Implant Retention Methods: Critical Decisions for Success

Millions of people experience tooth loss. The American Association of Oral and Maxillofacial Surgeons states that tooth loss affects about 69% of adults aged 35-44 years old. The implant market in the U.S. was valued at 1.1 billion in 2018 and is slated to grow by a 5.1% compound annual growth rate over the next few years, according to information from iData Research. There is no question that the exceptional advantage that implant therapy has over other treatment options is fueling this growth.

Implant rehabilitation can dramatically improve a patient’s quality of life. One of the main advantages is that an implant will provide normal oral processes like proper mastication. They can last a patient a lifetime, and due to their ability to take the place of a natural tooth, they help to prevent bone loss by providing stimulation in the jaw. Implants also play a significant role in keeping surrounding dentition stable and provide support in keeping patients free from gum disease.

It is no wonder then that implants have become a preferred method in restoring missing teeth. After deciding on this treatment option and setting the proper foundation for implant placement, one of the biggest questions is whether or not these implant restorations should be screw-retained or cement-retained. There is then a clinical decision that must be made that involves what type of restoration would work best as related to retention.

This decision of implant crown retention is dependent upon three key factors: the strength of the restoration, peri-implantitis risks, and aesthetics.

Cement-retained Implant Restoration

Cement-retained implant restorations are used in dentistry often, and the process of placing these types of restorations is a familiar one to most clinicians. One of the main benefits of these types of restorations is esthetics, as there is no screw access hole. The lack of a screw access hole can also help with providing ideal occlusal anatomy and occlusal load.

These restorations can be cemented over a custom abutment when there is challenging implant angulation. The margins can be placed right at or slightly below the tissue surface to help with cement removal. Another benefit is that since they are made from custom-designed abutments that mimic an ideal preparation, this can help to provide a natural emergence profile, a passive seat, excellent retention, and improvement with the load forces.

Advantages of cement-retained restorations:

• Issues with abutment screws loosening are significantly reduced in cement-retained restorations.
• Crowns are less likely to come off and be lost.
• Porcelain failure is reportedly not common in cement-retained crowns.
• When implants are angled too far to the facial and the access hole is exiting through the facial, cement-retained restorations can provide an excellent solution to this issue.
• Some patients can find a screw access hole objectionable. Overall, cement-retained restorations can be a more esthetic option.

Along with the many benefits, these restorations also have some disadvantages, and these must be considered when evaluating the optimum treatment options.

Disadvantages of cement-retained restorations:

• Residual cement that is left behind at the implant site is a crucial factor leading to peri-implantitis. (See the above image.)
• Cement-retained restorations are more challenging to retrieve should the need arise.
• These restorations are not indicated in cases where interocclusal space is limited, as they will have poor retention.

Screw-Retained Implant Restorations

Screw-retained restorations are another option that should be considered when cases are indicated for these restorations. These restorations are best suited when the implant is placed ideally. Because they are retained with a screw, there is no danger of residual cement being left behind, which can cause damage to the patient’s tissue and bone.

These restorations can be easily removed to check the implant site. The margin of these restorations can be placed well below the tissue reducing the chance of the titanium showing through the gums.

The following is a list of the advantages for using screw-retained restorations:

Advantages of screw-retained restorations:

• Peri-implantitis is not as common in screw-retained restorations due to the elimination of cementation.
• It is easy to remove the restoration because of the screw access hole.
• Screw-retained restorations work well when there is limited interocclusal space.

Along with the benefits and indications, there are also some disadvantages of using screw-retained restorations.

Disadvantages of screw-retained restorations:

• The access hole may compromise the strength of the restorative material, thereby increasing the chances of restoration failure.
• Screws can become loose over time, leading the restoration to fall out and get lost.
• These restorations are dependent on the angulation of the implant in terms of where to place the access hole. This can lead to the access hole being placed in an undesirable area.
• Some patients have esthetic concerns regarding the access hole.

It is important to note that many advances are being made with both cement-retained and screw-retained restorations to help mitigate the disadvantages associated with each of these restorations. For example, in the case of screw-retained restorations, setting the proper foundation, planning, and ultimately placing these restorations can open up more opportunities to use this modality and take advantage of being able to retrieve them when necessary. Also, with the introduction of angulated screw channels, the ability to use screw-retained restorations has expanded.

The most significant problem with cement-retained restorations is the difficulty in removing all of the residual cement from the implant site. Custom abutments can be designed with supragingival margins to create an easier cement removal process to help with this problem.

As in almost all restorative procedures, the importance of proper planning plays a big part in the overall success of the case. Understanding the advantages and limitations of each restorative option can help in determining the best way to proceed.

In implant cases, understanding the differences between screw-retained and cement-retained restorations plays a big part in ensuring a successful outcome.

Most importantly, staying on top of new developments, techniques, and materials is essential in providing patients with the very best options available. The Burbank Dental Lab implant team is available to offer support and help in planning these cases and recommending the best retention method for a specific case.