Durão et al. Progress in Orthodontics 2013, 14:31http://www.progressinorthodontics.com/content/14/1/31

REVIEW Open Access

Validity of 2D lateral cephalometry inorthodontics: a systematic reviewAna R Durão1*, Pisha Pittayapat2, Maria Ivete B Rockenbach3, Raphael Olszewski4, Suk Ng5, Afonso P Ferreira6

and Reinhilde Jacobs2

Abstract

Lateral cephalometric radiography is commonly used as a standard tool in orthodontic assessment and treatmentplanning. The aim of this study was to evaluate the available scientific literature and existing evidence for thevalidation of using lateral cephalometric imaging for orthodontic treatment planning. The secondary objective wasto determine the accuracy and reliability of this technique. We did not attempt to evaluate the value of thisradiographic technique for other purposes. A literature search was performed using specific keywords on electronicdatabases: Ovid MEDLINE, Scopus and Web of Science. Two reviewers selected relevant articles, corresponding topredetermined inclusion criteria. The electronic search was followed by a hand search of the reference lists ofrelevant papers. Two reviewers assessed the level of evidence of relevant publications as high, moderate or low.Based on this, the evidence grade for diagnostic efficacy was rated as strong, moderately strong, limited orinsufficient. The initial search revealed 784 articles listed in MEDLINE (Ovid), 1,034 in Scopus and 264 articles in theWeb of Science. Only 17 articles met the inclusion criteria and were selected for qualitative synthesis. Resultsshowed seven studies on the role of cephalometry in orthodontic treatment planning, eight concerningcephalometric measurements and landmark identification and two on cephalometric analysis. It is surprising that,notwithstanding the 968 articles published in peer-reviewed journals, scientific evidence on the usefulness of thisradiographic technique in orthodontics is still lacking, with contradictory results. More rigorous research on a largerstudy population should be performed to achieve full evidence on this topic.

Keywords: Cephalometry; Orthodontics; Systematic review; Reliability; Validity

ReviewIntroductionSince the introduction of lateral cephalometric radio-graphy in 1931 by Broadbent in the USA and by Hofrathin Germany, this radiograph and its related analyses havebecome a standard tool in orthodontic assessment andtreatment planning [1-3]. Lateral cephalometric radio-graphs are systematically collected prior to orthodontictreatment in many European countries [3,4]. Neverthe-less, the real value of this imaging technique for diagno-sis and planning of orthodontic treatment remainsuncertain [2-7]. Some authors showed that an adequateorthodontic diagnosis and treatment plan could not be

* Correspondence: paula.o.reis@gmail.com1Department of Dental Radiology, Faculty of Dental Medicine, University ofPorto, Porto, PortugalFull list of author information is available at the end of the article

© 2013 Durão et al.; licensee Springer. This is aAttribution License (http://creativecommons.orin any medium, provided the original work is p

performed without comparing a lateral cephalometricradiograph before and after orthodontic treatment andthat treating skeletal malocclusions without a cephalo-metric radiograph introduced serious errors [8]. Whileonly a small percentage of the orthodontic treatmentplanning are modified based on lateral cephalometricradiographic analysis [6], it could adjust some aspects oftreatment planning, such as tooth extraction, extractpattern and anchorage features [2,9].The controversy about the correct use of the lateral

cephalometric radiograph is also present in orthodontictextbooks where guidelines for orthodontic imaging arenot expressed properly [10]. Several radiographic tech-niques, like panoramic and full-mouth periapical radio-graphs, used in orthodontics are found unproductive,since it provides duplicate information [4]. The latter isan important finding as the use of ionising radiation

n Open Access article distributed under the terms of the Creative Commonsg/licenses/by/2.0), which permits unrestricted use, distribution, and reproductionroperly cited.

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should always be justified and kept ‘as low as reasonablyachievable’ and definitely in children as radiographs areoften performed at different time intervals during ortho-dontic treatment [11,12]. Even when there are means tooptimise radiation dose of cephalometric radiographs, theprimary issue is to justify the decision to take a lateralcephalogram prior to orthodontic treatment [10,11,13-15].The present systematic review was initiated by the

fact that three-dimensional (3D) cephalometric analysisis emerging, while there is still lack of scientific evi-dence on the validity and reliability of two-dimensional(2D) cephalometric imaging for orthodontic treatmentplanning [2,3].Therefore, the aims of this study were to systematically

review the available scientific literature and to evaluate theexisting evidence about the validation of lateral cephalo-metric radiograph in orthodontics. This review also stud-ied the accuracy and reliability of lateral cephalograms andits cephalometric analysis.

Materials and methodsInformation sourcesA comprehensive electronic database search to iden-tify relevant publications was conducted, and thereference lists in relevant articles were searched ma-nually for additional literature. We set no languagelimitations, although we did not attempt to explorethe informally published literature: conference pro-ceedings and abstracts of research presented at con-ferences and dissertations. The following databaseswere searched: Ovid Medline (1946 to 11 January2012), Scopus (to 11 January 2012) and Web of Sci-ence (1899 to 11 January 2012).

Search strategyWe developed the search strategy with the help of an in-formation specialist at King's College London DentalInstitute in London. The searches did not have a datelimit and were not restricted to particular types of studydesign. The search strategy focused on the followingterms: Cephalometr* and (orthodontic* or ‘orthodontictreatment planning’) and (‘efficacy’ or ‘reproducibility’or ‘repeatability’ or ‘reliability’ or ‘accuracy’ or ‘validity’or ‘validation’ or ‘precision’ or ‘variability’ or ‘efficiency’or ‘comparison’) not (‘Cone-Beam Computed Tomog-raphy’ or ‘Three-Dimensional imaging’ or ‘Cone BeamComputed Tomography’ or ‘Cone Beam CT’ or ‘Volu-metric Computed Tomography’ or ‘Volume ComputedTomography’ or ‘Volume CT’ or ‘Volumetric CT’ or‘Cone beam CT’ or ‘CBCT’ or ‘digital volume tomography’or ‘DVT’ or ‘Spiral Computed Tomography’ or ‘SpiralComputer-Assisted Tomography’ or ‘Spiral ComputerizedTomography’ or ‘spiral CT Scan’ or ‘spiral CT Scans’or ‘Helical CT’ or ‘Helical CTS’ or ‘Helical Computed

Tomography’ or ‘Spiral CAT Scan’ or ‘Spiral CAT Scans’or ‘3D’ or ‘3-D’ or ‘three dimension*’).

Study selectionAt the first stage, two reviewers (experienced dento-maxillofacial radiologists) independently screened thetitles of the retrieved records, and only the titles re-lated to 2D cephalometry, radiographs for orthodontictreatment and tracings were included. Next, the ab-stracts of the retrieved publications were read by thetwo observers and categorised according to the studytopic. An article had only to be justified by one obser-ver to be included for the second selection phase. Allarticles of interest in languages other than Englishwere included. Of these two were included, one articlewas written in Portuguese and another in French.Eligibility of potential articles was determined by ap-plying the following inclusion criteria to the articleabstracts: (1) technical efficacy, (2) diagnostic accur-acy efficacy, (3) diagnostic thinking efficacy, (4) thera-peutic efficacy, (5) patient outcome efficacy or anycombination of the previous items as published byFryback and Thornbury [16]. The other inclusion cri-teria were (1) accuracy, (2) reliability, (3) validity oflateral cephalometric radiograph, (4) landmark identi-fication on tracings (intra- and inter-observer errors)and (5) the effect of using 2D cephalometry on theorthodontic treatment plan.Diagnostic accuracy efficacy was defined as follows:

1. Observer performance expressed as overallagreement, kappa index or correlation coefficients

2. Diagnostic accuracy as percentage of correctlandmark identification and further tracing analysis,validity and effectiveness of cephalometry inorthodontic treatment planning

3. Sensitivity, specificity or predictive values oflandmark identification

Diagnostic thinking efficacy was defined as follows:

1. Percentage of cases in a series in which images werejudged ‘helpful’ for the diagnosis

2. Difference in clinicians' subjective estimateddiagnosis probabilities before and after evaluation ofthe cephalogram

Therapeutic efficacy was defined as follows:

1. Percentage of times the image was judged helpful inplanning management of the patients in a case series

2. Percentage of times therapy-planned pre-visualization of a lateral cephalogram needed to bechanged after the image information was obtained

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3. Percentage of times clinicians prospectively statedtherapeutic choices needed to be changed afterevaluating a cephalogram

4. Whether different analyses lead to differentdecisions on treatment planning

5. Intra- and inter-observer identification errors6. Reliability of landmark identification

The analysis had to be based on primary materialsor comprise a review on efficacy. When an abstract wasconsidered by at least one author to be relevant, it wasread in full text. At the second stage, the full texts wereretrieved and critically examined. Reference lists ofpublications that had been found to be relevant in thefirst stage were hand-searched, and articles containingthe words ‘cephalometry’, ‘lateral cephalometric radio-graphy’, together with ‘treatment planning’, ‘orthodonticradiographs’, ‘landmark identification’ and ‘error’ wereselected. Book chapters and reviews were excludedsince the aim of this systematic review was to evaluateprimary studies.

Data extractionData was extracted with the aid of protocol 1 (Table S1in Additional file 1). It was established by reading therelevant literature on how to critically evaluate studiesabout diagnostic methods. To minimise bias, two ob-servers independently evaluated the quality and validityof original studies according to the quality assessment ofdiagnostic accuracy studies tool using protocol 2 (qualityassessment of studies of diagnostic accuracy included insystematic reviews - QUADAS) (Table S2 in Additionalfile 1) [17]. When there was any disagreement con-cerning the relevance of an article, it was resolved by adiscussion between the two reviewers. Each observerpresented their arguments, and further discussion washeld until a consensus was reached. Before the assessment,the protocols were tested for ten publications. A furtherfive publications were read to calibrate the two reviewersregarding the criteria in protocol 2. Only publications thatwere found to be relevant to the reviewer in both proto-cols 1 (diagnostic efficacy) and 2 (level of evidence) wereultimately included. The quality and internal validity (levelof evidence) of each publication was judged to be high,moderate or low according to the criteria in the followingsubsection [18].

Levels of evidence and criteria for evidence synthesis

High level of evidence A study was classified with highlevel of evidence if it fulfilled all of the following criteria:

� There was an independent blind comparisonbetween test and reference methods.

� The population was described so that the status,prevalence and severity of the condition were clear.The spectrum of patients was similar to thespectrum of patients on whom the test method willbe applied in clinical practice.

� The results of the test method being evaluated didnot influence the decision to perform the referencemethod(s).

� Test and reference methods were well describedconcerning technique and implementation.

� The judgments (observations and measurements)were well described considering diagnostic criteriaapplied and information and instructions to theobservers.

� The reproducibility of the test method wasdescribed for one observer (intra-observerperformance) as well as for several (minimum 3)observers (inter-observer performance).

� The results were presented in terms of relevant dataneeded for necessary calculations.

Moderate level of evidence A study was assessed tohave a moderate level of evidence if any of the above cri-teria were not met. On the other hand, the study wasassessed not to have deficits that are described below forstudies with a low level of evidence.

Low level of evidence A study was assessed to have alow level of evidence if it met any of the following criteria:

� The evaluation of the test and reference methodswas nonindependent.

� The population was not clearly described, and thespectrum of patients was distorted.

� The results of the test method influenced thedecision to perform the reference method.

� The test or the reference method or both were notsatisfactorily described.

� The judgments were not well described.� The reproducibility of the test method was not

described or was described for only one observer.� The results could have a systematic bias.� The results were not presented in a way that

allowed efficacy calculations to be made.

Rating conclusions according to evidence gradeThe scientific evidence of a conclusion on diagnostic effi-cacy was judged to be strong, moderately strong, limitedor insufficient depending on the quality and internal vali-dity (level of evidence) of the publications assessed [18,19]:

� Strong research-based evidence: at least two of thepublications or a systematic review must have ahigh-level of evidence.

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� Moderately strong research-based evidence: one ofthe publications must have a high level of evidenceand two more of the publications must have amoderate level of evidence.

� Limited research-based evidence: at least two of thepublications must have a moderate level of evidence.

� Insufficient research-based evidence: scientificevidence is insufficient or lacking according to thecriteria defined in the present study.

Synthesis of evidenceThe results of this review were described narratively.No meta-analyses were attempted because of lack oforiginal studies.

ResultsThe number of articles reviewed in each phase to per-form this systematic review is presented in the PRISMAflow diagram (Figure 1) [20]. The initial search revealed784 articles listed in Medline (Ovid), 1,034 in Scopusand 264 articles in the Web of Science. The second stageof the search protocol was to retrieve the reference listsof the selected articles, which yielded 14 additional arti-cles of interest. After excluding 1,128 duplicates, 968 ar-ticles remained for review. In the first phase selection,the observers screened the articles by reading titles and

Records identified through database

searching (n =2082)

Additional records identified through other

sources (n =15)

Records after duplicates removed (n = 968)

Records excluded (n =765)

Records screened (n = 968)

Full-text articles assessed for eligibility

(n =35)

Full-text articles excluded, with

reasons (n =19)

Studies included in qualitative synthesis

(n =17)

Iden

tifi

cati

onSc

reen

ing

Elig

ibili

tyIn

clud

ed

Figure 1 Methodology followed in the article selection process(adapted from Moher et al. [20]).

abstracts. Articles that were not eligible because ofirrelevant aims and were not directly related to thissystematic review were excluded, thus 203 articlesremained for further reading. Thirty-five articles wereassessed for eligibility.After screening all the articles using protocols 1 and 2,

17 articles met the inclusion criteria and were selectedfor qualitative synthesis and appraised to present somelevel of evidence. All articles that remained after screen-ing passed the qualitative synthesis.These 17 articles were categorised by topics as follows:

7 studies on the role of cephalometry on the orthodontictreatment planning, 8 studies on cephalometric mea-surements and landmark identification and 2 studies oncephalometric analysis.

Role of cephalometry on the orthodontictreatment planningSeven articles related to the importance and contribu-tion of cephalometry to orthodontic treatment planningwere found (Table 1). Six of the publications were foundto have low levels of evidence [2-4,6,9,10] and one classi-fied as moderate level of evidence [7].

Cephalometric measurements and landmark identificationOnly eight articles were selected as eligible in this cat-egory (Table 2). Five publications presented a moderatelevel of evidence [21-25], while the other three wereidentified as having a low level of evidence [5,26,27].

Cephalometric analysisTwo publications with low-level evidence were found[28,29]. The studies did not use any reference standards,and the number of observers was not stated. The studydesigns were also not clearly explained (Table 3).

DiscussionThe validity, efficacy and contribution of cephalometryin orthodontic treatment planning remain questionable[2]. In 2002, 90% of orthodontists in the USA routinelyperformed cephalometric radiographs [3]. This system-atic review was performed to assess the validity and reli-ability of 2D lateral cephalometry used for orthodontictreatment planning as well as the errors that can occuron 2D tracing. Despite the abundant amount of articlesfound on lateral cephalometry (n = 968), it is surprisingthat the present systematic review could only identifyvery few studies (n = 16, 1.6%) on its validity and reli-ability. This finding underlines the need for the presentstudy and is an important cross point, considering thefact that we are flooding into 3D cephalometric studiesnowadays. Apart from our findings, 2D cephalometry hasother specific limitations, such as orthognatic surgery, air-way and growth assessment and skeletal maturation. In

Table 1 Publications related to the importance and contribution of cephalometry on the orthodontic treatment planning

Authors(year)

Aim of the study Observers Subjects Design of the study Statistical method Results according to authors Level ofevidence

Sillinget al. [9]

Assess usefulness ofcephalometric analysis

24 orthodontists 6 patients Stratified random design: 12orthodontists analysed 6 patients withcephalograms and 12 orthodontistsstudied 6 patients without cephalogram

Not referred Class I patient: disagreement onextractions, anchorage and growthpotential decisions

Low

No need for lateral cephalometry,except for atypical class II division 1patients, by 4 orthodontists

Anchorage problems SS betweenpatients with and without lateralcephalogram

Brukset al. [6]

Evaluation of lateralcephalometric andpanoramic radiography

4 dentists andseniororthodontist

70 patients Clinical evaluations and treatment planby 4 dentists:

Descriptive statistics andstatistical analyses withcomputer software. Kruskal-Wallistest to evaluate differencesbetween groups

Impact on diagnosis relating to theordering sequence of cephalogram:first choice, 68%; second choice,73%; third choice, 80%

Low

1. Study casts + photographs 93% of cases: same treatment planbefore and after radiographicanalysis2. Adding radiographs

Pae et al.[7]

Examine the link betweenlateral cephalograms andocclusal trays

16 orthodontists 80 patients T1: casts evaluated; T2 (1 week later):casts + lateral cephalograms

Rash model, regression plots,two-way ANOVA, post hocmultiple comparison Bonferroniand paired t test

Class II division 2 patients: 126extractions planned at T1; 80 at T2

Moderate

A lateral cephalogram influenceddegree of severity, but not thedifficulty of treatment

Nijkampet al. [3]

Influence of lateralcephalometry on treatmentplan

10 post-graduatetrainees and4 orthodontists

48 patients Randomised crossover design - T1: casts,T2 (1 month after): with lateralcephalometry and tracing, and T3 and T4(repeated after 1 and 2 months)

Overall proportion of agreement Consistency of treatment plan wasNS between the use only of dentalcasts or with additionalcephalometry

Low

Influence of cephalometrics onorthodontic treatment planning: NS

Devereuxet al. [2]

Influence of lateralcephalometry on treatmentplan

114 orthodontists 6 patients 3 groups: (a) no lateral cephalogram andtracings, (b) some with lateralcephalogram and tracings and (c) allwith lateral cephalogram and tracings

Chi-square and binarylogistic regression

Treatment plan changed forextraction pattern (42.9%),anchorage reinforcement (24%) anddecision to extract (19.7%)

Low

Class I patient: lateral cephalogramless times ordered. Only patientswhere treatment plan changedafter its analysis

NS impact of cephalometrics ontreatment plan

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Table 1 Publications related to the importance and contribution of cephalometry on the orthodontic treatment planning (Continued)

Atchisonet al. [4]

Determine quantitativelythe diagnosis andtreatment plan informationafter radiograph evaluation

39 orthodontists 6 patients A 2-h interview for diagnosis andtreatment planning of 6 cases. Studycast, intra- and extra-oral photographs,tracing and clinical findings available.

Analysis of variance withrepeated measures andcovariance, homogeneity valueand descriptive statistics

98% of cases: at least one of theradiographs unproductive

Low

A radiograph only if judged helpful 3/4 of radiographs did not provideinformation to change diagnosisand treatment plan

Atchisonet al. [10]

Identify selection criteriafor ordering orthodonticradiographs

39 orthodontists 6 patients A 2-h interview for diagnosis andtreatment planning of 6 cases. Studycast, intra- and extra-oral photographs,tracing and clinical findings available

Not referred 14.4% of radiographs ordered forskeletal relationship of the jaws

Low

Lateral cephalograms accounted for34% of required information

26% of all ordered radiographsproduced modifications ondiagnosis or treatment plan

Pretreatment lateral cephalogramrequired in all patients needingorthodontic treatment

NS, non-significant.

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Table 2 Publications concerning landmark identification

Authors(year)

Aim of the study Observers Subjects Design of the study Statistical method Results according to authors Level ofevidence

Baumrindand Frantz[21]

Quantification of errorsin landmarkidentification

5 observers 20 lateral skullradiographs

Observer identified 16 cephalometriclandmarks on a transparent plastictemplate

Mean, standarddeviation and standarderrors

Least r ble landmarks: gonion and lower incisor x

Moderate

Effects of errors onangular and linearmeasurements

Kvam andKrogstad [27]

Evaluation ofmeasurements inlateral cephalograms.

18 observers 3 lateral skullradiographs

Hand cephalometric analysis made byeach participant, 8 angles measured

Mean and standarddeviation

16 out 24 angular measurements: lessvariabi in post-graduates than students

Low

Assess influence ofknowledge and impactof angular errors

In 7 m rements, no difference was observed

Post-g ates' tracings used for diagnosticpurpo

Standa eviation of students greater thanpost-g ates

Haynes andChau [22]

Evaluation of landmarkidentification onDelaire analysis

2 observers 28 lateral skullradiographs

Establish a co-ordinate system formeasurement on tracings

Mean deviation Intra-o rver: NS differences between valuesof T1 a T2 tracings

Moderate

Comparison with dataof conventionalcephalometry

Radiographs were traced twice byeach observer (3 to 4 weeks)

Inter-o rver: differences between theaverag mean values on tracings were NS foreither y co-ordinates

Ahlqvist et al.[26]

Study the magnitudeof projection errors onmeasurements incephalometry

1 observer A patient wasmodelled

Computer software designed to allowmovement of model on the 3 axes.The magnitude of errors was studiedby a diagram

Measurement errorsstudied by a diagramwith the relative lengthof distances betweenmodelled landmarks

Less th 1% error on length measurements ifhead i tated up to 5°

Low

Study the effects ofincorrect patientposition on linearmeasurements

Head r ted more than 5° the error is increased

Houstonet al. [23]

Evaluate errors atvarious stages ofmeasurements incephalometricradiograph

4 observers 24 lateralcephalograms

2 radiographs of the same patient Analysis of variance Error v nce is small (radiograph andtracing hen compared with the varianceamong oups

Moderate

Radiographs traced on acetate sheetby each observer at T1/T2 (1-weekinterval)

SNA h higher tracing variance thanSNB d o the difficulty to identify point A

Kamoen et al.[24]

Determine errorsinvolved in landmarkidentification and itsconsequence totreatment results

4 observers 50 lateralcephalograms

Items studied: (1) accuracy of digitiser,(2) intra- and inter-observer digitisingerrors and (3) intra- and inter-observertracing errors

(1) Levene's test forhomogeneity ofvariances, (2) one-wayANOVA and (3) Levene'stest for homogeneity

(1) NS ances of co-ordinates for landmark atdiffere ositions on the digitiser. (2) NS intra-and in bserver differences in digitisation. (3)S diffe es in landmarks and in the samelandm on different cephalograms andbetwe bservers

Moderate

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Table 2 Publications concerning landmark identification (Continued)

Tng et al. [25] Evaluate the validity ofdental and skeletallandmarks. Effect onangles and distances.

1 observer 2 lateralcephalogramsof 30 dryskulls

Steel balls placed in 15 dental andskeletal landmarks

Mean and standarddeviation

7 out of 10 skeletal and 5 dental landmarkswere NS (p < 0.05)

Moderate

Two radiographs taken with andwithout the markers and digitised.Measurements compared

4 angles (SNA-SN/MnP, MxP/MnP and LI/MnP)and 3 distances (N-Me, MxP-Me and Lie to APg)were invalid (p < 0.05)

Major errors in angles with dental landmarks

Bourriauet al. [5]

Analyse the influenceof film-object distanceand type of receptoron landmarkidentification

53orthodontists

4 lateralcephalogramsof the samepatient

19 cephalometric landmarks on eachfilm

Mean NS difference between 2 imaging receptorsneither between 2 cephalograms achieved by 2equipments (p > 0.99)

Low

2 radiographs performed at anequipment with a 4-m arm and 2 in a1.50-m arm equipment with 2different imaging receptors (digitaland indirect digital)

Results obtained by cephalometric analysis wasjudged: ‘very important’ for 20.5%, ‘important’for 70%, ‘less important’ for 8% and ‘accessory’for 1 participant

NS, non-significant; S, significant.

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Table 3 Publications on cephalometric analysis

Authors(year)

Aim of the study Observers Subjects Design of thestudy

Statisticalmethod

Results according to authors Level ofevidence

De Abreu[28]

Assessment criteria ofunanimity for differentcephalometric analyses

Not referred 129patients

Diagnosis performedbased on Ricketts,Steiner, Cervera andCoutandcephalometricanalyses

Notreferred

3 out of 61 cases with similardiagnosis. In 23 cases, 4 analysesachieved similar diagnosis. In 13cases, 3 different diagnoses wereobtained. In 8 cases, thediagnosis was different for class IIand class III

Low

Abdullahet al. [29]

Examine accuracy andprecision of Steiner analysisfor changes on ANB angle,the Pg-NB distance and upperand lower incisor positions

Differentorthodontists(notreference tothe number)

275patients

Radiographs tracedand analysed byorthodontistsaccording to theSteiner analysis

Paired ttest, meanandstandarddeviation

The predicted change in L1(lower incisor) to NB wasunderestimated by 0.8 mm. Onlythe prediction for pogonion andNB showed improvement of theprecision (30%)

Low

Radiographs at theend of treatment(T2) were traced byone observer

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order to be included in this systematic review, publicationshad to satisfy pre-defined methodological criteria. Twoprotocols were used regarding the search strategy, onebased on diagnostic methods and the second based on theQUADAS tool [17]. The ‘levels of evidence’ for assessingthe quality and internal quality of each publication in-cluded in this review - how well the study was designed,how reliable its results appeared to be and the extent towhich it addressed the questions posed - were modifiedaccording to the Oxford Center for Evidence-Based Medi-cine levels of evidence for diagnostic methods (CBEM)[18]. Only publications assessed to present a high or mod-erate level of evidence can form the basis for any scientificconclusions. Ten articles were identified as low level ofevidence, five had moderate level and only one showedhigh level of evidence.All retrieved articles, assessing the importance and

contribution of lateral cephalometric radiograph inorthodontic treatment, concluded that there is no sig-nificant difference on treatment planning decision withor without the evaluation of the lateral cephalogram.However, it should be considered that the suitable stud-ies in this review were based on small samples ratherthan large cohorts representing the entire population. Inone study, the sample used was restricted (six patients)[2]. Furthermore, the short time lapse between observa-tions in some studies did not allow a full washout effect,which could lead to the repetition of the results [4,7,10].The latter bias is further strengthened by the fact thatrecognition factors were often included, e.g. the possibil-ity of identifying patient by photographic visualisation aspart of the examination. On the other hand, in onepaper, only dental casts were presented to the observers,which might also lead to error since it does not mimicthe clinical situation. Sample bias is also suspected basedon the fact that selection of subjects is often poorly de-scribed or unclear [2,6,9], like the questions made to the

observers that were not stated by any questionnaire [6],and in one article, observers were forced to choose yes/no answers, which again do not perfectly simulate thereality [3].In the two articles by Atchison et al. there was the

possibility to identify patients as well as sample size wasvery restricted (six patients). There was no repetition ofthe questionnaire to test the variability between answers[4,10]. When it comes to the validity and reliability ofcephalometric analysis, several errors should be consid-ered: landmark identification, tracing and measuring,and magnification of certain anatomical structures.Landmarks placed in anatomically formed edges are

easier to identify, while some landmarks placed oncurves are more prone to error. The gonion and lowerincisor apex are the least consistent landmarks [21]. Fur-thermore, landmarks such as point A have a higher vari-ance than others like point B because of wider variationand anatomical localisation of point A [23]. Dental land-marks tend to have poorer validity than skeletal land-marks. Also, when landmarks are located on a curve likepoint A, point B or pogonion, the error is larger [25].The evidence shows that landmark identification is agreat source of error in 2D lateral cephalometry [24].Major errors in angles with dental landmarks may occur[25]. In addition, different levels of knowledge and expe-riences between the observers also lead to varying re-sults on landmark identification. In a study using 18observers, in which 13 were dental students and 5 werepost-graduate students, post-graduate's revealed lowerintra-observer tracing variance than dental students [27].Patient positioning during the procedure is also very im-portant to avoid errors on measurements and landmarkidentification [23,26]. The publication of Ahlqvist et al.[26] was assessed with a low level of evidence becausethere was only one observer. A similar classification oc-curred for Bourriau et al. [5], intra-observer agreement

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could not be evaluated and the number of radiographs(n = 4) used was very low. Kvam and Krogstad's [27]publication also used a limited number of subjects (n =3). The choice of the observers also plays an importantrole on the results. Eighteen observers, in which 13 weredental and 5 were post-graduate students, participatedin their study [27]. The latter can also bias results be-cause of the distinct level of education and expertise dueto the lack of experience of the observers.Regarding the influence of magnification, Bourriau et al.

[5] could not identify significant differences betweenequipment with a 4-m distant cephalometric machine anda 1.5-m distant cephalometric arm. Despite that, it shouldbe considered that distance varying between the X-raysource and the image receptor will always cause a degreeof magnification, the larger the distance, the lower themagnification. A focus object distance of 4 m in 2D cepha-lometric equipment is usually favoured for the reducedradiation burden and lack of enlargement, while an equip-ment with 1.5-m arm has a direct advantage of being com-pact and integrated in a multimodal system as well ashaving an increased resolution. On the other hand, pano-ramic equipment with a cephalometric arm at a 1.5-m dis-tance may present shortcomings in enlargement factorsand superimposition of the bilateral structures more dis-tant from the midsagittal plane, considering the less mag-nified structures on the side nearby the image receptor[30]. We were not able to identify studies correlating land-mark identification errors in lateral cephalograms andtheir influence on the outcome of patient treatment.Finally, in 1982, De Abreu showed that different 2D

cephalometric analysis may lead to different diagnosis ofthe same patient, varying the diagnosis between class IIand class III in 8 out of 129 cases [28]. Also, Abdullahet al. [29] found that Steiner's cephalometric analysis isnot accurate enough to plan orthodontic treatment. Bothpublications were assessed with low levels of evidence.In both publications, the number of observers was notreferred. Furthermore, the statistical method used wasnot mentioned in [28].The accuracy in the evaluation of the results, as well

as producing changes in the treatment compared withclinical evaluation, seems to be one of the major bene-fits of 2D cephalometry. Risk-benefit analysis should becarefully evaluated.

ConclusionThe existing literature suggested that lateral cephalometricradiographs have been used without adequate scientificevidence of its usefulness and are often used prior to treat-ment. There is a need for diagnostic accuracy studies on2D lateral cephalometric radiograph where standardisedmethodological criteria for diagnostic thinking efficacyand therapeutic efficacy are incorporated. This systematic

review has shown that the evidence to agree or disagreeon the usefulness of this radiographic technique in ortho-dontics today is limited. Lateral cephalograms are used inmany occasions for reasons other than clinical diagnosisor treatment, such as medico-legal reasons in a teachingenvironment or due to a lack of experience in the field.These conclusions are rather worrying. The use of radiationin children should be even better justified, and scientificevidence of that justification seems lacking. At present,there is a need for further studies on larger patient po-pulations, focusing on the therapeutic efficacy of lateralcephalograms.

Additional file

Additional file 1: Protocols 1 and 2. The questionnaire for the initialselection of publications is shown. QUADAS-2 tool protocol was used toevaluate the methodology of included studies.

Competing interestsThe authors declare that they have no competing interests.

Authors’ contributionsARD and IBR selected and read the papers included in this systematicreview. ARD drafted the manuscript. PP, SN, RO, APF and RJ participated inthis systematic review by giving scientific support. All authors read andapproved the final manuscript.

AcknowledgementsWe are grateful to Sonya Lipczynska, from the research and learning supportfrom the library services at King's College London, for her support on thesearch strategy.

Author details1Department of Dental Radiology, Faculty of Dental Medicine, University ofPorto, Porto, Portugal. 2Oral Imaging Center, OMFS-IMPATH research group,Dept Imaging & Pathology, Faculty of Medicine, University of Leuven,Leuven, Belgium. 3Department of Surgery, Dentistry School, PontificalCatholic University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul,Brazil. 4Department of Oral and Maxillofacial Surgery, Université Catholiquede Louvain, Brussels, Belgium. 5Department of Dental Radiology, Guy's, King'sand St. Thomas' Dental Institute, King's College London, London, UK.6Department of Orthodontics, Faculty of Dental Medicine, University of Porto,Porto, Portugal.

Received: 31 May 2013 Accepted: 19 July 2013Published: 20 September 2013

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doi:10.1186/2196-1042-14-31Cite this article as: Durão et al.: Validity of 2D lateral cephalometry inorthodontics: a systematic review. Progress in Orthodontics 2013 14:31.

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