I have a restoration in amalgam(very good) on a 2nd inferior molar right side. It has the mesial, distal and oclusal parts restored. The lingual cusp broke but the restoration is in place and there is no damage to the restoration or the remaining of the tooth. There is no pain, just the lingual cusp is gone. Can the dentist restore just the lingual cusp with amalgam or composite and and keep the remain of the restoration because is in good shape?