Prosthetic Restoration on Unknown or Discontinued Implants

Although the success rate of implants is very high (approximately 95% after 10 years (1)), complication rates are observed in patients, requiring clinician intervention (2). Biological factors (3) such as soft tissue recession or marginal bone resorption caused by peri-implantitis may contribute to implant restoration failure. Mechanical factors (3) can also lead to complications, such as wear and fracture of the prosthesis or poor stabilization of the prosthetic components leading to loosening. In addition, large bridges sometimes need to be removed for maintenance purposes.

For all these reasons, interventions on an implant may be a regular occurrence in daily professional practice.

Nowadays, it is common for a dentist to be confronted with patients who have been treated outside their practice. This situation can lead to difficulties in identifying the exact reference of the implant (4) (traceability lost by the patient, dentist unreachable, unfamiliar implant system, etc.). An unknown implant requires expertise in all existing implant models, which is not always obvious to a general practitioner and may complicate the selection of compatible prosthetic components.

How does a dentist realize a prosthetic restoration on an unknown or discontinued dental implant?

It is true that this problem depends on the quantity and quality of information that the practitioner has about the patient's dental implant.

Nevertheless, for each situation and even in the most complex cases, there are one or more alternative solutions to avoid the removal of the implant, all developed in the following diagram:

1) Case of a restoration on a known and available implant

• (A) Manufacturer's prosthetic solution
• (B) Generic prosthetic solution

2) Case of a restoration on a known but discontinued implant

• (B) Generic prosthetic solution
• (C) Custom-made prosthetic solution
• (D) Implant removal

3) Case of a restoration on an unknown implant

Try to identify the unknown implant

If the implant cannot be identified

• (C) Custom-made prosthetic solution
• (D) Implant removal

1) Case of a restoration on a known and available implant

In order to perform implant treatment or supra-implant restoration, the dentist must be able to find the associated prosthetic components.

If the implant is known and still marketed by its manufacturer, the dentist can contact the manufacturer directly or use the services of Spotimplant to be guided in ordering the correct compatible parts:

(A) Manufacturer's prosthetic solution

If the dentist is able to identify the implant and the brand still distributes it, he/she can contact the manufacturer directly and get in touch with the sales department (this may depend on the distributors in each country) to obtain a quotation and validate the order.

(B) Generic prosthetic solution

In this solution, which is often less expensive and of equal quality, you can order generic parts compatible with the implant system you want to restore through specialized companies. As an example, Spotimplant.com offers a wide range of compatible components for thousands of implant models. By using this service, you can also benefit from the company's expertise in implant restorations and will be advised on the purchase of the parts.

2) Case of a restoration on a known but discontinued implant

It is possible that a well-known reference implant is no longer marketed by its manufacturer, is no longer available in the country of the treating dentist, or that the company has disappeared. The dental implant market is booming and competition is hard, some companies have short commercialization periods and can no longer offer solutions for the purchase of prosthetic parts. Fortunately, there are several alternative solutions for choosing the right prosthetic parts:

(B) Generic prosthetic solution

In the event that a dental implant is not marketed or distributed, companies like Spotimplant offer alternatives to the manufacturer's parts: These are generic parts that are compatible with the identified implant system and are of equivalent quality. The generic parts are CE or FDA-certified and enable the permanent rehabilitation of an implant.

(C) Custom-made prosthetic solution

In the few cases where the dentist cannot find generic parts that are compatible with the implant system, it is possible to solicit companies specialized in making custom parts in order to provide a solution for each patient. A physical or optical impression can then be taken via an intraoral scanner and sent to a specialized company, which will then manufacture the custom components needed.

(D) Implant removal

If the implant is well osseointegrated and has no pathology, the difficulty in finding prosthetic parts may force the practitioner to remove the implant. The protocol is very invasive and must include remodeling of bone and soft tissue to allow for subsequent implant placement. Here are the main steps of the protocol :

1. Removal of the old implant using a bone trephine or a surgical bur if it is well osseointegrated;
2. Regeneration of the bone volume for later reimplantation;
3. After 6 months: Placement of a new implant into the bone volume;
4. After 4 months: Prosthetic rehabilitation on the implant.

This medical practice carries a higher risk of complications for the patient (infection, graft rejection, etc.) and requires a long time for each step (healing, bone augmentation, etc.). In addition, this less comfortable and very invasive solution requires certain concessions from the patient during this long period: Avoid chewing in the reconstructed area, prefer a soft and cold/bound diet or try to maintain a very strict oral hygiene.

The removal of an implant should therefore be the last resort, hence the interest to prefer the previously mentioned solutions.

3) Case of a restoration on an unknown implant

Try to identify the unknown implant



Identification process :

To avoid an invasive procedure for the patient, it is important for the practitioner to prioritize implant identification. To this end, dentists have several online tools available to accurately identify an unknown implant and retrieve references.

• Implant databases such as Spotimplant or WhatImplantIsThat have been developed to assist the dentist in finding technical specifications of the unknown implant. This is possible by filtering the search according to physical technical characteristics that can be seen on the radiograph of the implant.
  
• If this solution is not satisfactory or the dentist does not want to spend time on tedious searches, there exists an implant identification service based on artificial intelligence (AI) that automatically identifies any dental implant. Simply upload an x-ray of the unknown implant and the AI technology compares it to thousands of models/brands. Once identified, compatible parts are proposed directly to the practitioner. Before ordering, the practitioner can get expert advice.

Once the implant is identified, the practitioner can be placed in case 1 or 2.
To learn more, you can consult the following article: How to identify an unknown implant?

If the implant cannot be identified

(C) Custom-made prosthetic solution

In some cases, the implant cannot be identified with the available tools. The final solution before considering the removal of the implant is the fabrication of custom prosthetic components. With the advent of digital technology, some companies offer services that allow an abutment or custom prosthetic parts to be made from a physical or digital impression.

(D) Implant removal

The clinician may opt for implant removal if this is the best option for the patient.
For more details, see "Implant removal", part 2.

In conclusion

Depending on the cases the practitioner is confronted with, performing an implant restoration can be difficult and time-consuming. Nevertheless, there are increasingly innovative and customized solutions to solve the most complex cases, such as the restoration for discontinued implants thanks to the alternatives of generic or custom-made parts that ensure compatibility for all implant systems.

Finally, given the expansion of the implant market, it seems impossible for a dental surgeon to know all the existing models. Identifying an unknown system is tedious. For this reason, some companies have developed identification solutions, such as Spotimplant, the dental implant assistant for restoration.

If the dentist is not able to accurately identify the unknown implant, the possibility of obtaining custom-made parts allows him to provide a quality solution to each patient and avoid the invasive procedures associated with the removal of the implant.

So, regardless of the circumstances, dentists can be guided by specialized companies in their implant restoration to receive quality advice, be guided in ordering prosthetic parts, and, in short, facilitate their practice while saving time to serve their patients.

References :

1. Hjalmarsson, L. , Gheisarifar, M. , & Jemt, T. (2016). A systematic review of survival of single implants as presented in longitudinal studies with a follow‐up of at least 10 years. European Journal of Oral Implantology, 9(1), S155–S162.
2. Sailer, I., Mühlemann, S., Zwahlen, M., Hämmerle, CH., Schneider, D. (2012). Cemented and screw-retained implant reconstructions: a systematic review of the survival and complication rates. Clinical oral implants research, 23 Suppl 6:163-201.
3. Papaspyridakos, P., Bordin, TB., Natto, ZS., El-Rafie, K., Pagni, SE., Chochlidakis, K., Ercoli, C. & Weber, HP. (2019). Complications and survival rates of 55 metal-ceramic implant-supported fixed complete-arch prostheses: A cohort study with mean 5-year follow-up. J Prosthet Dent, 122(5):441-449.
4. Walter, RD., Wiafe, S., Oyoyo, U., Suprono, MS. (2020). A Pilot Survey on the Prevalence of Clinical Challenges to Identify and Restore Unknown Dental Implants. Journal of Oral Implantology, 47(1):63-67
5. https://www.spotimplant.com/en/knowledge-base/