Page 56 - Dental Practice South Asia 18-6

implantology section

degree of soft tissue healing around an implant can impact later on? Conventional drilling also ruins the extracellular matrix these
What if the fat cell invasion that causes initial bone resorption signalling molecules attach to, so they cannot reach and stimulate
could be minimal enough to allow for osseointegration but leads to the cells that would initiate the repair of the surgical damage. On
some connective tissue forming around an implant that later pre- the other hand, a slow drilling protocol allows for bone harvested
cipitates a loss of integration? with the correct trabecular structure and is rich in signalling mole-
We don't know what we don't know, but what if a protocol that cules. The recipient site has a transport network, the extracellular
reduces the risk of fat cell invasion were to save us from these late matrix, which can facilitate their movement, allowing for faster and
complications? Enter the slow drilling protocol. more successful graft integration. The harvestable bone is the gold
standard for osteoconductive and osteoinductive properties. Bone
THE SLOW DRILLING PROTOCOL can be extracted directly from the drill flutes using a sterile instru-
The slow drilling protocol described here has been developed to ment. It should be placed on saline-moistened sterile gauze; how-
stay well within the margins of temperature safety and to mitigate ever, it should not be submerged in saline since this would result in
the temperature spikes induced by more dense bone, less sharp the loss of soluble signalling molecules. Theoretically, this damp-
drills, and additional time spent preparing an osteotomy. ened gauze can keep the bone cells vital for the half hour or so
Minimizing surgical trauma is vital, and although the above evi- needed between harvesting and using the graft material.
dence exists, a degree of extrapolation has had to be used to trans-
late this into clinical protocols. ADDITIONAL BENEFITS
Eduardo Anitua and his team at the Biotechnology Institute Slow drilling has other surgical advantages. Eliminating the
(BTI) in Vitoria, Spain, have conducted the most comprehensive requirement for irrigation improves patient comfort and operator
research on the practical factors for slow drilling. He has developed visibility. Greater tactile feedback allows for a more accurate assess-
a state-of-the-art clinical facility attached to a prolific research ment of bone quality, which helps determine drill sequence and
department. Their 'biological drilling protocol' was published in loading protocols. The resistance offered by cortical anatomical
2007 and combined slow drilling with a form of blood derivative boundaries can also provide guidance and safety when working
called Endoret. Considering your stance on using blood plasma in under challenging circumstances: the palatal shelf guiding the drill
implant dentistry, consider the slow drilling side of this protocol. in a narrow ridge, for example, or the sinus floor providing resist-
They suggest using a sharp initial drill (referred to in different sys- ance to decrease the risk of unplanned perforation. The drilling
tems as a lance, needle or spade drill) at 800rpm with saline irriga- speed also allows more time to react during surgery, for example,
tion. This allows for the penetration of the cortical bone, reducing when placing implants close to the inferior dental nerve under infil-
friction and the resulting temperature increase that the subsequent tration anesthetic. As guided surgery becomes more popular and
drills would cause. It also provides access to the underlying cellular more common, the effect of irrigation not reaching the surgical site
bone. However, there is no evidence for this first drill speed, and through these guides may lead to late complications.
this phase can be accomplished at 150rpm with drip irrigation from A slow drilling protocol with guided surgery could help avoid
a diabetic syringe in practice. potential temperature increases and complications. Although
Following this, there is evidence to suggest that the pilot and implant systems are intended for use with a slow-drilling protocol,
twist drills can be used successfully at 20-80rpm with no irrigation. for example, BTI's implant system and, more recently, Nobel
Anitua's publication suggests a speed of 50rpm, which buys you a Biocare's N1 system, I am yet to come across a system that does not
safety margin by staying mid-range. However, the team found that lend itself to slow drilling effectively. Perhaps using a design-specif-
this speed led to the bone temperatures at the tips of these drills ic system will prove to be of even more significant benefit in time.
increasing to 28°C, which is well below our established safe tem- Using a slow drilling protocol will take up a few more seconds, but
perature. the immediate and long-term effects might save you a lot of trou-
On a practical note, this decreased speed does not necessitate ble and make your surgery workflow easier. So, once you have
increased pressure on the handpiece when preparing for an pierced the cortical bone, turn your drill speed down to 50rpm,
osteotomy. Clearing the bone collected in the drill flutes should turn off your irrigation and enjoy access to a new type of surgery
improve the cutting efficacy, but if this does not work, it suggests that results in an abundance of easy-to-handle, effort-free autoge-
that the burs are not as sharp as they need to be. Using this proto- nous graft material. So, what have you got to lose?
col will keep your burs sharper for longer, but any blunting is a lot
more noticeable. Perhaps the most significant confirmed benefit of
the slow drilling protocol is the bone harvested from the drill flutes,
which can be recycled. Anitua's team did a split-mouth study to
compare the bone harvested this way versus that collected via bone About the AUTHOR
traps when using a conventional drilling protocol with irrigation.
When drilling at 1,200rpm, cells from within the bone are lost, and Dr. Aly Virani BDS (HONS) MJDF, RCS (ENG) DIP IMP, DENT RCS ED is an implant dentist
the trabecular structure that allows angiogenesis is compromised. and clinical director at North Cardiff Dental & Implants. He is a graduate of Cardiff
In addition, bone morphogenic proteins and growth factors, some University and holds a Diploma in Implant Dentistry from the Royal College of Surgeons
of which are already present in the tissues and others created in of Edinburgh. His dentistry practice is focused solely on the placement and restoration
response to damage, are water-soluble and therefore removed by of dental implants. Aly currently travels between his practice, North Cardiff Dental &
the irrigant. Implants, and Portman's Hereford Dental & Implant Clinic.

56 Dental Practice // November-December 2022 // Vol 18 No 6