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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↗
PubMed1996

Human monocytes stimulation by particles of hydroxyapatite, silicon carbide and diamond: in vitro studies of new prosthesis coatings.

Aseptic loosening due to wear and debris formation constitutes the major problem in longevity of joint replacements. Diamond coated onto the prosthesis surface may reduce wear, owing to its excellent tribological properties. A thin diamond coating may be brittle, and we plan eventually to reinforce it with silicon carbide whiskers (SiC). In the present study we compared particles of diamond, SiC and hydroxyapatite (HA) in serum-free cultures of human monocytes. All particles were found to be phagocytozed, and monocyte morphology changed except after the ingestion of diamond. Interleukin-1 beta production was increased on average 30-fold and 38-fold in cultures exposed to HA and SiC, respectively, compared to control and diamond cultures (n = 6). Addition of the phagocytosis inhibitor cytochalasin B inhibited the morphological changes of the monocytes and reduced interleukin-1 beta production. In some experiments particles of polymethylmethacrylate were also included, and the interleukin-1 beta stimulation was in the same range as after HA and SiC stimulation. The results show that diamond particles in serum-free monocyte culture are inert, while SiC and HA have a stimulatory effect comparable to polymethylmethacrylate. With its excellent tribological and biocompatible properties, future studies with diamond coating are warranted.

Biocompatible Materials↗
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↗
PubMed1995

Evaluation of the dosimetric characteristics of a diamond detector for photon beam measurements.

The dosimetric properties of a new diamond detector for the measurement of relative dose in photon beams have been investigated and compared to those of a silicon p-type photon diode and a 0.14 cm3 ionization chamber. The mass energy absorption ratio of carbon to water is nearly constant over a wide energy range making the diamond detector nearly tissue equivalent. The directional dependence of the radiation response of the diamond detector for cobalt 60, 6 MV and 18 MV photon beams was more uniform than that of the diode. As the incident photon beam moves from 0 degree (parallel to the detector stem) to a direction transverse to the detector stem (90 degrees), the diamond detector sensitivity remains nearly uniform whereas the diode sensitivity diminishes by approximately 15%-22%. The spatial resolution of the diamond detector, as measured by penumbra width, is slightly less than that of the diode detector but clearly superior to that of the 0.14 cm3 ionization chamber. The tissue maximum ratio measurements for small size photon fields (diameter < or = 4 cm) with the diamond, diode, and a Markus parallel plate chamber are in excellent agreement. The diamond detector with high radiation sensitivity and spatial resolution is an excellent choice as a detector in photon fields with high dose gradients such as brachytherapy and radiosurgery.

Humans↗
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↗
PubMed1995

Biocompatibility of chemical-vapour-deposited diamond.

The biocompatibility of chemical-vapour-deposited (CVD) diamond surfaces has been assessed. Our results indicate that CVD diamond is as biocompatible as titanium (Ti) and 316 stainless steel (SS). First, the amount of adsorbed and 'denatured' fibrinogen on CVD diamond was very close to that of Ti and SS. Second, both in vitro and in vivo there appears to be less cellular adhesion and activation on the surface of CVD diamond surfaces compared to Ti and SS. This evident biocompatibility, coupled with the corrosion resistance and notable mechanical integrity of CVD diamond, suggests that diamond-coated surfaces may be highly desirable in a number of biomedical applications.

Absorption↗
PubMed1996

Benign response to particles of diamond and SiC: bone chamber studies of new joint replacement coating materials in rabbits.

Wear particles from total joint replacements are thought to accelerate prosthetic loosening. Diamond coating may improve the smoothness and wear characteristics of the femoral head component of total hip replacements, and thus increase their longevity. The brittleness of a thin diamond coat may be overcome by using an SiC-whisker diamond composite. This study describes the reactions of regenerating bone tissue to phagocytosable particles of diamond and SiC, using implanted bone harvest chambers in rabbits. The particles were dispersed in hyaluronan and introduced into a canal transversing the implant. The tissue that entered the canal during the following 3 weeks was then harvested. In previous studies using this model, particles of high density polyethylene, bone cement and chromium-cobalt all caused an inflammatory reaction and a marked decrease in the amount of ingrown bone. In the present study, neither the diamond nor the SiC particles caused any decrease in bone formation. It appears that particles of diamond and SiC are comparatively harmless.

Animals↗
PubMed1995

A newly-developed electrodeposited diamond scaler with high abrasive resistance.

A diamond scaler on which blade diamond particles were coated by electrodeposition was developed to improve the abrasive resistance of scaler blades. The electrodeposited coating was tested with diamond particles of four different sizes, designated D-4000 with 2 to 4 microns diameter of the particles; D-800 with 12 to 25 microns; D-600 with 20 to 30 microns; and D-400 with 30 to 40 microns. The abrasive resistance of the scalers was examined quantitatively using a recently-developed automatic scaling apparatus that simulated the scaling process of hand instrumentation, as well as SEM observation of the blades. A series of abrasion tests suggested that all the diamond scalers except D-4000 showed better abrasive resistance than the control (D-0), and that D-600 showed the highest abrasive resistance and cutting quality. The SEM observation also suggested that D-600 and D-400 might have higher abrasive resistance. Furthermore, the profilometric evaluation of the surface roughness of the scaled natural dentin after hand instrumentation indicated that the average surface roughness increased in the order of D-4000, D-800, D-600, and D-400, although no marked differences were observed among D-4000, D-800, D-600 and D-0, but not D-400. These results suggested that the electrodeposited diamond scaler with 20 to 30 microns diamond particles (D-600) might have marked abrasive resistance as well as cutting quality without remarkable damage to the tooth surface after conventional scaling procedure.

Adult↗
PubMed1993

Effect of adding diamond particles on the fracture toughness of apatite ceramics.

Composite ceramics dispersed through diamond particles with hydroxyapatite as a matrix were prepared by firing at 1250 degrees C under reduced pressure or normal atmosphere. The fracture toughness and physical properties of sintered composite ceramics were examined to determine methods of strengthening hydroxyapatite ceramics. The diamond crystal in composite ceramics was transformed to graphite by firing and the fracture toughness of hydroxyapatite ceramics increased with diamond addition. At 10 wt% diamond, the maximum value for fracture toughness was obtained, and the further addition of diamond particles over 10 wt% caused fracture toughness to decrease. Such increases in fracture toughness were considered the result of microcracking which occurred during the transformation from diamond to graphite.

Dental Porcelain↗
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↗