The biology of platelet-rich plasma

Evaluation of platelet-rich fibrin versus collagen membrane for enhancing healing of secondary grafted alveolar cleft: a randomised controlled trial

The purpose of this study was to compare the efficiency of using autologous platelet-rich fibrin versus a resorbable collagen membrane in secondary alveolar bone grafting. Patients were randomly allocated to the three treatment groups: Group 1 - twelve children in whom the nasal layers of the alveolar clefts were repaired using autologous platelet-rich fibrin with autogenous chin bone; Group 2 - twelve children in whom the nasal layers of the alveolar clefts were repaired using bovine collagen membrane type I (Colla-D) with autogenous chin bone; and Group 3 - twelve children in whom the bony alveolar clefts were grafted with autogenous chin bone after construction of a watertight nasal floor had been completed. The study population comprised 36 patients with alveolar clefts, ranging in age from seven to 12 years. At the last follow-up period all groups had stable healing conditions and good radiological outcomes in terms of the alveolar bone height bordering the teeth (both mesially and distally) and the incorporation of grafting material with the surrounding bone. The use of either a PRF membrane and a collagen membrane as an interpositional layer between the nasal layer and the autogenous chin bone graft enhanced bone formation and density in alveolar clefts compared with the control group.

Revitalizing female fertility: platelet-rich plasma - hype or hope?

Platelet-rich plasma (PRP) has gained popularity as an experimental tool in regenerative medicine, with potential applications in reproductive medicine. This review will assess the existing literature on the role of PRP in female fertility enhancement, focusing on ovarian rejuvenation and increased endometrial thickness. PRP is being explored as a treatment for recurrent implantation failure, primary ovarian insufficiency and poor ovarian response. While the influence of PRP on endometrial thickness and implantation success is postulated, its effectiveness remains the subject of debate due to protocol variability and unclear patient selection criteria. This narrative review includes 36 articles published before December 2022, and highlights the lack of comprehensive molecular studies examining the impact of PRP on reproductive capacity. This review underscores the importance of standardizing PRP preparation protocols in reproductive medicine. However, challenges persist, and there is a need for well-planned randomized controlled trials and a deeper understanding of the patient population that would gain the greatest benefit from PRP treatment. Clarifying these aspects is crucial to improve outcomes for low-prognosis patients undergoing assisted reproductive technology.

Intraovarian Platelet-Rich Plasma Injections: Safety and Thoughts on Efficacy Based on a Single Centre Experience With 469 Women

BACKGROUND

Ovarian rejuvenation is an innovative procedure intended to restore ovarian fertility and development during the climacteric and has been used to enhance fertility in women with premature ovarian insufficiency (POI). This retrospective study was conducted to determine the effects of an intraovarian platelet-rich plasma (PRP) injection on ovarian stimulation outcomes in women referred to an in vitro fertilisation centre. Methods-Population: This was a retrospective observational study, and the inclusion criteria included women of reproductive age with at least one ovary with a history of infertility, hormonal abnormalities, an absence of a menstrual cycle, and premature ovarian failure. During the patient's first consultation, a detailed reproductive history was recorded, a pelvic scan for ovarian size was conducted, and hormonal analysis for follicle-stimulating hormone (FSH), anti-Müllerian hormone (AMH), estradiol (E2), and luteinizing hormone (LH) was conducted.

RESULTS

In the study, 469 women with a history of infertility, hormonal abnormalities, an absence of a menstrual cycle, and premature ovarian failure had hormonal levels recorded up to four months after treatment, and these were included in the study. The volume of peripheral blood required to prepare 6-8 mL of PRP for administration was 40-60 mL. The initial concentration of platelets in the peripheral blood sample was about 25000/µL, whereas the prepared PRP had a concentration of 900.000/µL. A volume of approximately 2-4 mL per ovary, depending on the ovarian volume, was used for the intraovarian injection. PRP intervention had significant effects on FSH concentration at the α = 0.05 level. Statistically significant increases in normal values of FSH and E2were observed for months three and four after the PRP intervention for all age groups.

CONCLUSIONS

The results of our observational study revealed that a PRP intraovarian injection is associated with improved ovarian tissue and function. Future randomised clinical trials are needed to shed light on the use of PRP in ovarian rejuvenation before offering it routinely in clinical practice.

[The use of platelet-rich plasma in the treatment of cicatricial stenosis of the larynx and cervical trachea]

Despite the technical achievements of recent years in medicine, the problem of frequent recurrent stricture formation of the lumen of larynx and cervical trachea remains urgent. The etiology and pathogenesis of development of scar stenosis of the larynx and trachea were considered, and the analysis of the drugs' use for topical therapy in the comprehensive treatment of this pathology was conducted in the presented review. Special attention was paid to plasma enriched with platelets, its use in otorhinolaryngology, in particular in the treatment of laryngeal diseases. Positive and negative sides of the adjuvant therapy use have been identified. The search for means helping to prevent recurrent stricture formation of laryngeal lumen and cervical trachea determines the interest of the considered problem.

The effect of protection of platelet-rich plasma against experimental ischemia/reperfusion injury in the rat ovary on in vitro fertilization outcomes

OBJECTIVE

Ovarian torsion is a common cause of local ischemic damage, reduced follicular activity and infertility. This study aimed to investigate how well platelet-rich plasma (PRP) protects against experimental ischemic (I) and ischemia-reperfusion (I/R) injury in rat ovaries and its effect on in vitro fertilization (IVF) outcomes.

METHOD

Fifty-six adult female Sprague-Dawley albino rats were randomly assigned to six groups of eight animals each: Sham, Ischemia, I/R, Sham + PRP, I + PRP, and I/R + PRP. The remaining eight animals were used to prepare the PRP. The ischemia groups were subjected to bilateral adnexal torsion for 3 h, while the I/R and I/R + PRP groups received subsequent detorsion for 3 h. Intraperitoneal (i.p.) PRP was administered 30 min prior to ischemia (I + PRP) or reperfusion (I/R + PRP). The ovaries were stimulated through an intraperitoneal injection of 150-300 internal units of IU/kg PMSG. After ovulation induction, oocytes were taken from the ovaries, and IVF was performed.

RESULTS

The number of MII oocytes reached the highest number with 4.63 ± 0.74 in the S group and had the lowest number with 0.50 ± 0.53 in the I/R group. There were statistically significant differences for the number of embryos obtained on the second day between the I and I + PRP groups and the I/R and I/R + PRP groups (p = 0.000). In comparing anti-Müllerian hormone 1 (AMH1) and AMH2 values within the group, the highest decrease was observed in the I and I/R groups.

CONCLUSION

PRP is effective in minimizing ovarian damage and preserving ovarian reserves following ovarian torsion.

Protective Effects of Platelet-rich plasma for in vitro Fertilization of Rats with Ovarian Failure Induced by Cyclophosphamide

OBJECTIVE

 Premature ovarian insufficiency (POI) contributes significantly to female infertility. Cyclophosphamide (CYC has adverse effects on folliculogenesis. Platelet-rich plasma (PRP) is an autologous product rich in many growth factors. We evaluated the protective effect of PRP on in vitro fertilization in female rats with CYC-induced ovarian damage.

METHODS

 Twenty-eight adult female Sprague-Dawley rats were randomly divided into four groups. Group 1 (control-sodium chloride 0.9%; 1 mL/kg, single-dose intraperitoneal [IP] injection); group 2 (CYC), 75 mg/kg, single-dose IP injection and sodium chloride 0.9% (1 mL/kg, single-dose IP injection); group 3 CYC plus PRP, CYC (75 mg/kg, single-dose and PRP (200 μl, single-dose) IP injection); and group 4 (PRP, 200 μl, single-dose IP injection).

RESULTS

 In the comparisons in terms of M1 and M2 oocytes, it was observed that the CYC group presented a significantly lower amount than the control, CYC/PRP, and PRP groups. (for M1, p = 0.000, p = 0.029, p = 0.025; for M2, p = 0.009, p = 0.004, p = 0.000, respectively). The number of fertilized oocytes and two-celled good quality embryos was found to be statistically significant between the CYC and control groups, CYC + PRP and PRP groups (p = 0.009, p = 0.001, p = 0.000 for oocytes, respectively. For embryos; p = 0.016, p = 0.002, p = 0.000).

CONCLUSION

 Platelet-rich plasma can protect the ovarian function against damage caused by CYC, and, in addition, it improves oocyte count and the development of embryos as a result of oocyte stimulation during the IVF procedure.

Use of platelet-rich plasma in the treatment of infertility in poor responders in assisted human reproduction procedures

Couple infertility is a pathology with an absolute number of cases growing markedly over the last decade in connection mainly with the increased age of couples wishing to conceive. Platelet-rich plasma (PRP) is an alternative treatment used for several years for experimental purposes. Yet, this method is not yet defined as a standard therapeutic option in the infertility protocol for poor responders in assisted human reproduction procedures. Thus, the present study is a retrospective study conducted between February 2019 and February 2020 to evaluate the effect of ovarian PRP injection in patients with a poor ovarian response (POR) to ovarian stimulation. Women (n=20; age 31-44 years) diagnosed with POR based on the European Society of Human Reproduction and Embryology criteria underwent ovarian injection with autologous PRP injection. Markers of ovarian reserve before, during the following two menstrual cycles, and at six months after treatment were followed as well as stimulation and fertilisation parameters before and post-treatment. PRP treatment resulted in increased antral follicle count and serum anti-Mullerian hormone, while levels of serum follicle-stimulating hormone and luteinising hormone were decreased. These changes were more pronounced during the 2nd menstrual cycle following treatment. By six months following the injection, their values return to pre-treatment levels and any small differences were not considered statistically significant. The average dose of gonadotropin used and duration remained statistically unchanged, but a significant increase in estradiol achieved by the day of the human chorionic gonadotropin trigger day was achieved. The cancellation rate decreased following PRP treatment while the number of collected oocytes, number of oocytes in metaphase II rose. The number of embryos (of A and B quality) resulting also increased but fell short of the significance level set (α=0.073). Following the PRP injection, two singleton pregnancies were achieved, resulting in live births at term without complications during pregnancy. Another pregnancy was achieved spontaneously 45 months following the PRP and a failed assisted human reproduction procedure. Although the group included a small number of women, the results indicate the potential benefits of an ovarian autologous PRP injection in women with POR. Positive results appear to be short-term for 2-6 months after the procedure.

Platelet activation and antimicrobial activity of L-PRF: a preliminary study

Leukocyte and platelet rich fibrin (L-PRF) is one of the platelet concentrates used to support regeneration and healing process. Many studies showed possible immunological and antibacterial properties of L-PRF. We perform an in vitro study to analyze the effect of L-PRF on platelet activation, platelet-leukocytes interactions and antimicrobial activity, important components in the healing process. Molecular biomarkers related with platelet activation and platelet-leukocyte interactions were analyzed by means of flow cytometry when L-PRF exudate was added to whole blood platelets. L-PRF membrane was used to evaluate antimicrobial activity using Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853) and Candida albicans (ATCC 90028). Our experimental design allows to evaluate platelet activation and analyze molecular biomarkers of other immune cells and platelet-leukocyte interactions. From the results obtained we can conclude that L-PRF can be a valuable tool in healing process, efficient in activating platelets of whole blood and inhibiting microbial growth. In our opinion, the use of L-PRF exudate, in addition to L-PRF membrane, presents some advantages that have to be considered in clinical trials. Additional research on the characterization and quantification of cells and its products present in the L-PRF exudate, as well as on the temporal factor released. Also, further studies using strains isolated from clinical cases are needed.

The Effects of Adipose Derived Stromal Vascular Fraction and Platelet-Rich Plasma on Bone Healing of a Rat Model With Chronic Kidney Disease

BACKGROUND

Chronic kidney disease (CKD) impairs osteoblast/osteoclast balance and damages bone structure with diminished mineralization and results in bone restoration disorders. In this study, we investigate the effects of adipose-derived stromal vascular fraction and platelet-rich plasma (PRP) on bone healing model in rats with CKD.

METHODS

Sprague-Dawley rats were separated into 4 groups. All groups except group I (healthy control) had CKD surgery using 5/6 nephrectomy model. All groups had intramedullary pin fixation after receiving bone fracture using drilling tools. Group II rats were used as control group for CKD. Group III rats received PRP treatment on fracture site. Group IV rats received PRP and stromal vascular fraction treatment on fracture site.Weight loss and blood samples were followed at the time of kidney surgery, third, sixth, and 12th weeks. Bone healing and callus formations were compared, biomechanically, radiologically, histopathologically, and immunohistochemically. Osteoblastic transformation of stem cells was assessed with DiI staining.

RESULTS

Negative effects of CKD on bone healing were reduced by increasing mechanical, histological, radiological, and biochemical properties of the bone with stromal vascular fraction and PRP treatments. Although thickness of callus tissue delayed bone healing process, it also enhanced biomechanical features and bone tissue organization.

CONCLUSIONS

Platelet-rich plasma and adipose-derived stromal vascular fraction treatments were effective for bone healing in animal model, which can be promising for clinical trials.

Assessment of Quality of Platelet-Rich Plasma Produced With Desktop Centrifuge and Comparison With Standardized Commercially Available Platelet-rich plasma

Aims:

The aim of this study was to assess the quality of platelet-rich plasma (PRP) produced by in-house desktop centrifuge method and compare it with that of standardized commercial PRP.

Materials and Methods:

REMI desktop centrifuge was used to prepare PRP and to compare with standardized commercial PRP by calculating the quantity of platelets using Beckman Coulter cell counter in 10 PRP samples and assessing the morphological quality of platelets using JEOL JEM transmission electron microscope (TEM).

Statistical Analysis Used:

The t test for platelet count in desktop PRP with the test value of therapeutic PRP was 12.618. The P value was <0.001, which was significant statistically. The data followed a normal distribution in normal Q-Q plot for platelet count in desktop centrifuge. So the test samples were not much deviated.

Results:

The platelet count was lesser than that of standardized commercial PRP. When viewed under JEOL JEM transmission electron microscope, the α granules in platelets were intact and the morphological quality of the PRP was good.

Conclusions:

With this study, we have determined that the morphological quality of PRP produced by the in-house desktop centrifuge method is comparable to that of standardized commercial PRP. Though the quantity of platelets was less than 1 million cells/μL, the clinical results were good with desired bone formation, thereby providing good avenue for further research.

Reactivating Ovarian Function through Autologous Platelet-Rich Plasma Intraovarian Infusion: Pilot Data on Premature Ovarian Insufficiency, Perimenopausal, Menopausal, and Poor Responder Women

Intraovarian platelet-rich plasma (PRP) infusion was recently introduced in the context of addressing ovarian insufficiency. Reporting on its effectiveness prior to adopting in clinical routine practice is imperative. This study aims to provide pilot data regarding PRP application for ovarian rejuvenation. Four pilot studies were conducted on poor ovarian response (POR), premature ovarian insufficiency (POI), perimenopause, and menopause, respectively. Each pilot study reports on thirty patients, 120 participants were recruited in total. All participants provided written informed consent prior to treatment. Primary outcome measures for the POR pilot study were levels of anti-müllerian hormone (AMH), antral follicle count (AFC) and oocyte yield. For the POI, perimenopausal and menopausal pilot studies primary outcome measures were restoration of menstrual cycle, and Follicle Stimulating Hormone (FSH) levels. A significant improvement on the hormonal profile and the ovarian reserve status was noted, along with improved intracytoplasmic sperm injection (ICSI) cycle performance concerning POR participants. Menstruation recovery was observed in 18 out of 30 POI patients, along with a statistically significant improvement on levels of AMH, FSH, and AFC. Similarly, 13 out of 30 menopausal women positively responded to PRP treatment. Finally, menstruation regularity, improved hormonal levels and AFC were reported for 24 out of 30 perimenopausal women. To conclude, PRP infusion appears to convey promising results in addressing ovarian insufficiency.

Live Birth Rates in Poor Responders' Group after Previous Treatment with Autologous Platelet-Rich Plasma and Low Dose Ovarian Stimulation Compared with Poor Responders Used Only Low Dose Ovarian Stimulation Before in Vitro Fertilization

BACKGROUND:

This prospective pilot study determined the efficacy of previous transvaginal intraovarian injection with autologous platelet-rich plasma (PRP) in poor ovarian responders (PORs) fulfilling the Bologna criteria before in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) with low dose ovarian stimulation. Current knowledge of efficient treatment for PORs is limited and often contradictory; also, LBRs of IVF remains disappointingly low.

AIM:

We assessed the live birth rates (LBRs) in PORs after previous ovarian treatment with PRP.

METHODS:

Overall, 40 patients undergoing IVF/ICSI between June 2017 ending December 2018 were included. A transvaginal intraovarian injection of PRP was performed on 20 patients. Both compered groups were balanced for all basic characteristics, and multivariate analysis was performed to adjust for all known confounders.

RESULTS:

Between the groups, a statistical significance in clinical pregnancies and LBR was not found. Clinical pregnancy and live birth rates were 33.33 ± 44.99 and 40.00 ± 50.71 in the PRP group and 10.71 ± 28.95 and 14.29 ± 36.31 in control group retrospectively. However, there is a trend towards higher implantation rates and LBRs in patients with previous treatment with PRP. Anyhow, the number of patients used in the research is insufficient to make a concrete conclusion, and more studies are needed in the future to confirm these results entirely.

CONCLUSION:

Even though the treatment of POR responders remains as a therapeutical challenge, the usage of intraovarian injection of autologous PRP in PORs before the IVF performance brings a glimpse of new hope in increasing the success of IVF defined by clinical pregnancy and LBRs.

A Case Series on Natural Conceptions Resulting in Ongoing Pregnancies in Menopausal and Prematurely Menopausal Women Following Platelet-Rich Plasma Treatment

Since the introduction of autologous platelet-rich plasma (PRP) in medical practice, various studies have documented that implementing PRP can enhance healing and the anti-aging process, employing angiogenesis regeneration due to the multiple growth factors and cytokines involved. Numerous reports have shown promising results with the use of PRP in ovarian treatment, regarding ovarian regeneration and reactivation of folliculogenesis. This case series reports on two women with premature ovarian failure (POF) aged 40 and 27 years, respectively, and one menopausal woman aged 46 years. All patients presented with lack of menstrual cycle for over a year. The women reported previous failed in vitro fertilization (IVF) attempts, and, after rejecting the option of oocyte donation, they opted for the approach of autologous ovarian PRP treatment. Following PRP treatment, the three patients were invited to conceive naturally. The primary outcome was the restoration of menstruation following autologous ovarian PRP treatment, as well as an improvement in hormonal profile, a decrease in follicle-stimulating hormone (FSH) levels, and a concurrent increase in anti-Müllerian hormone (AMH) levels. Further to that, our patients achieved pregnancy through natural conception within 2-6 months following PRP treatment, resulting in currently ongoing complication-free clinical pregnancies - a first report in the literature for menopausal and POF patients. Implementation of PRP should be further investigated through randomized controlled trials (RCTs), as it may hold the key to successful treatment for a certain cohort of patients exploring reproductive treatment options following menopause.

Platelet-rich plasma, a powerful tool in dermatology

Platelet-rich plasma (PRP), a platelet concentrate contained in a small volume of plasma, has become a promising option in the last decade to treat different diseases related to the skin due to its high concentration of growth factors. When it is of autologous origin, it decreases the probability of suffering adverse reactions and transfusion-transmitted infections, thus it is an optimal and safe therapy for the patient. PRP has been used in the treatment of several dermatological conditions such as acne, alopecia, and skin ulcers. Its use has also extended to other skin conditions such as melasma, hyperpigmentation, and burns, where it stimulates tissue repair and regeneration. The purpose of this article is to review the management and treatment of different dermatological alterations with PRP. Although there are a variety of studies that support the use of PRP, more research is needed to standardise the protocols for obtaining, processing, and applying it as well as understanding the biological and molecular bases of its functioning.

Extracorporeal Shockwave Therapy Increases Growth Factor Release from Equine Platelet-Rich Plasma In Vitro

Introduction

Extracorporeal shockwave therapy (ESWT) and platelet-rich plasma (PRP) are common treatments for soft tissue injuries in horses. Shockwave triggers cell specific responses to promote healing. Growth factors released from PRP also promote healing. It has been hypothesized that greater growth factor release would amplify the healing process. The combination of ESWT and PRP could promote healing in injured tendons and ligaments in the horse. The objective of this study was to determine if application of shockwaves to PRP samples increases the concentration of transforming growth factor-β₁ (TGF-β₁) and platelet-derived growth factor ββ (PDGF-ββ) released from the platelets in vitro.

Materials and methods

PRP was produced from blood drawn from six horses. The PRP from each horse was exposed to the following treatments: (1) positive control (freeze-thaw cycle), (2) untreated negative control, or shockwaves with either (3) a "standard probe" (ESWT-S) with a 2 cm focal width and medium energy density or (4) a "power probe" (ESWT-P) with a 1 cm focal width and high energy density. After each treatment, the samples were centrifuged, and the supernatant was harvested. The supernatant was then used for growth factor quantification via commercially available ELISA kits for TGF-β₁ and PDGF-ββ.

Results

Concentrations of TGF-β₁ and PDGF-ββ in PRP that underwent a freeze-thaw cycle were significantly increased compared with all other treatments. Both ESWT-S and ESWT-P resulted in significantly increased TGF-β₁ concentrations, 46 and 33%, respectively, when compared with the negative control. Both ESWT-S and ESWT-P resulted in significantly increased PDGF-ββ concentrations, 219 and 190%, respectively, when compared with the negative control.

Discussion

These data indicate that the application of ESWT to PRP increases the expression of growth factors in vitro. This suggests that the combination therapy of local PRP injection followed by ESWT may stimulate release of growth factors from platelets after they have been injected into the area of injury.

Conclusion

The combination of PRP and ESWT might result in synergism of two modalities previously utilized individually for tendon and ligament injuries in horses.

Platelet-rich plasma and hyaluronic acid - an efficient biostimulation method for face rejuvenation

BACKGROUND

Cosmetic applications of platelet-rich plasma (PRP) are new, and reports are scarce and dispersed in the literature. There are a variety of commercially available kits and injection techniques, and the number and intervals of injections vary. New investigations should focus on developing a standardized procedure for PRP preparation and application methods to augment its efficacy and potency.

OBJECTIVES

In this report, we aim to provide data and commentary to assist and add to current guidelines.

METHODS

A series of 94 female patients with varying degrees of facial aging signs were treated with PRP and hyaluronic acid (HA). Mean age was 53.0 ± 5.6. The mean injection number was 3.6 ± 2.0. Platelet-poor and platelet- rich plasma parts were mixed with 0.5 cc %3.5 hyaluronic acid and 0.5 cc procaine and injected with a 30G, 13-mm needle into deep dermis and hypodermis. Patients were asked to rate their personal satisfaction with their skin texture, pigmentation, and sagging. In addition, the overall results were rated by three independent physicians and the patients themselves. The outcomes were peer-reviewed, and correlations between the degree of the aesthetic scores and the number of injections were explored.

RESULTS

There was a statistically significant difference in general appearance, skin firmness-sagging and skin texture according to the patients' before and after applications of PRP. A statistically significant correlation was found between the number of injections and overall satisfaction.

CONCLUSIONS

Compared to the baseline, the PRP and HA injections provided clinically visible and statistically significant improvement on facial skin. The improvements were more remarkable as the injection numbers increased.

Evaluation of bone regenerative capacity in rats claverial bone defect using platelet rich fibrin with and without beta tri calcium phosphate bone graft material

Aim

To compare bone regeneration in noncritical rat calvarial bone defects filled with platelet-rich fibrin (PRF), alone or combined with beta-tricalcium phosphate (β-TCP), using micro-computed tomographic (MCT) evaluation.

Animals and methods

Two calvarial bone defects were created in each of 45 male Sprague–Dawley rats (age: 20–22 weeks, weight: 350–450 g), using a dental trephine with an external diameter of 3 mm. The 90 defects were randomly allocated among three groups, each containing 30 unilateral defects in a total of 30 rats. Defects in the control group were allowed to heal spontaneously. Defects in the PRF group received PRF alone. Defects in the PRF/β-TCP group received PRF mixed with β-TCP in a 50⧹50 percentage. Nine animals (three per group) were killed after 1, 2, 3, 4, and 6 postoperative weeks, and 18 calvarial defects from each period were analyzed for new bone formation and bone mineral density using MCT. Results were compared by a one-way Analysis of Variance with the POST HOC Least Significant Difference test.

Results

The volume and mineral density of bone formed in the control group were significantly different from those of the other two groups. Greater bone regeneration was observed in defects receiving PRF with β-TCP compared to defects receiving PRF alone in the first 2 weeks (P < 0.001). However, differences in the volume and density of newly formed bone between the PRF and PRF/β-TCP groups were not significant at 3, 4, and 6 postoperative weeks (P > 0.005).

Conclusion

The addition of β-TCP to PRF significantly improved bone regeneration in the first 2 weeks after surgery. Although the differences between results with and without the addition of β-TCP to PRF were statistically insignificant from weeks 3 to 6, it was nevertheless apparent that the group receiving the combination showed better results. We suggest a synergistic mechanism for this effect.

Mandibular Class II Furcation Defect Treatment: Effects of the Addition of Platelet Concentrates to Open Flap: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

BACKGROUND

To improve the efficacy and outcomes of regenerative therapy for furcation defects, the use of platelet concentrates (PCs) in addition to open flap debridement (OFD) has been investigated. The aim of this systematic review is to evaluate whether mandibular Class II furcation defects treated with the addition of PC to OFD heal with a significant improvement in the following: 1) horizontal clinical attachment level (HCAL); 2) vertical clinical attachment level (VCAL); 3) probing depth (PD); and 4) level of gingival margin (LGM).

METHODS

Electronic databases (MEDLINE, EBSCO Library, Cochrane Database of Systematic Reviews, and SCOPUS) were searched for randomized clinical trials to address the use of PCs in combination with OFD compared with a control group without PCs for the treatment of mandibular Class II furcation defects in humans and to provide data on the above reported outcome measures. The results of selected studies were converted to mean difference and standard error and interpolated using the inverse of variance test. Heterogeneity was investigated using both the Higgins index and the Q test.

RESULTS

Of 254 articles screened, only 11 were read in full text, and three of these were included in the meta-analysis. The addition of PCs to OFD revealed a small improvement in the following: 1) HCAL (mean difference, 1.36 mm; 95% confidence interval [CI] = 1.07 to 1.65); 2) VCAL (mean difference, 1.54 mm; 95% CI = 1.23 to 1.85); and 3) PD (mean difference, 1.83 mm; 95% CI = 1.36 to 2.29). No differences were found for the LGM. Heterogeneity across the studies was high, and all the three included studies were performed in one country.

CONCLUSIONS

Adding PCs to OFD for the treatment of mandibular Class II furcation defects may lead to slight improvements in clinical parameters. Nonetheless, because of the high heterogeneity of the very small number of reported studies and the small effect size, no definitive conclusion can be achieved about the clinical application of such a treatment option.

Platelet-Rich Fibrin Improves the Viability of Diced Cartilage Grafts in a Rabbit Model

BACKGROUND

Diced cartilage may be wrapped with synthetic or biological materials before grafting to a recipient site. These materials have unique advantages and disadvantages, and a gold standard is not available.

OBJECTIVES

The authors investigated the effects of platelet-rich fibrin (PRF) on the survival of cartilage grafts in a rabbit model.

METHODS

In this experimental study, diced cartilage pieces from the ears of 9 male rabbits were left unwrapped or were wrapped with PRF, oxidized regenerated cellulose, or fascia. Specimens then were placed into subcutaneous pockets prepared on the backs of the rabbits. The animals were sacrificed 2 months after the procedure, and the grafts were excised for macroscopic and histopathologic examination.

RESULTS

The cartilage graft wrapped with PRF showed superior viability compared with the cartilage graft wrapped with oxidized regenerated cellulose. No significant differences were found among the other groups. The groups were not significantly different in terms of rates of inflammation, fibrosis, or vascularization.

CONCLUSIONS

PRF enhances the viability of diced cartilage grafts and should be considered an appropriate biological wrapping material for cartilage grafting.

Surgical management of bisphosphonate-related osteonecrosis of the jaws: literature review

PURPOSE

Surgical management of bisphosphonate-related osteonecrosis of the jaws (BRONJ) has been performed in an attempt to increase healing rates of the affected cases. This literature review aimed to identify clinical studies of surgical management of bisphosphonate-related osteonecrosis of the jaws (BRONJ) in order to assess their surgical treatment modalities, outcome and the follow-up.

METHODS

A search in the PubMed (Medline) database using specific terms and/or phrases as "bisphosphonate-related osteonecrosis" or "jaw osteonecrosis", and "surgical treatment" or "surgical management" was conducted in order to identify clinical trials and cases of surgical treatment of BRONJ. The review search covered the time period from 2004 to 2014. All studies identified in the search were selected according to the inclusion criteria. Relevant information was recorded according to the following items: author, year, number of patients, BRONJ clinical stage, surgical treatment modality, clinical success, and follow-up.

RESULTS

The initial database search yielded 345 titles. After filtering, 67 abstracts were selected culminating in 67 full text articles. A variety of surgical approach was found in this review: debridement, sequestrectomy bone resection, and bone reconstruction. Adjunctive therapies included hyperbaric oxygen, laser therapy, growth factors, and ozone.

CONCLUSION

Although there are many indexed studies about BRONJ, well-documented reports concerning surgical therapeutically techniques are scarce, resulting from a lack of well-established protocols. Considerable differences were found regarding sample size, surgical treatment modalities and outcomes. Clinical studies with larger number of patients and longer follow-up are required to provide best information for each surgical treatment modality and its outcomes.

Clinical and radiographic evaluation of the efficacy of platelet-rich plasma combined with hydroxyapatite bone graft substitutes in the treatment of intra-bony defects in maxillofacial region

OBJECTIVE

The aim of this study is to evaluate the efficacy of platelet-rich plasma (PRP) clinically and radiographically when combined with bovine derived hydroxyapatite (HA) bone grafting materials and resorbable collagen membranes for the treatment of intra-bony defects frequently seen at the distal aspect of mandibular second molars following the surgical extraction of fully impacted mandibular wisdom teeth.

STUDY DESIGN

Eighteen patients were scheduled for post-operative visits at 1, 3 and 6 months post-operatively, probing depths were measured and digital panoramic radiographs were taken.

RESULTS

There were no significant differences on probing depths among two groups. Radiographic assessment also showed no significant difference among groups at 1st and 6th month intervals, while 3 months post-operatively the amount of radiographic density at the PRP side was significantly higher.

CONCLUSION

Combined use of PRP and bovine-derived HA graft materials for the treatment of intra-bony defects might be an appropriate approach when the main goal is providing earlier bone regeneration.

Platelet-Rich Plasma in Treatment of Zoledronic Acid-Induced Bisphosphonate-related Osteonecrosis of the Jaws

Background:

Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is a well-known challenging entity warranting management. Platelet-Rich Plasma (PRP) plays an important role in bone biology by enhancing bone repair and regeneration.

Objectives:

The aim of this animal study was to evaluate the effects of PRP on zoledronic acid-induced BRONJ.

Materials and Methods:

Seven rats were given 0.04 mg Zoledronic acid intravenously once a week for five weeks. Two weeks later, the animals underwent extraction of their first lower molars, bilaterally. After clinical confirmation of the osteonecrosis, PRP was injected randomly into one of the extraction sockets of each rat. Three weeks later, all rats were sacrificed in order to obtain histological sections. The analysis of epithelialization was performed by McNamar’s test, and the analysis of osteogenesis and angiogenesis was performed by the Wilcoxon Sign Rank test. P value was set at 0.05.

Results:

We found no significant differences between the two groups regarding the amount of epithelialization, angiogenesis or sequestrum formation (P > 0.05), but a significant difference was seen between the two groups regarding the amount of existing vital bone (P < 0.05).

Conclusions:

Our study demonstrates positive results (preservation or regeneration of bone) using PRP in treatment of BRONJ. Although PRP may enhance osseous regeneration, long-term follow-ups are required to confirm its benefits.

Construction of functional tissue-engineered bone using cell sheet technology in a canine model

The aim of the present study was to construct functional tissue-engineered bone with cell sheet technology and compare the efficacy of this method with that of traditional bone tissue engineering techniques. Canine bone mesenchymal stem cells (BMSCs) were isolated using density gradient centrifugation and then cultured. The BMSCs were induced to differentiate into osteoblasts and cultured in temperature-responsive culture dishes. The BMSCs detached automatically from the temperature-responsive culture dishes when the temperature was reduced to 20°C, forming an intact cell sheet. Demineralized bone matrix (DBM) and platelet-rich plasma (PRP) were prepared and used to construct a DBM/PRP/BMSC cell sheet/BMSC complex, which was implanted under the left latissimus dorsi muscle in a dog model. A DBM/PRP/BMSC complex was used as a control and implanted under the right latissimus dorsi muscle in the dog model. Immunoblot assays were performed to detect the levels of growth factors. Osteogenesis was observed to be induced significantly more effectively in the DBM/PRP/BMSC cell sheet/BMSC implants than in the DBM/PRP/BMSC implants. Immunoblot assay results indicated that the levels of the growth factors platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) in the experimental group were 3.2- and 2.5-fold higher compared with those in the control group, respectively. These results indicated that the BMSC cell sheets were functional and more effective than the control cell complex. Therefore, cell sheet technology may be used for the effective construction of functional tissue-engineered bone with ideal properties.

Bone tissue engineering with bone marrow-derived stromal cells integrated with concentrated growth factor in Rattus norvegicus calvaria defect model

Concentrated growth factor (CGF) is an autologous leukocyte-rich and platelet-rich fibrin (L-PRF) biomaterial termed "second-generation platelet concentrate". CGF contains autologous osteoinductive platelet growth factors and an osteoconductive fibrin matrix. The purpose of this study was to assess the ability of CGF combined with bone marrow stromal cells (BMSCs) to heal critical-size rat calvaria defects in vivo and to modulate the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro. In the in-vivo study, the CGF group regenerated bone better than the control group, and combined therapy with CGF and BMSCs almost completely repaired critical-size bone defects within 12 weeks after surgery. In the in-vitro study, the CGF extract, at concentrations between 1 and 10%, promoted proliferation, osteogenic maturation, and mineralization of hTERT-E6/E7 human MSCs in a dose-dependent manner but had an inhibitory effect at higher concentrations. In conclusion, a CGF extract promoted the proliferation, osteogenic maturation, and mineralization of mesenchymal stem cells in vitro, and combination therapy with CGF and BMSCs resulted in excellent healing of critical-size bone defects in vivo.

Properties of osteoconductive biomaterials: calcium phosphate cement with different ratios of platelet-rich plasma as identifiers

This study aims to evaluate further the performance of a platelet-rich plasma (PRP) additive incorporated with calcium phosphate bone cement (CPC) in vitro to prove its efficiency as bone graft substitutes and its compatibility to be incorporated into the CPC with other techniques in clinical restoration in vivo. The growth factor release ability and the osteogenic evaluation of PRP, CPC, and PRP/CPC testing groups with 5, 10, and 15 wt.% PRP were compared in vitro. Four groups were measured using non-decalcified staining methods in vivo, which include the testing group of 10 wt.% PRP/CPC selected from the evaluation in vitro, by using both the autograft with rabbit trabecular and CPC-only as comparison groups and the group without grafting material as the control sample. The results obtained through specimen immersion show that growth factor release and alkaline phosphatase activities after osteoprogenitor cell culture had a significantly better effect on 10 and 15 wt.% PRP/CPC than on the other groups in vitro. Analysis results suggest that PRP was still retained in the CPC matrix even after 32 days of immersion. The results in vivo show that the histology of the autograft bone and the control group without grafting material exhibited fibrous connective and adipose tissues, which obviously filled the created cavity even at nine weeks after the operation. Osteoregeneration was more successful in the PRP-additive group, which accumulated bone remodeling than in the other groups. In conclusion, CPC could be a potential carrier with adequate PRP additives that bear a therapeutic potential for enhanced bone tissue regeneration.

Effect of plasma-rich in platelet-derived growth factors on peri-implant bone healing: An experimental study in canines

BACKGROUND

Tissue engineering principles can be exploited to enhance alveolar and peri-implant bone reconstruction by applying such biological factors as platelet-derived growth factors. The objective of the present study is to investigate the effect of autologous plasma-rich in growth factors (on the healing of peri-implant bone in canine mandible).

MATERIALS AND METHODS

In this prospective experimental animal study, two healthy canines of the Iranian mix breed were selected. Three months after removing their premolar teeth on both sides of the mandible, 12 implants of the Osteo Implant Corporationsystem, 5 mm in diameter and 10 mm in length, were selected to be implanted. Plasma rich in growth factors (PRGF) were applied on six implants while the other six were used as plain implants without the plasma. The implants were installed in osteotomy sites on both sides of the mandible to be removed after 4 weeks with the surrounding bones using a trephine bur. Mesio-distal sections and implant blocks, 50 μ in diameter containing the peri-implant bone, were prepared By basic fuchin toluidine-bluefor histological and histomorphometric evaluation by optical microscope. The data were analyzed using Mann-Whitney Test (P<0.05).

RESULTS

The bone trabeculae and the type of bone generation in PRGF and control groups had no statistically significant differences (P=0.261, P=0.2) although the parameters showed higher measured values in the PRGF group. However, compared to the control, application of PRGF had significantly increased bone-to-implant contact (P=0.028)

CONCLUSION

Based on the results, it may be concluded that application of PRGF on the surface of implant may enhance bone-to-implant contact.

Role of platelet-rich plasma in combination with alloplastic bone substitute in regeneration of osseous defects

INTRODUCTION

Bone grafts are frequently used for the treatment of bone defects, but can cause postoperative complications, and sometimes a sufficient quantity of bone is not available. Hence, synthetic biomaterials have been used as an alternative to autogenous bone grafts. Recent clinical reports suggest that application of autologous blood plasma enriched with platelets can enhance the formation of new bone. There are very few in vitro or in vivo studies published on the efficiency of platelet-rich plasma (PRP). The objective of this study was to evaluate the alloplastic bone substitute for its osteogenic potential with or without PRP.

MATERIALS AND METHODS

Twenty-three patients with periapical bony defects were selected for this study. Clinical parameters such as pain visual analog scale (VAS), swelling, infection, graft migration, rejection, radiographical interpretations at regular interval and scintigraphic evaluation were done to evaluate osteogenic potential of alloplastic bone substitute with or without PRP.

RESULTS

The highest acceleration in bone formation was observed in groups where alloplastic bone substitute was used with PRP. There were no statistically significant differences between the two groups regarding other outcome variables throughout the postoperative period.

CONCLUSION

Addition of PRP significantly accelerates vascularization of the graft, improves soft tissue healing, reduces postoperative morbidity and enhances bone regeneration.

Bisphosphonate-related osteonecrosis of the jaws--an initial case series report of treatment combining partial bone resection and autologous platelet-rich plasma

PURPOSE

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a well-recognized pathologic entity that is challenging and difficult to manage. Recent literature contains several articles, with most recommending conservative management. This report describes a treatment modality for advanced cases of BRONJ that involves bone resection and autologous platelet-rich plasma (PRP).

PATIENTS AND METHODS

This case series consisted of 25 patients with BRONJ lesions and a history of intravenous bisphosphonate therapy for metastatic bone diseases that did not respond to conservative treatment. All patients were surgically managed by a standardized protocol combining bone resection and PRP.

RESULTS

Of the 25 patients, 20 (80%) showed complete wound healing during follow-up. Median follow-up was 36 months. Microscopic examination showed actinomyces in 15 specimens.

CONCLUSION

BRONJ has been shown to be refractory to conservative management. Treatment of refractory BRONJ with a combination of bone resection and PRP was found to be an effective therapy in most patients and should be considered an alternative treatment modality for management of advanced cases.

Effects of Choukroun's platelet-rich fibrin on bone regeneration in combination with deproteinized bovine bone mineral in maxillary sinus augmentation: a histological and histomorphometric study

PURPOSE

The potential effect of Choukroun's platelet-rich fibrin (PRF) in combination with allograft on promoting bone regeneration has been discussed in previous publications. This study aims to evaluate an influence of PRF on bone regeneration in sinus augmentation in combination with a xenograft, deproteinised bovine bone.

MATERIALS AND METHODS

Eleven sinuses from 10 patients with posterior maxillary bone atrophy were selected for the study. As a test group, six sinus floor elevations were grafted with a Bio-Oss and PRF mixture, and as control group, five sinuses were treated with Bio-Oss alone. Clinical and radiographic examinations were performed pre- and postoperatively. After 6 months of sinus augmentation, bone biopsies were obtained from the grafted posterior maxilla, and un-decalcified ground sections were prepared. Bone characteristics were evaluated using histological observation and histomorphometric analyses.

RESULTS

No adverse effect was observed in any case within the follow-up period of 6 months after sinus augmentation. Histological observation showed similar morphological characteristics for both the PRF and control groups. The percentage of new bone formation in the PRF group was about 1.4 times of that in control (18.35%±5.62% vs. 12.95%±5.33%), while the percentage of residual bone substitute in the control group was about 1.5 times higher as that in the PRF group (28.54%±12.01% vs. 19.16%±6.89%). The percentage of contact length between newly formed bone and bone substitute in the PRF group was 21.45%±14.57% vs. 18.57%±5.39% in the control. No significant statistical differences between the two groups were found in these observed parameters.

CONCLUSIONS

Our preliminary result demonstrated neither an advantage nor disadvantage of the application of PRF in combination with deproteinised bovine bone mineral in sinus augmentation after a healing period of 6 months.

Periodontal wound healing with and without platelet-rich plasma: histologic observations and assessment of flap tensile strength

BACKGROUND

Platelet-rich plasma (PRP) has been promoted as a surgical adjunct to enhance hard and soft tissue wound healing. Although anecdotally reported to be of value, the results of controlled studies examining the added effects of PRP on surgical procedures have been mixed. The purpose of this study was to test the effect of PRP on flap strength at various post-surgical time points in a minipig animal model.

METHODS

Twelve Yucatan minipigs provided four sites per animal. PRP was prepared from each animal at the time of surgery. Following reflection of a mucoperiosteal flap in each quadrant, subgingival plaque and calculus were removed. Each surgical site was irrigated with sterile saline; prior to suturing, one randomly selected test quadrant in each arch was treated with PRP. Four animals were euthanized at day 14, and two animals were euthanized at 2, 7, 10, and 28 days. The flap strength in each quadrant was tested by attaching to a loop of 3-0 silk suture through the tissue; the force required to separate the flap from the tooth/bone interface was recorded for each site. A separate portion of each flap site was prepared for descriptive histologic examination, including inflammation, hemorrhage, and new bone growth.

RESULTS

Flap strength was significantly less on day 2 compared to later time points, and there were no significant differences between the test and control groups. No histologic differences in healing between test and control sites were seen at any time point.

CONCLUSIONS

PRP did not seem to contribute to greater flap strength at any post-surgical time point, nor was it associated with any histologic differences in wound healing in this Yucatan minipig model. The time points chosen for observation post-surgery, as well as the variability in the PRP platelet count, may have contributed to the lack of positive findings in this study.

The use of plasma rich in growth factors on wound healing in the skin: experimental study in rabbits

The objective of this study was to use autologous plasma rich in growth factors (PRGF) on wound healing in the skin in New Zealand albino rabbits and to study reepithelialisation and inflammation at 7 and 28 days. A prospective study carried out on 20 adult rabbits. Two wounds were made on the in the skin on the back of each animal; one control, and the other in which PRGF was applied. The PRGF preparation was obtained from 10 ml of whole blood. The reepithelialisation and inflammation of wounds were measured at 7 and 28 days. Reepithelialisation improved in skin at 7 days (P = 0.007), with resolution of the inflammatory process (P = 0.005), having significant differences with respect to the control. Therefore, PRGF accelerates reepithelialisation and reduces inflammation at 7 days in skin.

The use of platelet-rich plasma in bone reconstruction therapy

The use of platelet-rich plasma (PRP) in bone reconstruction therapy was introduced in the late 1990s. Since then, many scientists and clinicians have employed it in orthopaedic and oral surgeries. Unfortunately, studies that analyze the use of PRP are somewhat controversial as some conclude that the use of PRP may favor bone regeneration and others conclude that the use of PRP is irrelevant. By listing and analyzing the biological effect that each factor released by the activated platelets can have in bone regeneration, the present review answers the question of why PRP may be useful in bone reconstruction therapy. Subsequently, by examining the studies that have both successfully and unsuccessfully utilized PRP, it suggests how PRP might be used in order to achieve successful results in orthopaedic and dental bone reconstruction surgeries.

Controlled delivery of platelet-rich plasma-derived growth factors for bone formation

Platelet-rich plasma (PRP) represents an autologous source of growth factors essential for bone regeneration. The clinical efficacy of PRP is, however, unpredictable, and this is likely due to the inefficient and inconsistent delivery of PRP-derived growth factors. Previous investigations have shown that current methods of PRP preparation result in a premature release of the relevant bone stimulatory factors. As successful bone regeneration requires multiple factors presented in a physiologic temporal and spatial cascade, the objective of this study is to control the bioavailability of PRP-derived growth factors using a hydrogel carrier system. Specifically, the release of platelet-derived growth factor, transforming growth factor beta-1, and insulin-like growth factor from two types of alginate carriers was compared over time. The effects of the released factors on the growth and alkaline phosphatase (ALP) activity of human osteoblast-like cells were also evaluated. It was found that factor release profiles varied as function of carrier type, and binding of growth factors to the alginate matrix also modulated their release. The bioactivity of released factors was maintained in vitro and they promoted cell proliferation and ALP activity. These results demonstrate the potential of this autologous multifactor delivery system for controlling the bioavailability of PRP-derived factors. Future studies will focus on optimizing this system to increase the clinical efficacy of PRP by matching the distribution and temporal sequencing of PRP-derived factors to the bone healing cascade.

Platelet-rich plasma and connective tissue grafts in the treatment of gingival recessions: a histometric study in dogs

BACKGROUND

The aim of this study was to histometrically evaluate the healing process of gingival recessions treated with platelet-rich plasma (PRP) in combination with a subepithelial connective tissue graft (SCTG) and to compare it to that obtained with SCTG alone.

METHODS

Six mongrel dogs were used in the experiment. Gingival recessions (5 x 7 mm) were surgically created and exposed to plaque accumulation for 1 month. Contralateral defects were randomly assigned to the test group (SCTG + PRP) or the control group (SCTG). Dogs were sacrificed 45 days after the surgeries, and the blocks containing the experimental specimens were processed for histologic analysis. The histometric parameters evaluated were length of sulcular and junctional epithelium, connective tissue adaptation, new cementum, new bone, and defect extension.

RESULTS

A greater length of new cementum was observed in the sites treated with PRP (2.18 +/- 0.78 mm) compared to the control group (1.19 +/- 0.62 mm) (P < or =0.05). No statistically significant differences were observed in the remaining parameters. The extension of total epithelium (sulcular and junctional epithelium) was 2.04 +/- 0.57 mm for the test group and 2.49 +/- 0.82 mm for the control group. The new connective tissue adjacent to the root without cementum formation was 0.29 +/- 0.28 mm and 0.23 +/- 0.18 mm for the test and control groups, respectively. Bone position was -0.57 +/- 0.95 mm for the test group and -0.46 +/- 1.34 mm for the control group.

CONCLUSION

Within the limits of this study, the combination of PRP with SCTG was more effective in promoting new cementum formation than the graft alone.

Effects of platelet rich plasma on colonic anastomosis

PURPOSE

To investigate the effect of platelet-rich plasma (PRP) on tissue maturation and wound healing in experimental colonic anastomosis.

MATERIALS AND METHODS

Thirty Sprague Dawley rats were divided into three groups of 10 rats each. Group I (control group) was subjected to colon anastomosis only. Group II (PRP group) was subjected to colon anastomosis and topical PRP was applied. Group III (Bioglue group) was subjected to colon anastomosis and topical tissue sealant was applied (Bioglue; Cryolife, Kennesaw, GA). The rats were sacrificed on postoperative day 7, and the bursting pressure of the anastomosis and tissue hydroxyproline levels were measured; histopathological changes on the anastomosis line were also examined.

RESULTS

The bursting pressure was statistically higher in the PRP group than in the control and Bioglue groups (P < 0.05). The hydroxyproline levels were also statistically higher in the PRP group than in the control and Bioglue groups (P < 0.05). Histopathologically, there was less inflammatory cell infiltration, intensive fibroblast development, and rich collagen production in the PRP group.

CONCLUSION

PRP may be used in colon anastomosis, especially in patients with impaired wound healing, to obtain a better anastomotic strength.

Platelet-rich plasma may not provide any additional effect when associated with guided bone regeneration around dental implants in dogs

OBJECTIVE

The aim of this study was to evaluate histometrically bone healing in surgically created dehiscence-type defects around titanium implants treated with an association of platelet-rich plasma (PRP) and guided bone regeneration (GBR).

MATERIALS AND METHODS

Ten male adult mongrel dogs were used, from which the three low premolars (P2, P3, P4) and the first molar were extracted. Three months after teeth extraction, two implant sites were bilaterally drilled, buccal bone dehiscences were created and four titanium implants were placed. Dehiscences were randomly assigned to the following groups: (1) PRP, (2) GBR, (3) PRP+GBR and (4) control. After 3 months, the animals were sacrificed and the implants and adjacent hard tissues were processed for undecalcified sections. Bone-to-implant contact (BIC), bone density within the limits of implant threads (BW), bone density (BD) and new bone area (BA) in a zone lateral to the implant corresponding to bone defects were obtained and measured.

RESULTS

Intergroup analysis (two-way ANOVA -alpha=5%) demonstrated that when PRP was utilized,no differences were observed for all parameters (P>0.05). However, significant differences were observed for BIC and BW toward membrane-treated groups (P<0.05).

CONCLUSION

Within the limits of this study, it was concluded that PRP does not exert additional effects on bone healing in bone defects created around dental implants and treated by GBR.

Sinus floor elevation using autogenous bone or bone substitute combined with platelet-rich plasma

OBJECTIVE

Sinus augmentation is a common approach for patients with severe alveolar ridge atrophy. However, autogenous bone sometimes results in donor site complications. Bone substitutes with platelet-rich plasma (PRP) promote early bone formation with autogenous bone. Use of PRP on autogenous bone and a bovine bone substitute were investigated in this split-mouth animal study.

STUDY DESIGN

Premolars were extracted from minipigs. Each animal received sinus augmentation using a lateral approach with simultaneous insertion of 3 implants in each site. Groups were randomized using autogenous bone alone and combined with PRP or a bovine hydroxyapatite alone in combination with PRP.

RESULTS

Microradiographic findings in the autogenous group did not show significantly different rates by using autogenous bone alone or combined with PRP. Using the bovine hydroxyapatite as augmentation material only at 8 weeks, a nonsignificant effect in the PRP group could be seen. At all other observation periods, no significant influence was observed.

CONCLUSION

No significant influence of PRP was found.

Flow cytometric and morphological characterization of platelet-rich plasma gel

BACKGROUND OF PROBLEMS: Platelet-rich plasma (PRP) gel is derived from an autogenous preparation of concentrated platelets and is widely used in implant dentistry as a vector for cell growth factors. However, limited data are available on its structure and composition. The present study was aimed at providing a flow cytometric and ultrastructural characterization of PRP gel.

MATERIALS AND METHODS

Twenty PRP gel samples were obtained from healthy volunteers. These PRP gel specimens were prepared for transmission (TEM) and scanning electron microscopy (SEM) examination of their morphological ultrastructure. Flow cytometry with CD41-PE monoclonal antibody was used to detect platelet cells, as this antibody recognizes human-platelet-specific antigen CD41.

RESULTS

Both SEM and TEM showed that PRP gel contains two components: a fibrillar material with striated band similar to fibrin filaments, and a cellular component that contains human platelet cells. Both techniques indicated that no morphological elements were bound between the cellular component and the fibrillar material. The cells were confirmed as platelet cells by flow cytometric study after incubation with specific monoclonal antibody CD41-PE.

CONCLUSION

PRP gel contains a fibrillar and a cellular (largely human platelet cell) component. This unique structure may be capable of acting as a vehicle for carrying of cells that are essential for soft/hard tissue regeneration.

Platelet-rich plasma activity on maxillary sinus floor augmentation by autologous bone

OBJECTIVES

This work aims to evaluate the regenerative potential of platelet-rich plasma (PRP) on an implant site of peculiar clinical impact, such as sinus augmentation.

MATERIAL AND METHODS

Sixteen consenting patients (11 females and five males), with symmetrical maxillary sinus atrophy, underwent bilateral sinus floor augmentation, using autologous (iliac crest) bone on one side and PRP plus autologous bone contralaterally. Implants were inserted 4, 5, 6 and 7 months after surgery in the patients randomly split into four groups. Orthopantomographies, computed tomography with transverse image digital reconstructions and densitometries were used to monitor the treatment progress. A core biopsy was performed at the site of implant.

RESULTS

Clinical performance across both sites showed no statistical significance (P=0.414). Densitometric values were higher at PRP sites (mean Hounsfield units approximately +57%), even if densitometry converged in the two sites 8 months after surgery. Histology documents enhanced bone activities in sites treated with PRP, 4 months after surgery. Reduced bone activity was observed in both sites 5, 6 and 7 months after surgery. Bone amount, higher in sites treated with PRP (mean trabecular bone volume approximately +37%), decreased in both sites over time.

CONCLUSIONS

Our results seem to indicate a certain regenerative potential of PRP when used with autologous bone. The effect of this enhancement of bone regeneration appeared to be restricted to shorter treatment times. A progressive extinguishment of the PRP effect is recorded after an interval longer than 6-7 months.