We all know that dental implant treatment is fantastic for those patient who are looking to replace a missing tooth with the best solution that we currently have.
(well, best in most cases)
As long as there is enough bone above the nerve, then it should be straight forward, right?
Lets look at this case...
At first glance, we can see the IDN, we can see the height of the adjacent teeth, and make an educated guess on the available height of bone above the IDN, and then have a selection of implants ready to place, dependant on the width of the ridge, once we open the area up.
About 10 years ago, when I was learning from a more experienced implant surgeon, 90% of the implants he placed, we from a 2D x ray.
It was rare that he had a CBCT done.
But that was 10 years ago, these days CBCT scans as far more common, and personally, I never place a dental implant without a CBCT Scan.
I think that most would be fine with only a 2D scan, however the risks that happen on the "odd occasion are massive".
So we took a CBCT scan for this area and this is what the measurements were like.
Not bad, right?
The blue coloured implant in 9mm long, and it looks like there is a good distance between the IDN and the bottom of the implant (I like to have 2mm).
But when we look in cross section, the story changes.
There are two things that we need to see here.
The first is the lingual concavity of the mandible, this was completely invisible in the OPG (first image) and also the slice of the CBCT scan, which shows a psudo OPG.
Secondly, the most crestal part of the bone is going to be removed at the time of the implant placement, so the distance to the nerve is actually much less than originally measured on the buccal view.
In fact, we only really have 6mm of bone here.
Luckily, the system I am using does have a 6mm option.
But only in a 4mm wide implant (and not the 5mm as planned above)
This is what it looks like with a new implant.
That's a lot more comfortable, right?
The reduced width of the implant has actually given is a little more height to play with.
But how small can we go?
My honest answer is - I don't know.
But in this case, I was not too concerned with dropping down to this size, as the patient is having a full mouth restoration carried out, and this will reduce the stress on a single implant tooth.
Secondly, there are two implants going in here. If the crowns are linked, then the force will be splinted on the two implants, and spread over a larger surface area.
I need to communicate this with the referring dentist, but we have worked together for a long time, and I am sure he would do this anyway.
On the day of surgery, I was still cautions. What if I accidentally perforated the lingual wall?
I mean, using it to engage the implant isn't terrible, but I definitely do not want to drop a drill into the lingual aspect there, this is where you could find branches of the lingual or facial arteries, and perforation of these could be life threatening.
So what can you do to mitigate the risk?
The easiest thing is to plan a smaller implant, when you choose this option, the risk of over drilling is minimal.
You can use drill stops of be even safer.
Another trick can be to angle the osteotomy to the buccal. This may adversely effect the prosthetic design, but its an option.
In this case, I elevated the lingual mucosa, below the bulbosity. There is a limit of what you can do due to the attachment of the mylohyoid muscle, but you can access quite far.
The point of doing this is to loosen the tissues there, and also, I placed a Mitchell's trimmer where the drill may exit, so if it does, there is some protection there before hitting something important.
In the end, both implants went in as planned, and we did not need any additional bone grafting.
The point here is that we have advanced imaging techniques, and using them forces you to mentally plan how you are going to carry out your surgery.
Visualisation is key, it is a critical skill in developing as you start to carry out more and more complex cases.
Try to think exactly what you are going to do, where is your incision - are you going to release, if so, where and how? How will you control your osteotomy etc.
Take the time to go over these questions in your head - it will dramatically reduce your stress and increase your confidence going into the surgery.
When I mentor my dentists, we often have discussions, where I will ask them to tell me exactly what they are going to do.
Again, verbalising the plan forces you to really think about it and identify the risks.