Platelet rich plasma in implant dentistry - current trends

REVIEW ARTICLEPlatelet rich plasma in implant dentistry- current trends1 2Dr. Manimaran , Dr. Saisadan12Professor & HeadPostgraduate studentDepartment of Prosthodontics,JKK Nataraja Dental College & Hospital, Komarapalayam,Namakkal District, Tamilnadu, India.Abstract:Implant dentistry entails surgical reconstruction of localizedalveolar defects to improve quality and quantity of the host bone usingn e w e r m a t e r i a l s w i t h b e t t e r o s s e o u s r e g e n e ra t i v eproperties(osseoconduction&osseoinduction). Guided boneregeneration is an accepted surgical method to help achieve this goal.Platelet rich plasma (PRP) is rich in growth factors like a)PDGF b)TGFβc)PDEGF d)IGF1 , derived from autologous blood. PRP is being usednowadays to derive these factors in high concentrations to sitesrequiring osseous-grafting, prior to or in conjunction with implantplacement .Advantages include better handling of the graftmaterial(alloplastic/autogenous) in the presence of an adhesivemedium aiding in compaction, increased rate of collagen matrixsynthesis, increased rate of bone deposition & quality of boneachieving benefits without risk of infection or disease transmission&obvious ease of procurement &preparation.KEY WORDS:P.R.P gel, platelet derived growth factors, plasmapheresis,cellular activation and response.Introduction:With the wide spread use of implants as a routinetreatment modality ,operators are on a constant look out toachieve more predictable results on the clinical outcome, visa vis the quantity and quality of bone deposition in the graftsites and the subsequent stability and longevity of theconcurrent implants placed.The methods described to achieving this goalinlcude use of autografts, allografts, xenografts andalloplastic bone substitutes, the most ideal beingautogenous bone, but which has an inherent disadvantageof requiring a second surgical donor site as well as limitedquantity of graft obtained. The allografts have shown resultswith inconsistent bioactivity ad osteoinductive potential,along with added patients concern about diseasetransmission.The newer advanced alloplastic materials haveshown good Osseoinductive properties, biocompatibilityand any adjuvant that enhance the predictability of thesetreatment modalities would be highly desirable . The use oflyophilized fibrin as an Osseo conductive material and as amedium for compacting grafts has been well documented1in orthopedic literature. The advent of techniques like GBR4–Guided Bone Regeneration and the use of BoneMorphogenic Protiens 5 have advanced this scienceimmensely. The high concentration of growth factors suchas 1)Platelet derived growth factor,2)Transforming growthfactor beta,3)Transforming growth factor beta -in theautologous fibrin used, prompted these researchers tostudy the original plasma from which the autologous fibrinwas obtained.Better understanding of the functions of thesegrowth factors along with the realization that the beneficialeffects of fibrin are not merely restricted to itsosseoconductive effect and graft agglutination, butcatalystic effect on bone deposition and healing by releaseof the above mentioned growth factors5,shifted focus onthe original plasma which possessed these in higherconcentration and additional factors like1)Platelet derived epidermal growth factors2)Platelet derived angio-genesis factor13)Insulin like growth factor4)Platelet factor-4Depending on the technique used to obtain this plasma, itis possible that additional growth factors can be obtained,thus enhancing its repair capacity. Moreover since this is anautologous preparation, any concerns regarding diseasetransmission and immunogenic reactions regardingallograftic and xenograftic preparations can beeliminated5.JIADS VOL -1 Issue 3 July - September,2010 |22|

Platelet rich plasma in implant dentistry - current trendsManimaran & SaisadanPlatelet Rich Plasma and its ConstituentsPRP is obtained by centrifugation ofautologous blood and addition of CaCl and25thrombin which makes it into PRP gel. This has ahigh concentration of platelets and fibrinogen. Theaddition of thrombin and CaCl results in the2release of a cascade of growth factors from thep l a t e l e t s ( α - g r a n u l e s ) . P l a t e l e t c o u n t s a r econcentrated more by the the “plasmapheresistechnique7”. The summary of growth factors8released from platelets are as followsPreparation of PRP with general-purpose centrifugesOne unit autologouswhole blood(5600rpm )Platelet-Poor plasma(PPP)Red blood cellsErythrocytes + buffy coat(2400rpm)Platelet RichPlasma (PRP)Wound Healing:-Role of PRPThree different stages in wound healing are,1)Bio-chemical activation2)Cellular activation3)Cellular response9Bio-chemical Activation:Triggered by Hageman factor,caused bymechanical injuryExposing the basement membrane to tissueproteins and pasma. This brings forth 4 cascades resultingin cellular activation.PRP-PreparationApproximately 50ml of whole bloodwithdrawn is centrifuged in a tube containing 10ml ofculture medium with 250 µ/ml of preservative freeheparin.The blood was first centrifuged for 5min at1100rpm.Subsequently,the yellow plasma containing thebuffy coat with platelets and leucocytes is againcentrifuged at 2500rpm for 10min. The resulting pelletso f p l a t e l e t s , t e r m e d P L A S M A F R A C TO N - w a sresuspended in 5ml of residual plasma and used for theplatelet gel.PRP gel is formed by mixing PRP with thrombin andCaCl . 2PRP gel includes a high concentration ofplatelets and a native concentration of fibrinogen.Cellular ActivationInflux of neutrophils, monocytes and plateletsleads to release of α granules in response to thrombin.These growth factors signal local mesenchymal andepidermal cell migration and increase collagen andglycosaminoglycan synthesis.Final Cellular ResponseMonocytes transformed into macrophages,helpneutrophils in host defence and repair.The properties of PRP are based on the activationand release of multiple growth factors upon activation.They enhance and accelerate soft tissue healing and boneregeneration. Owing to the availability of these growthfactors in high concentration in platelets, use of PRP offersJIADS VOL -1 Issue 3 July - September,2010 |23|