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PubMed2002

Adhesive bonding of composite material to cast titanium with varying surface preparations.

The purpose of the present study was to evaluate the surface preparation effects of eight metal conditioners and an adhesive system on bonding between a prosthodontic composite material and cast titanium. Eight primers designed for conditioning base metal alloys (Acryl Bond, All-Bond 2 Primer B, Alloy Primer, Cesead II Opaque Primer, Eye Sight Opaque Primer, Metafast Bonding Liner, Metal Primer II, and MR Bond) as well as a surface modification technique (Siloc) were assessed. Disk specimens cast from titanium (T-Alloy H) were either primed with one of the eight primers or treated with the Siloc system, and then bonded with a light-activated composite material (Artglass). Bond durability was evaluated by thermocycling (4 and 60 degrees C, 1 min each, 20, 000 cycles). After thermocycling, two groups either primed with the Cesead II Opaque Primer material or treated with the Siloc system exhibited significantly greater bond strength (20.0 and 19.0 MPa) than the other groups (0.2-12.6 MPa, P < 0.05). These two systems are considered to be useful for improving bonding between the titanium and the composite material tested.

Adhesives↗

PubMed2000

Bone formation into surface phosphonylated polymeric implants.

Through the use of two animal models, the present study demonstrates the ability of phosphonylated surfaces to bind bone. In one model, surface-treated polypropylene (PP) and polyethylene (PE) were implanted in the medial cortex of the goat tibia. In the second model, surface-treated poly(ether-ether ketone) (PEEK) and carbon fiber-reinforced PEEK (CFR-PEEK) were implanted through both cortices of the goat mandible. Selected rods of all material types were microtextured using crystallization induced microphase separation, a method for the formation of continuous, open-cell microporous surfaces in thermoplastic polymers. Microtextured and smooth rods were phosphonylated, and calcium was subsequently introduced to the phosphonylated surface by incubating the samples in a saturated solution of calcium oxide. For all substrate materials tested, phosphonylation and calcium posttreatment resulted in an increased propensity for bone binding and apposition, as measured by push out test. Microtextured PP, PE, and CFR-PEEK surfaces that were further phosphonylated and calcium treated resulted in test samples with an increased interfacial strength.

Animals↗

PubMedDate not supplied

Cytotoxicity of hard chairside reline resins: effect of microwave irradiation and water bath postpolymerization treatments.

PURPOSE: To evaluate the influence of water bath and microwave postpolymerization treatments on the cytotoxicity of 6 hard reline acrylic resins. MATERIALS AND METHODS: The materials tested were Tokuso Rebase Fast (TR), Ufi Gel Hard (UGH), Duraliner II (D), Kooliner (K), New Truliner (NT), and Light Liner (LL). LL resin was additionally tested with an air-barrier coating (LLABC). Nine disks of each material (10 x 1 mm) were made and divided into 3 groups: group 1 (no postpolymerization treatment); group 2 (postpolymerization in microwave oven); group 3 (postpolymerization in water bath at 55 degrees C for 10 minutes). L929 cells were cultured in 96-well plates and incubated for 24 hours in Eagle's medium. Eluates prepared from the disks or medium without disks (control) replaced the medium. Cytotoxicity was assessed by both dehydrogenase succinic activity (MTT) assay and incorporation of radioactive 3H-thymidine assay. Tests were carried out in quadruplicate and repeated twice. Differences between groups were determined by analysis of variance with Tukey multiple-comparison intervals (alpha = .05). RESULTS: For MTT assay, the postpolymerization treatments had no effect on the cytotoxicity of all materials (P > .05). For 3H-thymidine assay, the postpolymerization treatments significantly decreased the cytotoxicity of UGH (P < .05). The cytotoxicity of K, NT, LL, and LLABC increased after microwave irradiation (P < .05). TR, NT, and LLABC showed an increase in cytotoxicity after water bath (P < .05). CONCLUSION: When assessed by MTT assay, the cytotoxicity of the materials was not affected by postpolymerization treatments. 3H-Thymidine assay showed that the cytotoxicity of the resins was not improved by the postpolymerization treatments, with the exception of UGH.

Acrylic Resins↗

PubMed1997

Comparative pull-out strength of tapped and untapped pilot holes for bicortical anterior cervical screws.

STUDY DESIGN: This biomechanical study analyzed the axial pull-out strength of tapped versus untapped pilot holes for bicortical screws in the anterior cervical spine. OBJECTIVE: To determine which pilot hole preparation method was mechanically better. SUMMARY OF BACKGROUND DATA: Tapping pilot holes in the lumbar spine was previously shown significantly to reduce pull-out strength of pedicle screws. No study was found investigating the effect of tapping on pilot holes for anterior cervical bicortical screws. METHODS: Twenty-five unembalmed human cadaveric cervical vertebrae (C3-C7) were tested. Two identical pilot holes were drilled into each vertebra: one pilot hole was tapped, and the control pilot hole was not tapped. A fully threaded cortical bone screw was inserted into each pilot hole. Screw pull-out strength was determined using a servocontrolled hydraulic materials testing system and an axial load cell. Force-deformation and failure curves were obtained. RESULTS: There were no statistically significant differences between the axial pull-out strength of tapped and untapped pilot holes at any vertebral level. Mean force to-failure was 386 +/- 42 N in the untapped pilot holes and 397 +/- 48 N in the tapped pilot holes. CONCLUSIONS: Tapping a pilot hole for bicortical screws of the anterior cervical spine neither weakens nor strengthens the axial pull-out strength of fully threaded cortical bone screws. Tapping may be unnecessary; however, it may be desirable in patients with dense bone to cut the thread profile into the bone or if the screws have dull tips and threads.

Adult↗

PubMed2006

The effects of sodium hypochlorite (5.25%), Chlorhexidine (2%), and Glyde File Prep on the bond strength of MTA-dentin.

The purpose of this study was to evaluate the effects of sodium hypochlorite (5.25%), chlorhexidine (2%), and Glyde File Prep on the bond strengths of MTA-dentin in vitro. Standardized dentin disks were prepared and the central hole in each disk was filled with mineral trioxide aggregate (MTA). The specimens were randomly divided into four groups to be immersed in saline, 5.25% NaOCl, 2% chlorhexidine, and Glyde File Prep for 2 hours. The bond strengths of MTA-dentin were measured with a material testing system (MTS) and the fractured surfaces on the root walls were observed by scanning electron microscopy. Compared with the control group, the bond strengths were significantly lower in Glyde File Prep group (p < 0.05) and there was no significant difference in the chlorhexidine group or in the NaOCl group (p > 0.05). This study suggested that Glyde File Prep could negatively affect the bond strengths of MTA-dentin.

Aluminum Compounds↗

PubMedDate not supplied

[The use of monoclonal anti-M and anti-N antibodies in forensic medicine].

Anti-M and anti-N monoclonal antibodies (MA) may be useful for bloodstain analysis by absorption-elution reaction. In order to detect N antigen in bloodstains aged up to 4 weeks the material tested must be treated by methanol. The material fixation is not recommended for analysis of "aged" bloodstains as well as for M antigen detection. Anti-M MA may be used for analysis of liquid blood using agglutination reaction.

Agglutination Tests↗

PubMed2003

Hygroscopic expansion and solubility of composite restoratives.

OBJECTIVE: To quantify the changes of dimension (vol%), weight (microgram/mm(3)) and the solubility (microgram/mm(3)) of dental composite restorative materials after a period of 64 days immersed in de-ionized water or artificial saliva. METHOD: Six resin-based composite restorative materials were investigated. An organically modified ceramic (Definite((R))), an ion-leaching composite (Ariston pHc((R))), two high-density packable composites (Solitaire((R)) and SureFil((R))) and two sub-micron hybrid composites (Pertac II((R)) and Spectrum TPH((R))). Twelve disks of each test material were prepared, 10mm diameter by 1mm thickness. All specimens were kept dry for 48h during polymerization. Two control specimens of each group were kept in a desiccating chamber; five specimens in de-ionized water and five specimens in artificial saliva (Salivace((R)), Penn) at 37 degrees C. The diameter of each disc was measured automatically across 200 points by rotation through beam of a laser micrometer. These measurements, together with weight measurements, were carried out at intervals over a 64 day period. The equilibrium value at time infinity, the rate of change and the equilibrium solubility was calculated for each material. RESULTS: At 64 days, the mean dimensional change (vol%) after water immersion ranged between 0.15% (+/-0.05) for Pertac II((R)) to 2.39% (+/-0.6) for Ariston pHc((R)). Dimensional changes (vol%) values for specimens immersed in artificial saliva were significantly different only for the material Solitaire((R)) (p<0.05). Change in weight (microgram/mm(3)) values were significantly different (p<0.05), according to the immersing solution for the materials Solitarie((R)), Ariston pHc((R)) and Surefil((R)) At 64 days, all specimens gained weight with the exception of the material Ariston pHc((R)) that lost 20.57 microgram/mm(3) (+/-6.46). Only the specimens immersed in de-ionized water showed any significant dissolution of the material, with solubility values ranging up to 32.5 microgram/mm(3) (+/-2.7) for Ariston pHc((R)). SIGNIFICANCE: Currently available dental composite materials vary significantly in the post-placement expansion behavior demonstrating a lack of consensus view amongst developers as to the most desirable values that should be attained. The nature of the immersing solution in in vitro studies of this nature has a distinct effect on the results obtained for some materials.

Absorption↗

PubMed2004

Experimental efficacy study of coated VICRYL plus antibacterial suture in guinea pigs challenged with Staphylococcus aureus.

BACKGROUND: This study evaluated the ability of coated polyglactin 910 suture with triclosan (Coated VICRYL Plus Antibacterial) suture to inhibit the colonization of bacteria on the suture after direct in vivo inoculation challenge with Staphylococcus aureus utilizing a guinea pig model. METHODS: One control suture (4-5 cm) and one test suture (4-5 cm) were implanted subcutaneously in the dorsal-lateral regions (control on the left side, test on the right side, approximately 5 cm apart) in 16 female Hartley guinea pigs (300-400 g) via a 20-gauge catheter. Each implantation site was challenged directly with 2.1 x 10(4) colony forming units (cfu) of Staphylococcus aureus through the indwelling catheter. The test material was coated polyglactin 910 suture with triclosan (2-0, dyed), and the control material was coated polyglactin 910 suture (2-0, undyed). At 48 h, suture articles were explanted and a bacterial enumeration assay was performed. RESULTS: There was a significant difference (p < 0.05) in the number of bacteria recovered between the study groups at 48 h post-implantation. The mean recovery for test sutures was 559 cfu, and the mean recovery for control sutures was 16,831 cfu. Coated polyglactin 910 suture with triclosan provided a 30.5-fold (96.7%) reduction in the number of recovered bacteria compared to standard coated polyglactin 910 suture. CONCLUSIONS: This study demonstrates that coated polyglactin 910 suture with triclosan inhibits bacterial colonization of suture after direct in vivo challenge with S. aureus in a guinea pig model.

Animals↗

PubMed2004

Biomechanical comparison of inside-outside screws, cables, and regular screws, using a sawbone model.

Our aim was to conduct a biomechanical comparison of the pull-out strengths of inside-outside (I/O) screws, cables, and bone screws to determine whether I/O screws provide greater pull-out resistance than cables or bone screws, and their effectiveness with the screw diameter. There is no remarkable biomechanical experimental study comparing the I/O technique with conventional spinal techniques. The diameter of the screw heads were also biomechanically tested to determine the optimal size that can be used. In this study, 45 blocks of 50x50x5 mm of "sawbone" (synthetic bone, model 1137, Pacific Research Laboratories, Vashon, WA, USA) were used as bone substitutes. Fifteen sets of 14-mm inside-outside Dynalok screws and nuts, 15 wire cables, and 15 bone screws were inserted into a separate sawbone block. An MTS Bionx materials testing machine was used to measure the load to failure of each implant. The mean values and standard deviations of each group were calculated and Student's t-test was used for comparison. The load to failure of the inside-outside screws was significantly greater than that of the cables (p<0.0000004) and the regular bone screws (p<0.000002). The results also revealed that increasing the diameter of the head of the screw also increases the resistance against the pull-out strengths. Thus, using a larger screw in occipitocervical stabilization provides safe and stable fixation of the occipital bone to the cervical spine. This study also proved that sawbone is a useful and reliable alternative to allogenic fresh cadaveric bone grafts or animal bones for certain biomechanical testing.

Atlanto-Occipital Joint↗

PubMed1998

Effect of a resin-modified glass ionomer liner on volumetric polymerization shrinkage of various composites.

OBJECTIVE: The aim of this study was to evaluate the volumetric polymerization shrinkage of a selection of composite resins alone, and in contact with a resin-modified glass ionomer (RMGI) liner. METHODS: Volumetric polymerization shrinkage was measured for five different composite resins by means of the Watts and Cash deflecting disk method. Shrinkage measurements were determined for 300 s for each composite alone, and when placed over pre-cured RMGI liner. Each sample was placed within a brass ring fixed to a glass microscope slide. A linear vertical displacement transducer (LVDT) was brought into contact with a flexible glass coverslip placed over the composite sample. On curing, the contraction of the setting composite sample caused distortion of the coverslip, the resulting deflection being recorded via the LVDT by means of data-logging software. All RMGI samples were prepared at 85% relative humidity (RH) and 35 degrees C. In all cases the composite was light-cured at ambient RH and 35 degrees C. RESULTS: Analysis of the data demonstrated statistically significantly less shrinkage for each composite when cured in contact with the set RMGI liner than when cured alone, at p < 0.001. SIGNIFICANCE: Use of an RMGI liner was found to significantly reduce volumetric polymerization contraction for all the light-curing composite resin restorative materials tested.

Analysis of Variance↗

PubMed1998

Cleveland Clinic continuous flow blood pump: progress in development.

The Cleveland Clinic continuous flow blood pump is the central element of our innovative ventricular assist system (IVAS). Recent progress has been made in the design/fabrication of a pulsatile mock loop, journal bearing materials testing, and evaluation of a system control algorithm. These results have allowed an acceleration of our program.

Algorithms↗

PubMed1992

Tissue responses to Hydron, assessed by intraosseous implantation.

Teflon tubes containing freshly mixed, polymerized Hydron root canal filling material, fully set AH26 or Teflon were implanted into the mandible of guinea pigs and assessed histologically at 2 days, 1, 2, 4, 12 and 26 weeks. None of the materials tested elicited signs of overt or significant tissue damage, and polymerized Hydron was assessed to be as biocompatible as fully set AH26 and Teflon. Bone formed in very close apposition to the polymerized Hydron, whereas a soft tissue capsule separated the regenerated bone from implants of AH26 and Teflon.

Animals↗

PubMed1994

Correlation between magnetic resonance imaging disturbances and the magnetic susceptibility of dental materials.

OBJECTIVES: The purpose of this study was to correlate the size and the orientation of image disturbances observed on specific samples of dental materials with their magnetic susceptibility. The measurement of the magnetic susceptibility was performed in the 10(-5) or 10(-6) range using MRI to establish a classification of dental materials. METHODS: Cylindrical dental alloy samples incorporating gold, silver, and palladium were placed in a Pyrex beaker filled with distilled water. Images were performed at 0.13 Tesla using two-dimensional Fourier transformation and projection reconstruction at 360 degrees imaging methods. The magnetic susceptibilities were obtained by measuring distances between spots having the highest intensity on the image. RESULTS: A very discriminating classification may be established on MRI criteria. This method permits one to determine the dia- or para-magnetic character of the dental materials tested. Only palladium-based alloys have been detected to be paramagnetic with kappa > 0. One of the silver-based alloys did not induce detectable distortion because its susceptibility was very close to that of distilled water. Based on this MRI data, the use of this material may be recommended for applications that may be subjected to MRI evaluation. SIGNIFICANCE: With the increasing use of MRI as a diagnostic tool, it is useful to establish a classification of prosthetic biomaterials compatible with MRI.

Artifacts↗

PubMed2001

Microleakage of adhesive restorative materials.

PURPOSE: To compare the marginal sealing ability of two conventional and one polyacid-modified resin-based composite, and two conventional and three resin-modified glass-ionomers in conventional cylindrical box cavities following a silver-staining microleakage evaluation method. MATERIALS AND METHODS: In 80 freshly extracted and caries-free human third molars, three standardized cylindrical butt-joint cavities were prepared: the first cavity in coronal enamel, the second at the cemento-enamel junction (CEJ) and the third completely in root cementum. A control group of 10 additional teeth was chosen. After the cavities were restored randomly using the eight restorative materials tested, the specimens were first stored in distilled water at 37 degrees C for 7 days and then thermocycled (500 cycles). Thereafter, the specimens were centrifuged for 10 min in plastic bottles containing 50 wt% silver nitrate aqueous solution. The degree of microleakage was recorded at four different depths along the restoration margins using an optical stereomicroscope equipped with a measuring gauge. RESULTS: None of the tested systems prevented microleakage completely, but the extent of leakage decreased towards the bottom of the restorations. The resin-modified glass-ionomers performed better than the conventional resin-based composites and conventional glass-ionomers. CLINICAL SIGNIFICANCE: Distinct leakage patterns were recorded among all materials investigated. Complete marginal sealing could still not be reached with the new adhesive restorative materials.

Analysis of Variance↗

PubMed2002

A quantitative evaluation of apical leakage of four root-canal sealers.

AIM: This in vitro study evaluated the microleakage of root fillings involving four root-canal sealers including AH Plus (De-Trey, Switzerland), RoekoSeal (Roeko, Germany). Ketac-Endo (ESPE, (Germany) and Sultan (Sultan Chemists, USA. METHODOLOGY: Forty extracted human maxillary anterior teeth were used. The coronal part of each tooth was removed and the root canals were prepared using the step-back technique and apical enlargement to size 60 file. The specimens were randomly divided into four groups of 10 samples, filled with one of the test materials and gutta-percha cones by the cold lateral condensation technique. A fluid filtration method was used for quantitative evaluation of apical leakage. The leakage was measured by the movement of an air bubble in a capillary glass tube connected to the experimental root section. Measurements of fluid movement were made at 2-min intervals for 8 min. Water transport through existing voids in the obturated canals could be measured reproducibly in this way. The quality of the seal of each specimen was measured after 7,14 and 21 days. RESULTS: Statistical analysis indicated that all the root fillings showed less leakage after 21 days (P < 0.05). Fillings incorporating Sultan showed significantly more leakage than all other sealers. CONCLUSIONS: Root fillings with RoekoSeal in combination with cold lateral condensation technique showed better sealing than those with Ketac-Endo, AH Plus and Sultan sealers after 21 days. The fluid filtration test used in this study gave quantitative results and allowed nondestructive long-term evaluation of specimens.

Analysis of Variance↗

PubMed1996

Factors influencing shear strength of incrementally cured composite resins.

Factors influencing the shear strength of incremental curing of three different composite resins were examined. The first increment was cured under different surface conditions, in air, or under a coverglass. A separate experiment studied the effect of curing in nitrogen atmosphere. There was no difference in the shear strength of the specimens if the first increment was created in air or under a coverglass. One material (Heliomolar RO) showed higher shear strength when cured in increments and one when bulk-cured (Herculite XR). Curing increments in a nitrogen atmosphere increased the shear strength for two of the three materials tested (P50 and Heliomolar). The results showed that the bond strength between the increments of composites was influenced by the surface properties of the composites themselves after they had been cured under the different conditions; it was also affected by the inherent chemical and physical properties of the materials utilized.

Acrylic Resins↗

PubMed1990

An investigation of test-house variability in the mechanical testing of dental materials and the statistical treatment of results.

The suitability of a test for standard specification testing depends inter alia on the ability to repeat the tests in a reproducible manner at a number of test centres. This work involved the investigation of three tests currently proposed as standard specification tests for dental materials. It was found that one test (compressive strength of cements) is inappropriate for inclusion in standards due to an unacceptable variation in test results between test centres. The treatment of results suggested in standards should place less emphasis on the mean value of a relatively small number of test specimens and the use of a simple form of probability theory in which, say, 80 per cent of specimens are required to achieve a certain pass level. In some standards there may be a need to increase the numbers of test specimens significantly in order to achieve a more meaningful and reliable result. The use of Weibull statistics can be adopted as a means of identifying tests which are suitable for inclusion in standard specifications, although it is doubtful that a test at this level of sophistication is required or desirable for inclusion in the standards themselves.

Composite Resins↗

PubMed1995

[The force level of pseudoelastic leveling wires in relation to interbracket distance].

One of the arguments for the introduction of pseudo-elastic wire materials was "the way they work biologically", that is to say, on the one hand small and uniform force over an extended period of time and on the other the avoidance of excessive forces during the leveling phase. Since an evaluation of the operative force of such an arch wire is dependent on temperature, stress-strain curve, and method of activation, and because the extent of the activation is no longer directly proportional to the operative force, the result is that it is often difficult to determine clinically, whether a safe maximum force is not being exceeded. To clarify this issue arch wires were tested in a three bracket test simulating to the greatest degree possible a clinical situation. The inter-bracket distance was selected in accordance with the situation in the upper and lower incisor region independent of the width of the bracket. The results showed rather high forces for some of the wires. Often these forces were higher in the mandibular situation due to non-ideal force deflection curves than in the supramaxilla. One of the tested materials did, however, effectively limit the operative force in the upper and lower jaw. Especially significant is that the differing characteristics of the tested wire materials result in a completely different action in relation to force development.

Dental Stress Analysis↗