Dear colleagues, welcome to Short and Narrow Implants. We'll ask the question, as many as possible or as few as required? Here on the left side, you see a traditional way to place implants and surely is as many as possible. On the right side, you see a more modern way, as few as required. This brings us to the key question, how do we know how few or how many are required? Just some background information. Bone integration of dental implants. The bone is a load bearing structure. The occlusal forces exerted onto the implant during function are transferred to the surrounding bone via the bone to implant interface. So, the bone at the end picks up the loading forces. On the left side, we see a histological section to an implant, and in red, you see the surrounding bone. Back to our question. How do we know how long an implant needs to be? Now we focus on the length. There's an interesting systematic review by Tellemann and co-workers. They did a meta analysis of 29 studies and they looked at 2,600 short implants. They included a range from 5mm to 9.5mm. Let's look at their results just very briefly. You see on the left the 5mm implants and then the rise and length until 9.5(mm) at the right side. From 6, 7, 8, 8.5 (mm), 9 and 9.5 (mm), it's from 97% to 98% of survival they recorded. It's only the 5mm implants that are a bit lower with 93%. So we can conclude that the largest difference was found between 5mm and 6mm implants. 6mm and longer implants show very good survival rates. Now, let's expand this to some other clinical situation where the length is not maybe the primary issue but some other issues representing biomechanical challenges come into play. For instance, cantilevers here on the left side. You see an implant, a single implant, with two occlusal units, a crown and a cantilever. It's clear this single implant now has to be bearing the load of two occlusal units, so this is a more challenging situation than having two implants with one occlusal unit each. Or, here in the center, high crown to implant ratios. So, a short implant and a long crown. We have higher lever forces. Again, I'm sure more challenging biomechanically than standard situation. Then back to our short implants. Short implants, normal crowns, normal load bearing, again, a higher biomechanical challenge. What do we find in the literature? It's clear that the amount of load in relation to the bone in contact with the implant surface is increased in comparison to standard situation for all these three different situations. For cantilevers, we do not find loss of osseointegration. For height to crown to implant ratios, we do not find loss of osseointegration. For short implants, we do not find loss of osseointegration. These three biomechanically challenging situations, as they are used in clinical practice, do not lead to more loss of osseointegration. Here, we're on the safe side, that we're using as few as required. Bone integration of dental implants, generally speaking, the peri-implant bone has a high load-bearing capacity. This allows us to place fewer and shorter implants than what has been recommended in the past. We can expand this now to less implant surface not due to the length of the implant, but due to the diameter of the implant. And some titanium alloys which have more recently or further back been developed, some novel titanium alloys represent significantly enhanced mechanical properties compared to our titanium grade 4 which is traditionally being used for implants. We can reduce the diameter and still maintain the strength. But why would we want to reduce the diameter? Let me illustrate with these two images. You can see a tooth, the histological section on the left side, and you see an alveolar process where the tooth recently has been extracted. If we place a standard diameter implant, you will see that we have very few bone at the buccal aspect. If we reduce this diameter, you see that we have increasingly more bone. And with this narrow diameter implant, you can even move it a little bit more to the palate and maybe have a congruent bony bed. The potential benefits here in summary. We can better maintain peri-implant tissues. We have less need for bone augmentation. We have less risk of damage of adjacent structures. All these are in favour of diameter reduced implants. Now, how does this knowledge translate into clinical practice? Here we have a patient situation with a vertical bone height of only 6mm. Treatment of what choice was to place a short 6mm implant and reconstruct a premolar crown. Here you see the supreme position of a short implant. Here we have a normal gap width and a diameter reduced implant was placed and see a canine has been reconstructed. Here we have a three-year follow up of this clinical situation. These are standard clinical procedures with short or diameter reduced implants. Let me summarize and conclude. Short and narrow implants are viable clinical options. Biomechanically challenging situations, including cantilevers, high crown to implant ratios, short implants, are not associated with significantly more implant loss than comfortable situations. The use of short and narrow implants helps to reduce costs, treatment time, and patient morbidity. Recent scientific data allows us to place fewer and shorter implants compared to what has been recommended in the past. Thank you very much for your kind attention.