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Query: UNIPROT:A7KAX9 (grit)
 1,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influences of nine dentin surface treatments were evaluated on the shear bond strength of a new light-cured glass-ionomer cement (GIC) and on the SEM morphology of the treated dentin surfaces. The following treatments were performed: saline solution (control), NaOCl, acidic glycine, EDTA, malic acid, malic acid plus glycine, polyacrylic acid, tannic acid, and neutral+acidic oxalate solutions. Buccal dentin surfaces were polished with #320-grit abrasive paper, treated with one of the chemicals, washed, and air-dried. Cylindrical GIC samples were then applied to the dentin surface, stored in 100% humidity, and tested after 24 h. SEM observations demonstrated no effect of saline or NaOCl treatment on the smear layer but its complete removal with exposure of collagen fibrils after malic or malic acid plus glycine treatment. Partial removal of the smear layer occurred following glycine treatment and with tannic or polyacrylic acids. Complete removal of the smear layer was seen after EDTA or pyruvic acid treatment. Oxalate treatment produced a layer of crystals, which completely covered the dentin surface. Shear bond strength of GIC was significantly increased only by treatment with the oxalate solutions.
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PMID:Effects of dentin surface treatments on the shear bond strength of Vitrabond. 152 80

The present study investigated the effectiveness of treating dentin with 2-hydroxyethyl methacrylate (HEMA) prior to application of an adhesive resin. The adhesive resin was 5% 4-methacryloxyethyl trimellitate anhydride (4-META) in methyl methacrylate (MMA) combined with poly-MMA powder. Polymerization of this resin was initiated by tri-n-butyl borane (TBB). Bovine dentin samples were ground with 600-grit Carbimet paper discs, and demineralized with either an aqueous solution of 10% citric acid/3% ferric chloride (10-3) or an aqueous solution of 10% citric acid (10-0). Improved bond strengths were achieved with HEMA treatment of bovine dentin samples, and improvement of bond strengths was dependent upon the time period of HEMA application. Scanning electron microscope (SEM) examination revealed the formation of a transitional zone of resin-reinforced dentin, termed the "hybrid" layer, in those specimens receiving 10-3 pre-treatment. The adhesive resin impregnated the exposed collagen bundles with which it entangled to create the "hybrid", essential in the attainment of high tensile bond strengths. Specimens pre-treated with 10-0 did not readily form "hybrid" layers. However, if HEMA application followed the 10-0 pre-treatment, "hybrids" were demonstrated on SEM, and bond strength increased to 13 MPa. The ferric ions in the 10-3 effectively improved the diffusivity of dentinal substrates, as did HEMA. This study indicates that HEMA applied to dentinal substrates enhances monomer diffusion and entanglement with dentinal components, and facilitates the formation of a "hybrid" layer.
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PMID:Effect of HEMA on bonding to dentin. 152 92

The purpose of this study was to evaluate the effect of a fluoridated etching gel on the shear bond strength of a composite resin to enamel. A total of 75 extracted human permanent molars were used. A flat enamel surface was obtained with 600-grit silicon carbide paper and cleaned with a rubber cup and a water slurry of fine flour of pumice. The teeth were randomly distributed into 5 groups of 15 teeth each and etched as follows: group 1: 37% non-fluoridated phosphoric acid gel (Coe) for 60 seconds (control); group 2: 60% phosphoric acid gel with 0.5% NaF (Orthoprep) for 5 seconds; group 3: Orthoprep for 15 seconds; group 4: Orthoprep for 30 seconds; group 5: Orthoprep for 60 seconds. After etching, rinsing and drying, an unfilled resin (Coe Bond) was thinly applied with a brush and cured for 30 seconds. A nylon ring was placed over the area and filled with a light-cured composite resin (Occlusin). The teeth were thermocyled (100x), mounted in plastic cups and plaster, and sheared with a knife-edged blade in an Instron machine running at a crosshead speed of 1 mm/min. The results in MPa were as follows: group 1: 14.49 +/- 4.43; group 2: 10.81 +/- 3.70; group 3: 13.51 +/- 3.21; group 4: 14.79 +/- 3.76; group 5: 15.47 +/- 4.07. An analysis of variance showed that the results in groups 1, 4 and 5 were not significantly different but that the bond strengths in groups 2 and 3 were significantly lower. Fracture within the enamel occurred in 8 specimens in group 1, 5 in group 2, 6 in group 3, 8 in group 4, and 13 in group 5. In the fluoridated etchant groups the number of specimens showing enamel fracture increased as the application time of the etchant increased.
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PMID:Effect of a fluoridated etchant on the shear bond strength of a composite resin to enamel. 152 28

Most anatomy texts depict gear-like apposition of adult upper and lower teeth. But this apposition generally does not occur in civilized man. On the contrary the widespread tooth attrition which occurs in primitive man, is well established. This attrition, which is not depicted in anatomy texts or correctly evaluated in medical and dental education, is a natural protective mechanism that functions to preserve, oral, pharyngeal, and respiratory physiology throughout life. As man removed grit, sand and other abrasive food from his diet, he deprived himself of a natural aid, i.e. attritional wear of teeth that protects the physiology of his mouth and the swallowing and respiratory apparatus (4). In contrast to this the unworn teeth, characteristic of present-day man, prevent anatomic and physiologic changes that normalize oral pathways. For these reasons, 'textbook' tooth occlusion should be re-evaluated.
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PMID:Organic tooth wear--overlooked in anatomy texts. 152 52

Osteoarthritis (OA) is a common disease which affects nearly 50% of people over age 60. Histologic evaluation suggests that fibrillations approximately 20-150 microns are among the earliest changes in the articular cartilage. We propose a technique to quantify these surface fibrillatory changes in osteoarthritic articular cartilage by considering the angular distribution of the envelope-detected backscattered pressure field from an incident 30-MHz focused transducer. The angular distribution of the scattered acoustic field from an inosonifying source will directly relate to the distribution of surface fibrillatory changes. Data are presented for three different grades (400, 500 and 600 grit) of commercially available emory paper and three samples of osteoarthritic femoral head articular cartilage, which were visually assessed as having smooth, intermediate and rough surfaces, respectively. Our preliminary results indicate a probable monotonic relationship between articular cartilage roughening and the degree of broadening in the angle-dependent pressure amplitude. When applied to the emory paper, the technique indicates sensitivity to differences as small as approximately 5-10 microns in mean roughness. This procedure may provide an extremely sensitive and reproducible means of quantifying and following the cartilage changes observed in early osteoarthritis.
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PMID:Quantitative assessment of cartilage surface roughness in osteoarthritis using high frequency ultrasound. 156 26

Larvae of the screwworm, Cochliomyia hominivorax (Coquerel), were reared on meridic diets containing ground corncob material (grit) in test 1 and the cob grit or sawdust in test 2 to reduce or replace the amount of an expensive synthetic copolymer gelling agent. Biological parameters for the tests included pupal yield (total number), pupal weight (size), pupal malformation, adult emergence, adult malformation, egg weight, and egg hatch to assess for any significant differences. In the first test, larval propagation was successful for five consecutive generations on 24 of an original 37 formulations. Results indicate that a minimum concentration of 4% of the cob grit is needed to reduce the gel by 50%; at least 8% concentration is needed to reduce the gel by 80%; and at least 12% concentration is needed to replace the gel completely. In the second test, the larvae were successfully propagated for five consecutive generations when the copolymer gel was reduced by 50 or 75% in the diet by using either sawdust or the no. 60 cob grit size. The cost savings and applications of use of sawdust or the cob grit incorporated into the larval diet can be beneficial to a mass-production screwworm program.
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PMID:Gel extenders in larval diet of Cochliomyia hominivorax (Diptera: Calliphoridae). 159 16

Fifty-six endosseous cylindrical implants were placed in dog mandibles 12 weeks after the extraction of all mandibular premolars and first molars. Eight implants, four coated with 50 microns of hydroxylapatite (HA) and four grit-blasted and titanium-surfaced, were placed in each dog. Ideal implant placement sites were modified by creating standardized 3 x 5-mm facial dehiscence defects. Half the dehiscences were treated with a modified expanded polytetrafluoroethylene (PTFE) membrane; the remainder served as controls. After 8 weeks of healing, the animals were sacrificed and measurements made to determine the percentage of dehiscence repair. The HA-coated implants had a mean defect fill of 95.17% and the grit-blasted implants had a percent fill of 82.8% in the guided tissue regeneration (GTR) test group; the control implants demonstrated a mean fill of 55% and 39% in the HA-coated and grit-blasted implants, respectively. Significant differences (P less than .05) were noted between both test groups and the titanium control group, and between the HA test and HA control groups. Histologic evaluation showed significantly greater repair associated with HA-coated implants, as well as significant bone loss associated with clinically exposed membranes. It was concluded that within the limitations of this study, guided tissue regeneration is a viable option in treating defects associated with dental implants.
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PMID:Histological and clinical comparisons of guided tissue regeneration on dehisced hydroxylapatite-coated and titanium endosseous implant surfaces: a pilot study. 166 24

Under practice-related conditions 100 human molars and premolars were prepared with diamond grinding instruments of different grit. We obtained the smoothest surfaces by using the extra-fine grit at 250,000 rpm, thus indicating the suitability of these instruments for finishing cavity walls especially at high rotating speeds. Only slight differences were found between medium and coarse grit. The time saved by choosing the super-coarse grit for preparation is largely compensated because finishing of rough cavity walls will take longer. No constant effect of the rotating speeds on the depth of roughness of cavity walls was observed.
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PMID:[The effect of diamond grinding instrument of different grit on dental hard tissue]. 166 52

Static stresses affect the corrosion behaviour of 316L stainless steel, Ti-6AI-4V, and a Co-Cr-Mo alloy. Several corrosion parameters are modified by stress, although the changes most relevant to the clinical situation are lowering of breakdown potentials and increases in corrosion currents. AC impedance techniques to measure capacitance allowed the latter effect to be partitioned into components of true current density and true area changes. Although loading past the yield point can definitely cause stress-enhanced ion release (SEIR), it is not required. SEIR can also be caused by elastic loading. The basic mechanism for this phenomenon appears to be passive film disruption followed by slow repassivation kinetics. Polished, grit-blasted, and porous-coated surfaces were examined. The porous-coated materials seemed to be most susceptible to SEIR. If effects similar to those observed here apply to in vivo conditions, then tests on unstressed alloys in vitro could grossly underestimate ion release rates of stressed implant devices in vivo.
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PMID:Stress-enhanced ion release--the effect of static loading. 174 5

Adhesive bond strength studies for the tray adhesive of an addition vinyl polysiloxane (President) impression material were conducted with an acrylic resin, chromium-plated brass, and plastic trays. Tensile and shear stress studies were performed on the Instron Universal testing machine. Acrylic resin specimens roughened with 80-grit silicon carbide paper exhibited appreciably higher bond strengths compared with different types of tray material and methods of surface preparation.
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PMID:Properties of the tray adhesive of an addition polymerizing silicone to impression tray materials. 180 22


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