Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:A7KAX9 (grit)
 1,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have become increasingly aware of the presence of a type of image artifact normally appearing in anechoic areas (eg, cyst, bladder, gallbladder) and giving the appearance of "sludge" or "debris." These artifactual echoes may be caused by the fact that the finite width of the transducer beam pattern produces a finite thickness of the patient scan plane. All echoes produced in this "thick" scan plane are misinterpreted as being due to structures in the normally assumed "thin" scan plane. We have tested and verified this hypothesis by simulating soft tissue interfaces with 400 grit silicon carbide sandpaper in a water tank. A set of clues are proposed to enable the rapid identification of these artifacts.
 ...
PMID:Slice-thickness artifacts in gray-scale ultrasound. 679 35

Use of porcelain denture teeth may be desirable in many clinical situations, including implant-supported prostheses. However, lack of space because of frameworks often precludes the use of conventional retention by diatorics and pins. Adhesion of porcelain denture teeth to denture resin could also stiffen and possibly strengthen dentures and decrease stain ingress between porcelain teeth and resin denture bases. Unlike previous studies that investigated the bond between conventional feldspathic metal-ceramic porcelain and bis-GMA based composite resin, this study investigated adhesion of denture tooth porcelain to polymethyl methacrylate (PMMA). High-energy air abrasion, hydrofluoric acid etching, and the use of a general purpose bonding agent resulted in an improved bond strength of heat-cured denture PMMA bonded to denture tooth porcelain. Silane coating did not improve bond strengths, and conventional air abrasion was no more effective than polishing with 600-grit silicon carbide. Storage in water and artificial aging substantially decreased bond strengths. The strongest bond strengths were achieved by a high-energy-abrasion + etching + multi-purpose bonding-agent treatment, but a simpler etching + multiple-purpose bonding-agent treatment also produced reliable results. A laboratory technique was suggested. The role of surface treatment in the mechanism of adhesion was examined with scanning electron microscopy. High-energy abrasion produced a slightly more detailed initial topography than conventional air abrasion, but after etching, the high-energy topography became much more detailed. Surface topography alone did not account for all differences found.
 ...
PMID:Adhesion of denture tooth porcelain to heat-polymerized denture resin. 747 77

The purpose of this study was to assess the effect of etching time with Gluma 2000 conditioning agent on, first, the shear bond strength of composite resin to tooth enamel and, secondly, the micromorphology of the enamel. In the first part of the study flat enamel surfaces were prepared with 600-grit silicon carbide paper on 40 primary and 40 permanent teeth. Ten specimens of each group were etched for 15, 30, 60 or 120 seconds before applying bonding resin and restorative composite resin. After 24 hours' storage in water, the shear bond strength of each specimen was tested. Analysis of variance indicated a significant difference between the eight groups. However, the Student-Newman-Keuls test indicated that the only differences that were significant were the greater bond strengths of the 15-second primary tooth specimens compared with the 15- and 30-second permanent tooth specimens. In most cases the debonded specimens showed cohesive failure in resin close to the coupling interface. In the second part of the study the morphology of the enamel etching patterns in 96 other teeth was studied by scanning electron microscopy. The patterns were similar in primary and permanent teeth, and the longer the etching time the more pronounced was the pattern. The patterns produced in ground enamel were more uniform and predictable than those in pumiced enamel. Examination of bonded resin surfaces after dissolution of the teeth showed complete reproduction of the etched enamel surfaces, indicating excellent flow of the resin into the etched enamel.
 ...
PMID:The effect of etching time with Gluma 2000 conditioning solution on shear bond strength of a composite resin and on micromorphology of the enamel. 774 60

Dye penetration tests are very commonly used to detect the absence of a fluid seal at the tooth-restoration interface. Airlocks in the marginal gap, leaching of water-soluble tracers during processing, and the failure of only a few sections to allow interpretation of the full pattern, limit these tests to low reproducibility and precision. The purpose of this present study was to generate high-resolution three-dimensional images of waterfast tracer patterns. Cylindrical class V (3 mm diameter, 2 mm deep) dentine-bonded resin composite restorations in buccal coronal dentine were thermally cycled (1000 x, 8 degrees C, 55 degrees C, 30 s dwell at each temperature) and then silver stained using an initial vacuum (100 mmHg pressure). Each restoration was sequentially abraded from the free surface on wet 180 grit silicon carbide paper, producing up to 30 parallel surfaces at approximately 0.15 mm separation through the restoration down to the pulp. Images of the ground surfaces were captured, and assembled by a computer image analyser program to give a three-dimensional model of the tracer pattern. The maximum depths of tracer penetration below the reference surfaces were 3.00 mm, 2.09 mm, 3.16 mm and > 2.29 mm for the four specimens. Projections of the models were viewed from several directions with sections in various locations to allow investigation of the full tracer pattern. This method allows the creation of high-resolution three-dimensional tracer patterns.
 ...
PMID:Three-dimensional reconstruction of microleakage pattern using a sequential grinding technique. 784 67

This study evaluated the shear bond strength of resin-reinforced glass ionomers to enamel etched or unetched. Human, non-carious extracted permanent molars stored in distilled water were used. Flat buccal and lingual enamel surfaces were ground wet on 600-grit silicon carbide paper. The teeth were then distributed at random into six groups of 5 teeth (10 surfaces) each: Group 1: Fuji II LC, no enamel etching; Group 2: Fuji II LC, enamel etched with 10% phosphoric acid for 10 seconds; Group 3: Dyract, no enamel etching; Group 4: Dyract, enamel etched with 10% phosphoric acid for 10 seconds; Group 5: Photac-Fil, no enamel etching; Group 6: Photac-Fil, enamel etched with 10% phosphoric acid for 10 seconds. Cylindrical samples of the glass ionomers were prepared in plastic molds and bonded to the enamel surface according to the manufacturers' instructions. All samples were placed in distilled water for 24 hours, and sheared with an Instron at a crosshead speed of 0.5 mm/minute. The results (in MPa) were: Group 1: 11.29 +/- 4.84; Group 2: 19.64 +/- 5.43; Group 3: 8.26 +/- 3.61; Group 4: 22.04 +/- 5.40; Group 5: 2.05 +/- 3.05; Group 6: 9.12 +/- 6.61. ANOVA and Student-Newman-Keuls procedure revealed that on etched enamel, Fuji II LC and Dyract had a significantly higher bond strength than all the other groups tested (P < 0.0001), but not significantly different between each other. With these two groups, cohesive failure within the material was recorded in all samples while in the unetched samples, all specimens displayed an adhesive failure (glass ionomer-enamel interface). All samples with Photac-Fil, with or without enamel etching had adhesive failures.
 ...
PMID:Bond strength of resin-reinforced glass ionomer cements after enamel etching. 788 Apr 80

The aim of this in vitro study was to compare the adhesive properties of a manufacturer's third and fourth generation dentin adhesive. Vestibular sections of recently extracted third molars were embedded in chemical-cured acrylic resin and ground with 600-grit silicon carbide sandpaper. Fifteen samples were prepared with the adhesive products and the dentin surfaces were analysed by SEM. Twenty-four samples were divided into two groups and prepared with third and fourth generation systems, respectively. Composite filled tubes were then positioned on the prepared dentin surfaces and photopolymerized. The treated samples were kept in distilled water at 37 degrees C for 24 h. Four samples were used to analyze the resin-dentin surface. A tension test was performed on the remaining twenty samples at a crosshead speed of 0.5 mm/min. The results were analyzed using the Fisher and Student t-tests. The fractured surfaces were examined by SEM. The resistance to tensile forces of specimens prepared with the fourth generation system was significantly higher than that obtained after using the third generation system. Thus, as expected from the in vitro tests, the fourth generation system provided better adhesion to dentin than the third generation material.
 ...
PMID:An in vitro study of two adhesive systems: third and fourth generations. 798 69

This study determined the shear bond strength (SBS) of composite bonded to chlorhexidine-treated enamel and untreated enamel. Fifty human molars were mounted in cold- cure acrylic and the superficial enamel of the buccal or lingual surface was exposed using 600-grit silicon carbide paper. During the experimental protocol, the control group (n = 25) and the experimental group (n = 25) were stored in distilled water at 37 degrees C. The experimental group was immersed in 0.12% chlorhexidine gluconate for 1 minute, 4 times daily, for 7 days. Prisma APH composite was then bonded to all samples following acid etching for 30 seconds, and the SBS was determined. Shear bond strengths for the control (13.23 +/- 3.22 MPa) and the experimental (13.67 +/- 4.59 MPa) groups were not significantly different using a t-test. The result may be attributed to either a lack of effect of chlorhexidine or to the acid etch which dissolves the affected superficial enamel leaving an unaffected substrate for bonding.
 ...
PMID:Shear bond strengths of composite to chlorhexidine-treated enamel. 805 91

Microscopic tooth-wear (microwear) patterns can be an important tool for assessing modes and rates of abrasive tooth wear, but their analysis and interpretation is complicated by the fact that microwear is influenced by many factors. Three of these factors were here tested under conditions of compressive loading: (1) species differences in enamel structure, (2) abrasive particle size and (3) magnitude of force. Teeth of four species (Homo sapiens, Lemur fulvus, Ovis aries and Crocodylus rhombifer) were abraded in vitro using three sizes of abrasive silicon-carbide grit (average diameters 73, 23 and 14 microns), at two loads (50 and 100 kg). Microwear features were assessed by scanning electron microscopy of lightly etched enamel surfaces and epoxy replicas. Microwear pits (length:width < 4:1) were the predominant feature type. Factorial analysis of variance of rank-transformed, feature-area measurements demonstrated that, under conditions of compressive loading, the size of abrasive particles was the primary determinant of microwear size. These results contrast with previous experimental tests of abrasion by predominantly shearing loads, where feature size was influenced by interaction among experimental factors, including the microscopic orientation of enamel crystallites. Although magnitude of compressive force was not a factor in microwear size variation, it may be a critical factor in explaining the presence or absence of microwear on tooth surfaces. The relatively small compressive bite force generated during typical chewing may not consistently produce abrasive pitting. These experiments demonstrate that, as the same abrasive regime can produce both large and small pits, the mechanism by which wear features are formed (i.e. compression or adhesion) cannot be determined from the size of features alone. Nevertheless, the dependence of pit size on abrasive particle size demonstrates that metrical variation in wear features can elucidate important attributes of an animal's diet.
 ...
PMID:A scanning electron-microscopic study of in vitro abrasion of mammalian tooth enamel under compressive loads. 817 3

The purpose of this study was to evaluate the effect of an APF gel treatment on the shear bond strength of a resin composite to enamel. A total of 45 noncarious human extracted permanent molars were used. A flat enamel surface was obtained with 600 grit silicon carbide paper and cleansed with a rubber cup and a water slurry of fine flour of pumice. The teeth were randomly distributed into three groups of 15 teeth each: Group 1: Etched for 30 sec with 37% orthophosphoric acid gel (control); Group 2: APF treatment (Topex gel--Sultan Dental Products, Englewood, NJ) for 1 min and then etched as in Group 1; Group 3: APF gel treatment for 4 min and then etched as in Group 1. After etching, rinsing, and drying, an unfilled resin (XR-Bond--Kerr Manufacturing Co., Romulus, MI) was applied thinly with a brush and cured for 20 sec. A nylon ring (internal diameter: 6.69 mm2) was placed over the area and filled with a light-cured composite resin (Herculite XR--Kerr Manufacturing Co., Romulus, MI). The teeth were thermocycled (x500), mounted in plastic cups and plaster, and sheared with a knife-edged blade in an Instron Testing Machine (Instron Engineering Corp., Canton, MA) running at a crosshead speed of 0.5 mm/min. The results in MPa were as follows: Group 1: 24.88 +/- 6.16; Group 2: 23.20 +/- 5.11; Group 3: 21.29 +/- 8.44. An ANOVA and Student-Newman-Keuls procedure revealed no statistically significant difference among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Shear bond strength of a resin composite to enamel treated with an APF gel. 824 3

This study determined, quantitatively, the role of resin infiltration in dentin bonding. Four groups contained 10 molar teeth. Thirty were sectioned in the mid-coronal region and the dentin ground flat with 600 grit silicon carbide paper. Group 1: smear layer intact; Group 2: smear layer removed with a Prophy Jet; Group 3: conditioned with 10% H3PO4 for 20 seconds; Group 4: comprised dentin exposed by a transverse, mid-coronal fracture. Dentin surfaces were treated with All-Bond 2, its companion bonding agent, followed by P50 resin composite, polymerized in 1 mm increments. After storage in water at 37 degrees C for 24 hours, the assemblies were tested to failure in a shear mode at a crosshead speed of 5 mm/minute. Surface and interfacial morphology was characterized using SEM. Values in MPa were: Group 1: 10.24 +/- 2.98; Group 2: 20.37 +/- 4.62; Group 3: 32.68 +/- 7.12; and Group 4: 26.77 +/- 4.85. ANOVA and student t-test showed the means statistically different (P < 0.05). Since resin penetration was only found appreciably in dentin tubules in Group 4 and tubular and intertubular penetration in Group 3, it was concluded that resin infiltration can contribute approximately one third of the shear bond strength of this total etch system.
 ...
PMID:Quantitative contribution of resin infiltration/hybridization to dentin bonding. 832 67


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>