An arc-shaped oscillating saw blade with sparse and dense teeth and an oscillating saw are provided. The arc-shaped oscillating saw blade with sparse and dense teeth includes a cutting end composed of a plurality of sawteeth distributed in an arc shape, and a tooth spacing between adjacent sawteeth gradually increases from a middle position to positions at two sides of the cutting end, thus forming a sawtooth arrangement structure with dense sawteeth at a middle and sparse sawteeth at two sides. With a tooth structure with arrangement of proper tooth density gradient, a contact area between the saw blade and a material in the cutting process can be reduced, so that cutting resistance can be reduced. Arc-shaped tooth distribution facilitates improving of the cutting accuracy and surface smoothness, reduces cutting errors and surface defects, reduces impact and vibration in the cutting process, and further improves the cutting accuracy.

A saw blade includes a blade body having a top surface and a bottom surface, wherein the blade body is at least partially comprised of a first composite material or a metal; a cutting edge on a distal end of the blade body; and a coupling configured to connect the blade body to a handpiece adapted to oscillate the blade body. The saw blade may include: a first inlay portion and a second inlay portion, where the first inlay portion is either embedded in the top surface or covers the top surface, and the second inlay portion is either embedded in the top surface or covers the bottom surface; or an inlay portion sandwiched between a top portion and a bottom portion of the blade body.

An oscillating multi-tool blade may comprise a blade body and a bonded material for cutting teeth harder than the blade body. A total depth of the bonded material may be greater than one and a half times a height of original blade teeth. The bonded material may comprise high-speed steel, tungsten carbide, or a material harder than the blade body. The blade body may be designed for resharpening or reshaping of the cutting teeth after the original teeth are dull, worn down, or broken. The blade may be initially created with no teeth, allowing a user to create custom blade teeth. The blade body may be designed for replaceable teeth, a strip of teeth, or replaceable material for shaping new teeth. The blade may be cryofrozen. The blade may have a secondary coating for added blade life or friction reduction.