Implant placement

One of the most difficult cases , tooth #17 single visit , pt has kimited mouth opining , my question will does it need post ?

29 Y.O saudi female patient came to the dental clinc with multiple carious teeth and recurrent caries Radiographic examination showed: #47 with OM class II amalgam restoration with recurrent caries under the mesial box Tx: Redo of the whole amalgam and restored with amalgam too

A 23 Y/O female Pt. came to the dental clinic for regular check-up, unaware of any medical problems. Upon Examination, multiple carious teeth and defected restorations were found. Comprehensive Restorative treatment was carried out. Below you can have a look at before and after pictures of some teeth... Have a nice weekend to All.

Today case as an undated case , if u remember that i did re treatment of this tooth , cast post cementation can u tell which canal classification of this premolar ?

Pt comes to clinic with M recurrent caries anterior of tooth #21 as you see in the pic below. But the question is what you think the cause of this discoloration and recurrent caries?