Interview: Dr Narayan Venkataraman with Dr Pinak Kapadia on augmentation in implantology
Renowned implantologist, great educator, and one of the most sought-after experts in the field of implantology - Dr. Narayan Venkatraman has answered questions on all augmentation and tissue management aspects of implantology. To pick his brain, to ask the right questions, and to get the best out of him - we have one of the most brilliant and inquisitive minds in implantology- Dr. Pinak Kapadia.
Hard tissue augmentation:
PK: Hello Dr. Narayan - This is a pleasure, to pick your head about the science of augmentation, I feel like a child with an open candy jar. Let's begin. My first question is - do you remember your first case of augmentation?
NV: I remember my first augmentation case clearly. It was a 50 something smoker lady with generalized Periodontitis who had to have both maxillary 5s extracted. This was way before the CBCT era, so post-extraction defect sounding was really the only way to confirm defects, and I ended up doing a formal Guided Bone Regeneration (GBR) with an open flap, using Bio-Oss and a collagen membrane from Equinox (I forget the brand name). I did get great results at reentry after six months, so I guess that was the much-needed beginner’s luck that encourages one to try more. My understanding of regenerative techniques and material science has certainly evolved from then to what I believe is now a more rational and mature approach to bone augmentation.
Interesting choice of words, Dr. Narayan. Rational and mature. Knowing what not to do or what is redundant is equally important as what to do. I remember when we had Mark Bartold as a keynote speaker at an ISP conference, and he said bone grafting has to evolve beyond the “see hole must fill” philosophy. Maybe augmentation in implant dentistry also has to evolve and has evolved. The PET philosophy is an example. Where do you think the next change in grafting or bone manipulation is going to come from? How will it evolve from a procedure reserved for the super-skilled ones to one that anyone with proper training can do, say like a root canal?
I believe there is still a way to go before it gets there. As dentists first, the tendency to fill all visible holes has not left the psyche of most, and it does not help that the industry is so pushy. And then there is the lure of lucre. Bone grafting is far less forgiving than an RCT, and therefore the importance of training takes on a greater significance. Having said that, I believe that more than traditional “Evidence,” social media has played a significant part in influencing the thought processes of thousands of clinicians who would otherwise not have delved into the depths of literature to draw their own inferences, and this is changing paradigms to a large extent. PET philosophies, for one, Osseodensification and the resurgence of autologous bone as the “Gold” standard for another, compelling discerning clinicians to seek training and hone their skills. It is also encouraging to see people question the biological rationale of certain procedures, which implies that people are “Thinking” about what they are doing. Having said that, there are also a lot of arbitrary concepts without any scientific basis that have found a foothold in the mainstream due to the same exposure.
In GBR especially, there are multiple religions and multiple gods - you have the religion of the Sausage technique by Dr. Urban, you have the fast-growing religion of Dr. Khoury, you have the minimalistic but almost blasphemous religion of Ethoss and Dr. Fairbairn, then you have the excellently skilled Koreans and their use of Sticky bone or Titanium Meshes. Which of these do you belong to, and how does one make sense of all these conflicting data?
As far as “Religions” in grafting goes, my answer is closely linked to my previous statement. I always maintain that the “absolute” is the biggest difference between science and religion, and there is no room for it in the sciences, and the day we decide that there is only one way, we shut the door to new ideas. Each of these techniques and philosophies has its place and application, and I am open to using each of them when the circumstances and situations demand.
Is it possible for something coming out of a bottle to form bone over the surface of an implant without the use of an autogenous graft? How often do you see this happening?
With regards to the bone depositing on an implant surface with bottled substitutes, without an autologous graft, it becomes a function of the defect morphology, its regenerative potential, and the regenerative potential, and rate of turnover of the material itself. For instance, we routinely place substitutes over immediate implants in sockets, with the expectation that it will be replaced by bone, either as a result of resorption and replacement or one of displacement and replacement in a highly competitive environment. The same cannot be expected in a single wall defect or a Class II dehiscence, which is extrabony. So by default, I like to have some autologous bone in contact with the implant before any substitutes (Except, of course, in immediate implants, where the healing dynamics are so different)
I wish someone had explained to me the Melchers concept in college using these three words - Highly Competitive Environment. This is so important to understand - the concept of space maintenance and compartmentalization. The bone is a tortoise, and the epithelium is a hare. We have to keep the hare out to allow the tortoise to win.
Ok, I shall ask you a tough one - Have you seen bone in one of your own cases in a class 2 dehiscence around the implant after GBR? (I confess I have not been so fortunate)
Yes, Pinak! I have several cases with over a decade of follow-up with bone over Class II dehiscences with different grafting materials, so I believe it is possible if the principles of space creation and maintenance are adhered to.
As someone trained in and passionate about Histology, can you tell us something about your experiences with core biopsies of regenerated bone? Have you tried to do a few biopsies, and what have been the outcomes? I am always worried about the graft being just incorporated into a meshwork, looking like bone and then, over time, disappearing once the implant is loaded.
I have had the opportunity to receive core biopsies from several clinicians in India and abroad for histological evaluation with all kinds of materials, including Autologous bone with stem cells, Allografts, Alloplasts, Xenografts, PRF, and Dentin autograft. In all these, I can tell you that the material that seems to show the least tendency to turnover is Anorganic Bovine Bone Mineral, which tends to remain and gets encapsulated in soft tissues. All other materials show robust regenerative response with variable turnover times, while Dentin shows a unique phenomenon of ankylosis, followed by replacement resorption, not unlike that of a replanted tooth.
What have your experiences with the dentine graft been like?
With the limited experience I have had with Dentin autografts, I have found the clinical outcomes to be extremely satisfactory, with very convincing radiographic evidence of its integration.
Soft tissue augmentation:
Being a periodontist, soft tissue augmentation is very close to my heart. In post-graduation, we used to study that teeth can survive perfectly well without attached gingiva, but one should intervene if there is marginal inflammation. The paradigm for implants could be different. What algorithm or mental model do you use to decide whether the case may benefit from soft tissue graft? Of course, it is clear when there is no attached tissue - but is there something else to look for, where you give one glance and say - if I do not augment the tissue now, there will be issues later?
Great question. The more I do, the more I see the room and need for enhancing soft tissues around implants. There is the obvious need for attached tissue lateral to the implant, i.e., buccal and lingual, but perhaps of greater importance is the vertical thickness of attached tissue on the ridge itself, as also the contour of the tissue in relation to the final restoration. Locations like the posterior mandible where the crestal tissue tends to be thin, attached tissue on the lateral aspects are often deficient, and muscle pulls are prominent, set off the alarm bells.
How do you deal with the deficiency of Lingual attached tissue, especially in full arch cases which have been edentulous for a long while?
Lingual attached tissue is a problem, very difficult to augment successfully. One often ends up with some mobile keratinized tissue around these implants. My approach to augmenting or not is often related to the patient’s overall ability to withstand additional surgical procedures. My go-to technique for these cases would be an overlay free gingival graft (FGG) with apically positioned flaps.
I agree. It often depends on consent and the patient’s willingness. Do you think the currently available soft tissue substitutes have a role to play during implant surgeries in such cases? For example, say I know there is less attached tissue on the lingual during implants in the posterior mandible. Should I stuff in a soft tissue substitute during surgery between the bone and the mucosa?
I have had mixed results with substitutes for soft tissue augmentation. And let’s not forget that we need a source of the keratinized epithelium at the edge of the wound to start with, so I’m not sure just stuffing a substitute is the answer for those cases. It needs a more algorithmic approach of soft tissue augmentation prior to implant placement, and if it is after the fact, one may even need to re-submerge the implant to gain the tissue and then distribute it.
This is a question for the academician in you. Is there something called attached non keratinized tissue? Could there be something like movable keratinized tissue?
Yes, you can have tissue that is keratinized and mobile- classically seen on flabby ridges, and of course, lining mucosa that gets keratinized due to friction like the Line alba (We will not consider pathologies here- that is dyskeratosis). Around implants, with deep sulci, all the marginal tissue is actually keratinized but not attached.
Conversely, it is possible to see attached non keratinized tissue- the junctional epithelium to start with, and on a more macroscopic level, most of the erythematous tissue you see on pontic sites when you get old bridges off is attached but non keratinized.
If there is one soft tissue grafting skill a beginner should master, what would it be?
There are two soft tissue techniques that I think every beginner should learn even before starting to place implants (As a matter of fact, I believe that beginners should learn about bone grafting as well, before starting to place implants).
One is the simple yet underutilized Apically Repositioned Flap, and the second is the versatile Free Gingival Graft harvest and stabilization. The FGG is simple to harvest, can be used as it is, in the epithelialized form or de-epithelialized for obtaining a free connective tissue, and the fact that it is easy to visualize, unlike the subepithelial harvest procedures, gives the operator more confidence in going to the palate to harvest tissue.
I have learned sinus lifts from you, and I have first-hand knowledge about the depths you have explored inside the sinus literally and metaphorically. So we will start with the most common belief about the sinus graft. Is it true that anything and everything works as a graft inside the sinus? Is there a first among equals, or is this a modern myth?
Haha Yes!, I have heard that “even sand” works in the sinus: It just happens to be a very expensive sand called Bioactive glass. To an extent, the statement is true since we know that if the membrane is held up well and long enough, be it by an implant, bone graft, or any other kind of osteoconductive/inductive means, we will get bone in the sinus. Then it all comes down to the convenience of delivery, safety, Biological activity, regenerative potential and turnover rates, cost-effectiveness, etc. I would still like to see the material that I place in the sinus to turnover and get replaced with vital bone eventually, and for this reason, my first choice (Lateral window) when available is a Cortico-Cancellous Allograft with at least 30-40% Autologous Cortical chips/shavings, followed by Carbonate Apatite Xenograft with 50% Autologous, particulate Alloplasts with 50% Auto, and if push comes to shove, ABBM with >50% auto. For the crestal approach, my default material is a Calcium Phosphosilicate Putty for its hydraulic capabilities more than any other reason.
I would like to know about your worst sinus lift failure too
My worst Sinus failure was when an implant got displaced into the sinus two weeks after a crestal lift. I had placed an immediate implant in the 17 region with a crestal lift for an elderly gentleman and left the cover-screw on, something that I rarely do with immediate implants. 2 weeks later, when I was away in Mumbai for a course, he met my then associate to get the sutures clipped off, and she, in her youthful enthusiasm, thought that the cover screw looked loose, and decided to tighten it, inadvertently displacing the implant into the sinus (This was on a Saturday afternoon). I received a phone call from the patient on Saturday night describing classic symptoms of an Oro-antral communication. All of Sunday was spent on tenterhooks at the course, where it did affect my clinical demonstration surgeries as well. I got back late Sunday night and saw him first thing on Monday to do a lateral window and extricate the implant. I think all of us learned some lasting lessons in those few days.
This is an unappreciated aspect of surgical practice when you say the case affected your clinical demonstration surgeries as well. What could be said to be the difference between efficacy and effectiveness in procedures - something that’s possible only on the best days of the best people or in controlled conditions, or something that is possible routinely, even on average days. That is why I have become a big fan of crestal lifts and MITSA. I could have had an awful fight at home, my wife could have called me a few unpublishable names, and yet, that internal lift will go so smoothly. What is the boundary you have pushed in MITSA? 2 mm? 3 mm? Furthermore, what is the percentage of direct vs indirect in your practice now, and how has it evolved over time?
The most I have gone with the Crestal approach is in 1.5 mm RBH. I remember the patient names and implant regions, number of implants, materials used, etc., for each and every lateral window case of mine over nearly two decades, out of hundreds of sinus floor elevations, so that must indicate the rarity of the procedure in my office. About 97-98% of my cases have been crestal, and it has stayed that way over time.
Thank you Rajeev, for thinking of me for this interview, and for getting Pinak to frame these astute questions. I thoroughly enjoyed replying to them. My best regards to all the great teachers out there on this Teachers’ day.
About Dr Narayan Venkataraman:
Dr. Narayan Venkataraman did his post-graduation in Oral Pathology from Nair Hospital Dental College, Mumbai in 1996. He then taught Oral Pathology for two years after which he started his own practice in 1999 while continuing to be active in academia till 2013. He is trained in Implant Dentistry at Berlin, Seoul, and DGI (Germany). He is a Fellow and Diplomate of the prestigious International Congress of Oral Implantologists (ICOI). He is also the Founder Director of the International Team for Implantology’s (ITI) study club in Bangalore where he is also a certified speaker. He is on the Editorial Board of Quintessence India journal and also an expert on Dental XP, the premier online dental education portal. Being one of the most sought-after experts in this field Dr. Narayan is also a key opinion leader for 3MESPE and Novabone. He has also embarked on a parallel consulting of Oral & Maxillofacial Pathology.
About Dr. Pinak Kapadia:
One of the leading periodontists and implantologists from Surat, Dr. Pinak practices exclusive periodontics and implantology. He was an associate professor at Vaidik Dental College Daman in periodontics. He is an avid reader, a bookaholic, and a trekker.