Direct to implant vs. abutment
- A prosthesis directly supported by implants is indicated when inter-arch distance is limited
- A prosthesis supported by abutments is indicated when implant angulation needs to be corrected, especially for screw-retained prosthesis designs
- Abutments designed for cement-retained restorations are preferred in situations where an access screw hole is not desired
- For a prosthesis directly supported by implants, soft tissues around implants must be carefully manipulated during impression and trial placement appointments
Advantages of abutment-supported prostheses
- When implants are not parallel to each other, the use of angulated abutments can "correct" for the non-parallelism.
- Angulated abutments are available for a screw-retained prosthesis.
- Custom abutments can be fabricated for a cemented prosthesis.
- Placement of abutments permits the abutment-prosthesis interface to be placed crestally or supra-crestally making impression-taking and trial placement much easier and less invasive for the soft tissues.
Disadvantages of abutment-supported prostheses
- When there is limited interarch space, placing abutments reduces the size and hence the strength of the prosthesis framework.
- The typical implant to prosthesis system involves two retentive interfaces of implant-abutment and abutment-prosthesis meaning that in the case of cement-rertained prostheses, access to the abutment screw may be difficult.
- Cement excess is a major cause for peri-implant inflammation and peri-implant crestal bone loss.
Advantages of implant-supported prosthesis
- When there is limited interarch space, this type of prosthesis allows for the necessary size and strength of the prosthesis framework.
- With the typical implant-prosthesis-prosthetic screw system, retrievability is enhanced.
- There is only one retentive mechanism to manage.
Disadvantages of implant-supported prosthesis
- Cannot be used with a cement-retained prosthesis.
- Non-parallelism of implants may lead to compromised esthetics due to the position of the access holes for the prosthetic screws.
- Impressions and trial placement procedures may traumatize the peri-implant soft tissues.
- Connection and disconnection of the prosthesis may influence the periimplant tissue condition/crestal bone levels.
- Connection and disconnection of the restoration may be more uncomfortable for the patient in comparison to an abutment supported prosthesis.
Additional internal materials
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