A significant lower mean deviation at the entry point ( @ mm , range : @-@ @ ) , at the apex ( @ mm , range : @-@ @ ) and angular deviation ( @ , range : @-@ ) was observed for the guiding systems when compared to mental navigation ( @ mm , range : @-@ @ ; @ mm , range : @-@ @ and @ , range : @-@ @ ) and to the surgical template group ( @ mm , range : @-@ @ ; @ mm , range : @-@ @ and @ , range : @-@ @ ) .