Eligible studies
Of 2413 articles retrieved from databases and screened, 64 articles used the PRP/PRF in the treatment of oral diseases and compared the effect of PRP/PRF on outcomes in several oral diseases (Fig. 1- PRISMA Flow Chart). These reported the data from 2477 patients treated with PRP/PRF alone or in combination. In addition, only a few studies reported the growth factor levels in PRP/PRF.
Characteristics of included studies
The included sixty-four articles were published between 2004 and 2024 [16–79]. Most of these studies were randomized controlled trials (RCTs- split-mouth, prospective, and double-blind). Only few studies were retrospective, comparative, or observational study designs. Out of these 64 studies, 9 studies were formally documented through registration identifiers, including NCT numbers [16–20], CTRI numbers [16], or adherence to institutional protocols [21–26]. The duration of study and patient follow-up in these studies was ranging from one week [27] to eight years [28] showing significantly variation between studies. All studies were focused on use of PRP or PRF in dental and oral surgical interventions (Supplementary file 1: Table S1). These studies involved a heterogeneous patient demographic characteristics from different age groups, genders, and health statuses, including smokers, those with periodontal or systemic diseases, and healthy participants. Cohort sizes in these studies also varied substantially, from small groups of five participants [29] to larger assemblies of nearly five hundred [30]. The studies addressed a spectrum of clinical needs, including routine tooth extractions, complex bone grafting procedures, and the management of various oral defects. Some trials incorporated control groups [26, 31–35] receiving conventional procedures without PRP [16, 17, 22, 23, 35–40], while others compared the outcomes of distinct graft materials [21, 29, 33, 34, 41–45] or surgical methodologies [17, 46–48]. The demographic data consistently showed an equitable distribution of male and female participants across a broad age range, with specific exclusion criteria often based on systemic health conditions or other risk factors. The primary objective of these studies was to evaluate treatment outcomes concerning healing processes and the incidence of complications within surgical environments, with a particular emphasis on bone repair and regeneration in the dental context.
The included papers provide an overview of the methodologies employed for preparing and applying PRP and PRF in several dental and oral surgical procedures (Supplementary file 1). Key parameters scrutinized across these investigations include baseline platelet concentrations, the specific protocols utilized for PRP/PRF preparation, and application sites. Preparation methods were having variations, from single-step [30] to two-step centrifugation methods [32]. Several studies notably reported achieving substantial platelet concentrations [21, 32–34, 37, 39, 46, 47, 49, 50], frequently several times higher than baseline levels [21, 33, 46, 51]. Platelet activation often involved agents like calcium chloride or thrombin [21, 41, 44, 49, 51–58]. While few studies endeavoured to quantify specific growth factors [34, 39, 43, 44, 48, 53, 54, 56], other studies did not provide detailed descriptions of the analytical methods employed for their assessment. PRP and PRF was used for healing of extraction sockets, maxillary sinus floor augmentation procedures, and a bony defect, suggesting utilization of PRP and PRF in different dental treatment.
Finally, the comprehensive data illuminates the diverse quantities of blood utilized for PRP and PRF preparation across numerous studies. The studies have estimated volume of PRP/PRF obtained and the types and measured levels of associated growth factors. Blood volumes ranged 8 mL [38] to 500 mL [57], with the consequent quantity of derived PRP/PRF showing wide variation, often unstated or only implicitly referenced. Growth factors frequently identified in conjunction with PRP/PRF included Platelet-Derived Growth Factor (PDGF), Transforming Growth Factor (TGF), Vascular Endothelial Growth Factor (VEGF), and Insulin-like Growth Factor (IGF), among others [21, 25, 34, 39, 44, 45, 48, 50, 53–57, 59, 60]. It's important to note that while some studies offered precise quantitative measurements for these growth factors, others merely indicated their presence without direct quantification. The limited number of studies that provided correlation coefficients suggested potential relationships between growth factor levels and clinical healing outcomes, underscoring the considerable methodological and reporting inconsistencies within the analyzed literature.
3.3 PRP quantity from Blood
According to Pooled analysis of data from eight published studies from 2004 to 2020, the average yield of PRP/PRF was estimated at approximately 0.115 mL per mL of whole blood processed (Fig. 2). The average was derived from 82.38 mL of PRP/PRF obtained from 719 mL of blood, indicating a consistent yet variable efficiency across centrifugation method and devices.
The comparison of PRP/PRF yield per ml of blood, indicates substantial variation in centrifugation methods (Fig. 3). PRP/PRF yields ranged from 0.012 mL/mL[59] to 0.20 mL/mL [51], with 0.115 mL/mL pooled mean. Variation in PRP/PRF yield reflects methodological variation in centrifugation process, machine configurations, and amount of blood volume used. Interestingly, Current centrifuge methods are optimized to produced yields exceeding 0.10 mL/mL from limited blood volumes. Moreover, there a significant linear relationship between blood volume and PRP/PRF yield (Pearson correlation coefficient of 0.99 (p = 7.78 × 10⁻⁷) (Fig. 3). This mean PRP/PFR yield can act as a reference for evaluating the volumetric efficiency of platelet concentrate preparation methods as well as can help in creating standardized protocols for clinical application.
Further, findings indicate that blood volume is a primary determinant of platelet concentrate yield. This relationship may serve as a benchmark parameter for yield normalization in future studies or device comparison.
The forest plot summarizes the pooled estimates of PRP volume per millilitre of blood across eight studies using a fixed-effect meta-analysis model. The overall pooled yield is 0.084 mL/mL, with a 95% confidence interval of [0.037; 0.131], when blood volume is standardized (Fig. 4). Overall result is significant suggesting a consistent positive yield of PRP across different methods of PRP/PRF preparations (p < 0.05). However, high heterogeneity (I² = 89.3%, p < 0.001) suggests effect of methodology, instruments, and centrifugation methods on yield.
Table I
Different growth factor concentrations in PRP/PRF preparations
| Growth Factor | Author | Year | Level (ng/mL) | Reference |
| VEGF | Fang D | 2020 | 1.39 | [31] |
| | Marukawa E | 2011 | 20 to 60 | [36] |
| | Passaretti F | 2014 | 1.3763 ± 0.129 | [50] |
| | Qiao J | 2016 | 0.23136 ± 0.04401 | [40] |
| TGF-β / TGF-β1 / TGF-B | Fang D | 2020 | 93.4 | [31] |
| | Marukawa E | 2011 | 40 to 120 | [36] |
| | Passaretti F | 2014 | 265.6675 ± 39.8516 | [50] |
| | Qiao J | 2016 | 703.02 ± 86.77 | [40] |
| | Ouyang Xiang-ying | 2006 | 650.5 ± 82.0 | [41] |
| | Lee C | 2009 | 170.9 ± 42.2 | [53] |
| | Raghoebar GM | 2005 | 60600 ± 23600 | [64] |
| PDGF | Marukawa E | 2011 | 0.1 to 0.4 | [36] |
| | Passaretti F | 2014 | 2.18909 ± 0.225 | [50] |
| | Verma R | 2019 | 31.92 ± 10.47 | [51] |
| | Qiao J | 2016 | 176.88 ± 52.32 | [40] |
| | Ouyang Xiang-ying | 2006 | 110.2 ± 55.2 | [41] |
| bFGF | Passaretti F | 2014 | 0.00766 ± 0.00065 | [50] |
| IGF-1 | Qiao J | 2016 | 533.69 ± 67.35 | [40] |
Within the included studies, growth factor concentrations in PRP/PRF exhibit significant variation, mostly attributed to assay methods, donor profiles, and preparation protocols (Table I). Mean Vascular endothelial growth factor (VEGF) levels ranged from 1.3–1.4 ng/mL from low of 0.23 ng/mL [40] to high of 60 ng/mL [36]. TGF-β/TGF-β1) showed a markedly variation ranging from 40 ng/mL [36] to 60,600 ng/mL [64]. Similarly, Platelet-derived growth factor (PDGF) concentrations range from as low as 0.1 ng/mL to r 176 ng/mL, with Verma R et al [51] reporting a relatively highre mean of 31.92 ng/mL. Basic fibroblast growth factor (bFGF) level was 0.0077 ng/mL [50] which was very low in quantity in PRP/PRF. Contrary, Insulin-like growth factor-1 (IGF-1) found in a high concentration of 533.69 ng/mL [40].
3.4 Correlation of Platelet count and Obtained PRP quantity
The summarized data from seven studies reveal that baseline platelet counts ranged from a lower threshold of ≥ 150 ×10⁹/L [59] to upper values of 300–450 ×10⁹/L [47], with most studies reporting means between 216 and 315 ×10⁹/L (Table II). The data shows considerable variation in PRP quantity ranging from 0.48 mL to 10 mL. Mazor Z et al. [48] obtained the highest PRP volume (10 mL) despite a moderate platelet count of 216 ± 68 ×10⁹/L, while Cieslik-Bielecka A et al. [60] reported 6 mL with a comparable baseline. In contrast, studies such as Refahee SM et al. [18] and Célio-Mariano R et al. [47] could obtained only 1 mL of PRP despite higher platelet counts.
Table II
Correlation of Platelet Count and Obtained PRP Quantity
| Author | Year | Platelet Count (×10⁹/L) | PRP Obtained (mL) |
| Célio-Mariano R et al | 2012 | 300–450* | 1 |
| Lindeboom JA et al | 2007 | 248.5 ± 13.5 | 0.8–1.0 |
| Cieslik-Bielecka A et al | 2008 | 244 ± 68 | 6 |
| Mazor Z et al | 2004 | 216 ± 68 | 10 |
| Refahee SM et al | 2020 | 315.33 ± 26.12 | 1 |
| Sammartino G et al | 2005 | ≥ 150** | 0.48 |
| Lee C et al | 2009 | 273 ± 63 | 3 |
| *(converted from /µL) |
**(estimated lower bound)
Further, this is supported correlation analysis between baseline platelet count and PRP volume (Fig. 5). there was a weak negative correlation between these variables (–0.3757; r² = 0.0865). Thus, higher baseline platelet counts are not reliably associated with increased PRP yield, and may be inversely related. Further, analysis reflects limited use of platelet count in predicting PRP quantity, indicating that additional methodological or biological variables likely influence PRP yield. Thus, it can suggests that platelet count alone may be insufficient as a predictive marker for yield optimization.
The highest baseline platelet concentration, exceeding 400 ×10⁹/L [47] reports, while records the lowest at approximately 150 ×10⁹/L [59] (Fig. 6). Further, the highest yield ratio per platelet is 0.0463 mL/×10¹² platelets [48], whereas lowest was 0.0032 or below [18, 59] (Fig. 7). This variation could be attributed to within and between study heterogeneity in participant selection criteria, measurement methods, and platelet isolation protocols.
A meta-analysis was conducted to evaluate the standardized mean differences (SMD) in growth factor (GF) yield per 10^9 platelets for PDGF and TGF-β1. For the PDGF subgroup [41, 50, 51], the pooled effect was SMD = 0.01307; 95% CI: 0.01072–0.01542; p < 0.0001, with extreme heterogeneity (I² = 98.9%, τ² = 0.0485). This indicates a small but statistically significant standardized effect, although study-level variability was high. For the TGF-β1 subgroup [41, 50, 53], the pooled effect was markedly greater, with SMD = 0.84031; 95% CI: 0.72985–0.95078; p < 0.0001, and again high heterogeneity (I² = 97.4%, τ² = 1.0359). This reflects a large and consistent effect size across studies. The overall pooled analysis yielded an effect of SMD = 0.01344; 95% CI: 0.01110–0.01579; p < 0.0001, which was heavily weighted by PDGF estimates. Importantly, the test for subgroup differences was highly significant (χ² = 215.33, df = 1, p < 0.0001), confirming that the effect of TGF-β1 on GF yield per 10^9 platelets was significantly greater than that of PDGF.