Application of platelet-rich fibrin in endodontic surgery: A pilot study

EDITORIAL

◆ CONE BEAM TC: A DOUBLE CONCERN FOCUS

◆ ENDODONTIC APPLICATIONS OF CONE BEAM COMPUTED TOMOGRAPHY: CASE SERIES AND LITERATURE REVIEW

ORIGINAL ARTICLES

◆ APPLICATION OF PLATELET-RICH FIBRIN IN ENDODONTIC SURGERY: A PILOT STUDY

◆ CONDITIONING OF ROOT CANAL ANATOMY ON STATIC AND DYNAMICS OF NICKEL-TITANIUM ROTARY

INSTRUMENTS

◆ THE ACTIVATION OF IRRIGATION SOLUTIONS IN ENDODONTICS: A PERFECTED TECHNIQUE CASE REPORT

◆ IMPORTANCE OF CBCT IN THE

MANAGEMENT PLAN OF UPPER CANINE WITH INTERNAL RESORPTION

ISSN 1121 – 4171

2

|

November 2015

|

Vol. 29

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Organo Uffi ciale della SIE – Società Italiana di Endodonzia

Editorial/Editoriale

37

Cone Beam TC: a double concern

Cone Beam TC: una doppia preoccupazione M. Gagliani

Focus

38

Endodontic applications of cone beam computed

tomography: case series and literature review

Applicazioni della tomogra a computerizzata a fascio conico in Endodonzia: casi clinici e revisione della letteratura F. Abella, K. Morales, I. Garrido, J. Pascual, F. Duran-Sindreu, M. Roig

Original articles/Articoli originali

51

Application of platelet-rich  brin in endodontic

surgery: a pilot study

Applicazione del platelet-rich  brin in endodonzia chirurgica: studio pilota

D. Angerame, M. De Biasi, I. Kastrioti, V. Franco, A. Castaldo, M. Maglione

TABLE OF CONTENTS

SIE BOARD 2015

Editor in Chief Massimo Gagliani Executive Assistant Editors Filippo Cardinali Gianluca Plotino Assistant Editors Elio Berutti Antonio Cerutti Elisabetta Cotti Roberto Di Lenarda Adriano Piattelli Editorial Committee Massimo Amato Mario Badino Filippo Cardinali Davide Fabio Castro Cristian Coraini Camillo D’Arcangelo Cristiano Fabiani Roberto Fornara Francesco Mangani Claudio Pisacane Dino Re Silvio Taschieri Eugenio Tosco

SIE - BOARD OF DIRECTORS

Past President Marco Martignoni President Pio Bertani President Elect Francesco Riccitiello Vice President Giovanni Cavalli Secretary-Treasurer Vittorio Franco Cultural Secretary Roberto Fornara Advisers Mario Lendini Damiano Pasqualini Auditors

Maria Teresa Sberna Katia Greco SIE - Società Italiana di Endodonzia

ORIGINAL

ARTICLE/ARTICOLO

ORIGINALE

Application

of

platelet-rich

fibrin

in

endodontic

surgery:

a

pilot

study

Applicazione

del

platelet-rich

fibrin

in

endodonzia

chirurgica:

studio

pilota

Daniele

Angerame

*

,

Matteo

De

Biasi

,

Iva

Kastrioti

,

Vittorio

Franco

,

Attilio

Castaldo

,

Michele

Maglione

a_{DentalClinic,UniversityClinicalDepartmentofMedical,SurgicalandHealthSciences,UniversityofTrieste,}

Trieste,Italy

b_{GraduateSchoolofNanotechnology,UniversityofTrieste,Trieste,Italy} c_{PrivatePractice,Rome,Italy}

Received30June2015;accepted28July2015 Availableonline4September2015

GiornaleItalianodiEndodonzia(2015)29,51—57

KEYWORDS Endodonticsurgery; Healing; Platelet-richfibrin; Postoperativepain; Swelling. Abstract

Aim: Toassesspreliminarilythepotentialbenefitsoftheuseoftheplatelet-richfibrin(PRF)in modern endodontic surgical procedures in terms of radiographic healing acceleration and postoperativediscomfortreduction.

Methodology: Elevenpatientswithchronicapicalperiodontitiswererandomlyassignedtoeither thePRF(n=7)orthecontrolgroup(n=4).Postoperativeswellingandpainwereassessedwitha questionnaire.RadiographichealingwasscoredaccordingtoMolven’sscaleuptoaperiodofone year.Datawerestatisticallyanalyzedwithnon-parametrictests.

Results: InthePRFgroupthepatientsexperiencedlesspaininthe2—6hpostoperativelyaswellas oedema,whichneverexceededthemoderateintraoralswelling.Radiographichealingwas detecta-bleearlierinthePRFgroup,withthemajorityofcasesscoredascompletehealingafter2—3months. Conclusions: TheadjunctiveuseofPRFmightpromotetheaccelerationoftheradiographichealing andreducethepostoperativediscomfort.

2015Societa` ItalianadiEndodonzia.ProductionandhostingbyElsevierB.V.Allrightsreserved.

PeerreviewunderresponsibilityofSocieta` ItalianadiEndodonzia.

* Correspondingauthorat:UniversityClinicalDepartmentofMedical,SurgicalandHealthSciences,PiazzaOspedale1,I-34125,Trieste,Italy. Tel.:+390403992761;fax:+390403992665.

E-mail:[email protected](D.Angerame).

Availableonlineatwww.sciencedirect.com

ScienceDirect

jo u rn al ho m e p ag e: ww w. el s ev i e r.c o m /l o ca t e/ gi e

http://dx.doi.org/10.1016/j.gien.2015.08.003

Introduction

Untreatedpulptissuenecrosismayleadtoperiapical period-ontitis,whichrepresentsaresponseofthebonearoundthe apextorestrainthelocalinfectiveoffence.Periapical heal-ingcanbeachievedbyrootcanaltreatment,whosepurpose is to remove bacteria and remnants of infected tissue by shaping,cleaningandfillingwithaninertmaterialtheentire rootcanalsystem.1_{Themaincauseofunsuccessfulperiapical}

healingafterprimaryendodontictherapyisthepersistence ofbacteriaandinfectedtissueintheendodonticspace2_even

afterorthogradeendodontictreatmentandretreatment;in such cases, thelastresort to maintain the toothis repre-sentedbyapicalsurgery.3_{Inthechoicebetweenorthograde}

re-treatment and surgical approach, the latter has to be preferredwhentherootcanalfillingisadequate,but symp-toms are persisting, when re-treatment involves high risk proceduresorlongpostsarepresentintherootcanal.4

Improvement in technical instruments and in surgical techniquesmightenhancetheoutcomeof endodontic sur-gery.5_{Infact,theemploymentofmicrosurgicaltechniques}

andmodern obturation materials raised the success rates afterroot-endresectionandretrogradefillingtoabout80— 90%.6,7Inordertoinduceboneregenerationandsofttissues healingafteroralsurgery,thelocalapplicationofhormones, grow factors and plasma derivates has been advocated.8 Platelet-rich plasma (PRP), bone morphogenic proteins (BMPs),platelet-derivedgrowthfactor(PDGF),parathyroid hormone(PTH),andenamelmatrixproteins(EMD)havebeen locally applied to promote the healing potential of the surgicalsite.8Nevertheless,theeffectivenessoftheir appli-cation in endodontic surgery is still questionable and the advantages they provide to both surgeon and patient

have been reported to be moderate and remain still

controversial.9—14

IthasbeenadvocatedthatPlatelet-richFibrin(PRF)can beconsideredahealingbiomaterialbecauseitisconstituted byafibrinnetworkinwhichplatelets,leukocytes,cytokines andstemcellsareenmeshed.15_{Moreover,theplateletsinthe}

PRFnetworkarecapableofslowlyreleasingplatelet-derived growth factor (PDGF) and insulin-like growth factor

(IGF),16,17_{evenuptooneweek.}18_{Theosteogenicpotential}

ofthesemoleculeshasbeenalreadydemonstrated.19,20PRF can be thought as a grow factor reservoir that can be employedwithoutexposingthepatienttoany immunogeni-city or infection risk,21 _{becauseit is entirelycomposed of}

nothingbut thepatient’sblood. Theapplicationof such a specificbiomaterialtoendodonticsurgeryhasalreadybeen describedinsomerecentcasereports22—24_{andarandomized}

clinicaltrialinthespecificalfieldofthetreatmentof api-comarginaldefects.25

Consideringthattheteethundergoingapicalsurgeryhave less predictable prognosis and even a single tooth can be strategicinthewholeoralprostheticrehabilitation,the pos-sibility of accelerating thebone regenerationin periapical surgicaldefectsmightbeofgreatinteresttotheclinician,in ordertoproceedsoonerwiththepermanentrehabilitation.

Theaimofthepresentone-yearfollow-uppilotstudyisto evaluate the radiographic healing and the postoperative discomfortinpatientsundergoing apicalsurgery, eitherby leavingtheapicalsurgicalcavityemptyorbyfillingitwith thePRFgel.Thenullhypotheseswerethatperiapicalsurgical defectsfilledwiththePRFgelrequirethesamehealingtime ofsitestreatedbyconventionalsurgicaltechniquesandthat thepatientsexperiencedthesamepostoperativediscomfort withorwithoutPRFapplication.

Materials

and

methods

Patientselection

Inthisstudy11patientsunderwentendodonticsurgeryfor the treatment of refractory periapical periodontitis. The wholeexperimentation was conducted in accordancewith the declarationof Helsinki of 1983.The patients involved werefullyinformedabouttheintentandthedesignofthe studyandtheywereaskedtogivetheirapprovalbysigninga writtenconsent.

Patients with severe systemic disorders (i.e. non-con-trolleddiabetes,immunologicdiseases,malignantneoplastic processes), thrombocytopenia or insufficient compliance were excluded from the present study. For inclusion of

PAROLECHIAVE Endodonziachirurgica; Guarigione; Platelet-richfibrin; Dolorepostoperatorio; Gonfiore. Riassunto

Obiettivi: Valutarepreliminarmenteipotenzialibeneficidell’usodelplatelet-richfibrin(PRF) nellamodernaendodonziachirurgicainterminidiaccelerazionedellaguarigioneradiograficae riduzionedeldiscomfortpostoperatorio.

Materialiemetodi: Undici pazienti conparadentite periapicalecronica sonostati assegnati casualmentealgruppoPRF(n=7)oalgruppocontrollo(n=4).Gonfioreedolorepostoperatori sonostativalutaticonunquestionario.Nell’arcodiunannodiosservazionee` statoassegnatoun punteggioallaguarigioneradiograficasecondo lascaladiMolven.Idati sonostatianalizzati statisticamentecontestnonparametrici.

Risultati: IpazientidelgruppoPRFhannoprovatomenodolorenelle2—6orepostoperatoriee sviluppatominoredema,cheerasemprelimitatoeintraorale.NelgruppoPRFlaguarigione radiografica era individuabile precocemente, con la maggioranza dei casi classificata come guarigionecompletadopo2—3mesi.

Conclusioni: L’uso aggiuntivo del PRF sembra promuovere l’accelerazione della guarigione radiograficaeridurreildiscomfortpostoperatorio.

 2015 Societa` ItalianadiEndodonzia.Production andhosting byElsevier B.V.Tuttiidiritti riservati.

patients,we selected adult individualspresenting atooth withpersistingperiapicalradiolucency,thepresenceof fis-tulaandsymptomsafterorthograderetreatmentandahigh riskofjeopardizetherootintegritybyorthogradeapproach. Each patient was randomly assigned to the control group (n=4) or PRF test group (n=7) by simple computerized randomizationprocedures. Detailed informationabout the patientsinvolvedinthestudyarereportedinTable1.

Surgicalprocedure

Asinglesurgeonperformedallsurgicalinterventionsunder operating microscope magnification. Lidocaine with epi-nephrine 1:50,000 was employed as local anaesthetic. Twenty minutes were waited for the vasoactive agent to constrictthelocalbloodvesselsinordertoachieveoptimal

haemostasis.3 _{Surgical access to the apical area of the}

involvedtoothwasobtainedviaafull-thickness muco-gingi-valflapwithverticalreleasingincisions.Thebonearoundthe rootapexwasremovedwitharoundburmountedona low-speedhandpiece underconstant waterirrigation.All gran-ulomatoustissuewasremovedbymanualcurettage.Ferric sulphate(Astringedent, Ultradent, South Jordan, UT,USA) wasusedashaemostaticagent.Therootwassectioned3mm from the anatomical apex. The root-end cavity was per-formedbyusingultrasonictips(KiS,SpartanObtura,Fenton, MI,USA),driedwithsterilepaperpoints(Inline,BMDentale, Turin,Italy)andfilledwithSuperEba(Regularsettingpowder, Bosworth,Skokie, IL, USA). Afterthe cement setting,the apicalsurfaceoftheresectedrootwasdyedwithmethylene bluandasurgicalmirrorwasemployedtoverifytheabsence of visible marginal defects. At the end of root-end filling procedure the surgical site was abundantly flushed with salinetoremoveblood clotsandferric sulphateresiduals. Inthefourpatientsofthecontrolgroup,thebonedefectwas not filled and the flap was sutured with 50 and 60 monofilamentpolypropylene.Intheother7cases(PRFtest group),PRFgelwaspreparedasdescribedbelowandapplied inthebonedefectbeforerepositioningandsuturingtheflap (Fig.1).Antibioticswereprescribedduringthe6days post-operatively(1gamoxicillinevery12h).Thechoicetoassume analgesics was left to the patient. Sutures wereremoved within48—72hfromsurgery.

PRFpreparation

The PRF gel was obtained by following the protocol by Choukrounetal.26_{Thisconsistedofcollectingasmallamount}

Table1 Patientsinvolvedinthestudy.

Group Subject Gender Age Tooth Controlgroup C1 F 45 1.3 C2 M 72 4.3 C3 F 37 1.5 C4 M 60 2.3 PRFtestgroup T1 F 45 2.5 T2 M 43 1.5 T3 F 44 1.1 T4 F 47 1.2 T5 M 28 3.6 T6 M 42 3.7 T7 F 52 3.2

Figure1 PhasesofthePRFgelapplication:(A)checkofthepropersealoftheretrogradefillingwithasurgicalmirror;(B)appearance oftheperiapicalbonydefect;(C)positioningofthePRFgelinthebonydefectwithforceps;(D)adaptationofthegeltothedefectafter compressionwithagauze.

ofthepatient’sblood(10—40mLinthecaseofourstudy)at the needed moment of the surgical operation into dried monovetteswithoutanticoagulantagent(Vacuette,Greiner Bio-One,Kremsmu¨nster,Austria). The collected blood was immediatelycentrifugedfor10minat 2,500rpm.The pro-ducedclotwasextractedfrom thecontainerbyusing thin sterileforcepsandentirelyemployed,withoutdeprivingitof theredthrombus.

Radiographiccenteringandexamination

CustomizedfilmholdersanddigitalX-ray system(Vistascan DentalPerio, Du¨rrDental AG, Bietigheim,Germany) were usedthroughoutthestudywithaparallelingtechnique;27_the

X-ray device (2200 Intraoral X-Ray System, Kodak Dental Systems, Rochester, NY, USA) was set at 70kVp, 10mA, and0.20s exposuretime. Radiographs weretaken before andaftersurgery,andateachfollow-upvisit;recallswere plannedatthe1st,2nd,3rd,4th,5th, 6thand12thmonth aftersurgery.

Twoendodontistswith16and20yearsofclinical experi-enceextraneoustoinvolvedpatientsandstudydesignwere calibrated.28,29_{Allradiographswereblindlyexaminedtwice}

at interval of at least 30 days. Inter- and intraobserver reproducibilitywasassessedbymeansofKappastatistics.30

Eachfollow-upradiographwas assignedtotheappropriate category of the classification introduced by Molven etal.:28,29 complete,incomplete, uncertain or unsatisfac-toryhealing(failure).Independentlyoftheradiological peri-apical condition, the presence of postoperative clinical complications(e.g. sinustract, apicomarginal communica-tion,infection with tendernessto palpationor percussion) reportedatanytimeofthecontrolvisitswasconsideredas failure.

Painandswellingassessment

Themodelforsubjectivedatacollectiondescribedby Pen-narochaetal.31_{wasadopted.Eachpatientwasaskedtofill}

outaquestionnaireinwhichpain andswellinginformation wererecordedafter2,6,and12hfromtheintervention,and eachdayduringthefirst7postoperativedays.Painwasrated asfollows:

0,absenceofpain;

1(mild),recognizablebutnotdiscomfortingpainthatdid notrequiretheassumptionofanalgesics;

2 (moderate), discomforting but bearable pain that is effectivelyrelievedbyanalgesics,ifassumed;

3(severe),painthatisdifficulttobear.

The following scale was formulated to score the post-operativeswelling:

0,absenceofswelling;

1,minorintraoraloedemalocalizedtothesurgicalsite; 2,moderateextraoralswellinginthesurgicalzone; 3,severeextraoralswellingbeyondthetreatedarea.

Statisticalanalysis

TheStatisticalPackageforSocialSciencesv.15(SPSSInc., Chicago,IL,USA)wasusedforstatisticalanalysis.Descriptive statisticsoftheconsideredvariableswereperformed.The

significanceofthedifferencesbetweenthegroupsinterms ofperiapicalhealing,painandswellingscoreswasassessed by meansof a Mann-Whitneytest. Since thepresent pilot studywasconductedonarestrictednumberofpatients,ap valuelessthan0.01wasregardedasstatisticallysignificant.

Results

Thedistributionoftheperiapicalhealingscoresisshowedin

Fig.2.Afterthe1stradiographicalrecall,onlyonepatientof thePRF testgroupwasclassified as healedbytheblinded examinersandnosignificantdifferenceswerefoundbetween thetwogroups.Attherecallsafter2and3monthsfromthe surgical intervention, thePRF test groupexhibited signifi-cantly better periapical healing scores than the control group.Fromthatmomenton,theperiapicalhealingscores ofthecontrolandtestgroupweresimilarandnosignificant differencewaspointedoutbythestatisticalanalysis.

The graphs in Figs. 3 and 4 represent the changes in postoperativepainandswellingduringthetimeof observa-tionhoursanddaysafterthesurgicalintervention.By con-sideringbothinvestigatedparameters,averagetolowscores wereregisteredinthetwogroupswithatrendoflowerscores associatedwiththeapplicationofPRF.Morespecifically,the patientsofthePRFtestgroupfeltlessintensepainthanthe controlgroupduringthefirsthoursanddayspostoperatively,

Figure2 Medianvaluesandinterquartilerangesofperiapical healingscoresaftermonths(m)fromthesurgicalintervention: 1,completehealing;2,incompletehealing;3,uncertain heal-ing; 4, unsatisfactoryhealing. The asterisks markstatistically significant differences betweencontrol andPRF experimental groupsatthespecifictimepoint(p<0.01).

Figure3 Meanvaluesandstandarddeviationsofpainscores afterhours(h)and days(d)fromthesurgicalintervention:0, absenceofpain;1,mildpain;2,moderatepain;3,severepain. Theasterisksmarkstatisticallysignificantdifferencesbetween controlandPRFexperimentalgroupsatthespecifictimepoint (p<0.01).

withsignificantlylowerscoresafter2and6h(p<0.01).As to the swelling assessment, the maximum scores in both groups werereachedin thetime periodbetween the12h andthe second postoperativeday. Starting from the third postoperative day, the swelling slowly decreased in both groups. The score in the PRF test group never exceeded themoderateintraoralswelling.

Discussion

Thepresentstudyevaluatedtheeffectsoftheapplicationof PRFinendodonticsurgery.Similarperiapicalhealingscores were assigned to the two groups at the first radiographic control;truetoform,onemonthwasnotenoughtoobserve mineralization changes with intraoralradiography, even in thePRFtestgroup.Onthecontrary,radiographichealingin PRFtestgroupappearedtobesignificantlyimprovedafter two and three months from the surgical intervention. If confirmedbystudiesinvolvingalargernumberofpatients, such an advantage is likely to arouse the interest of the clinician,becausetheuseofthePRFgelseemstoaccelerate thehealingprocess,whichwasdetectableearlier.Inmany clinicalandoperativesituationsthepossibilitytoshortenthe follow-upperiodtoonlyfewmonthsbeforeproceedingwith thepermanentrehabilitationwouldbeasubstantialasset. Moreover,ageneraltrendofreducedpostoperativepainand local swelling was noticed andmust be considered in the management of the patient’s overall comfort. In the first hourspostoperativelythemajorityofthepatientsbelonging tothetestgroupexperiencedonlymildpain(i.e.bearable withoutassumingdrugs);thismeansthattheiruseof analge-sics could be limited and has both clinical and economic advantages.Aclinicaltrialreportedabeneficialeffectofthe useofplasmarichingrowthfactors(PDGF)duringendodontic surgeryin affecting postoperativesymptoms and patient’s qualityoflifeaftersurgery.32Theauthorsdescribedindetail theproceduretoobtainandapplythisplasmaconcentrateto the surgical site, which required several stepsto be per-formed,namelyseparatingtheplasmaticcomponentintwo fractions,storingthem,addingCaCl2toenableclot

forma-tion and finally apply liquid and a clot of PRGF in three steps.32_{WechosetousePRFoverPRGFbecausetheformer}

hassimplerproceduresforbothpreparationandpositioning

thatallowtospareoperativetimepotentiallywithout com-promisingtheclinicaleffectiveness.

Oneofmostcommonindicationstoapicalsurgeryisthe presenceofanobstructionthatdoesnotallowtheaccessto theentire endodonticspaceandcannotbeovercome.The orthograde techniques for overstepping the obstruction dependontheavailabilityofspecificinstrumentsandabove all on the operator’s dexterity, so that they are hardly standardizeable.4 Thus,itcanbeconcludedthatthereare noabsoluteindicationstoapicalsurgery,33_{astheydependon}

ahostoffactors.ThebenefitsthatPRFcouldprovideinterms ofacceleratedradiographic healingandlimited postopera-tivesorenessmightinfluencethetherapeuticchoice.

PreferringPRFoverPRPinendodonticsurgerydependson severalfactors.Sinceinmostcasesthesurgicalbonedefect islikelytobesmall,PRF,differentlyfromPRP,wouldbethe first choicebecause it requires thecollection of veryfew millilitersofblood.PRPisobtainedfromthepatient’sown bloodtowhomcitratedextrosesolutionAisaddedpriorto centrifuging.34,35_{PRFwas specifically createdfor oral and}

maxillofacial surgery.26 The preparation of PRF requires neitheranticoagulantinthecontainernoradditionofgelling agent(i.e.bovinethrombin).36Theabsenceofanticoagulant impliestheneedoffasttransferandimmediate centrifuga-tionofcollectedbloodbecausefibrinpolymerizationisnot inhibited. During thefirst centrifugationphase, fibrinogen concentrates in the upper part of the tube; thereafter, circulatingthrombincausestheslowtransformationof fibri-nogeninto fibrin and the clot formsin the middle of the tube.36 Red corpuscles sediment at tube’s bottom, whilst acellular plasmasupernatant collects at its top. The slow gellingprocess distinguishesPRF by PRPand otherplasma derivatesasitmodifiesthemechanicalandbiological char-acteristicsofthefibrinmatrix.37Infact,physiological throm-binconcentrationdeterminestheorganizationofthefibrin networkinabiochemicalarchitecturecharacterizedby tri-molecular or equilateral junctions between monomers.36

This three-dimensional structure allow the establishment ofaflexible,elasticandresistantPRFgel,inwhichcytokines areretainedandcellularmigrationissupportedbythefibrin network.38,39Plateletsare mainlyentrappedintheclotat theinterfacebetweenthefibrinclotanditslower portion (theredthrombus);thus,thisportionoftheplasmaderivate gains in clinical relevance because of the substances it contains.38_{PRFseemsalsocapableofenmeshing}

glycosami-noglycans,38whoseaffinityforcirculatingplateletcytokines canenhance thecellmigration andthe healing process.40

Cytokinesaresolublemoleculesthatplayarelevantrolein healingandregenerationmechanismsininjuredtissues;38,41

theircapabilityof regulateinflammationand healing phe-nomenaconsistsofamultitudeofmolecularinteractionsthat hasnotbeen completely understood anddescribed.39 _The

biologicactivityandclinicaleffectivessofthePRFgel ben-efitsfromapartiallyknowncytokinesaction.Ourpreliminary resultshighlight atrendoflower postoperativediscomfort andacceleratedbonehealinginthepatientswhoreceived thePRFgel;thesefindingscanbeindicativeofaattenuated inflammatoryresponseandenhancedhealingofthesurgical site.The actionofhealing cytokinesthePRFgel contains, consistsofinterruptingtheinflammationprocessor promot-ing angiogenesis. The effects of interleukin 4 (IL-4) pro-foundly depend on the cytokines environment.42 When

Figure 4 Mean values and standard deviations of swelling scoresafterhours(h)anddays(d)fromthesurgicalintervention: 0,absenceofswelling;1,minorintraoralswelling;2,moderate extraoralswelling; 3,severeextraoralswelling. Theasterisks mark statistically significant differences betweencontrol and PRFexperimentalgroupsatthespecifictimepoint(p<0.01).

inflammatoryprocessesarepresent,IL-4actsasregulatorby inhibiting the IL-1b-mediated signal.43 _{The most powerful}

agentforangiogenesispromotionisthevascularendothelial growthfactor(VEGF),whichcancontrolgrowth,migration anddifferentiationofepithelialcells.44PRFhasbeendefined an‘‘immuneorganizingnode’’owingtoitscontentin cyto-kineswithbothpro-(IL-1b,IL-6,TNF-a)and anti-inflamma-tory(IL-4) action, whichwas foundto be superiorthanin plasmaconcentrates.39

AlthoughcytokinesandcellsenmeshedinPRFfibrin net-workinfluencetissuehealing,themolecularfibrinstructure seemsto be thecrucial characteristic ofPRF.15 _{It is}

note-worthy that fibrin employed in surgery as a single agent cannotleadtosufficientboneregeneration.45Thecomplex fibrin matrix of PRF can induce angiogenesis, because endothelialcells can migrate andadhere to its articulate structureinwhichtheydifferentiateandproliferate.46

More-over, one of the main angiogenesis soluble factors, the platelet-derivedgrowthfactor(PDGF),binds tofibrin with highaffinity.47,48

Since PRF has been introducedin recent years, only a small number of clinicalstudies on its efficacy have been produced;nevertheless,hopefulresultshavebeenobtained indifferentfieldsoforalsurgery.21,49—51_{Someclinicalcase}

reportsorserieshavebeenproducedonthePRFapplication toendodonticsurgery,withtheauthorsgenerallydescribing reducedmorbidityanddiscomfortforthepatientand accel-eratedhealing.22—24_{Nevertheless,noeffortismadeinthese}

studiesto standardize the surgical techniquesor the pre-operativeconditions;23moreover,someauthorsmakeuseof bonesubstitutes—e.g.hydroxyapatiteorb-tricalcium phos-phate(TCP)22,24—whicharelikelytoaffectthereliabilityof theradiographicassessment.Onsimilarbasicprinciples,also acasereportofasingleperiapicallesiontreatedwithPRP andallogenicgraft(TCP)hasbeenpublished.52_Theauthors

speculated that PRP could accelerate TCP resorption and reported a subtotal replacement of the grafting material with newly-formed bone 12 months after surgery. Since a 3-yearfollowupstudyon146teeththatunderwentstandard periapicalsurgeryreportedthat66%oftreatedteethcould beconsideredhealedafter12months,7theuseofPRPand TCP as grafting material appears questionable at the moment. Recently, a randomized controlled trial on the surgical treatment of apicomarginal defects with PRF has been published.25 _{However, endoperiodontal defects are}

peculiarlesions,whosetreatmentisknowntobeparticularly arduous.Theauthorsdidnotfindsignificantbenefitfromthe useofPRF.Differently,theaimofthepresentstudywasto assesstheeffectofPRFinendodonticlesionswithout period-ontal communication, so it is probable that the gel can express its beneficial effect in the absence of bacterial interference from the marginal periodontum and other non-controlledfactors.

Similarlytothecaseofperiodontalregenerativetherapy, bonegraftingmaterials havebeen frequently employedin endodonticsurgerytopromoteboneregenerationandtheir ability to induce new bone formation has been described well.53_{Notwithstanding,theriskofankylosisaftertheuseof}

a grafting material in endodontic surgery has still to be assessed because grafting materials might interfere with the regeneration of the periodontal ligament. There are nospecificindicationstobonegraftinginperiapicalsurgery

on accountoftheircontroversialabilityto provide favour-able healing and because of a lack of controlled clinical trials.53_{PRF isanautologous materialthatsurmounts}

pro-blemsrelatedtograftrejection,whichmightoccurwhenthe source of the grafting material is allograft, alloplast or xenograft.

Conclusions

TheapplicationofPRFgelinapicalsurgeryshowedpromising result in stimulatingbone formationafter2 and3months aroundperiapicalsurgicaldefectsandinreducing postopera-tivediscomfort.Furtherclinicalstudiesareneededto con-firmthefindingsofthispilotstudy.

Conflict

of

interest

Theauthorshavenoconflictofinteresttodeclare.

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