surgical residents recorded alcohol-related information on 30% of their patients. Residents were more likely to interview male than female patients, and residents and nurses tended to interview patients with higher GGTP values.

CONCLUSIONS

(1) Compliance with administering a standardized alcohol screening interview was low. (2) Nurses, and residents in family practice and internal medicine made some assessment of drinking for most patients. Surgeons assessed drinking in a minority of patients. (3) Expressed reasons for not administering the standardized interview included discomfort with the interview, viewing the interview as too time-consuming, or not part of the usual responsibilities of the nurses or residents. Other possible reasons for the low levels of compliance are discussed.