w w w . e l s e v i e r . p t / s p e m d
Revista
Portuguesa
de
Estomatologia,
Medicina
Dentária
e
Cirurgia
Maxilofacial
Review
Sagittal
joint
spaces
of
the
temporomandibular
joint:
Systematic
review
and
meta-analysis
Eugénio
Martins
a,
Joana
C.
Silva
a,∗,
Carlos
A.
Pires
b,
Maria
J.
Ponces
a,
Jorge
D.
Lopes
aaFaculdadedeMedicinadaDentáriadaUniversidadedoPorto,Portugal
bDepartamentodematemática,UniversidadedeTrás-os-monteseAltoDouro,Portugal
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:
Received9February2015 Accepted12April2015 Availableonline26May2015
Keywords:
Temporomandibularjoint Review
Meta-analysis
a
b
s
t
r
a
c
t
Theaimofthisstudywastoperformasystematicreviewandmeta-analysisonthesagittal jointspacesmeasurementsofthetemporomandibularjoint.Anelectronicdatabasesearch wasperformedwiththeterms“condylarposition”;“jointspace”AND“TMJ”.Theriskof biasofeachstudy wasassessedwith“Cochraneriskofbiastool”.Thevaluesusedinthe meta-analysiswerethejointspacemeasurementsandtheirdifferencesbetweentheright andleftjoint.
Fromtheinitialsearch2706articleswereretrieved.Eighteenarticlesclassifiedforfinal review.Onlyonestudywasclassifiedashavinghighlevelofevidence.Seventeenofthe reviewedstudieswereincludedinthemeta-analysisconcludingthatthemeansagittaljoint spacevalueswere:anteriorjointspace1.86mm,superior2.36mmandposterior2.22mm. However,theanalysisalsoshowedhighlevelsofheterogeneity.Rightandleftcomparison hasshownstatisticallysignificantdifferences.
©2015SociedadePortuguesadeEstomatologiaeMedicinaDentária.Publishedby ElsevierEspaña,S.L.U.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Espac¸os
articulares
sagitais
da
articulac¸ão
temporomandibular:
revisão
sistemática
e
meta-análise
Palavraschave: Articulac¸ãotemporomandibular Revisão Meta-análiser
e
s
u
m
o
Oobjetivo deste estudo foi realizar uma revisão sistemática e meta-análise sobre os espac¸osarticularessagitaisdaarticulac¸ãotemporomandibular.Foirealizadaumapesquisa eletrónicacomostermos“condylarposition”,“jointspace”AND”TMJ”.Onívelde evidên-ciadecadaestudofoiavaliadocom“Cochraneriskofbiastool”.Osvaloressumariados nameta-análiseforamosespac¸osarticulareseadiferenc¸aentreaarticulac¸ãodireitae esquerda.
∗ Correspondingauthor.
E-mailaddress:joanacristinapsilva@gmail.com(J.C.Silva).
http://dx.doi.org/10.1016/j.rpemd.2015.04.002
1646-2890/©2015SociedadePortuguesadeEstomatologiaeMedicinaDentária.PublishedbyElsevierEspaña,S.L.U.Thisisanopenaccess articleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Dapesquisainicialresultaram2076artigosdosquais18foramselecionadosparaarevisão. Apenasumestudofoiconsideradodeelevadoníveldeevidência.Foramincluídosna meta-análise17dos artigosdarevisãoconcluindo-seque,osvaloresmédiosparaos espac¸os articularessagitaisforam:1.86mmparaoanterior,2.36mmparaosuperiore2.22mmpara oposterior.Noentanto,a análiserevelouaindagrandeheterogeneidadenosresultados dosestudosavaliados.Verificaram-sediferenc¸asestatisticamentesignificativasentreas articulac¸õesesquerdaedireita.
©2015SociedadePortuguesadeEstomatologiaeMedicinaDentária.Publicadopor ElsevierEspaña,S.L.U.EsteéumartigoOpenAccesssobalicençadeCCBY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
Themandibularcondylepositionhasbeenatthecentreofa longlastingcontroversyamonggnathologistsand orthodon-tists.Theidealconceptofthemandibularcondyleposition haschangedfromthemostretrudedpositionofthecondylein theglenoidfossatothemostsuperiorpositionofthecondyle. Nowadaysitisacceptedasthemostanterosuperiorpositionof themandibularcondyleintheglenoidfossawiththearticular diskplacedinbetween.1–4 Theliteraturealsoshowsagreat
confusionconcerningtherelationshipbetweendental occlu-sionandthetemporomandibularjoints.Itispossibletofind articlesprovingtherelationshipbetweenthesetwovariables, whileothers achievedcontrary resultswithnorelationship beingsuggested.5–8Themajorfocusofthediscussionusually
istheidealmandibularcondylepositionandthe effectsof itsvariation.4,9,10 Withtheevolutionofradiographicexams
like computerized tomographies (CT), including the new 3Dcone-beamcomputed tomography(CBCT)and magnetic resonanceimaging(MRI)itisnowpossibletoradiographically examinethepositionofthecondyle.11–13Themostcommon
methodfoundintheliteraturetodeterminethispositionis theassessmentofthejointspacemeasurements,whichare theradiographicspacefoundbetweenthe condyleandthe glenoidfossawherethearticulardiskisplaced.14Avariation
onthevaluesofthesemeasurementssuggestadisplacement ofthecondyleandso,thedeterminationofthe“goldstandard” forthesevalueswouldbeaveryimportanttooltodetermine anyvariationtothecondyleposition.Theaimofthisstudy istoperformasystematicreviewandmeta-analysisonthe sagittaljointspacemeasurementsofthetemporomandibular jointtoassessthemeanvaluesforthesemeasurements.
Methods
Searchstrategy
Acomprehensiveelectronicdatabasesearchtoidentify rel-evantpublicationswasconducted,andthereferencelistsin relevantarticlesweresearchedmanuallyforadditional liter-ature.Nolanguagerestrictionswereset,althoughnoattempt wasmadetoexploretheinformallypublishedliterature,like conferenceproceedingsandabstractsofresearchespresented atconferencesanddissertations.Theresearchextendedtothe followingdatabases:Medline(Pubmed),Lilacs,Scopus,Ebsco
(HostbyUniversityofPorto)andCochraneCentralRegisterof ControlledClinicalTrials.
The search terms were “condylar position” and “joint space”AND “TMJ”withnoyearofpublicationrestrictionin order toincludethehighestnumberofarticles(to22April 2014).Norestrictiontostudydesignwasapplied.
FacultyofDentalMedicineofUniversityofPortoand Por-tugueseSocietyofDentofacialOrthopedics’librarieswerealso consultedforprintedarticlesnotavailableonline.
Criticalevaluation
Atthefirststage,tworeviewersscreenedindependentlythe titles ofthe retrievedrecords,and onlythe titlesrelatedto TMJjointspace assessmentwere included.Joint spacewas definedastheradiographicimagebetweenthemandibular condyleandtheglenoidfossawherethediskisinterposed. Next, the abstracts ofthe retrieved publications were read bythetworeviewersandcategorizedaccordingtothe radio-graphicprocedureusedtoassessthejointspace.Anarticle had only tobe justifiedby onereviewer to beincluded in thesecondselectionphase.Eligibilityoftheretrievedarticles wasdeterminedbyapplyingthefollowinginclusioncriteria: (1) tomographicexamination of the TMJ (2) determination of sagittal joint space measurements at least on two dif-ferentpoints(anteriorandposterior).Themainreasonsfor exclusionwere:mandiblefractures,studiesnotperformedin livinghumans,surgicalinterventions,studieswithpatients withsyndromesorchronicdiseases(includingdegenerative pathology oftheTMJ), samplescontainingpatientsonlyin theprimaryormixed/earlypermanentdentition,clinicalonly evaluationofthemandibularcondyleposition,2Dradiograph ormagneticresonanceimaging,previousorthodonticorsplint therapy, casereports, discussion ordebate articles. All not publishedstudieswerealsoexcluded.
Theanalysiswasbased onprimarymaterials.When an abstractwasconsideredbyatleastoneauthortoberelevant, itwasreadinfulltext.Atthesecondstage,thefulltextswere retrievedandcriticallyexamined.Referencelistsfromthe arti-clesselectedonthesecondstagewerescreenedandarticles relatedtojointspacemeasurementswerehand-searched.
Datagathering
The following data were extracted from the selected arti-cles:year ofpublication,studytype,study method,sample description,jointspacemeasurementsonthesagittalplane,
erroranalysismethod,statisticalanalysisandauthor’s con-clusion. This method was pilot-tested on ten randomly selected included articles and then refined. One reviewer authorthenextractedthementioneddatafromtheincluded articlesand the second author checked. Anydisagreement wasresolvedwithdiscussionbetweenthetwoauthorsuntila consensuswasreached.Theriskofbiaswasassessed accord-ing to the “Cochrane risk of bias tool”15 as suggested by
the“PRISMAstatementforreportingsystematicreviewsand meta-analysesofstudiesthatevaluatehealthcare interven-tions:explanationandelaboration”.16
Meta-analysis
Thevalues studiedin this meta-analysis were the sagittal jointspace measurements(anterior,superior and posterior jointspace) and thedifferences betweenthe rightand left joints.Asnotalltheincludedarticlespresentedthevaluesfor allthespacesfromtherightandleftjoints,theanalysiswere performedincludingallthedatapresentedineachselected study.For the comparative analysis betweenthe right and
left joints, mean and standard deviation values from the samples of each article were used. For global joint space assessment,meanandstandarddeviationofthetotalsample (includingboththevaluesfromtherightandleftjoints)were used.
The restrictedmaximum-likelihood (REML)method was usedtoestimatedevariabilitybetweenthestudies.Inverse variancemethodwasusedtoassesstheweightofeachstudy. Heterogeneitywasdeterminedusing theQCochrantest andtheI2statisticsbyHigginsandThompson.17
Statisticalanalysiswasperformedusing“R”,version2.15.2 from“TheRProjectforStatisticalComputing”,availablefrom
http://www.r-project.org.
Results
Searchresults
Theinitialsearchstrategyallowedretrieving916articlesfrom Medline (Pubmed),1114fromScopus,158 fromEBSCOhost,
Records identified through database searching
(n=2706)
Additionnal records identified through other sources
(n=2)
Records after duplicates removed (n=1427)
Identification
Screening
Eligibility
Included
Records screened (n=1427) Records excluded (n=1362) Full-text articles excluded, with reasons(n=10) Full-text articles
assessed for eligibility (n=28) Studies included in qualitative synthesis (n=18) Studies included in quantitative synthesis (meta-analysis) (n=17)
Fig.1–Flowdiagramillustratingthesearchstrategyresults.
Source:Adaptedfrom:MoherD,LiberatiA,TetzlaffJ,AltmanDG,ThePRISMAGroup(2009).PreferredReportingItemsfor
SystematicReviewsandMeta-Analyses:ThePRISMAStatement.PLoSMed6(6):e1000097. doi:10.1371/journal.pmed1000097.
19fromLilacsandnonefromtheCochraneCentralRegister ofControlledClinicalTrials.Thenumberofarticlesreviewed ineach phaseofthissystematicreviewispresentedinthe PRISMAflowdiagram(Fig.1).Afterexcluding978duplicates, 1230articles remained forreview. Inthe first phase selec-tion,theobserversscreenedthearticlesbyreadingtitlesand abstracts.Articlesthatwerenoteligiblebecauseofirrelevant aimsandwerenotdirectlyrelatedtothissystematicreview wereexcluded,thus61articlesremainedforfurtherreading. 28articleswereassessedforeligibility.Afterscreeningallthe articlesfulltextaccordingtotheinclusion/exclusioncriteria, 18articlesclassifiedforfinalreview.
Typeofstudyandmethodusedforjointspaceassessment
ARandomizedClinicalTrial(RCT)18 wasfound.Aditionally,
sixprospective19–24andelevenretrospective25–35studieswere
found that fullfilled the elegibility criteria defined for this review. Sixofthe selectedarticles22,25,27,32–34 used CBCTto
assesstheTMJjointspacewhilenine18–21,23,26,28,30,35used
con-ventionalCTandthree24,29,31usedlineartomography.
Twelve of the selected studies19–21,23,24,26,28–30,32,33,35
assessedthejointspacemeasurementsbydeterminingthe closest distance between the mandibular condyle and the glenoidfossasurface.
Table1–Summaryofthequalityanalysisofthe18includedstudies.
Estimationof samplesize Sample description Error analysis Normality tests Adequate statistics provided Randomization Statistical analysis Levelof evidence 125 No/Not known
Yes No Yes Yes No Adequate Low
232 No/Not known Yes No No information N>30 Yes No Adequate (correlation) Low 326 No/Not known Yes Yes No information
Yes No Adequate Low
419 No/Not known Incomplete No No information N>30 Yes No Adequate (correlation) Low 527 No/Not known Yes Yes No information
Yes No Adequate Low
618 No/Not
known
Yes Yes Yes Yes Yes Adequate Moderate
728 No/Not
known
Incomplete Yes No
information
Yes No Adequate Low
829 No/Not known Yes No No information N>30 Incomplete No Adequate (correlation) Low
933 Yes Yes Yes No
information Non-parametric tests
Yes No Adequate Low
1020 No/Not
known
Incomplete Yes No
information N>30
Yes No Adequate Low
1121 No/Not known Incomplete Yes No information Yes No Adequate (correlation) Low 1222 No/Not known No Yes No information
Yes No Adequate Low
1331 No/Not
known
Yes No No
information N>30
Yes No Adequate Low
1423 No/Not
known
Incomplete No No
information
Yes No Adequate Low
1534 No/Not
known
Yes No No
information
Incomplete No Adequate Low
1624 No/Not known Yes No No information Incomplete No Adequate (correlation) Low 1730 No/Not known Yes No No information
Incomplete No Adequate Low
1835 No/Not known Incomplete No No information N=30 Yes No Adequate (correlation) Low
Study 1 Study 2 Study 3 Study 4 Study 5 Study 6 Study 7 Study 8 Study 9 Study 10 Study 11 Study 12 Study 13 Study 14 Study 16 Study 17 Study 18 80 80 80 60 24 44 78 78 45 60 92 40 464 79 80 40 60 2 2.6 1.96 1.25 1.3 1.8 2.81 1.53 2.25 1.26 1.21 1.97 2.59 1.94 1.88 2.06 1.28 0.51 0.83 0.29 0.48 0.2 0.93 1.03 0.43 0.61 0.56 0.48 0.92 0.95 0.62 0.71 0.86 0.66 5.98% 5.86% 6.03% 5.97% 6.02% 5.62% 5.75% 6.00% 5.86% 5.93% 6.00% 5.59% 6.01% 5.94% 5.91% 5.64% 5.89% 2.00 [ 1.89 , 2.11 ] 2.60 [ 2.42 , 2.78 ] 1.96 [ 1.90 , 2.02 ] 1.25 [ 1.13 , 1.37 ] 1.30 [ 1.22 , 1.38 ] 1.80 [ 1.53 , 2.07 ] 2.81 [ 2.58 , 3.04 ] 1.53 [ 1.43 , 1.63 ] 2.25 [ 2.07 , 2.43 ] 1.26 [ 1.12 , 1.40 ] 1.21 [ 1.11 , 1.31 ] 1.97 [ 1.68 , 2.26 ] 2.59 [ 2.50 , 2.68 ] 1.94 [ 1.80 , 2.08 ] 1.88 [ 1.72 , 2.04 ] 2.06 [ 1.79 , 2.33 ] 1.28 [ 1.11 , 1.45 ] Study n Mean RE Model Q(16)=1032.11, p<.001, I2 =98.49 0.50 1.25 2.00 2.75 Mean 3.50 100.00% 1.86 [ 1.62 , 2.10 ]
SD Weight Mean [95% CI]
AJS
Fig.2–Meananteriorjointspaceineachstudyandglobally.
Ontheother hand,four articles25,27,31,34 useda
geomet-ricalconstruction toassess the jointspace measurements. DifferentauthorsusedtheFrankfurthorizontallineorthetrue horizontallineasareferenceplanetodeterminethe most superiorpointofthe glenoidfossa.Following,the distance betweenthispointandthehighestpointofthecondyle (deter-minedbythesamemethod)wasmeasured,resultingthevalue ofthesagittaljointspace.Afterthis,startingfromthemost superiorpointoftheglenoid fossa,twotangentlineswere tracedtothemostanteriorandposteriorpointofthecondyle respectively.Thedistancebetweeneachofthesepointsand thepointwhereaperpendicularlinetothetangentscrosses thesurfaceoftheglenoidfossawastheanteriorandposterior jointspacerespectively.
Twostudies18,22usedasimilarmethodtotheonedescribed
above,butusedthecentreofthemandibularcondyleasthe referencepoint.
Qualityassessment
Thesummaryofthequalityanalysisoftheselectedarticlesis presentedinTable1.
Ingeneral,thestatisticalanalysisperformedwasadequate to the objectives defined oneach study and the statistical data are adequately presented in most cases. Apart from this, nine of the included articles21–24,26–28,30,34 used
para-metric tests (T Student or ANOVA) in small samples (less than30),withnoinformationonthenormalityofthedata.
Study 1 Study 3 Study 4 Study 5 Study 8 Study 9 Study 10 Study 11 Study 12 Study 13 Study 14 Study 16 Study 17 Study 18 80 80 60 24 78 45 60 92 40 464 79 80 40 60 3.3 2.49 1.67 2.5 1.92 2.45 1.58 1.68 2.44 3.33 2.73 3.58 1.99 1.35 0.9 0.55 0.63 0.5 0.71 0.71 0.55 0.72 0.8 0.97 0.68 1.37 1.24 0.6 7.15% 7.24% 7.20% 7.15% 7.20% 7.13% 7.22% 7.22% 7.07% 7.27% 7.21% 6.96% 6.76% 7.21% 3.30 [ 3.10 , 3.50 ] 2.49 [ 2.37 , 2.61 ] 1.67 [ 1.51 , 1.83 ] 2.50 [ 2.30 , 2.70 ] 1.92 [ 1.76 , 2.08 ] 2.45 [ 2.24 , 2.66 ] 1.58 [ 1.44 , 1.72 ] 1.68 [ 1.53 , 1.83 ] 2.44 [ 2.19 , 2.69 ] 3.33 [ 3.24 , 3.42 ] 2.73 [ 2.58 , 2.88 ] 3.58 [ 3.28 , 3.88 ] 1.99 [ 1.61 , 2.37 ] 1.35 [ 1.20 , 1.50 ] Study n Mean RE Model Q(13)=1117.08, p<.001, I2 =98.64% 1.00 1.75 2.50 3.25 Mean 4.00 100.00% 2.36 [ 1.99 , 2.72 ]
SD Weight Mean [95% CI]
SJS
Study 1 Study 2 Study 3 Study 4 Study 5 Study 6 Study 7 Study 8 Study 10 Study 11 Study 12 Study 13 Study 14 Study 16 Study 17 Study 18 80 80 80 60 24 44 78 78 60 92 40 464 79 80 40 60 2.25 3.12 2.31 1.86 2.1 2.02 2.52 1.82 1.76 2.21 1.93 2.76 2.05 3.26 1.83 1.86 0.76 1.02 0.41 0.66 0.3 0.7 0.74 0.47 0.46 0.79 0.57 1.01 0.62 1.31 0.85 0.78 6.27% 6.10% 6.43% 6.27% 6.38% 6.15% 6.28% 6.41% 6.39% 6.29% 6.24% 6.43% 6.35% 5.87% 5.96% 6.18% 2.25 [ 2.08 , 2.42 ] 3.12 [ 2.90 , 3.34 ] 2.31 [ 2.22 , 2.40 ] 1.86 [ 1.69 , 2.03 ] 2.10 [ 1.98 , 2.22 ] 2.02 [ 1.81 , 2.23 ] 2.52 [ 2.36 , 2.68 ] 1.82 [ 1.72 , 1.92 ] 1.76 [ 1.64 , 1.88 ] 2.21 [ 2.05 , 2.37 ] 1.93 [ 1.75 , 2.11 ] 2.76 [ 2.67 , 2.85 ] 2.05 [ 1.91 , 2.19 ] 3.26 [ 2.97 , 3.55 ] 1.83 [ 1.57 , 2.09 ] 1.86 [ 1.66 , 2.06 ] Study n Mean RE Model Q(15)=440.70, p<.001, I2 =97.37% 1.00 1.75 2.50 3.25 Mean 4.00 100.00% 2.22 [ 2.00 , 2.45 ]
SD Weight Mean [95% CI]
PJS
Fig.4–Meanposteriorjointspaceineachstudyandglobally.
Pearson correlation was used by six authors,19,21,24,29,32,35
with no mention to the linear relation between the vari-ables, which is necessary to the use and interpretation of this coefficient. Seven studies19–23,28,35 did not present an
adequate sample description, with no information about the age or gender. The other eleven18,24–27,29–34 showed at
least, the number of patients from each gender and data concerning the age of the included sample (mean, stan-darddeviation, minimumandmaximumvalues).Theerror analysiswaspresentedinsevenofthearticles.18,21,22,26–28,33
Onlyonestudy presentedthe estimation ofsample size.33
Randomization was used by Tsuruta et al.18 and none of
the retrieved articlespresented blinding inmeasurements. Onlyone18 of the studies was classified asmoderate level
of evidence, as it presents randomization and adequate statistics but fails to presents blinding in measurements. All the other articles were classified as low level of evidence.
Meta-analysisresults
Seventeen of the studies presented on the review were includedinthismeta-analysis.Onestudy34 didnotpresent
standarddeviationvaluesandso,statisticalcomparisonwith otherstudieswasnotpossible.
Themeananteriorjointspacefromthe17considered stud-ies was1.86mm(95%CI:1.62–2.10),althoughhighlevelsof heterogeneitywerefoundamongthestudies(Q(16)=1032.11;
P<0.001;I2=98.49%)(Fig.2).
The superior joint space presented a mean value of 2.36mm(95%CI:1.99–2.72),alsowithhighlevelsof hetero-geneity between the 14 articles that presented this value (Q(13)=1117.08;P<0.001;I2=98.64%)(Fig.3).
Theposteriorjointspacealsopresentedhigh heterogene-ity amongthe16 includedsamples(Q(15)=440.70;P<0.001;
I2=97.37%)withameanvalueof2.22mm(95%CI:2.00–2.45)
(Fig.4). Study 1 Study 2 Study 3 Study 4 Study 10 Study 11 Study 12 Study 13 Study 14 Study 16 40 40 40 30 30 46 20 232 39 40 1.9 2.66 1.91 1.28 1.22 1.15 2.02 2.5 1.98 1.7 0.5 0.88 0.25 0.53 0.51 0.52 0.93 0.93 0.65 0.61 2.1 2.53 2 1.22 1.29 1.27 1.92 2.68 1.91 2.07 0.5 0.78 0.32 0.44 0.61 0.44 0.94 0.96 0.59 0.75 10.04% 3.63% 30.44% 7.94% 5.96% 12.45% 1.44% 16.30% 6.43% 5.37% –0.20 [ –0.42 , 0.02 ] 0.13 [ –0.23 , 0.49 ] –0.09 [ –0.22 , 0.04 ] 0.06 [ –0.19 , 0.31 ] –0.07 [ –0.35 , 0.21 ] –0.12 [ –0.32 , 0.08 ] 0.10 [ –0.48 , 0.68 ] –0.18 [ –0.35 , –0.01 ] 0.07 [ –0.20 , 0.34 ] –0.37 [ –0.67 , –0.07 ] Study n Mean Left Right RE Model Q(9)=9.94, p=.355, I2 =0.02% –0.75 –0.38 0.00 0.38 Mean difference (left -right)
0.75
100.00% –0.10 [ –0.17 , –0.03 ] SD Mean SD Weight Mean diff [95% CI]
AJS
Study 1 Study 3 Study 4 Study 10 Study 11 Study 12 Study 13 Study 14 Study 16 40 40 30 30 46 20 232 39 40 3.4 2.47 1.66 1.59 1.65 2.56 3.44 2.65 3.47 0.9 0.51 0.66 0.54 0.69 0.81 1 0.71 1.38 3.2 2.52 1.67 1.57 1.7 2.32 3.23 2.81 3.7 0.9 0.6 0.62 0.56 0.76 0.79 0.93 0.66 1.37 7.11% 15.54% 9.95% 12.72% 11.50% 4.71% 24.06% 11.14% 3.27% 0.20 [ –0.19 , 0.59 ] –0.05 [ –0.29 , 0.19 ] –0.01 [ –0.33 , 0.31 ] 0.02 [ –0.26 , 0.30 ] –0.05 [ –0.35 , 0.25 ] 0.24 [ –0.26 , 0.74 ] 0.21 [ 0.03 , 0.39 ] –0.16 [ –0.46 , 0.14 ] –0.23 [ –0.83 , 0.37 ] Study n Mean Left Right RE Model Q(8)=8.24, p=.410, I2 =19.31% –0.85 –0.42 0.00 0.42 Mean difference (left-right)
0.85
100.00% 0.04 [ –0.07 , 0.15 ] SD Mean SD Weight Mean diff [95% CI]
SJS
Fig.6–Meandifferencebetweenthesuperiorjointspaceontherightandleftjointsforeachstudyandglobally.
Themeanglobaldifferencesandthedifferencesamongthe studiesbetweentherightandleftanterior,superiorand pos-teriorjointspacesareshowinFigs.5–7respectively.Inallof thecomparisons,thedifferenceisclosetozero.
For the anterior joint space, the mean difference is −0.10mm (95% CI: −0.17; −0.03), without heterogeneity betweentheincludedsamples(Q(9)=9.94;P=0.355;I2=0.02%)
(Fig.5).
As for the mean difference between the right and left superiorjointspaces,thevaluewas0.04mm(95%CI:−0.07; 0.15), presenting low heterogeneity among the differences foundonthedifferentstudiesconsidered(Q(8)=8.24;P=0.410;
I2=19.31%)(Fig.6).
Theposteriorjointspaceoftherightandleftjointsshowed moderate heterogeneity between the samples (Q(9)=21.07;
P=0.012; I2=56.48%) with a mean global difference of
−0.04mm(95%CI:−0.17;0.10)(Fig.7).
Discussion
Joint space measurements have been used to assess the mandibular condyle position radiographically since this methodwasusedinlaminographies.36Sincethenthe
tech-nologyhasevolvedsomuchthatitisnowpossibletoassess thejointspacein3DradiographicimagingwithCT,CBCTand MRI.Therefore, asystematicreviewtoassesstherelevance ofthesemethodsandtheirscientificevidenceisnecessary.In thepresentstudy,allthearticlesaboutjointspaceassessment on2DradiographicexaminationoftheTMJwereexcludedas thesemethodshaveprovenloweraccuracybothintheimage acquisition process and in measurements, than 3D radio-graphicmethods.37MRIwasalsoexcludedbecausethisexam
isnot indicatedtoassess hardstructuresand,as boththe mandibularcondyleandtheglenoidfossajointspacelimits aremainlyboneandcartilage,thisisnotthebestexamfor
Study 1 Study 2 Study 3 Study 4 Study 10 Study 11 Study 12 Study 13 Study 14 Study 16 40 40 40 30 30 46 20 232 39 40 2.4 2.98 2.31 1.76 1.65 2.1 1.98 2.89 2 3.12 0.8 1.08 0.38 0.62 0.45 0.73 0.63 0.97 0.61 1.23 2.1 3.26 2.32 1.96 1.87 2.32 1.87 2.63 2.1 3.4 0.7 0.94 0.44 0.69 0.45 0.83 0.51 1.04 0.63 1.38 9.22% 6.47% 14.54% 9.15% 12.68% 9.52% 8.50% 14.43% 11.01% 4.48% 0.30 [ –0.03 , 0.63 ] –0.28 [ –0.72 , 0.16 ] –0.01 [ –0.19 , 0.17 ] –0.20 [ –0.53 , 0.13 ] –0.22 [ –0.45 , 0.01 ] –0.22 [ –0.54 , 0.10 ] 0.11 [ –0.25 , 0.47 ] 0.26 [ 0.08 , 0.44 ] –0.10 [ –0.37 , 0.17 ] –0.28 [ –0.85 , 0.29 ] Study n Mean Left Right RE Model Q(9)=21.07, p=.012, I2 =56.48% –0.86 –0.43 0.00 0.43 Mean difference (left-right)
0.86
100.00% –0.04 [ –0.17 , 0.10 ] SD Mean SD Weight Mean diff [95% CI]
PJS
accuratelydeterminejointspace measurements.38
Further-more,allthearticlesincludingextensivetreatmentthatcould significantlyinfluencethejointspace,likeorthodontic treat-mentandsplinttherapy,havebeenexcluded.Finally,studies withsamplesexclusivelyonthemixedandearlypermanent dentitionwereexcludedas,accordingtosomeauthors,the mandibularcondyleisnotcompletelyformedbeforetheend ofthe growth, inother words until15–16 years old.39 The
exclusionofstudiesthatonlyassessedthejointspaceinless thantwoseparatepointsoftheTMJwasduetothedefinition ofthepositionofanobjectinspacedependingonthree coor-dinates.Accordingtothis,jointspaceanalysisdoneonlyon onepointdoesnotprovideenoughinformationtodetermine thepositionofthemandibularcondyleintheglenoidfossa.
The meta-analysis showed high levels of heterogeneity amongtheselectedstudieswhatispossiblyexplainedbythe high heterogeneity betweenthe selected studies:the sam-plesizesvaries between2427 and 464patients,31 thereare
differentsamplesfrom carefullyselected normaljoints19,27
topatientspresentingmalocclusions21,26,31–33,35or
temporo-mandibulardisorders23,24 anddifferentmethods19,25,27were
usedtodeterminethejointspaces(asshowedduringthe sys-tematicreview).Allthesefactorsmayhavecontributedtohigh heterogeneitybetweenthesamples.
Theresultsfromthisinvestigationalsoshowedstatistically significantdifferencesbetweentherightandleftjointsforthe anteriorjointspace(AJS),whiletheoppositewasfoundforthe posteriorjointspace(PJS).However,themeandifferencewas −0.10mm(95%CI:−0.17;−0.03)and,therefore,itisveryclose to0.Moreover,comparisonoftheAJSandthePJSbetweenthe rightandleftjointswasperformedon10oftheretrieved arti-cles,andonlytwoshowedstatisticallysignificantdifferences fortheAJS.Thefactthatoneofthestudieshadthebiggest sample(n=232)withapowerof16.30%onthemeta-analysis mightexplainthestatisticallysignificantresultforthe AJS. Aprevious study suggestedthat this asymmetry would be relatedtonormallyasymmetriccranialbasesorside prefer-encesduringmastication.31Moreover,mostpatientsshowa
centricrelation-centricocclusiondiscrepancy,usuallycaused byaposteriorinterferencethatisunilateralinmostcases.40–43
Asanadaptation,thecondylesmightmoveasymmetrically andwhilethecontra-lateralcondylemovessagittaly,the ipsi-lateralrotatestoestablishamorebalanceddentalocclusion. Theabsence ofstatisticallysignificant differences between rightandleftjointsforthePJSmaybeexplainedby stabiliza-tionoftheTMJposteriorlybythearticulardisk.
Conclusion
There isinsufficient scientificevidence concerningsagittal jointspacesoftheTMJ,astherearenoarticleswithhighlevel ofevidenceandonlyonestudy presents moderatelevel of evidence.
Althoughno high level ofevidencestudies were found, theauthorsdecidedtoperformameta-analysisofthemean sagittaljointspacesoftheTMJandthedifferencesbetween therightandleftjoints.Themeananteriorjointspacewas 1.86mm (CI 95%: 1.62–2.10), the superior joint space was 2.36mm(CI 95%:1.99–2.72) andthe posterior was2.22mm
(CI95%:2.00–2.45).However,ahighlevelofheterogeneitywas found,meaningthattheseresultsmustbeconsideredwith care.However,theresultsofthemeta-analysissuggestthat theposteriorjointspaceislargerthantheanteriorjointspace. Thisresultisinaccordance tothe conceptinuse that the mandibularcondylemustbeonthe mostsuperior-anterior positionintheglenoidfossa.5,8–10
Theanalysisofthedifferencebetweentherightandleft sagittal joint spaces showed statistically significant differ-encesbetweenthetwojointsintheanteriorjointspace,but notinthesuperiorandposteriorjointspaces.
Moreresearchwithmoresolidmethodologyisneededon thistopic.
Conflicts
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