As promised, here is the step-by-step walkthrough of converting an All-on-4 denture. In my upcoming ebook, The Implant Ninja All-on-4 Handbook, I will cover this process in more depth and will discuss different approaches & materials, and most importantly, complications. (It will become available in Spring 2017. Pre-order to reserve your copy! )
If you’re interested in learning my technique, we are also offering All-on-4 learning webinars.
This is the patient’s pre-op presentation. He had an old partial denture that was retained by a ball attachment inside of the canine root. (I have extracted a lot of teeth with these types of attachments as they commonly decay from the inside.)
Nice thick alveolar ridge. It looks like this procedure will be a piece of cake. One of my main concerns here is that he will break the future prosthesis. Look at the risk factors:
- His upper denture is worn down
- His lower remaining teeth are worn
- He has a lot of bone height which means limited inter-arch restorative space.
- He is a stalky guy with thick masseter muscles (although you can’t see this here)
The teeth were extracted easily. Then I started placing the anterior implants. I start with these because this area is easier to access and visualize. I begin with using a narrow pilot drill.
I begin by using a narrow pilot drill at the #27 site. Before I drill, I have the upper denture in place to give me a reference for my angulation. Also, I try on mandibular duplicate denture that was made in clear acrylic. This will give me an idea of how to angle the implants so that I do not have the screw access coming out of the facial aspects of the teeth.
Then I proceed to use the narrow pilot drill at the #22 site. I then take the drill off of the handpiece and insert one drill in each osteotomy. This allows me to gauge the parallelism and the angulation when compared with the upper denture.
Then I proceed with the 2mm twist drill in both of these sites, which allows me to then place the paralleling pins inside the osteotomy. Once I am happy with their positioning. I proceed with an additional implant at #24 site.
This is a picture with all 3 paralleling pins in place:
Once all three implants in the anterior region are placed, I proceed to preparing the posterior sites. When there is limited bone height, I use the tilted protocol for the distal implants. However, there is plenty of bone above the IA canal, so I place axial implants in all of the positions. This makes everything so much easier. There is no need to tilt implants just for the hell of it.
After that, the posterior implants are put into place. You can see in the above picture, that I use the implant transfer driver as a paralleling tool after the implant has already been placed. This is very useful.
Once All of my implants are positioned where I want them, I placed 2.5mm tall straight multi-unit abutments. In this case, I used a kit from Implant Direct called Simply Fixed. Each pack costs $200-230 and comes with an implant analog, temporary titanium cylinder, multi-unit abutment, comfort cap, and impression coping. As far as convenience goes –it’s hard to beat that!
Then, I place the comfort caps on the multi-unit abutments and suture up my flap. I like to use interrupted sutures. In this case I used catgut 3-0.
Next, I placed blue mousse inside the intaglio of the mandibuar denture, seated it on the ridge, and have the patient bite down into occlusion. This provides an index of the implant positions. I use a football acrylic bur and just make a hole right through the denture in each of those locations.
I took off those comfort caps and placed multi-unit temporary titanium abutments on each implant.
I check that there is clearance between each cylinder and the denture. This clearance is important because it will provide access for me to inject an acrylic pick-up material. In the following picture, you can see that some of the titanium cylinders are binding so the denture still has to be adjusted. Also, now is a good time to see if any of the cylinders protrude through the denture and will interfere with occlusion. If so, make sure to cut them down a little shorter.
Now that there is enough clearance and I am happy with the occlusion, I will punch some holes into a rubber dam and slip that over the cylinders. The purpose of the rubber dam is so that 1) acrylic doesnt seep into the wound and 2) the acrylic does not harden around the sutures and rip them out when I remove the denture.
I place teflon tape inside of the access holes to make sure that I don’t get any acrylic inside the cylinders and make a huge headache for myself.
I mix up some acrylic in a medicine cup, quickly pour it into a Monoject syringe and squirt it around the titanium cylinders. For this case, the acrylic I used was Jet acrylic. However, I also really like a super-fast set acrylic called Unifast Trad. (This acrylic is crazy fast set, so if you’re just starting out, I would not recommend it) Some colleagues have mentioned that they use Locator Chairside Processing Material to attach the cylinders.
Upon reading this article, my U Mich Prosthodontics buddy, Dr. Kevin Aminzadeh mentioned that he also places some buccal injection holes at the cylinder site. This will help prevent some major voids at the base of the cylinder. (Thanks for the tip, Kevin!)
I do this for each one of the implants. Make sure your patient bites down into occlusion as soon as you are done injecting acrylic. This will make sure vertical dimension and occlusion is correct.
As the acrylic material hardens, it gets hot so I squirt a little bit of water over the acrylic to avoid burning the patient. After the material is set, I remove the teflon and unscrew each abutment.
Now I fill the voids around the titanium cylinders in the intaglio surface with more acrylic. After the voids are filled and I am 100% comfortable with the fit of the titanium cylinders onto the abutments (sometimes the cylinders move and it can become a mini-nightmare to manage it) I will proceed to cut off the flange, cut off the tooth distal to the last implant, and trim polish the denture.
Here is the converted denture in place:
I cover up the access holes with teflon tape and put composite over them.
Do you use different methods for converting All-on-4 dentures? I would be happy to hear about it!
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