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At least 19 recordsLinked to original sources
PubMed1990

Effects of the diamond grit sizes of the commercial dental diamond points on the weight-load cutting of bovine enamel and glass-ceramic Typodont teeth.

To evaluate the effect of the diamond grit size of commercial dental diamond points on the dental cutting, we conducted weight-load cutting tests on bovine enamel and glass-ceramic typodont teeth using 3 different diamond grit sizes and air-bearing and ball-bearing air-turbine driven handpieces. With the transverse load applied on the diamond point varied between 20 and 80 g, we measured rotational cutting speed and cutting volume. Generally, increases in applied load caused decreases in rotational cutting speed and increases in cutting volume. The intensity of this trend, however, differed between grit sizes. Regular grit diamond points most strongly showed this tendency, while super-fine grit diamond points were least affected. Fine grit diamond points behaved in a manner similar to regular grit points.

Animals↗
PubMedDate not supplied

A study of the optical micrometer, the coin gauge, and the diamond knife micrometer in diamond knife calibration.

Reproducible results in refractive keratectomy are greatly influenced by an accurate setting of the diamond knife blade length. In this study, we evaluated the accuracy and reproducibility of three existing techniques of blade calibration: the KOI coin gauge, the KOI diamond knife handle micrometer, and the Magnum optical micrometer. Serial blade length measurements of three similarly designed KOI diamond knives were made using each of the above calibration methods. The three knife handle micrometers had the largest measurement error (3.55%, 2.83%, 1.82%), and therefore the sole reliance of the handle micrometer for blade calibration was not recommended. The measurements made by the coin gauge on the three knives had measurement errors of 1.03%, 1.64%, and 1.46%. The optical micrometer achieved an accuracy of 0.005 mm and an interobserver precision of 0.009 mm. We prefer using the optical micrometer because the potential for parallax error is eliminated; it has a lower risk of blade damage; it is easier to use; and it also allows detection of defects in the footplates, the diamond knife, and of the wobbling blade, which may contribute to calibration error.

Calibration↗
PubMed1986

The diamond knife "semi": a substitute for glass or conventional diamond knives in the ultramicrotomy of thin and semi-thin sections.

The diamond knife "semi" for ultramicrotomes was originally designed by its manufacturer (DIATOME S.A.), for cutting semi-thin sections from 0.2 micron to 2.0 micron. Cutting tests of Epon-embedded material (nervous system, myelin sheat) with this knife have shown that the quality of semi-thin sections is equivalent or better than that obtained with a glass knife, and much time could be saved during the microtomy of serial sections. The quality of thin sections (0.07 micron to 0.12 micron) is excellent and comparable to that obtained with a conventional diamond knife. Furthermore, when adjacent sections are cut thin and semi-thin (for immunochemistry or high voltage microscopy), both are excellent in that they are of uniform thickness. In conclusion, this tool has advantages for both light microscopy and transmission electron microscopy.

Animals↗
PubMed1991

Cutting effectiveness of diamond instruments subjected to cyclic sterilization methods.

The effect of repeated sterilization on the cutting effectiveness of one brand of rotary dental diamond cutting instruments was measured. Four groups of five diamond burs were sterilized by four methods: (1) sterilization with a chemical agent (Sporicidin); (2) steam under pressure (autoclave); (3) dry heat (Dri-Clave); or (4) chemical vapor (Chemiclave). Each group of diamond instruments made a timed cut in a ceramic block. This cut and all subsequent cuts were measured and were used to determine a baseline cutting effectiveness. Each group of diamond burs was then ultrasonically cleaned, sterilized, and another cut was made. At the end of 10 cycles there was no difference in cutting efficiency of the dental diamond instruments. However, there are differences in the cutting efficiency of individual diamond instruments. The SEM evaluation made prior to cutting and at the end of the 10 cycles of sterilization demonstrated that diamond wear was similar in all groups and that little diamond particle loss occurred in any group.

Analysis of Variance↗
PubMed1989

[Practical application of diamond points in mucosalplasty of edentulous ridges].

In order to establish a new operative method of mucosalplasty in the edentulous ridges to improve pontic adaptation, newly revised diamond points were produced and tested. The efficiency of these diamond points were tested on the edentulous ridges of dogs in relation to its shape, size of the diamond particle, and appropriate rotational speed, and the tissue damages and healing processes were observed under a light microscope and SEM. The results were as follows: 1. Light microscopic observations showed immediate post operative necrosis of the wound surface, and degeneration below the necrosed layer of high rotational speed diamond points. 2. Tissue damage became larger as the size of the diamond particle increased, but there appeared to be no influence upon the healing process of the wound. 3. Tissue damage also became larger as the diameter of the diamond point increased, but again no influence upon the healing process was observed. 4. Middle to low rotational speeds showed no differences in tissue damage or wound healing, but high rotation caused larger tissue damage and prolongation in the healing process. 5. The most suitable condition for mucosalplasty revealed the size of the diamond particle to be 200 microns, and rotational speed to be between 12,000-20,000 rpm.

Alveoloplasty↗
PubMed1989

[Relation of surface texture of fine finishing diamond point for composite resin and polished surface of composite resin].

Distribution of diamond grain size of seven fine finishing diamond points was measured by a digital image analyzer. Also influence of diamond grain size of fine finishing diamond points on finished surface of two types of visible light cured composite resins (semihybrid type and submicron filler type) were investigated. Diamond grain size was almost from 10 to 100 microns 2 in area. Diamond grain size was closely related to the surface roughness of semihybrid type composite resin, although it was not related to that of submicron filler type composite resin. Surface roughness of a submicron filler type composite resin finished at a low speed was less than that at a high speed. Grain size of diamond point and revolution speed may play an important role in surface texture of composite resin.

Composite Resins↗
PubMed1989

[Experiments on abrasion and wear of dental diamond instruments].

In spite of identical ISO standards for shape, grain size, and largest head diameter of diamond abrasive instruments there are major differences in the machining performance among the various makes. These differences are largely due to variations in shape and diamond partical size. Diamond burs from different manufacturers of the same visual shape and particle size do not show any significant differences in performance. However, not only the abrasive performance but to a greater extent the design of the preparation margin determine the selection of a bur. It would be desirable that manufacturers be more specific about the particle size used and the shape of the bur, since the ISO standard does not include sufficiently accurate data about diamond particle size and shape design. The life of a diamond instrument is limited by the wear of its tip. Here the diamond layer wears off faster than on the rest of the instrument. This calls for early replacement of the instrument in clinical use even if the shaft still might be functionable.

Carbon↗
PubMed1991

Ulnar neuropathy at the elbow in diamond assorters.

Unilateral ulnar neuropathy at the elbow was detected in 12 men employed as diamond assorters. Asymptomatic diamond assorters were studied as controls. In the symptomatics, the ulnar neuropathy was restricted to the hand which held the eye-glass used for inspecting the diamonds. Electrophysiological studies using several parameters revealed neurapraxia sometimes combined with axonal degeneration in the ulnar nerve at the elbow, compatible with compression at that site. The most sensitive parameters of abnormality in the symptomatic subjects were segmental slowing of motor nerve conduction velocity across the elbow (P less than 0.001) and the amplitude of the compound muscle action potential obtained on stimulating the nerve above the elbow (P less than 0.001). In the 18 asymptomatic diamond assorters, electrophysiological studies revealed an ulnar neuropathy in two (again in the hand used for holding the eye-glass). Ulnar mononeuropathy at the elbow thus seems to be an occupational hazard for diamond assorters and it is worthwhile to elicit occupational history from patients presenting with an ulnar mononeuropathy, especially in Bombay and Gujarat where diamond industry is concentrated.

Adult↗
PubMed1992

Survey of cobalt exposure and respiratory health in diamond polishers.

This cross-sectional study was undertaken after the discovery of cobalt-related fibrosing alveolitis and bronchial asthma in diamond polishers occupationally exposed to cobalt. A total of 194 workers from 10 diamond polishing workshops and 59 workers from three other workshops from the diamond industry (control subjects) were studied; a questionnaire was administered and spirometry was performed. Cobalt exposure was assessed by environmental air sampling using both area and personal sampling and by measuring urinary cobalt concentration. When considered on a workshop basis, these environmental and biologic indices of exposure correlated well with each other. These measurements led to the definition of three cobalt exposure categories: a no exposure group, a low exposure group, and a high exposure group. The high exposure was, however, still below the present threshold limit value for cobalt (50 micrograms/m3). Spirometry showed that indices of ventilatory function (FVC and FEV1) were significantly (p less than 0.05) lower in the group with the highest exposure to cobalt. These differences were not due to differences in smoking habits. The results were confirmed when the data were analyzed by covariance analysis of lung function indices against smoking status, taking mean cobalt exposure in each workshop as a covariate, and when the data were analyzed by multiple regression analysis. This analysis showed that cobalt exposure correlated with decreased pulmonary function. Our results suggest that, during diamond polishing, exposure to cobalt at levels below the current threshold limit value is associated, on a group basis, with measurable effects on lung function parameters. The relationship between these cross-sectional epidemiologic findings and the occurrence of overt lung disease in diamond polishers remains to be established.

Air Pollutants, Occupational↗
PubMed1985

Postoperative corneal astigmatism in cataract extraction: diamond knife versus Beaver blade.

Postoperative corneal astigmatism was studied in two groups of patients who had cataract extraction. The technique in both groups was identical except for the knife used for the partial-thickness limbal incision. In 49 patients the incision was performed with a Beaver blade and in 35 patients, with a diamond knife. Six weeks postoperatively the astigmatism was 1.27 +/- 0.90 diopters (D) in the diamond knife group, and 2.85 +/- 1.78 D in the Beaver blade group (P less than 0.0001). Sixty-one percent of the Beaver blade cases had with-the-rule astigmatism and 8% had no astigmatism. Thirty-one percent of the diamond knife cases had with-the-rule astigmatism and 26% had no astigmatism. At six months, the astigmatism was equal in both groups and practically identical to that found six weeks postoperatively in the diamond knife group. We conclude that incision of the limbal tissue with a diamond knife is associated with lower postoperative astigmatism and a more stable refractive state than incision with a Beaver blade.

Astigmatism↗
PubMed1989

Fibronectin on excimer laser and diamond knife incisions.

The experiment was designed to illustrate the difference between the diamond knife and the excimer laser (ArF 193 nm) on keratotomy incisions. The histopathologic effect of fibronectin applied to these wounds was observed. Fibronectin demonstrated a chemotactic effect on fibroblasts and increased the amount of newly synthesized collagen deposited at the incision sites. The excimer laser incisions treated with fibronectin had 43% more fibroblasts per 2,500 microns 2 than the excimer laser incisions not treated with fibronectin. The adjustable diamond knife incisions treated with fibronectin had 42% more fibroblasts than the adjustable diamond knife incisions not treated with fibronectin. The excimer laser ArF 193 nm incisions had 18% more fibroblasts in the incision area than the adjustable diamond knife incisions independent of fibronectin usage. This indicates that the excimer laser incisions and the diamond knife incisions may have different healing mechanisms--perhaps because of the distinctive modes of action of these instruments.

Animals↗
PubMed1990

Ambiguous fluidity and rigidity and diamonds that ooze!

If white hemicircles rotate over the edges of a black diamond, there occurs an ambiguity of rigidity and motion. As the hemicircles obscure the vertices of the diamond, the figure transforms from a diamond to a rotating, nonrigid cross made of a tar-like fluid. When the corners reappear, the stimulus again becomes a rigid, solid diamond. Visibility of the vertices implies rigidity. If white squares are rotated, fluidity is not perceived. If the diamond has sawtooth edges and the hemicircles are rotated, no fluidity is perceived. Similarly, if illusory contours suggest the amodal completion of the vertices, rigidity is maintained.

Adult↗
PubMed1990

'Diamond-shaped' crypts and mucosal elastin: helpful diagnostic features in biopsies of rectal prolapse.

The biopsy diagnosis of prolapsing rectal mucosa syndrome can be difficult. We present two newly described features--'diamond-shaped' crypts and mucosal elastin--which appear to be helpful in histological diagnosis. Of 32 biopsies of prolapsing rectal mucosa syndrome, all showed diamond-shaped crypts or mucosal elastin, and 28 contained both. Control biopsies comprised cases of normal or irritable bowel syndrome (46), irradiation colitis and ischaemic colitis (16), inflammatory bowel disease (26), and adenomas (30). Mucosal elastin and 'diamond-shaped' crypts with distinctive scalloped edges, which were never seen in prolapse, were observed in half the cases of irradiation and ischaemic colitis. Diamond-shaped crypts were seen in one case of inflammatory bowel disease. Diamond-shaped crypts and elastin were seen in the base of adenomas large enough to cause localized prolapse, and in four biopsies from patients with irritable bowel syndrome, all of whom had given a history of straining at stool.

Adenoma↗
PubMedDate not supplied

Flow in sequential vein grafts with diamond anastomoses.

Flow in single grafts was compared to flow in sequential grafts with diamond anastomoses to the branches of the right and circumflex coronary arteries. The mean flow was 36 ml/min for single grafts, 51 ml/min for sequential grafts with one diamond anastomosis, and 69 ml/min for sequential grafts with two diamond anastomoses. The flow in two single grafts, 72 ml/min, was significantly more than the flow in sequential grafts with one diamond anastomosis and equalled the flow in sequential grafts with three distal anastomoses. Constructing diamond anastomoses with interrupted sutures did not significantly enhance flows in sequential grafts.

Blood Flow Velocity↗
PubMed1978

[Studies on the cutting ability of dental diamond points--the trial manufacture of the cutting test apparatus (author's transl)].

Diamond points and tungstencarbite burs are used as the dental cutting tools for many appliance accordingly with the many purpose of used positions. Notwithstanding that the dental cutting tools have been usually applied for many purpose of dental treatment, the paper on these studies have scarcely been reported. In this studies the test of dental cutting tools curried out using the diamond points and examined these characteristics. As the problems on the cutting tests are the push load of cutting tools and the cutting quantities. This studies tried to make the test apparatus for the cutting test of dental diamond points considering to dental treatments. The glass plates used for photograph are used for cutting materials supposing to the enamel properties of teeth and the cutting tests put into practice for the types of diamond points with different diameter. The cutting characteristics of the diamond points are examined with the using of the test results and are appreciated with the considering to the test apparatus.

Dental High-Speed Equipment↗