DRILL PROTOCOL
To create the correct osteotomy diameter and depth
without overheating the bone during the osteotomy
it is important to use implant brand, diameter and
depth specific drills in a predetermined sequence.
Drill speeds of around 2000 rpm are recommended. Some
implant manufacturers offer drills for one time use
while others offer multi use drills with and without
internal irrigation. All drills have depth markings
on the drill for visual depth verification. Some
manufacturers have their drills designed as to create
a osteotomy depth that is 1mm to 2mm deeper than the
actual implant length. This fact should be taken in to
consideration during the treatment planning phase and
subsequent decision on what length implant is most
favorable for the patient specific situation without
interfering with vital anatomical structures (mandibular canal).
Implant manufacturers provide implant diameter, length
and bone quality specific drill sequence charts for
their implants.
Lindemann drill
The cortical bone is usually scored first at the proposed
implant site with a round drill to avoid "wandering"
of the first depth dill (pilot drill). After scoring
the cortical plate the pilot dill (2mm diameter) is
used to create the initial osteotomy depth and angle.
On occasion the thickness of the cortical bone varies
from the vestibular portion of the osteotomy to the lingual
portion of the osteotomy. This will force the drill towards
the thinner portion of the bone and the position of the osteotomy
ends up in a different position than originally started. To avoid
this a Lindemann (XEMAX)drill can be utilized after the pilot drill to
remove bone from the thicker portion of the osteotomy.
In effect creating a oval osteotomy which will be corrected
back to a perfect circular osteotomy by subsequent drills
in the drill sequence.
A pumping motion and copious amounts of external or internal
irrigation will lessen the chance of overheating the bone
during each drill procedure.
Osteotomy sequence
Depending on the bone quality and diameter of the planned implant, a
number of successively larger diameter drills are used
in sequence to widen the osteotomy site. The final site maybe
slightly smaller than the actual diameter of the implant in D1 and D2 bone.
This will allow the self tapping feature of the implant
to engage the bone in the sidewalls of the osteotomy
and result in greater initial stability through increased
bone to implant contact (BIC). In case of D1 and D2 bone
it might be necessary to pretap the osteotomy site
because the bone is too dense to facilitate self tapping
of the implant. Tapping the bone can be accomplished
with a hand ratchet or surgical motor at no more than 30 rpm.
Drill protocols for D3 and D4 bone usually
result in a osteotomy diameter significantly smaller
than the implant itself.
Depending on the implant brand and implant geometry the
crestal bone might need to be modified with a profiling
dill to accommodate the coronal portion of the implant.