The size of the PRF clot is a common question. Below we review the 3 important factors to consider when analyzing the clot.

First of all, when creating PRF membrane/plugs with Solid PRF, please make sure you are following all the necessary steps included in our instructions. A quick review:

• You must use the Red Glass Tubes.
• Use Setting 1 on the Centrifuge. 2,300 RPM (~750RCF) for 8 Minutes.
• Be sure the tubes are balanced. We recommend 6 tubes per cycle. Fill tubes with water, if you don't have enough.
• After the spin, take off the caps from the tubes and place the tubes in the sterile tube holder and let them rest for about 5 to 10 minutes.

Now assuming, you have followed the directions, it is worth reviewing where these settings come from and the nature of the clot. The literature by Miron et al. [1,2], especially the most recent article entitled, "Evaluation of 24 protocols for the production of platelet-rich fibrin", have reached the conclusion that on a horizontal centrifuge, the optimal centrifugation speed and time ranged between 400g and 700g for 8 min for solid-PRF protocols. Based on the mathematical formula for computing g-force (RCF), 700g equates to approximately 2,300 RPM on our horizontal centrifuge (actually it's 750RCF, but our machine can only move in 100 increments of RPM).

However, if you read thru the article "Evaluation of 24 protocols for the production of platelet-rich fibrin", you will see that based on the research and the images provided, that other centrifugation protocols can be used, and essentially a bigger clot will be created by running the machine at a higher RPM (higher g-force) for an extended period of time. So if you are interested in a larger clot simply extend the time for the 1st setting for another 4 minutes (that's setting 3 on the machine, 2,300 RPM for 4 minute) or just create a custom setting for a higher speed. For example, based on the paper above, you can try an 1,000g spin for 8 to 12 minutes (1,000g or RCF is equivalent to ~2,700 RPM on our machine). This should create a larger clot. However, bear in mind that a larger clot has nothing to do with the effectiveness of the PRF plug/membrane. In fact, as mentioned above, the researchers concluded that:  "The best yield of leukocytes was achieved after centrifugation for 8 min utilizing the 700, 1000 and 1200g protocols. Of those the highest concentration was achieved at 700g for 8 min (owing to the reduced total plasma volume). Another noteworthy trend that was apparent was that as centrifugation time was increased, a general increase in percent yield was observed, however generally speaking, an overall decrease in concentration was observed..." [1,2]

So basically, if you are looking to create the most effective clot, the better protocol is the lower centrifugation protocols that are set on the machine. The clot maybe smaller, but it has the highest concentration, and therefore would, in theory, be the most effective.

Finally, please remember that in reality each patient is unique, and you will certainly experience variability between patients with regards to the final size of PRF membranes. This is due to inherent differences in various blood components between patients. Theoretically some patients will require lower centrifugation speeds and/or time, and others higher speeds/time. For example, it has been reported that blood from female patients will produce a larger PRF membrane, as compared to males. [3] It is simply not possible to provide an exact spin cycle that will work on every single patient to produce the optimal PRF membrane/clot. The best we can do is provide a setting that works on average for most patients. However, you may have to adjust the spin cycle or time to get the results you want for a specific patient.

In sum, a larger clot can theoretically be achieved with a higher RCF and/or time. However, the size of the clot has nothing to do with the effectiveness of the clot. Therefore, we recommend using the pre-settings on the machine as a guideline as those are settings the research has concluded are optimal for most patients. You can always adjust the time and/or RPM as you see fit, based on a specific patient or situation. However, remember that significantly elevated protocols may prove ineffective, even if the clot may appear larger to your naked eye.

1. J Biomed Mater Res A. 2019 Oct;107(10):2257-2271. A novel method for evaluating and quantifying cell types in platelet rich fibrin and an introduction to horizontal centrifugation. Miron RJ et al.
2. Miron, R.J., Chai, J., Fujioka-Kobayashi, M. et al. Evaluation of 24 protocols for the production of platelet-rich fibrin. BMC Oral Health 20, 310 (2020).
3. Miron RJ, Dham A, Dham U, Zhang Y, Pikos MA, Sculean A. The effect of age, gender, and time between blood draw and start of centrifugation on the size outcomes of platelet-rich fibrin (PRF) membranes. Clin Oral Invest. 2018;23:2179–85.

You can get all the Horizontal instructions here. You can also watch the [Instructional Video](https://www.youtube.com/watch?v=hBoU6Zdt1eI) on youtube. Please refer to the Instructions linked above, as these are updated.