Serrated ultrasonic cutting blade with varied tooth pitch

An ultrasonic surgical tool, comprising:

• a substantially planar blade body having a pair of opposed lateral surfaces, a pair of straight longitudinal edges and a convexly arcuate distal edge contiguous with said straight longitudinal edges;
• and
• a shank integral on a distal side with said blade body and provided at a proximal side with a connector for operatively linking the blade to a source of ultrasonic mechanical vibrations,
• said substantially planar blade body defining a through slot that extends longitudinally and axially along a portion of the substantially planar blade body, the through slot being configured to deliver a fluid to an area adjacent to the substantially planar blade body,
• said substantially planar blade body including an array of teeth disposed along said convexly arcuate distal edge and at least one straight longitudinal edge of said pair of straight longitudinal edges, the array of teeth including a first subset of teeth disposed along said convexly arcuate distal edge and a second subset of teeth disposed along at least one straight longitudinal edge of said pair of straight longitudinal edges,
• said first subset of teeth exhibiting a first inter-tooth separation or pitch and said second subset of teeth having a second inter-tooth separation, said first inter-tooth separation or pitch being different from said second inter-tooth separation or pitch.