Information taken from https://www.fgdp.org.uk/use-fgdpuk-post-nominals-following-transfer-faculty-college-general-dentistry.

Post-nominal letters show past achievement, accreditation or honours. Post-nominal letters can also be used (amongst other things) to show membership or fellowship of learned societies and professional institutions*. This guidance can be used for the correct use of post-nominals following the transfer of FGDP(UK) to CGDent.
 
Post-nominals denoting qualifications
The right to use post-nominal letters which show qualifications which were awarded by the Faculty of General Dental Practice UK and/or Royal College of Surgeons of England (RCS Eng) will not be affected by the transfer of the FGDP(UK) into the College of General Dentistry (CGDent) on 1 July 2021. Neither the name nor specific post-nominal designation of any award will change retrospectively as a result of the transfer. Such awards include:

  • Diploma in Implant Dentistry Dip Imp Dent RCS (Eng)
  • Diploma in Restorative Dentistry Dip Rest Dent RCS (Eng)

Post-nominals denoting membership
In line with the above, current members and fellows of FGDP will be able to continue to use those post-nominals where an FGDP or RCS England award qualified them for membership or fellowship of the Faculty – typically diplomas of membership or fellowship.

  • Diploma of Membership of FGDP(UK) Dip.MFGDP(UK)    
  • Diploma of Fellowship of FGDP(UK) Dip.FFGDP(UK)    
  • Diploma of Membership of the Joint Dental Faculties (RCS England) Dip.MJDF    
  • Diploma in General Dental Practice (RCS England) DGDP(RCS Eng)
  • Diploma of Membership in General Dental Surgery (RCS England) Dip.MGDS (RCS Eng)

However those post-nominal letters which convey ongoing membership or fellowship of the FGDP(UK) – as distinct from qualifying awards – should no longer be used from 1 July 2021 as the FGDP will no longer be the title of an ongoing institution. These include MFGDP(UK) or FFGDP(UK).
 
These will be superseded by post-nominal letters conveying ongoing membership or fellowship of the CGDent (e.g. MCGDent and FCGDent). Your membership or fellowship will however not transfer automatically between the organisations. CGDent will recognise your membership or fellowship of FGDP(UK) as giving eligibility for equivalent status in the new College, but you will need to positively elect to transfer your membership to CGDent in order to be eligible to use CGDent membership post-nominals. (Please note that the opportunity to transfer has now ended. Former FGDP Members who wish to join the College can do so, on production of evidence of former FGDP status)

 
Honorary awards
Honorary memberships and honorary fellowships of FGDP (Hon.MFGDP(UK), Hon.FFGDP(UK)) are considered awards rather than denoting substantive/ongoing membership/fellowship, and may therefore continue to be used, and neither the name nor specific post-nominal designation associated with such awards will change retrospectively. However the CGDent will continue to publish the names of those given honorary awards by the FGDP.
  
Dental professionals practising in the UK should also be aware that the use of post-nominals in a patient-facing context is covered by General Dental Council guidance on advertising.
 
 
*https://web.archive.org/web/20150316010023/www.debretts.com/forms-addres…