In 5-axis milling, tool and workpiece move in five degrees of freedom: three translational and two rotational. In dental technology this considerably extends the reachable geometry compared to 3-axis machines, for example with divergences, complex insertion directions and steep flanks. 5-axis setups have limits too: tool length, tilt angles and fixture collisions still define unreachable regions.
Does 5-axis milling make undercut checks unnecessary?
No. It shifts the limit of what is feasible but does not remove it. A reliable millability check runs against the specific machine setup, not against the axis count alone.
Learn more: Milling simulation in Mill Check