1.        The bone block coming out within the lifter is irrelevant to reasons for perforation. 

2.        The fact that the bone block came out with the lifter means that the sinus floor may have been damaged during malleting (overload of force). The instrument is designed such that the diameter of the bone block is bigger than the diameter of the instrument (the hole created in the residual bone). The fact that it came out together may indicate that the striking was too hard, and/or the surgeon did not follow the protocol of having 2mm residual bone. If the residual bone is more than 2mm, the “off-set loading” cannot take place, thus, the force will be transferred similar to an osteotome. 

3.       During lifting, the velocity of the lifter may have been excessive. The force imposed onto the membrane has an exponential relationship to the velocity of the instrument. If the velocity is reduced by 30%, the force will be reduced by 90%. 

4.       The lifter may have been wiggled too widely and strongly/quickly while within the sinus while the bone block was held within the hole of the sinus lifter.

5.       The lifter may have been pulled out too fast.