A few tips from C. Marshall
A patient presented with an MOD amalgam and a palatal cusp fracture. This is a common sight and most probably needs an onlay or full coverage crown in the future (That's what you'll tell the patient) But to get them sorted for the meantime you can replace the cusp by placing retention grooves in the mesial and distal box sections (Cylindrical preps) ideally non parallel) and restore the cusp only with composite resin or amalgam). The alternative would be to charge the patient to replace the whole restoration i.e a 4 surface restoration and a cusp replacement which may cause them to be less likely to accept fixed treatment in the future. This is a quick and easy solution to the missing cusp that may not even need LA as you won't be cutting into the tooth structure. This is most ideal when the restoration is entirely intact meaning that the occlusal record is unchanged. If your preparation damages the occlusal anatomy in any way you are apparently better off replacing the who