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.