A surgical drill bit , comprising: a mounting portion extending from a first end to a second end , the mounting portion configured to mount to a tool; and a working portion adjacent the first end of the mounting portion , the working portion configured for cutting a hole in a bone, the working portion including: a body portion extending from a distal end to a proximal end, the body portion including a top surface and a side surface ; a blocking portion formed at the proximal end of the body portion and having a first diameter greater than a maximum diameter of the body portion ; at least one channel formed in a longitudinal direction of the working portion , the at least one channel extending from the top surface through the blocking portion, wherein the at least one channel defines, along the body portion, a cutting blade portion configured to cut the bone upon rotation of the surgical drill bit , the cutting blade portion including: a first top cutting surface (30A-1) having a first angle relative to a longitudinal axis of the body portion ; and a second top cutting surface (30A-2) having a second angle relative to the longitudinal axis , characterized in that the second angle is smaller than the first angle. a mounting portion extending from a first end to a second end , the mounting portion configured to mount to a tool; and a working portion adjacent the first end of the mounting portion , the working portion configured for cutting a hole in a bone, the working portion including: a body portion extending from a distal end to a proximal end, the body portion including a top surface and a side surface ; a blocking portion formed at the proximal end of the body portion and having a first diameter greater than a maximum diameter of the body portion ; at least one channel formed in a longitudinal direction of the working portion , the at least one channel extending from the top surface through the blocking portion, wherein the at least one channel defines, along the body portion, a cutting blade portion configured to cut the bone upon rotation of the surgical drill bit , the cutting blade portion including: a first top cutting surface (30A-1) having a first angle relative to a longitudinal axis of the body portion ; and a second top cutting surface (30A-2) having a second angle relative to the longitudinal axis , a body portion extending from a distal end to a proximal end, the body portion including a top surface and a side surface ; a blocking portion formed at the proximal end of the body portion and having a first diameter greater than a maximum diameter of the body portion ; at least one channel formed in a longitudinal direction of the working portion , the at least one channel extending from the top surface through the blocking portion, wherein the at least one channel defines, along the body portion, a cutting blade portion configured to cut the bone upon rotation of the surgical drill bit , the cutting blade portion including: a first top cutting surface (30A-1) having a first angle relative to a longitudinal axis of the body portion ; and a second top cutting surface (30A-2) having a second angle relative to the a first top cutting surface (30A-1) having a first angle relative to a longitudinal axis of the body portion ; and a second top cutting surface (30A-2) having a second angle relative to the longitudinal axis , characterized in that the second angle is smaller than the first angle. <EOS>