Whenever there is a change made to an existing device first thing a company should do is check whether the change affect safety, efficacy and performance of the device. This information can be documented in a Letter to file (document that used for internal record) or a PMA/510K based on device classification and regulatory logic. In the example of change in material if the material is from an approved list by the FDA than a simple letter to file will do and no FDA pathway is required but if the material is not on of the approved one than it needs to go through FDA pathway and change in material wont affect class of device. But once everything is approved it needs to be updated on device label.