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Implant Restorations: Screw-Retained vs. Cemented

December 27, 2023
Author
David Hochberg image
David G. Hochberg, DDS
Implant Restorations: Screw-Retained vs. Cemented

In recent years, there have been several reports and much discussion surrounding the role played by dental cements in the development of peri-implant mucositis and peri-implantitis.1,2,3 As a result, many dentists have changed their restorative procedures, resulting in a significant shift toward screw-retained restorations.

Screw-retained crowns continue to grow in popularity for single-tooth implant cases.

Screw-retained crowns continue to grow in popularity for single-tooth implant cases.

Derived from internal data on October 23, 2023.

It is important to note that the cement itself is not the contributing factor toward peri-implant disease. More precisely, it is the excess cement that is allowed to remain around the restoration that acts as the nidus for soft tissue — and eventual hard tissue — disease. It should also be noted that in the early days of implant restoration, doctors routinely used stock abutments — universal abutments sold by implant manufacturers — that often placed restorative margins 5 mm or more below the soft-tissue crest. These deep margins made complete removal of excess cement virtually impossible, leading to the frequent occurrence of residual cement and subsequent tissue inflammation.

On the left, the deeply subgingival margin is associated with a stock abutment. On the right, an equigingival margin is created with a custom abutment.

On the left, the deeply subgingival margin is associated with a stock abutment. On the right, an equigingival margin is created with a custom abutment.

The development of custom abutments — first by the wax-and-cast technique, and later with CAD/CAM — allowed the supragingival and equigingival placement of restorative margins. These more accessible restorative margins are more readily cleaned, which may well mitigate the risk associated with cemented restorations.4

So, if we put aside the issue of retained cement, what are the actual indications for screw-retained or cemented restorations? In my experience, the most significant indication for a screw-retained restoration is insufficient restorative space. In order to have a successful cement-retained crown, the abutment should have a minimum height of 4 mm above the margin with minimal taper. Allowing for the space needed for the restoration, there is a minimum required restorative space of 7 mm for a cemented restoration. A screw-retained restoration requires less restorative space because we are not relying on a bonded surface. It is possible to fabricate these restorations with restorative space as little as 4 mm.5

This BruxZir restoration is fabricated directly to a titanium base that is designed specifically for the implant platform.


Screw-Retained Crowns

A screw-retained crown requires no clinical cementation procedure. This BruxZir® restoration is fabricated directly to a titanium base that is designed specifically for the implant platform. The titanium base is treated with titanium nitride, which provides a gold color that helps with the esthetic appearance of the gingival portion of the restoration.

Cement-retained crown has a CAD/CAM custom abutment with BruxZir crown


Cement-Retained Crowns

This cement-retained crown has a CAD/CAM custom abutment. After the titanium nitride treated abutment is screwed to the implant, the BruxZir crown is cemented over it.

In contrast, the most significant indication for a cement-retained restoration is an implant position that would create a screw access opening through the facial surface of the crown. While we have become more adept at hiding this access opening with composite, there is little question that it can create an esthetic compromise that will make some patients uneasy.

Both restorative options are associated with straightforward clinical and laboratory procedures. Let’s look at two cases that illustrate the predictability of these procedures.

CASE 1: SCREW-RETAINED CROWN

The preoperative appointment: The upper bicuspid was fractured and non-restorable.

Figure 1: The preoperative appointment: The upper bicuspid was fractured and non-restorable.

The X-ray taken after extraction and socket grafting showed bone regeneration after four months of healing.

Figure 2: The X-ray taken after extraction and socket grafting showed bone regeneration after four months of healing.

After a flapless surgical procedure, a Hahn Tapered Implant was placed.
Fapless surgical procedure
A Hahn Tapered Implant was placed

Figures 3a–3c: After a flapless surgical procedure, a Hahn™ Tapered Implant (Glidewell Direct; Irvine, Calif.) was placed.

A digital impression was taken with a scan body in place, and the screw-retained restoration was designed
A digital impression was taken with a scan body in place, and the screw-retained restoration was designed
Note the optimal emergence profile and placement of the screw access channel.

Figures 4a–4c: A digital impression was taken with a scan body in place, and the screw-retained restoration was designed. Note the optimal emergence profile and placement of the screw access channel.

Placement of the final BruxZir screw-retained crown
The crown was then delivered using a stent
With the crown in place
Teflon tape was used to block the screw access opening prior to sealing the opening

Figures 5a–5d: Placement of the final BruxZir screw-retained crown: Glidewell returned the crown and screw along with a stent to properly position the crown for securing (a). The crown was then delivered using a stent (b). With the crown in place (c), Teflon tape was used to block the screw access opening prior to sealing the opening (d).

The final restoration: The screw-access hole was sealed with composite.
The final restoration: The screw-access hole was sealed with composite.
The final restoration: The screw-access hole was sealed with composite.

Figures 6a–6c: The final restoration: The screw-access hole was sealed with composite.

CASE 2: CUSTOM ABUTMENT AND CROWN

A healing abutment was placed at the implant site
A custom abutment, screw and placement stent were supplied from Glidewell
The abutment was placed using the supplied stent

Figures 7a–7c: A healing abutment was placed at the implant site (a). A custom abutment, screw and placement stent were supplied from Glidewell (b). The abutment was placed using the supplied stent (c).

The final abutment was torqued into place and the final crown seated.
The final abutment was torqued into place and the final crown seated.

Figures 8a, 8b: The final abutment was torqued into place and the final crown seated.

The patient was pleased with the results.
The postoperative appointment and the patient was pleased with the results.

Figures 9a, 9b: The postoperative appointment: The patient was pleased with the results.

CONCLUSION

Both screw-retained and cemented crowns are viable restorative options for the single-tooth implant. The choice depends on specific factors such as restorative space, implant trajectory, as well as the preference of the clinician.

References

  1. Raval NC, Wadhwani CP, Jain S, Darveau RP. The interaction of implant luting cements and oral bacteria linked to peri-implant disease: an in vitro analysis of planktonic and biofilm growth — a preliminary study. Clin Implant Dent Relat Res. 2015;17(6):1029-35.

  2. Wadhwani C, Schonnenbaum TR, Audia F, Chung KH. In vitro study of the contamination remaining on used healing abutments after cleaning and sterilizing in dental practice. Clin Implant Dent Relat Res. 2016;18(6):1069-74.

  3. Wadhwani C, Rapoport D, La Rosa S, Hess T, Kretschmar S. Radiographic detection and characteristic patterns of residual excess cement associated with cement-retained implant restorations: a clinical report. J Prosthet Dent. 2012;107(3):151-7.

  4. Linkevicius T, Vindasiute E, Puisys A, Peciuliene V. The influence of margin location on the amount of undetected cement excess after delivery of cement-retained implant restorations. Clin Oral Implants Res. 2011;22(12):1379-84.

  5. Carpentieri J, Greenstein G, Cavallaro J. Hierarchy of restorative space required for different types of dental implant prostheses. J Am Dent Assoc. 2019;150(8):695-706.