Objectives Platelet-rich fibrin (PRF) has been utilized in regenerative dentistry as a supra-physiological concentrate of autologous growth factors capable of stimulating tissue regeneration. Due to the variability in the macroscopic morphology/size of PRF membranes observed between patients, we were interested in studying the effects of patient age, gender, and time between blood draw and the start of centrifugation on the size outcomes of PRF membranes. Despite PRF therapy being increasingly more popular in private practice, to date, no study has investigated the effects of the delay between blood draw and the start of centrifugation in a clinical setting. Materials and methods A total of 60 patients enrolled in this study were divided into 6 groups of 10 patients each, including male and female patients categorized into age groups 21-40, 41-60, and 61-80 years. From each patient, a total of five PRF membranes were fabricated from 10-mL tubes following centrifugation starting after 0, 30, 60, 90, and 120 s. In total, 300 PRF membranes were produced in this study to investigate the effects of patient age, gender, and time on the size outcomes of PRF membranes. Results A longer delay by the clinician before starting centrifugation following blood draw led to a smaller final size of PRF membranes. At 90 s following blood draw, a significant (13%) reduction in PRF membrane size was observed. After 120 s, a significant (23%) reduction was observed. Additionally, female patients had on average 17% larger membranes compared to men (p < 0.05, 300 samples). Lastly, the size outcomes of the PRF membranes was largest in patients aged 61-80, followed by those aged 41-60 and 21-40. However, no statistically significant differences in PRF membrane sizes were reported between age groups. Conclusions The time at which a centrifugation procedure begins following blood draw is critical to optimize the size outcomes of PRF membranes. In general, approximately 15 s is required per tube to harvest 9-10 cc of blood. Therefore, a 60-to 90-s interval between blood draw and the start of centrifugation should be a parameter that is respected by clinicians to avoid significant changes in the macroscopic morphology/size of fabricated PRF membranes. Furthermore, females and older patients produced larger membranes, likely due to lower red blood cell counts derived from their peripheral blood. Clinical relevance The findings from the present study demonstrate that on average, a clinician has approximately 60-90 s between blood draw and the start of the centrifugation cycle to produce standard-sized PRF membranes. Shortly thereafter, a significant reduction in size is observed. Additionally, females and older patients were found to produce larger PRF membranes. Centrifugation protocols may therefore be adapted accordingly.

Background Platelet-rich fibrin (PRF) has been widely utilized in modern medicine and dentistry owing to its ability to rapidly stimulate neoangiogenesis, leading to faster tissue regeneration. While improvements over traditional platelet rich plasma therapies (which use chemical additives such as bovine thrombin and calcium chloride) have been observed, most clinicians are unaware that many tubes utilized for the production of ‘natural’ and ‘100% autologous’ PRF may in fact contain chemical additives without appropriate or transparent knowledge provided to the treating clinician. The aim of this overview article is therefore to provide a technical note on recent discoveries related to PRF tubes and describe recent trends related to research on the topic from the authors laboratories. Methods Recommendations are provided to clinicians with the aim of further optimizing PRF clots/membranes by appropriate understanding of PRF tubes. The most common additives to PRF tubes reported in the literature are silica and/or silicone. A variety of studies have been performed on their topic described in this narrative review article. Results Typically, PRF production is best achieved with plain, chemical-free glass tubes. Unfortunately, a variety of other centrifugation tubes commonly used for lab testing/diagnostics and not necessarily manufactured for human use have been utilized in clinical practice for the production of PRF with unpredictable clinical outcomes. Many clinicians have noted an increased variability in PRF clot sizes, a decreased rate of clot formation (PRF remains liquid even after an adequate protocol is followed), or even an increased rate in the clinical signs of inflammation following the use of PRF. Conclusion This technical note addresses these issues in detail and provides scientific background of recent research articles on the topic. Furthermore, the need to adequately select appropriate centrifugation tubes for the production of PRF is highlighted with quantitative data provided from in vitro and animal investigations emphasizing the negative impact of the addition of silica/silicone on clot formation, cell behavior and in vivo inflammation.