Vertical alveolar crest split and widening – an experimental study on cow ribs, ultrasonic tool development and test on human cadaver heads

Vertical alveolar crest splitting and horizontal distraction of narrow alveolar crests is limited when rotating and low frequency oscillating tools are used due to large amounts of procedural bone loss and poor handling provisions. Aim of this study was to determine the safest osteotomy depth and to develop ultrasonic-surgery- tips to enable flapless vertical crest splitting and distraction of narrow alveolar crests of 2 mm or less. The safest osteotomy depth was determined on a cow-rib-model. To enable a flapless crest splitting and widening procedure, prototype-tips for the Piezotome-device were developed and tested against mechanical tools (widening screws and distractors) on cow-ribs, as well as their safe use in the hands of novicesurgeons on human cadaver heads. A minimum vertical osteotomy depth of 7-8 mm revealed the least fracture rates (3%). The use of the ultrasonic distraction tools showed the least risk of procedural failures (2%). Twentythree Piezotome-trainees performed the procedure with the developed tips on fresh full human cadaver skulls with a success rate of 100%. The results of this study suggest that, with the use of ultrasonic surgical devices, the indication for vertical crest-splitting can be narrowed down to a crest width of 2 mm and even less and that it can be performed flapless, thus leaving the physiological bone-periosteum system fully intact.