Rotary cutting instruments – dental drills and burs along with special surgical drills are available on the market with features for optimal bone cutting.These have high torque and have bur speeds of 1000 to 30000 revolutions per minute (rpm) and a straight handpiece for maximum control of cutting direction.It is awkward trying to cut bone using a contra-angle handpiece.Tungsten carbide tipped burs designed for surgical use are ideal for cutting bone.Sharp new stainless steel burs are also adequate for the purpose but they become blunt very quickly and then must be discarded.Blunt burs do not cut effectively but generate excessive heat at the bone surface.
All the burs must be cooled by penty of irrigation with sterile saline delivered to the interface of the bur and the bone.A rise in temperature of just 10 degrees is lethal to the osteocytes and an uncooled bur cutting the bone for only a few seconds will readily exceed this and thus burn the bone.A useful secondary effect of the cooling irrigation fluid is to wash away bone debris from the operative field thus helping to maintain clear visual access and preventing the bur blades from being clogged.
Bone removal can be accomplished by using a slow or mid-range spped hand piece designed for restorative dental procedures provided that a sutable irrigant fluid can be delivered at a sufficient flow rate to cool the bur.Air turbines that operate at high speed and spray a mixture of air and water under high pressure are inappropriate for surgical use as they may force air under the flap and in to the tissues causing surgical emphysema.
Bone can be removed in one or two ways using a bur.The bone surface can be simply be shaved down with a bur large enough to be effective.A size of 8 to 12 and a round or fissure bur can be used for this purpose.A block of bone is outlined using smaller bur and the whole piece is then dislodged.
Rosehead(round) burs are versatile and efficient in that they can cut in any direction and have less of a tendency to clog with particles of bone than fissure burs.It is more difficult to control the direction of lateral cuts using a round bur and once the head of the bur is buried in bone the judgement of cutting depth is curtailed.Fissure burs cut neatly and precisely in a lateral direction but are less good than round burs at drilling penetrating holes.The cutting blades of a fissure bur cuts a little less aggressively and the operator has a great feel through the instrument of what is being cut and this helps in distinguishing the difference in hardness between bone and dentine.A medium sized fissure bur(number 6) is a good choice for removing bone in this way(the guttering technique) thus making a space for a small elevato