Dr. Kowar

“Long-term implant success requires careful planning, precise placement techniques, good oral hygiene, and patient compliance.”

Drs. Jan Kowar, Henrik Lund, and Victoria Franke Stenport from the University of Gothenburg have recently published the results of their retrospective clinical study of implant-supported single tooth restorations, with up to 15 years of follow-up.1 The study included 97 patients with 129 implants, all placed in a two-stage approach with delayed loading. We asked Dr. Kowar, the first author of this study, to discuss the clinical outcomes and key learnings.

1. Dr. Kowar. How did you decide to initiate this retrospective clinical study?

Deciding to initiate a retrospective clinical study requires careful consideration of several factors. The first step is to identify a specific research question that will be addressed. In this case, the research question was: "What is the long-term success rate of single tooth replacement using moderately rough surface dental implants?" Before initiating a new study, it is important to review existing literature to ensure that the research question has not already been answered or to identify gaps in the literature. We found that there is a need for truly long-term studies on single tooth replacement and we could conduct this kind of study because we have access to a database from the Brånemark clinic. This database includes all treated patients from 1986 and gives us the opportunity to follow up on different treatments over time.

2. What were the key findings?

The study included 97 patients with 129 TiUnite surface implants, all treated in 2003 and 2004. All implants were placed in a two-stage approach with delayed loading. The last follow-up visit was 14-16 years after implant surgery which is a “real” long-term follow-up. Only three implants failed, and most of the implants had neither biological nor technical complications. The bone level was stable over time for most of the implants. So, our conclusion was that moderately rough implants have shown favorable long-term outcomes in single-tooth indications, with high survival and a low rate of technical complications after 15 years in function.

Initial clinical situation

Initial clinical situation

15 years

15 years results

The patient was treated for aplasia in positions 12 and 22 (FDI system). TiUnite surface implants were placed using a 2-stage approach and restored with cement-retained implant crowns. After 15 years of function, marginal peri-implant bone levels remained stable and soft tissue was healthy.

3. What was the biggest challenge?

The aim was to include all or most of the patients who were treated in 2003/2004, and the biggest challenges were to collect the 15-year follow-up data, to find the patients, and “convince” them to come to the clinic for a clinical and radiological examination.

4. Three out of the 129 implants failed in 3 patients. What were the reasons? How were the failures handled?

Two implants failed within the first year after implant placement; specifically, one implant failed to osseointegrate and was found mobile at the second surgery, three months after implant placement. The other implant was diagnosed with bone loss six months after placement. Both failed implants were removed and successfully replaced with new implants. The third implant failure occurred 15 years after placement and was associated with severe bone loss, local site infection, and peri-implantitis. After implant removal, the patient received a conventional tooth-supported bridge.

5. The rate of peri-implantitis reported in your study is very low. What would you identify as key factors that contributed to this result?

Peri-implantitis is a serious condition that can lead to the loss of the implant and the prosthetic construction. To reduce the risk of peri-implantitis, it is important to practice good oral hygiene, including brushing and flossing regularly and visiting your dentist for regular check-ups and cleanings. If the patient has a history of periodontitis, it is important to manage the condition before getting dental implants. It is also important to follow instructions regarding the care of the implants. However, while peri-implantitis is a potential risk, with proper care and maintenance, the risk can be minimized, and the benefits of dental implants may outweigh the potential risks for many people.

6. What are the most valuable lessons learned from this 15-year clinical study, in terms of patients’ compliance and oral hygiene?

Education is crucial. Many patients may not understand the importance of oral hygiene and how it affects their overall health. It is crucial to educate patients on the importance of brushing and flossing regularly, and the potential consequences of poor oral hygiene. Consistency is also key. Patients need to be consistent with their oral hygiene habits in order to see long-term benefits, including regular dental checkups and cleanings. It’s important though, to understand that patients’ oral hygiene needs can vary greatly from person to person. It is important for dental professionals to provide individualized care and recommendations based on patient-specific needs and circumstances. We must also provide them with motivation and support. Patients may struggle with compliance. Dental professionals can provide encouragement and resources to help patients stay motivated and committed to their oral hygiene routine.

7. Today, how often, and in which indications do you place two-stage implants?

On this point, we think very conservatively. Two-stage implants are typically used in situations where the implant needs to be placed in a site with compromised bone quality or quantity. The two-stage approach allows for initial healing and osseointegration of the implant before the final restoration is placed. This gives us a more secure treatment and predictability of the outcome. The most important for the patient is the long-term result, not a “quick fix”.

8. Looking back over the past 15 years, what would you say are the most relevant achievements and improvements in implantology which help treat patients better today?

Implant design has evolved significantly over the past 20 years, with improved surfaces, thread designs, and materials. These advancements have led to increased implant stability, faster osseointegration, and good long-term success rates. I mentioned before that we are a very “conservative clinic” and we do not change our treatment protocol more than necessary. But digital technology has changed implantology, with the use of digital planning software, intraoral scanners, and CAD/CAM technology. These tools may have improved implant placement accuracy and improved restorative outcomes.

9. You are one of the investigators of the Nobel Biocare-sponsored surface study with 1000 patients. What did you have to change in your practice to be able to place TiUltra-surface implants?

We are one of 30 centers worldwide involved in this study and we treated over 30 patients with NobelParallel CC TiUltra implants. The treatment protocol was like the TiUnite surface NobelParallel which we already used in the clinic. We included different indications, from single-tooth restorations to edentulous patients treated with full-arch implant bridges and we follow the results with interest.

10. What do you consider key to long-term implant success?

Adequate bone quality and quantity: Implants require sufficient bone density and volume to support them and ensure long-term stability. Patients with poor bone quality or quantity may require additional bone grafting procedures which could lead to more problems over time. Long-term implant success requires careful planning, precise placement techniques, good oral hygiene, regular follow-up appointments, and patient compliance with post-operative instructions and recommended appointments. And sometimes the treatment will take some time or as we say: Good things take time. Great things take a litter longer.

11. One of your research interests is edentulous and elderly patients. Is there anything you'd like to share with our readers about your recent findings in this domain?

Yes, this is my topic research field and we have recently found that edentulous patients who get implant-supported prostheses have longer survival compared to patients treated with removable dentures regardless of socioeconomic factors.2 The reason for that is still unclear but I think that it is not the implant per se that gives a longer survival. Instead, we assumed that the treatment improves the masticatory function and increases patient satisfaction and quality of life.


1. Kowar J, Lund H, Stenport VF. Long-term performance of implants with moderately rough anodized surface supporting single-tooth restorations: A retrospective analysis with an up to 15-year follow-up. Clin Oral Implants Res. 2023 Feb 11.
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2. Kowar J, Stenport V, Nilsson M, Jemt T. Mortality in Edentulous Patients: A Registry-Based Cohort Study in Sweden Comparing 8463 Patients Treated with Removable Dentures or Implant-Supported Dental Prostheses. Int J Dent. 2021 30;2021:9919732. 
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