A process for manufacture of a dendritic polyether comprising a core, derived from a compound having two or more hydroxyl groups, and at least one branching generation being built up from at least one hydroxyoxetane having one oxetane group and at least one hydroxyl group is disclosed. A wedge distractor employing opposing ramps through which an inserterimpactor holding an artificial intervertebral disc is admitted, the passage of which through the distractor results in distraction of the intervertebral space simultaneous with insertion of the artificial intervertebral disc. The mixing machine 1 further includes a device for producing a mix stream and at least one rotary-driven mixing tool interacting in the mix stream. The operator is charged for the supplied content. The valve element is movable between a closed position wherein the inlet port is closed and an open position wherein the inlet port is opened.