Laboratory strength of glass ionomer cement, compomers, and resin composites

PURPOSE: The study evaluates the compressive, flexural, and diametral tensile strengths of 8 core build-up materials from different material classes (highly viscous glass ionomer cement, autocured resin composite, and compomers). MATERIALS AND METHODS: All materials were manipulated according to the manufacturers' recommendations for use as core materials. At a temperature of 23.0 +/- 1.0 degrees C the properties of compressive, diametral tensile and flexural strength were determined using a universal testing machine at 15 minutes, 1 hour, and 24 hours after material preparation. Using one-way analysis of variance (ANOVA), multiple mean value comparisons were performed to determine significant differences (p< or =.05) between the core restoration materials. RESULTS: The values for compressive strength varied from 40.3 +/- 5.2 MPa (compomer) to 237.4 +/- 37.3 MPa (autocured resin composite) for the 3 measurement times. At 15 minutes, 1 hour, and 24 hours after first mixing, the ANOVA showed significant differences (p < or =.05) between the resin composite Core Paste and all of the other materials. Diametral tensile strengths ranged from 5.5 +/- 1.1 MPa for glass ionomer cement to 39.1 +/- 2.9 MPa for composite core material. Three-point flexural strength showed values ranging from 12.1 +/- 2.5 MPa for glass ionomer cement to 92.1 +/- 9.7 MPa for compomer between the 3 measurement times. CONCLUSIONS: Setting time influences the mechanical properties of the materials tested in this study. Autopolymerizing resin composite Core Paste demonstrated greater compressive and flexural strengths at the 3 measurement times than the other materials tested. Reinforced composites, in comparison to the autocured resin composites, yielded no improvement in tensile strength. Flexural and tensile strengths of the glass ionomer cement were lower than those of autocured resin composites and compomers.     

Fracture characteristics of carbon fibre, ceramic and non-palladium endodontic post systems at monotonously increasing loads

A carbon fibre post system, three non-palladium and one palladium metal post systems, two ceramic post systems, and a metal post system with a ceramic core were studied in vitro. The control group consisted of root-filled test teeth without posts. The test teeth were identical artificial roots of an upper central incisor made from a posterior composite whose module of elasticity was similar to that of natural dentine. All posts were cemented in the roots using Panavia 21 TC. Subsequently, standardized full crowns were cemented onto all roots. On a universal testing machine, the test teeth were loaded palatally at monotonously increasing loads until root fracture. The highest mean fracture loads were found for the carbon fibre post system (312.5 +/- 58.8 N). The fracture load of non-palladium metal posts (242.3-300.4 N) did not differ significantly from that of the Perma-dor post (265.9 N), which does contain palladium. Values of 300.3 +/- 89.3 N (aluminium oxide ceramics) and 193.5 +/-57.0 N (zirconia ceramics) were found for the ceramic posts. The control group exhibited a fracture load of 228.8 +/- 35.7 N. The mean distance between the vestibular end of the fracture gap and the point of force application was between 10.1 +/- 2.3 and 14.7 +/- 1.2 mm.     

Klinische Anwendung von im Tissue engineering gewonnenen autologen Mundschleimhauttransplantaten

Background. Tissue engineering of autogenous oral mucosa is a significant enrichment for various indications in oral and maxillofacial surgery. Besides preprosthetic surgery and prelamination of microvascular fasciocutaneous flaps, interdisciplinary work such as reconstruction procedures in cases of hypospadias and epispadias are the main indications for tissue-engineered oral mucosa. Results. One main advantage of this technique is the reduction of second surgical procedures. The morbidity is decreased and the quality of life may be significantly increased. The manufacture of tissue-engineered autogenous oral mucosa up to 15 cm² requires a small biopsy of oral mucosa (4–8 mm³) and 40 ml of autogenous serum. Discussion. The clinical and morphological long-term follow-up after different surgical procedures with tissue-engineered oral mucosa establishes this technique as an excellent additional tool in oral and maxillofacial surgery.     

Clinical application of tissue-engineered transplants. Part I: mucosa

OBJECTIVES: The study series aims at testing the feasibility of the clinical application of tissue-engineered oral mucosa. The preliminary results were gathered over a period varying from 6 months to 12 years depending on the surgical method. METHODS: Tissue-engineered oral mucosa was used to cover defects in various surgical procedures like vestibuloplasty (n=42), freeing of the tongue (n=10), prelaminating the radial flap (n=5) and reconstruction of the urethra (n=16). In all interventions small samples of oral mucosa were harvested, cut into small pieces, resuspended in culture medium and seeded into a culture flask. Cultured keratinocytes were transferred onto membranes which then were used to cover mucosal defects in the oral cavity. RESULTS: To gain a graft of 15 cm(2) size a mucosa biopsy of 4-8 mm(2) and 40 ml autologous patients serum is needed. Tissue-engineered oral mucosa was applied successfully in all four surgical methods. Six months after transplantation a regular epithelial layering with a histological delimitation of the stratum, epithelial crest and a strong basal membrane appeared. According to the reception site the tissue engineered oral mucosa differentiated in several ways. CONCLUSION: Tissue-engineered oral mucosa fulfils the requirements for clinical routine. With view to healing time and outcome it does not appear to be superior to regular harvested oral mucosa transplants. Because of a smaller harvesting defect and primary wound closure at the actual operation site the patients' convenience is increased. Thus this method reduces morbidity and advances the quality of life.     

A Randomized Controlled Trial on the Effects of Cycling With and Without Electrical Stimulation on Cardiorespiratory and Vascular Health in Children With Spinal Cord Injury

Johnston TE, Smith BT, Mulcahey MJ, Betz RR, Lauer RT. A randomized controlled trial on the effects of cycling with and without electrical stimulation on cardiorespiratory and vascular health in children with spinal cord injury.

Objective

To examine the cardiorespiratory/vascular effects of cycling with and without functional electrical stimulation (FES) in children with spinal cord injury (SCI).

Design

Randomized controlled trial.

Setting

Pediatric referral hospital.

Participants

Children with SCI (N=30), ages 5 to 13 years, with injury levels from C4 to T11, and American Spinal Injury Association grades A, B, or C.

Interventions

Children were randomly assigned to 1 of 3 groups: FES leg cycling exercise, passive leg cycling, or noncycling control group receiving electrical stimulation therapy. After receiving instruction on the use of the equipment, children exercised for 1 hour 3 times per week for 6 months at home with parental supervision.

Main Outcome Measures

Oxygen uptake (V̇o₂) during an incremental arm ergometry test, resting heart rate, forced vital capacity, and a fasting lipid profile.

Results

There were no differences (P>.05) between groups after 6 months of exercise when comparing pre- and postvalues. However, there were differences between groups for some variables when examining percent change. The FES cycling group showed an improvement (P=.035) in V̇o₂ (16.2%±25.0%) as compared with the passive cycling group (–28.7%±29.1%). For lipid levels, the electrical stimulation–only group showed declines (P=.032) in cholesterol levels (–17.1%±8.5%) as compared with the FES cycling group (4.4%±20.4%).

Conclusions

Cycling with FES led to gains in V̇o₂, whereas electrical stimulation alone led to improvements in cholesterol.     

The autologous mixed lymphocyte response: isolation of mononuclear cell populations by counterflow centrifugal elutriation

We have used counterflow centrifugal elutriation (CCE) to isolate cell populations for an autologous mixed lymphocyte response (AMLR). Enriched T lymphocyte and monocyte populations were obtained rapidly without the need for cells to first form rosettes with sheep RBC (T cells) or adhere to plastic (monocytes). In 16 separate experiments, peripheral blood (PB) was separated by CCE (9) and/or a plastic adherence and nylon wool column method (9). Viability by all methods was greater than 95% CCE yielded greater than 97% lymphocytes in F20 and greater than 90% lymphocytes in F26. Cells obtained after passage through nylon wool yielded greater than 90% lymphocytes. Both CCE (F34) and plastic adherence techniques yielded greater than 75% monocytes. Similar AMLR response was obtained using either cell separation method. We conclude that mononuclear cells isolated by CCE are responsive in the AMLR and yield comparable data to other more tedious techniques.     

Reduced toxicity of F-deficient Sendai virus vector in the mouse fetus

Current concerns over insertional mutagenesis by retroviral vectors mitigate investigations into alternative, potentially persistent gene therapy vector systems not dependent on genomic integration, such as Sendai virus vectors (SeVV). Prenatal gene therapy requires efficient gene delivery to several tissues, which may not be achievable by somatic gene transfer to the adult. Initially, to test the potential and tropism of the SeVV for gene delivery to fetal tissues, first-generation (replication- and propagation-competent) recombinant SeVV, expressing beta-galactosidase was introduced into late gestation immunocompetent mice via the amniotic and peritoneal cavities and the yolk sac vessels. At 2 days, this resulted in very high levels of expression particularly in the airway epithelium, mesothelium and vascular endothelium, respectively. However, as expected, substantial vector toxicity was observed. The efficiency of gene transfer and the level of gene expression were then examined using a second-generation SeVV. The second generation was developed to be still capable of cytoplasmic RNA replication and therefore high-level gene expression, but incapable of vector spread due to lack of the gene for viral F-protein. Vector was introduced into the fetal amniotic and peritoneal cavities, intravascularly, intramuscularly and intraspinally; at 2 days, expression was observed in the airway epithelia, peritoneal mesothelia, unidentified cells in the gut wall, locally at the site of muscle injection and in the dorsal root ganglia, respectively. Mortality was dramatically diminished compared with the first-generation vector.     

Defining the directionality and quality of influenza virus-specific CD8+ T cell cross-reactivity in individuals infected with hepatitis C virus

Cross-reactivity of murine and recently human CD8(+) T cells between different viral peptides, i.e., heterologous immunity, has been well characterized. However, the directionality and quality of these cross-reactions is critical in determining their biological importance. Herein we analyzed the response of human CD8(+) T cells that recognize both a hepatitis C virus peptide (HCV-NS3) and a peptide derived from the influenza neuraminidase protein (Flu-NA). To detect the cross-reactive CD8(+) T cells, we used peptide-MHC class I complexes (pMHCs) containing a new mutant form of MHC class I able to bind CD8 more strongly than normal MHC class I complexes. T cell responses against HCV-NS3 and Flu-NA peptide were undetectable in normal donors. In contrast, some responses against the Flu-NA peptide were identified in HCV(+) donors who showed strong HCV-NS3-specific reactivity. The Flu-NA peptide was a weak agonist for CD8(+) T cells in HCV(+) individuals on the basis of novel pMHCs and functional assays. These data support the idea of cross-reactivity between the 2 peptides, but indicate that reactivity toward the Flu-NA peptide is highly CD8-dependent and occurs predominantly after priming during HCV infection. Our findings indicate the utility of the novel pMHCs in dissecting cross-reactivity and suggest that cross-reactivity between HCV and influenza is relatively weak. Further studies are needed to relate affinity and functionality of cross-reactive T cells.