After replacing the right lower control arm is a front end alignment necessary?

Get a new mechanic, it has been proven that changing any front end part even the ball joint, let alone a entire control arm can alter the toe in, the most important most critical part of the alignment.

We would recommend that the alignment be checked. The actual replacement of the control arm would not change the alignment angles, but what caused the need to change the control arm(impact with curb or pothole?) may have caused the alignment angles to change. Alignment angles should be checked on a regular bases to insure tire tread life and maximum fuel economy.

While parts are made to much closer tolerances today, they still aren't going to be exactly the same. Replacing a control arm could very easily cause the ball joint to move to a different location and that would have an impact on caster and or camber which will cause the toe angle to change. The big question is "why did you need to have the control arm changed"? Is your mechanic a professional technician working in a full shop? Why isn't your mechanic doing the control arm? With your car, not only is an alignment necessary, the steering angle sensor should also be reset as part of the alignment process because it can have an impact on the performance of the vehicle stability control system. (anti-skid)