Saturday, September 27, 2008

CVD DIAMOND BURS 2


Slide 4
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MANUFACTURING

These tips, called CVD, are produced in a reactor in which a mixture of methane and hydrogen gases results in the formation of a single artificial diamond layer without space between the grains on the substrate (a molybdenum rod)

WORKING PRINCIPLE

CVD diamonds burs present unidirectional oscillating movement with maximal displacement ranging from 50 to 60 micron,at oscillating frequencies ranging from 25,000 to 32,000 Hz.

CVD diamond tip require only a slight touch to promote tooth grinding

This differs from the high speed handpiece, which is manipulated with pendulum movements over tooth structure.

Movement with maximal displacement ranging from 50 to 60 micron,at oscillating frequencies ranging from 25,000 to 32,000 Hz.


CVD diamond burs must be handled with light hand pressure,just enough to guide the instrument.

If too much load pressure is applied,the cutting effectiveness is reduced and pain,noise,and heat will be generated.

A greater application force reduces the cutting ability of the tip and may lead to fracture of the molybdenum substrate.

In addition the lack of irrigation of the ultrasound instrument on the treated surface may cause the tip to heat up and fracture.

This system doesn’t lose superficial diamond during cutting,subsequently extending the lifetime.

CVD feature significantly decrease the risk of metal contamination

CVD instrument allows the capability of working at high inclination angles,resulting in safer proximal finishing with less chance of hitting adjacent tooth.

Sunday, September 21, 2008

CHEMICAL VAPOUR DEPOSITION(CVD) DIAMOND BURS

CHEMICAL VAPOUR DEPOSITION(CVD) DIAMOND BURS

CVD technology allows high adherence of the diamond as a unique stone on the metallic surface with excellent abrading performance.

CVD diamond burs become an option for cavity preparation,and preservation of tooth structure.

In 1996,CVD diamond burs coupled with an ultrasonic handpiece were introduced in dentistry to eliminate problems relate with diamond burs

CVD method produce high adherence between the diamond film and metal surface,induced by chemical bond

Because of the inherent roughness of the sharp edged and polycrystalline diamond layers,these tools are well suited for tooth grinding










They are obtained by chemical vapour deposition( CVD) of diamond film over a molybdenum substrate.

They were synthesized inside an enhanced hot filament assisted reactor.

This manufacturing process,and the adaptation to an ultrasonic handpiece,provide some potential advantage.