Performance characteristics of drills with different geometries for dental implantation in unfavorable anatomical conditions with a consistent drilling protocol with a minimum step of increasing the diameter of the drill

Four surgical osseodensification drills with different geometric parameters were designed and manufactured from martensitic stainless steel (equivalent to AISI 420) with a wear-resistant titanium nitride (TiN) coating applied by physical vapor deposition (PVD). For the experimental study, bone samples (blocks) were prepared from cattle ribs, corresponding to C. Misch’s D3—D4 bone type, which is commonly found in the distal jaws. The processed samples were divided into groups according to the previously assigned surgical drill number. After every 4th osteotomy, an optical assessment of the cutting edge wear was performed using a scanning electron microscope and the change in bone tissue temperature was determined using a K-type thermocouple. Our experimental study on cattle ribs confirms the complex influence of the osseodensification drill geometry on the heating of bone tissue and its density estimated by Hounsfield unit (HU) value during the preparation of a dental implant bed using a sequential drilling protocol with a minimal step of increasing the working diameter of the drill. Surgical drills made of AISI 420 steel with a TiN (PVD) coating showed no wear after 24 osteotomies, which is comparable to the reference Densah drills. Drill with the largest clearance and helix angles, provides the best thermal conditions during the osteodensification procedure. Drills with a clearance angle α =20° provided a 2—6 times higher densification increase than drills with an α=6°. Drills with α=20° increased bone density by 34—51%, while those with α=6° increased density by only 7—20%. Further studies to refine and validate the obtained models of functional relationships, including the use of experimental drills using other drilling protocols, seem relevant.