Interview with Prof. Jan Lindhe: Free thinking is important in research

Professor Dr. Jan Lindhe, periodontist and Professor emeritus at the University of Gothenburg in Sweden, is one of the scientific research pioneers in oral tissue regeneration, and his work is well known among other researchers and practitioners worldwide. During a visit by Professor Lindhe to Switzerland, the Osteology Foundation took the opportunity to talk to him about the work of the Foundation, and its role in research and education.


Professor Lindhe, you were among the founding members of the Osteology Foundation. In this role you have contributed considerably to the development of the Foundation during its first years. Could you explain, from your perspective, what the particular strengths of the Osteology Foundation are?

Prof. Lindhe: The strength of the Osteology Foundation is its independence. When Dr. Peter Geistlich established the Foundation, he was of course giving money, start-up money, and he also made sure that the Osteology Foundation received continued support. However, despite the funding from this side, the board never felt that it was operating under the command of neither Dr. Peter Geistlich himself nor Geistlich as a company. We were given the opportunity of developing the Foundation and understanding bone tissue better without any directives. We could create and establish directions ourselves. This is the strength of the Osteology Foundation: it is a rather independent body lead by the people on the Board, who think independently, and express their thinking independently.

Do you think this makes the Foundation unique compared to other similar organisations?

Prof. Lindhe: You know, in the research environment free thinking is important. And in this context the Osteology Foundation is unique because it is a private foundation. Normally, research foundations are state or federal, like for example the Swedish Medical Research Council, which is state owned and supported. The Osteology Foundation is like an institute. It has its own dynamics, and it is independent from everyone outside. What is happening is happening inside the foundation, and that I believe is the strength, which makes it in some sense unique.

One of the core tasks of the Osteology Foundation is promoting research in the field of regeneration. Usually, one first thinks of  regeneration of bone in this context. However, a few years ago you said: “The bone sets the tone, the soft tissue is the issue.” What do you think now: should the Osteology Foundation focus more on soft tissue when promoting research, or is it mainly the classical topic “bone regeneration” that should be addressed?

Prof. Lindhe: Let me clarify this a little bit: when you talk about periodontitis and peri-implantitis, the problem is always the soft tissue. The inflammation in these cases is in the soft tissue, and the bone tissue disappears as a result of it. I believe that there is a lack of knowledge about this particular fact. We can today see articles with the title “the use of biomaterials to treat peri-implantitis”. That's not correct! The problem is not the hard tissue. The problem is to get closure of the soft tissue around the implant in order to remove the infection, of course. And then after you have removed the infection, after you have dealt with the soft tissue problem, then grafting to get new bone tissue around the implant may be necessary. But the important issue in the beginning - for periodontitis as well as peri-implantitis - is to deal with the soft tissue. The lesion always resides in the soft tissue.

Should the Osteology Foundation do more on that topic to educate people on these mechanisms?

Prof. Lindhe: The title of the Foundation is not “Regeneration” or “Repair”, it is Osteology! So the main object for research and development should be the hard tissue. But that does not mean that you shouldn't deal with soft tissue, because soft tissue may be a prerequisite for new bone formation, regeneration and repair. You don't get bone healing in the oral cavity without  proper soft tissue coverage. But it is difficult for an outsider to give this advice to the Osteology Foundation, because that's something that the Foundation should, by definition, decide itself.

Well, that’s done – but we are still interested to hear your opinion about it – and we certainly wouldn't consider you an outsider...

Prof. Lindhe: (laughs) That's nice - thank you very much! You know, I think the idea with the establishment of the Osteology Foundation was to get a better understanding of bone as a living tissue, and not something that you are just drilling in without attention. And by the way, I think the Osteology Foundation has accomplished that very well.

But I guess there are still plenty of open questions in the field.

Prof. Lindhe: Of course!

So, which research topics would you consider most important, and where should the Osteology Foundation focus?

Prof. Lindhe: I think that it is necessary to learn more about the bone that is attaching the tooth to the alveolar process via the periodontal ligament. It is necessary to learn more about this particular kind of bone. We should try to understand how the bone is changing in shape when teeth are removed and why this happens. Why is it so that over time in a patient without teeth, the entire former alveolar process, which is now the edentulous ridge, is melting away? Is it the lack of stimulus? Will placing implants, as most believe, stop this melting-away of bone? And why is this so? Why will bone remain if you have implants placed? There are many such topics and questions that the Osteology Foundation could address and try to develop.

You have answered quite a lot of these questions already. Like for instance that the implant cannot preserve the bundle bone.

Prof. Lindhe: Yes, the implant cannot preserve the bundle bone. It may not preserve the buccal bone plate at all, and the lingual or palatal bone plate as well. But we have never really observed that, because when we evaluate the success of implant placement we have always taken only mesio-distal intraoral radiographs, which disclose the mesio-distal bone height. So mesio-distally I think: ok, yes the implant placement preserves the bone height - there it works. But bucco-lingualy: no! However, I don't know why exactly the implant keeps the bone height mesio-distally. I don't understand that. And that is an issue that could be part of a research project in the Osteology Foundation.

Another topic that I think we should look into is, that when you have a big defect in the edentulous ridge, can you get a more stable wound bed by placing biomaterial in the defect on top of which the soft tissue can heal better or faster?

And another topic that I find very interesting is, that normally in an extraction wound you get this immediate invagination. Is it because the connective tissue of the gingiva is moving down, not allowing bone tissue to grow up? And if we place a biomaterial in the extraction socket, that the wound healing will be facilitated and we will thereby prevent the ingrowth of connective tissue cells? These are some really interesting questions that could be addressed by the Osteology Foundation.

So, I understand there are many basic questions that should be answered.

Prof. Lindhe: Oh yes, many basic questions!

And these are also questions that are not going to be answered by the industry. So it probably needs independent organisations to address this?

Prof. Lindhe: Well - you know, the industry by nature is of course "selfish" - isn't it? It is a business, and they have to earn money. The whole idea behind the Osteology Foundation is that it is not a business, it is an open forum for ideas, for research and education - and the exchange of ideas. But don't tell anybody that I said the industry is selfish.... (laughs).

Talking about research: it seems that today there is a trend away from evidence-based dentistry, and we hear more and more the phrase "expert" and "expert opinions", which become more and more important. Do you see that trend as well?

Prof. Lindhe: First of all: evidence-based is a very demanding term. We usually say that randomised controlled clinical studies are the best system to evaluate the validity of a procedure or a material. That's one thing. So you can say, if the evidence is based on this type of research then obviously it is important, very important.

Experts – well, they often happen to be opinionated. They have their own idea of what is right. And if they base this idea on clinical trials, randomised clinical trials, then it is of course fine. But if they base their opinion solely on their own experience then it is questionable.

There was a good friend of mine, Dr. Berni Kieser from London, who unfortunately passed away a few years ago. He said at a meeting regarding clinical experience: “That is when you repeat the same mistake over and over and over again, with more and more confidence.”

So, you have to be careful with these types of experts. I would not necessarily trust an expert if he doesn’t explain to me, where he got his expert advice from, and how he generated the evidence for his expert advice.

So we should trust expertise based on evidence?

Prof. Lindhe: Yes, you should rely on expertise rather than experts.

A major focus of the Osteology Foundation is funding of research - you know that of course. What you might not know is that the granting programme of the Foundation has developed further and grown recently. We started with just one type of grants, the Advanced Researcher Grants. And now we extended the programme with Young Researcher Grants, and from next year on we will also have Large Clinical Grants for big controlled clinical trials. Besides that, we will also start a scholarship programme to allow young investigators to spend one year abroad in a research institute.

Prof. Lindhe: That's fantastic - but where does the Osteology Foundation get the money for that?

Fortunately, we have a high degree of confidence from our founders.

Prof. Lindhe: That’s good – you know, the reason for my question is, that if you give out extensive grants for clinical research, the research is often long-term, and then it may be difficult if you have no security in respect to income, but you have committed yourself to spending more.

The Osteology Foundation will only spend money that is already in our accounts. So there is no risk for the investigator.

Prof. Lindhe: That’s good, very good.

What do you think about the scholarship programme, which is new as well?

Prof. Lindhe: By definition the scholarship programme is very important - that's the way you really train young people to become researchers in the field of oral tissue regeneration. It is great. I congratulate the Osteology Foundation to this. It shows that the Osteology Foundation is interested also in what happens in the future. We are dependent on the young people. You know, old people like me are not necessarily so important anymore. But young people, they are the important guys!

Well, I think you have already done a lot for the research in this field, and the young researchers will also follow you as a role model in this context. But you are right, the Osteology Foundation has also realised that the young people are important, and so we do more and more now for them, like our research education programmes, with the two Research Guidelines books, and the Research Academies - they all have the young researchers as a target group.

Prof. Lindhe: Oh yes, the books – I am looking forward to receive the new book about the clinical research. Do you already know, when it will be available?

We will present it for the first time at the EAO congress in Rome in September.

Prof. Lindhe: That’s great – these research guidelines are really relevant for the researchers. And I think you have selected a wonderful group of people to contribute to the new book. It’s wonderful - congratulations to the Osteology Foundation for this new book!

Let me ask you one final question regarding our theme "Linking Science with Practice" - that means taking the scientific knowledge to the dentist for the benefit of the patient. Which of the work of the Osteology Foundation do you consider important in this context? Which topics should be transferred to the practitioner?

Prof. Lindhe: Everything that the Osteology Foundation has been doing and is currently and will be doing, it is all for the benefit of the patient. And in order to convey this you have to go through the general practitioner, so I think that increasing the knowledge and presenting the knowledge through meetings, publications and so on, that’s what you can do - and I think that the Osteology Foundation is already doing this very well.

Thank you very much, Professor Lindhe, for your time. It was a pleasure talking to you!

Interview (transcript): Dr. Kay Horsch, Dr. Heike Fania