Digital dentistry and new technologies geek. I can quote Star Wars better than you and your friends.
Latest posts by Francisco T. Barbosa (see all)
- 3 Reasons Why High Implant Insertion Torque Backfires - May 15, 2017
- Some Concepts We Should Know About Implant Surfaces Topography - January 16, 2017
We could say that torque is like jealousy.
Lack or excessive jealousy may kill a relationship. Just like the insertion torque during an implant placement. Too much can be counterproductive.
But, what is the torque value we should consider to be the maximum during an implant placement?
Do torque affects all type of bone the same way?
And, what can we do to avoid complications caused by an excessive torque?
These questions are just an example of the doubts that may come up to our head when we are stuck in a surgery placing an implant in a type I bone.
First of all, like I always do, I asked on Twitter about this topic. Based on what I know about torque so far, I´m only concerned about 7% of them who voted that they think more than 60 N.Cm is the best option.
Which torque value you think is the best during the implant placement ? 🤔
Rt please 🙏
— Francisco T. Barbosa (@Cisco_research) February 1, 2017
But a vast majority voted the 25-40 N.Cm torque range option (69%. I´m starting to think that people who voted, were trolling the poll just to get that “69” number 🤔).
Don´t get me wrong: primary stability is important, and it is a key
factor for implant success (Chiapasco 2003).
It makes sense to connect “high torque” with “high primary stability” which leads to an implant that is less likely to suffer any micro-movement during the healing process.
This micro-movement threshold should be somewhere between 50 µm and 100 µm during the osseointegration healing process (Trisi 2009).
There are other authors that this range is between 50 µm-150 µm, but as clinicians, it is impossible to know how much micro-movement is being applied to an implant that we just placed (Szmukler- Moncler 2000).
We have to control the risk factors that can lead to that micromotion and implant fibrointegration. You can read more about this in this post about immediate loading.
First of all, we should take a look at the events that occur after placing an implant (Berglundh 2003, Abrahamsson 2004).
Knowing this, we can understand better why some problems may occur if we place implants with a high torque.
1. Bone compression and bone density. Key factors that may cause marginal bone loss.
The more underprepared is the site where the implant is going to be placed the more strain and stress will be applied to the surrounding bone.
We should know what the size of the last drill compared with the implant width and only place the implant in the underprepared site in the maxillary posterior region where the bone quality is often poor (Turkyilmaz 2008).
When we apply osseocompression to a high-density bone, the physiological limit is exceeded bone resorption is triggered (Jimbo 2015).When we apply osseocompression to a high-density bone, the physiological limit is exceeded bone… Click To Tweet
We should avoid exceeding this physiologic limit when we place the implant by properly prepare the site for the fixture.
TAKEAWAY 1: When I´m placing an implant in a high-density bone I often perform several times the bone tapping with the adequate instrument until it can be introduced with a torque of 35 N.cm.
2. High torque doesn´t mean optimal primary stability.
When a micromotion phenomenon above 150 µm is present during the healing phase, the implant will be very likely to suffer a fibrointegration instead of an osseointegration (Gao 2012).
So the primary goal is to reduce that micromotion to the minimum during the earlier phase of osseointegration. This issue is critical in an immediate loading approach.
We tend to place implants with a high torque just because “we feel comfortable” when we do an immediate loading in implants that were placed with a high torque.
Some publications proved that maybe there is no correlation between high torque and micromotion and no need to have a high torque to perform an immediate loading (Norton 2011).Some publications proved that maybe there is no correlation between high torque and micromotion… Click To Tweet
In this publication, Norton proved that in single implants immediately restored a torque of only 25 N.Cm was enough to achieve favorable survival rates and optimal maintenance of marginal bone levels.
On the other hand, Jimbo tested an implant with a modified macrogeometry that yielded to a reduced bone remodeling and lower levels of micromotion (Jimbo 2015).
Excessive torque (≥50 N.Cm) can lead to more peri-implant bone resorption and tissue recession, and the negative impact of high torque can be more clear if the buccal bone thickness is inferior to 1 mm (Barone 2015).
TAKEAWAY 2: Torque should be monitored and recorded. Using a calibrated torque wrench, or a drive unit that measures the insertion torque, for example, the Implantmed (W&H).
3. Thin buccal bone wall? Be careful.
If there is a thin buccal bone wall during the implant placement, we should know the more likely it will be to resorbed. Some publications stated that we should have at least 2 mm of buccal bone when we place the implant. More exactly 1.8 mm (Spray 2000).
In a case scenario where we place an implant with a high torque and the buccal wall is very thin (less than 1 mm), the more likely we will have more resorption and more soft tissue recession (Barone 2015).
With such a thin buccal bone wall, the blood supply to that cortical is very limited and also applying strain and compression to that fragile bone is not a good idea.
TAKEAWAY 3: In a case of a thin buccal bone wall we should avoid high torque in any case. Also, consider performing a horizontal guided bone regeneration.
Collecting that from the latest publications we should consider to avoid a torque above 50 N.Cm in every case. There seem to be no advantages in placing implants above this torque value even for the cases where we are going to perform an immediate loading (Norton 2011).
Also, we have to consider the macro-geometry of the implant that we are using. Some authors demonstrated that adding a modified cutting flute to an implant with a similar macro-geometry, decreased the insertion torque without raising the micro-movements in the tested implant (Jimbo 2014).
In the last decade, there is a clear trend to design implants with more “aggressive” macro-geometry that are promoted as implants that allow high insertion torque that ensures an “excellent” primary stability.
Needless to say that these conclusions could not be more untrue.
We already discussed in this article that the insertion torque can be decreased by modifying slightly the macro-design of an implant (Jimbo 2015).
This changes on the macro-design should decrease the micromovements during the healing phase.
Also, we should know that during the osseointegration or the establishment phase, there is a delicate interplay between the bone resorption in the areas where the implant is in contact with the mineralized bone and the areas where the bone is being formed (Abrahamsson 2003).
Is important to underline the surface topography has an important role during osseointegration. You can read more about implant surfaces on this article.
An ideal Sa value for the surface topography provides the best biological behavior to the fixture. This Sa value should be around 1 µm-2 µm regarding the classification proposed by Wenneberg (Wenneberg 2004).An ideal Sa value for the surface topography provides the best biological behavior to the fixture. Click To Tweet
So if the implant has an adequate macro-geometry that decreases the insertion torque and also a surface with a Sa value somewhere between 1µm and 2 µm the result will be a shorter time for the establishment phase of osseointegration.
Contrary to what we may think, an implant that during the installation has a large contact-free surface will have a shorter osseointegration time (Abrahamsson 2003, Berglundh 2004).
After reading this article ¿Do you still believe that we should seek for more aggressive implant designs?
¿What is your favorite implant macro-geometry?
I would love to hear your feedback about this topic and also your ideas about what is the ideal implant macro-geometry and recommended insertion torque.
As a final gift here it is an x-ray of an implant that I placed in hard bone with a 70 N.Cm torque. Great outcome as you can see 😢.