BritishJournalofOralandMaxillofacialSurgeryxxx(2016)xxx–xxx
ScienceDirect
Intraosseous generation of heat during guided surgical drilling: an ex vivo study of the effect of the temperature of the irrigating fluid
Kristof Boa
a,∗, Ibrahim Barrak
b,1, Endre Varga Jr
d, Arpad Joob-Fancsaly
c, Endre Varga
a, Jozsef Piffko
baUniversityofSzeged,DepartmentofTraumatology,Semmelweisu.6.,Szeged,H-6725,Hungary
bUniversityofSzeged,DepartmentofOralandMaxillofacialSurgery,Kalvariasgt.57.,Szeged,H-6725,Hungary
cSemmelweisUniversity,DepartmentofOralandMaxillofacialSurgery,Mariau.52.,DistrictVIII.,Budapest.,H-1085,Hungary
dDicomLABKft.,Pulzu.46/B.,Szeged,H-6724,Hungary Accepted7June2016
Abstract
Wemeasuredtheriseintheintraosseoustemperaturecausedbyfreehanddrillingordrillingthroughasurgicalguide,bycomparingdifferent temperaturesofirrigationfluid(10◦C,15◦C,and20◦C),foreverystepofthedrillingsequence(diameters2.0,2.5,3.0,and3.5mm)andusing aconstantdrillingspeedof1200rpm.Theaxialloadwascontrolledat2.0kg.Bovineribswereusedastestmodels.Intheguidedgroupwe used3-dimensionalprintedsurgicalguidesandtemperaturewasmeasuredwithathermocouple.Thesignificanceofdifferenceswasassessed withtheKruskal-Wallisanalysisofvariance.Guideddrillingwith10◦Cirrigationyieldedasignificantlylowerincrementintemperature thanthe20◦C-guidedgroup.Whencomparedwiththe20◦Cfreehandgroup,thereductionintemperatureinthe10◦Cguidedgroupwas significantlymorepronouncedatalldiametersexcept3.5mm.Finally,whenthe10◦C-guidedgroupwascomparedwiththe15◦Cgroups,the temperaturerisewassignificantlylessat2.5and3.0mmthanwiththeguidedtechnique,andat3.0mmcomparedwiththefreehandtechnique.
Wesuggestthattheuseof10◦Cpre-cooledirrigationfluidissuperiortowarmerfluidforkeepingtemperaturedown,andthisreducesthe differencebetweenguidedandfreehanddrilling.
©2016TheBritishAssociationofOralandMaxillofacialSurgeons.PublishedbyElsevierLtd.Allrightsreserved.
Keywords:Irrigationfluid;Implants;Guidedsurgery;Drillingguide;Temperature;Bonedrilling
Introduction
Keepingbonytrauma toaminimum duringpreparationof thebedofanimplantpermitsoptimalconditionsforosseoin- tegration, which plays a key part in primary healing and socontributestothelongtermsuccessofdentalimplants.1
∗Correspondingauthor.Tel.:+36204353329.Fax:+3662545531.
E-mailaddresses:boa.kristof@gmail.com(K.Boa), barrakibrahim@gmail.com(I.Barrak).
1 Fax:+3662561340.
Drillingofboneisacommontechniqueusedinvarioustypes ofsurgery,andthegenerationofheatandassociatedmechan- icaldamageduringrotarycuttingcaninfluencetheprocessof osseointegration.Previousstudieshaveshownthatnecrosis candevelopwhenthetemperatureduringosteotomyexceeds 47◦C.2,3
In recentyears progress in the field of guided surgery hasaccelerated,andstaticsurgicalguidesarenowcommon devices.4,5Misiretal.foundthatwhenaguideisusedduring drillingtheincreaseintemperatureisgreaterthanwhenthe implantsiteispreparedconventionally.6Inanotherstudy,the
http://dx.doi.org/10.1016/j.bjoms.2016.06.004
0266-4356/©2016TheBritishAssociationofOralandMaxillofacialSurgeons.PublishedbyElsevierLtd.Allrightsreserved.
superiortofluidwarmedtoroomtemperatureinminimising rises.12,13
However, tothe best of our knowledge there has been noresearchinto the useof irrigationsolutionsatdifferent temperatures togetherwithasurgical guide.Wehavepre- viouslyfoundthat withahigher drillingspeed(1200rpm) theriseintemperaturecouldbenearthenecroticthreshold, sowewished toknowiftheuseofsalinesolutionsatvar- ioustemperaturesduringguidedsurgicaldrillingataspeed of1200rpmwouldresultinsmallerrises.
Materialandmethods
Bovine ribs were used, because of their favourable ther- mophysical and anatomical characteristics. Davidson and James had already shown that bovine ribs are thermally isotropic, whilst their conductivity is identical to that of humanmandible.14
Thedensitiesofthecorticalandcancellousboneofbovine ribshavebeenshowntobeanalogoustothoseofhumanbone asmeasured bycomputedtomography,15 andthestudy by Katranjietal.concludedthatthemeanedentulousanddentate corticalthickness fallsbetween 1 and2 mm, and 1.6and 2.0mm,respectively.16 Thethicknessesofoursegmentsof bovineribwerewithinthesamerange.Seneretal.concluded thattheincreaseintemperaturewasgreaterincorticalbone thaninthedeeperpartsof thedrilling cavity,12 whichhas beenconfirmedbyotherstudies.17,18Specimensofbovine ribbonewithacorticalthicknesssimilartothatofthehuman mandiblewerethereforeused,andthemeasurements(which weremade inthecorticallayerof thebone) describedthe peaktemperatureduringdrilling.
Everyspecimenwastakenfromthesameanimal,andthey wereallstoredat-10◦Cinnormalsalinesolutionbetween theexperiments,asdescribed bySedlinandHirsch.19 The animalwasnotkilledfortheexperiment.
Ourmeasurementsweredesignedtoreplicatetherisein temperatureduringpreparationofanimplantsitethroughout afulldrillingsequence(2.0,2.5,3.0,and3.5mmdrilling), using astandard drillingspeed (1200rpm) and astandard quantityofexternalirrigationsolution.Thefactorsthatwere varied were whether the drilling was freehand or guided, andthetemperatureoftheirrigatingsaline:20◦C,15◦C,or 10◦C.Eachgroupwasdefinedbythedepthofdrilling,the technique,andthetemperatureoftheirrigant.Twenty-four groups were studied, and20 measurements made in each group.Inthegroupsinwhichguidedsurgerywasevaluated weusedamodelsurgicalguidethathad2×5guidingholes withmetalsleeves(Fig.1)andfourholesforthefixingpins.
2.0mmindiameterandadepthof1.8mm(sothatwecould makesurethatthedepthofthecavityneverexceededthecor- ticallayer).Thethermocouplewasplacedsothatittouched the lateral bonywall of the cavity that was closestto the implantbedtobe drilledandthentightly filledwithbone chipsderivedfromspecimensofribfromthesameanimal, andtheholewasthoroughlysealedwithplasticinetomaintain adequateinsulation(Fig.2).
Measurementcavitieswerepositioneddirectlyunderneath themetalsleeveofthesurgicalguide,1.75mmhorizontally from the 2.0mm drilling canal, 1.5mm from the 2.5mm drillingcanal,1.25mmfromthe3.0mmdrillingcanal,and 1.0mmfrom the 3.5mm (final)drilling canal(Fig.2). To ensure comparable results,the measurement cavities were prepared in the same positions for the freehand groups.
Theprecisepositionofthemeasurementcavitieswascalcu- latedfroma3-dimensionallyprintedguide,whichcouldbe anchoredwithpinsinthesamepositionasthemodelsurgical guide(Fig.1).
Aconstantaxialpressurewasmaintainedthroughoutthe procedure,andtheaxialloadwascontrolledat2.0kg.Tehe- maretal.hadconcludedthat2.0kgcanbeconsideredaslow handpressure,20andthiscorrelatedwiththeobservationsof arecently-publishedsystematicreviewbyMöhlhenrichetal.
whichconfirmedthat2.0kgisthemostextensivelyusedaxial load.21Abenchdrill(BoschPBD40,Bosch,Germany)with adjustablespeedwasusedfordrilling.
Before the measurements were made the specimens of bonewerewarmedto37◦Cinsalinetanks,andwedrilled only when the baseline temperature had fallen between 35◦C and 37◦C. Standard, constant, external irrigation generatedbyacommercially-availablephysiodispensersur- gical unit(W&H ImplantmedSI-923,W&H, Austria)was appliedthroughastandardcannula(W&H,Austria)attached to the drilling machine and directed to the drill bit at a flow rate of 105ml/minute. The temperature of the irrigation fluid was either 20 (1)◦C (room temperature), or 15 (1) ◦C, or 10 (1) ◦C. Before each measurement the temperature of the saline solutions was checked with aninfraredthermometricdevice(Holdpeak-320,Holdpeak, China).
ThefullexperimentisshowninFig.3.Eachonewasmade (andthe fullapparatus stored)inthe sameair-conditioned room at a temperature of 20 (1) ◦C. Temperature rises (peak temperature minus baseline temperature) were ana- lysed statistically withthe helpof Statisticafor Windows 10.0 (StatSoft,Tulsa, OK,now DellSoftwareGroup, CA, USA).AstheShapiro-Wilktestindicatedthatthedistribu- tionswereskewed,weused theKruskal-Wallisanalysisof varianceforcomparisonsbetweengroups.
Fig.1.The3-dimensionalprintedsurgicaldrillingguide(left)andthe3-dimensionalprintedguidetohelpmeasurethepositionofthecavity(right).
Fig.2.Cross-sectionofthedrill(1)=surgicaldrillingguide,(2)=drillingcanal,(3)=drillsleevefortheactualdiameterofthedrill,(4)=projecteddrilling path,(5)=thermocouple,(6)=insulation,(7)=bonechips,(8)=layerofcorticalbone,(9)=layerofcancellousbone,and(10)=distancefromthecanaltobe drilled(1.75mmforthe2.0mmdrill,1.50mmforthe2.5mmdrill,1.25mmforthe3.0mmdrill,and1.0mmforthe3.5mmdrill).
ResultsandDiscussion
TheresultsofourmeasurementsareshowninTable1.Data fromthedrillingproceduresweredividedintogroupsbythe followingaspects:temperatureoftheirrigationfluid,method ofdrilling,anddiameterofthedrill.Thevaluesofthethermal changesineachgroupareshowninFigure4(supplementary data).
Fig.3.Theexperiment.
Therewasasignificantlysmallerriseintemperaturewith freehand drilling with10◦C irrigation compared with the 20◦Cguidedgroup(p=0.000foralldiameters),regardless of thediameterof thedrill.Iffreehand drillingwith10◦C irrigationwas comparedwithfreehand drillingwith20◦C irrigation,thedifferencebetweengroupswiththesamedrill diameter wassignificant (p=0.026for2.0mm,(p=0.000 for2.5and3.0mm),withtheexceptionof3.5mmdrilldiam- etergroups.When10◦Cfreehandirrigationwascompared with15◦Cguidedirrigation,thedifferencewassignificantat 2.5(p=0.005)and3.0(p=0.004)mm,indicatingthesupe- riorefficiencyoflowertemperatureirrigation.
Guideddrillingwith10◦Cirrigationalsoyieldedasig- nificantly lower temperature than the 20◦C guided group (p=0.000foralldiameters),regardlessofthediameterof thedrill.Whenthe10◦Cguidedgroupwascomparedwith the20◦Cfreehandgroup,thereductionintemperaturewas significantly more pronounced at all diameters except for 3.5mm(p=0.431for2.0mm,p=0.000for2.5and3.0mm, whereasp=0.055for3.5mmandp=0.??).Finally,when the10◦Cguidedgroupwascomparedwiththe15◦Cgroup, there were significantly lower rises in temperature at 2.5 (p=0.003)and3.0(p=0.000)mmcomparedwiththeguided technique,andat3.0mmcomparedwiththefreehandtech- nique(p=0.025).
1 2.0 Free-hand 10 0.11(0.61) 17*,21***
2 2.5 Free-hand 10 0.15(0.49) 14**,18***,22***
3 3.0 Free-hand 10 0.71(0.96) 15**,19***,23***
4 3.5 Free-hand 10 1.48(0.74) 24***
5 2.0 Guided 10 -0.04(1.15) 17*,21***
6 2.5 Guided 10 -0.02(0.80) 14**,18***,22***
7 3.0 Guided 10 0.10(0.76) 11*,15***,19***,23***
8 3.5 Guided 10 1.40(0.58) 24***
9 2.0 Free-hand 15 0.66(0.52) 21***
10 2.5 Free-hand 15 1.13(0.51) 18*,22**
11 3.0 Free-hand 15 1.75(0.65) 7*,23**
12 3.5 Free-hand 15 1.89(0.70) 24**
13 2.0 Guided 15 1.44(0.46) -
14 2.5 Guided 15 1.85(0.71) 2**,6**
15 3.0 Guided 15 2.48(0.91) 3**,7***
16 3.5 Guided 15 2.75(0.82) -
17 2.0 Free-hand 20 1.74(0.73) 1*,5*
18 2.5 Free-hand 20 2.84(1.19) 2***,6***,10*
19 3.0 Free-hand 20 3.11(1.14) 3***,7***
20 3.5 Free-hand 20 3.30(1.52) -
21 2.0 Guided 20 2.56(0.92) 1***,5***,9***
22 2.5 Guided 20 3.45(1.49) 2***,6***,10**
23 3.0 Guided 20 4.35(1.36) 3***,7***,11**
24 3.5 Guided 20 4.86(1.67) 4***,8***,12**
Inallcasesthedrillingspeedwas1200rpmandthenumberofepisodesofdrillingwas20.Forthegroupingnumbersmarkedwithone*,theexactp-values roundedtothreedecimaldigitsarethefollowing:Group1:17*(p=0.026);Group5:17*(p=0.043);Group7:11*(p=0.025);Group10:18*(p=0.031);
Group11:7*(p=0.025);Group17:1*(p=0.026)and5*(p=0.043);Group18:10*(p=0.031).
Kondoetal.concludedthatcoldirrigationmightlessen theriseintemperaturecausedbydrilling,13andtheuseof 10◦Cirrigationcould bebetteratkeepingthetemperature underthenecroticthreshold.12Isleretal.concludedthatthe useofa4◦Csalineirrigationmightresultinbetter,quicker healing.22
Publicationsabouttheproductionofheatduringguided surgeryhavesofarstudiedonlytheuseofnormalsalineat roomtemperature,andtheirfindingsmaybesummarisedas follows.Misiretal.showedthatasignificantlyhigherpeak intemperature could be measured during guided prepara- tionoftheimplantsite.6Inastudyinwhichtheyusedresin modelstherewasnocomparabledifferencewhentheyused aflaplessoraflap approachduringguidedsurgery.7Anin vitrostudy byMiglioratietal.concluded that withproper irrigation,guidedsurgerycanbeassafeastheconventional method.8DosSantosetal.alsoshowedthattheriseintemper- aturestayedwithinthesafezonewhenasurgicalguidewas used.9 Finally,we havealsoshownthat externalirrigation canefficientlycontroltheriseintemperaturewiththeguided technique.10
Alimitationofourstudyisthatitwasexvivo.However, itsstrengthsincludethecomparisonofguidedandfreehand techniques,theuseofsalinesolutionsatdifferenttempera- tures(10◦C,15◦C,and20◦C),drillingthroughoutawhole sequenceoffourdifferentdrilldiameterswiththesameaxial
load,andthequantityofexternalirrigationbeingwellcon- trolled.
Conclusion
The use of saline as irrigating fluid at 10◦C meant that a significant reduction in peak temperature was achieved regardless of both the preparationtechnique of the site or the diameter ofthe drill.Consideringourresults thatwith irrigation at room temperature (20◦C) at a drilling speed of 1200rpm,andadrilldiameter of3.5mm, near-necrotic temperatures may be reached, we suggest that the use of 10◦C precooled irrigation fluid is abetter way to control temperature.
ConflictofInterest
EVJr.istheCEO,andEVisaconsultantforandpart-owner, ofDicomLABKft,Szeged,Hungary.
Ethicsstatement/confirmationofpatientpermission No ethicsapprovalwas requiredas theresearch wasdone usingsamplesofdeadbone.
Acknowledgements
WewouldliketothankGaborBraunitzerforhissupportin preparingthetext.
AppendixA. Supplementarydata
Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/
j.bjoms.2016.06.004.
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