Conventional Cephalometric Radiographs Research Articles

Effectiveness of cone-beam computed tomography-generated cephalograms using artificial intelligence cephalometric analysis

Lateral cephalograms and related analysis constitute representative methods for orthodontic treatment. However, since conventional cephalometric radiographs display a three-dimensional structure on a two-dimensional plane, inaccuracies may be produced when quantitative evaluation is required. Cone-beam computed tomography (CBCT) has minimal image distortion, and important parts can be observed without overlapping. It provides a high-resolution three-dimensional image at a relatively low dose and cost, but still shows a higher dose than a lateral cephalogram. It is especially true for children who are more susceptible to radiation doses and often have difficult diagnoses. A conventional lateral cephalometric radiograph can be obtained by reconstructing the Digital Imaging and Communications in Medicine data obtained from CBCT. This study evaluated the applicability and consistency of lateral cephalograms generated by CBCT using an artificial intelligence analysis program. Group I comprised conventional lateral cephalometric radiographs, group II comprised lateral cephalometric radiographs generated from CBCT using OnDemand 3D, and group III comprised lateral cephalometric radiographs generated from CBCT using Invivo5. All measurements in the three groups showed non-significant results. Therefore, a CBCT scan and artificial intelligence programs are efficient means when performing orthodontic analysis on pediatric or orthodontic patients for orthodontic diagnosis and planning.

Renklendirilmiş Sefalometrik Filmlerin Ölçüm Güvenirliliğinin Konvansiyonel Sefalometrik Filmlerle Karşılaştırılması

Amaç: Çalışmanın amacı, renklendirme yöntemi kullanılan lateral sefalometrik filmlerin tanısal güvenilirliklerini ve geçerliliklerini, geleneksel sefalometrik filmlerle karşılaştırmaktır. Gereç ve Yöntemler: Çalışmamızda ortodonti bölümünün kayıtlarından, eşit sayıda Sınıf I, Sınıf II ve Sınıf III maloklüzyona sahip 15 hastanın (8 kadın ve 7 erkek hasta; yaş ortalaması 15,6±1,3 yıl) filmleri, farklı çalışma deneyimlerine sahip 13 ortodonti uzmanı tarafından konvansiyonel yöntemle çizildi. İki hafta sonra ise aynı sefalometrik çizim programının renklendirme özeliği kullanılarak çizimler gerçekleştirildi. Her bir radyografide, konvansiyonel sefalometrik analizlerde daha sık kullanılan 22 iskeletsel, yumuşak doku ve dental sefalometrik ölçümü, film üzerinde standardizasyon işleminin ardından film üzerinde 'landmark'ları işaretleyerek gerçekleştirdi. Her gözlemcinin güvenilirliği, sınıf içi korelasyon katsayısı [intraclass correlation coefficient (ICC)] endeksi ile hesaplandı. 0,9'un üzerindeki ICC değeri, iyi güvenilirlik; 0,7-0,9 arası ICC değeri orta güvenilirlik ve 0,7'den az ICC değeri az güvenilirlik olarak kabul edildi. Bulgular: Çalışmamızda, maksiller kesici diş konumlarını değerlendirmemizi sağlayan U1-SN (°), U1-NA (mm) ölçümleri ile mandibular kesici diş konumlarını değerlendirmemizi sağlayan L1-NB (°), L1-NB (mm), Pg-NB (mm) parametrelerinin korelasyon değerleri, diğer iskeletsel ve dentoalveoler ölçümlere kıyasla daha düşük bulunmuştur (r0,800). Sonuç: Renklendirilmiş sefalometrik radyografiler, geleneksel radyografilere kıyasla daha yüksek bir ICC katsayısına sahip bulundu, istatistiksel olarak yumuşak doku ölçümlerinde anlamlı fark bulundu.

A Comparison between 2D and 3D Images to Study Maxillary and Mandibular Widths: A Pilot Study

The objective of this study is to compare the transverse dimensions of the jaws, obtained from traditional posteroanterior (PA) cephalometric radiographs, and with the similar respective measurements obtained by means of cone beam computed tomography (CBCT). Data of twelve subjects were selected from the clinical records of Orthodontic Department. All of the subjects had their permanent teeth in occlusion and had good quality regular (2D), and CBCT (3D) images as part of their initial records. Subjects were divided to a posterior cross-bite and non-cross bite groups. The ratio of the maxillary, to mandibular transverse widths was calculated for the sample. In subjects without dental cross-bites the average ratio of the maxillary, to mandibular jaw widths was 0.75 on the standard radiographs and 1.04 on the CBCT scans. In subjects with dental cross-bites the average ratio of these widths was 0.70 on the standard radiographs and 0.9 on the CBCT scans. The ratios of the maxillary, to mandibular widths differ when obtained from conventional cephalometric radiographs as compared to the respective ratios obtained from CBCT scans. Maxillary, to mandibular width ratio is in the order of 1:1 as determined by means of CBCT scans.

Cephalometric evaluation of posteroanterior projection of reconstructed three-dimensional Cone beam computed tomography, two-dimensional conventional radiography, and direct measurements

IntroductionThe purpose of this study is to assess the reliability of 2D postero-anterior (PA) projection derived from 3D Cone Beam Computed Tomography (3D) in comparison with conventional 2D PA cephalometric radiographs as well as to direct measurements. Material and MethodsFull head CBCT and 2D Postero-Anterior (PA) Cephalograms were obtained on 23 dry skulls with intact skeletal structures. Subsequently, another set of 2D PA cephalometric radiographs were generated from the CBCT images. Landmarks have been identified for each postero-anterior projection. Linear measurements (15 horizontal and 3 vertical) derived from Ricketts frontal cephalometric analysis were compared for the 2D radiographs, 3D CBCT, and direct measurements. ResultsOnly one cephalometric measurement (ZAR-ZAL) indicated clinically and statistically significant mean difference when comparing 2D vs 3D and 3D vs direct measurements. ConclusionThe study found linear postero-anterior cephalometric measurements of 2D conventional cephalometric radiographs (2D) to be reliable when compared to CBCT derived images (3D) and direct measurements.

Imagens em 2D e 3D geradas pela TC Cone-Beam e radiografias convencionais: qual a mais confiável?

OBJETIVO: comparar a confiabilidade de identificação dos pontos visualizados sobre radiografias cefalométricas convencionais e sobre imagens geradas pela Tomografia Computadorizada Cone-Beam em 2D e 3D. MÉTODOS: o material constou de imagens obtidas através do tomógrafo computadorizado Cone-Beam, em norma lateral, em 2D e 3D, impressas em papel fotográfico; e radiografias cefalométricas laterais, realizadas na mesma clínica radiológica e no mesmo dia, de dois pacientes pertencentes aos arquivos do Curso de Especialização em Ortodontia da Faculdade de Odontologia da Universidade Federal Fluminense (UFF). Dez alunos do Curso de Especialização em Ortodontia da UFF identificaram pontos de referência sobre papel de acetato transparente e foram feitas medições das seguintes variáveis cefalométricas: ANB, FMIA, IMPA, FMA, ângulo interincisal, 1-NA (mm) e ¯1-NB (mm). Em seguida, foram calculadas médias aritméticas, desvios-padrão e coeficientes de variância de cada variável para os dois pacientes. RESULTADOS E CONCLUSÃO: os valores das medições realizadas a partir de imagens em 3D apresentaram menor dispersão, sugerindo que essas imagens são mais confiáveis quanto à identificação de alguns pontos cefalométricos. Entretanto, como as imagens em 3D impressas utilizadas no presente estudo não permitiram a visualização de pontos intracranianos, torna-se necessário que softwares específicos sejam elaborados para que esse tipo de exame possa se tornar rotineiro na clínica ortodôntica.

A comparison between 2D and 3D cephalometry on CBCT scans of human skulls

The purpose of this study was to evaluate whether measurements on conventional cephalometric radiographs are comparable with 3D measurements on 3D models of human skulls, derived from cone beam CT (CBCT) data. A CBCT scan and a conventional cephalometric radiograph were made of 40 dry skulls. Standard cephalometric software was used to identify landmarks on both the 2D images and the 3D models. The same operator identified 17 landmarks on the cephalometric radiographs and on the 3D models. All images and 3D models were traced five times with a time-interval of 1 week and the mean value of repeated measurements was used for further statistical analysis. Distances and angles were calculated. Intra-observer reliability was good for all measurements. The reproducibility of the measurements on the conventional cephalometric radiographs was higher compared with the reproducibility of measurements on the 3D models. For a few measurements a clinically relevant difference between measurements on conventional cephalometric radiographs and 3D models was found. Measurements on conventional cephalometric radiographs can differ significantly from measurements on 3D models of the same skull. The authors recommend that 3D tracings for longitudinal research are not used in cases were there are only 2D records from the past.

Comparison of Cephalometric Radiographs Obtained From Cone-Beam Computed Tomography Scans and Conventional Radiographs

We evaluated whether measurements on conventional cephalometric radiographs are comparable to measurements on cone-beam computed tomography (CBCT)-constructed cephalometric radiographs taken from human skulls. The CBCT scans and conventional cephalometric radiographs were made using 40 dry skulls. With I-Cat Vision software (Imaging Sciences International, Inc, Hatfield, PA), a cephalometric radiograph was constructed from the CBCT scan. Standard cephalometric software was used to identify landmarks, and calculate distances and angles. The same operator identified 15 landmarks on both types of cephalometric radiographs on all images 5 times with a 1-week interval. Intraobserver reliability was good for all measurements. The reproducibility of measurements on cephalometric radiographs obtained from CBCT scans was better, compared with the reproducibility of those on conventional cephalometric radiographs. There was no clinically relevant difference between measurements on conventional and constructed cephalometric radiographs. Measurements on CBCT-constructed cephalometric radiographs are comparable to conventional cephalometric radiographs, and are therefore suitable for longitudinal research.

In Vivo Comparison of Conventional and Cone Beam CT Synthesized Cephalograms

To compare measurements from synthesized cone-beam computed tomography (CBCT) lateral cephalograms using orthogonal and perspective projections with those from conventional cephalometric radiographs. Thirty-one patients were imaged using CBCT and conventional cephalometry. CBCT volume data were imported in Dolphin 3D. Orthogonal and perspective lateral cephalometric radiographs were created from three-dimensional (3D) virtual models. Twelve linear and five angular measurements were made on synthesized and conventional cephalograms in a randomized fashion. Conventional image measurements were corrected for known magnification. Linear and angular measurements were compared between image modalities using repeated measures analysis of variance. Statistical significance was defined as an alpha level of .01. With the exception of the Frankfort-mandibular plane angle (P < .0001), angular measurements were not statistically different for any modality (P > .01). Linear measurements, whether based on soft or hard tissue landmarks, were not statistically different (P > .01). Measurements from in vivo CBCT synthesized cephalograms are similar to those based on conventional radiographic images. Thus, additional conventional imaging may generally be avoided when CBCT scans are acquired for orthodontic diagnosis.

Comparison of conventional and cone beam CT synthesized cephalograms

To compare cephalometric measurements from synthesized cone beam CT (CBCT) lateral cephalograms using orthogonal and perspective projections with those from conventional cephalometric radiographs and dry skulls. Ten skulls were imaged using CBCT and conventional cephalometry. CBCT volume data were exported in DICOM format and imported in Dolphin 3D (pre-release version). Orthogonal and perspective lateral cephalometric radiographs were created from 3D virtual models. Nine linear and five angular measurements were made in Dolphin at three different times. Three calliper measures of midsagittal landmarks were made directly onto skulls. Perspective and conventional image measurements were corrected for known magnification. Reproducibility of measurements was assessed using multivariate analysis of variance (MANOVA). Linear and angular measurements were compared between image modalities by measurement using a repeated measures MANOVA model. Differences and absolute value of differences between image measurements and skull measurements were assessed using analysis of variance (ANOVA). Measurements were not different between the imaging modalities (P>0.05), except for the mandibular unit length (P=0.01). Linear midsagittal measurements were significantly greater than skull measurements for perspective CBCT and significantly less than skull measurements for conventional images (P=0.003). Precision of orthogonal CBCT midsagittal linear measurements was significantly better than the other modalities (P=0.007). Orthogonal CBCT projections provided more accurate midsagittal skull measurements than perspective CBCT or conventional cephalometric radiographs. CBCT can reproduce conventional cephalometric geometry with similar precision and accuracy. Orthogonal CBCT projections provided greater accuracy of measurement for midsagittal plane dimensions than perspective CBCT or conventional cephalometric images.

Comparing digital and conventional cephalometric radiographs

With the introduction of digital cephalometry in orthodontics, many clinicians have cephalometric radiographs for a patient taken on 2 different cephalostats. Comparing these images is difficult because of differences in magnification between the 2 units. This article describes how to determine the magnification of a cephalometric radiograph and how to change the dimensions of a digital image to match a conventional image.

Reliability of Digital Versus Conventional Cephalometric Radiology: A Comparative Evaluation of Landmark Identification Error

The purpose of this study was to determine whether direct digital lateral cephalometric radiographs are of equal value in diagnosis and treatment planning as conventional cephalometric radiographs by investigating differences in landmark identification on direct digital and conventional cephalometric radiographs. An evaluation of precision and the distribution of landmark identification error at each cephalometric landmark was undertaken. Ten observers, all orthodontists or postgraduate orthodontic residents, identified 19 landmarks twice on 6 digital images and 6 conventional cephalometric films obtained from the records of 6 patients at the University of Alabama School of Dentistry Graduate Orthodontic Clinic. Patient records selected were of adults with existing pretreatment conventional cephalometric films and posttreatment direct digital cephalometric images on file. Landmark identification recordings were transferred into a standardized coordinate system, adjusted for magnification differences, and evaluated separately along both the x- and the y-coordinates. Statistically significant differences in landmark identification error were found along the x-coordinate for A point (Apt) and along the y-coordinate for anterior nasal spine (ANS) and condylion (Co). These statistically significant differences, as well as those found to be not statistically significantly different, were all below 1 mm, indicating that even the statistically significant differences between the two methods of image acquisition were unlikely to be of clinical significance. Each landmark exhibited its own unique pattern of landmark identification error, the magnitude and distribution of which must be taken into consideration when selecting landmarks for use in cephalometric analysis or when interpreting these analyses for diagnostic or treatment planning purposes. The results of the present study indicate similar precision and reproducibility in landmark identification using both direct digital images and conventional lateral cephalometric head films. The purpose of this study was to determine whether direct digital lateral cephalometric radiographs are of equal value in diagnosis and treatment planning as conventional cephalometric radiographs by investigating differences in landmark identification on direct digital and conventional cephalometric radiographs. An evaluation of precision and the distribution of landmark identification error at each cephalometric landmark was undertaken. Ten observers, all orthodontists or postgraduate orthodontic residents, identified 19 landmarks twice on 6 digital images and 6 conventional cephalometric films obtained from the records of 6 patients at the University of Alabama School of Dentistry Graduate Orthodontic Clinic. Patient records selected were of adults with existing pretreatment conventional cephalometric films and posttreatment direct digital cephalometric images on file. Landmark identification recordings were transferred into a standardized coordinate system, adjusted for magnification differences, and evaluated separately along both the x- and the y-coordinates. Statistically significant differences in landmark identification error were found along the x-coordinate for A point (Apt) and along the y-coordinate for anterior nasal spine (ANS) and condylion (Co). These statistically significant differences, as well as those found to be not statistically significantly different, were all below 1 mm, indicating that even the statistically significant differences between the two methods of image acquisition were unlikely to be of clinical significance. Each landmark exhibited its own unique pattern of landmark identification error, the magnitude and distribution of which must be taken into consideration when selecting landmarks for use in cephalometric analysis or when interpreting these analyses for diagnostic or treatment planning purposes. The results of the present study indicate similar precision and reproducibility in landmark identification using both direct digital images and conventional lateral cephalometric head films.

Are collimated low-dose digital radiographs valid for performing Delaire's architectural analysis?

Computed radiography (CR) provides the dynamic exposure range to reveal objects in film areas exposed by very low X-ray exposure. Conventional cephalometric radiographs are normally beam limited to the facial skeleton. The cranial vault and cervical vertebra are collimated and only exposed by extra-focal radiation and scatter. We hypothesize that, on conventional cephalometric radiographs obtained with CR, image data of collimated film areas can be enhanced for reliable performance of Delaire's cephalometric analysis of the entire skull. Therefore the aim of the present study was to compare the reproducibility of landmark placement on normal and underexposed film areas of CR images. Intra- and inter-observer reproducibility of landmark identification was evaluated on 200 randomly selected radiographs by calculating the error radius of repeated landmark placements. A paired-samples t-test revealed differences (P< 0.001) between intra- and inter-observer reproducibility. Intra-observer accuracy was influenced (P< 0.001) by variability of suture obliteration (bregma). Identification of landmarks in areas of extra-focal radiation showed no difference (P> 0.05) from that of landmarks inside the normally exposed area. CR offers the opportunity to perform of a full cranial analysis on a cephalometric radiograph collimated to the facial region.

Landmark identification on direct digital versus film-based cephalometric radiographs: A human skull study

The purpose of this study was to investigate differences in landmark identification on vertically scanned, direct digital and conventional (18 × 24 cm) cephalometric radiographs. Eight observers, all orthodontists or postgraduate orthodontic students, recorded 6 landmarks twice on 3 digital and 3 conventional cephalograms obtained from 3 human skulls in a standardized fashion. Digital images were displayed on a 15.1-in TFT monitor in 3:1 mode (20 × 26 cm). Recordings were transferred into standardized coordinate systems and evaluated separately for each coordinate. After correcting for magnification, precision was assessed with Maloney-Rastogi tests, and intraobserver and interobserver reproducibility was calculated from squared differences. Effective magnification was larger for the digital images (x, 13%; y, 12%). Significantly different (P <.05) precision was found for nasion (N), posterior nasal spine (PNS), sella (S), supraspinale (A), and orbitale (Or), but average differences were entirely below 1 mm. Interobserver and intraobserver reproducibility did not differ significantly between the 2 image modes. Squared differences were largest for PNS and Or in both modalities. Our results indicate comparable errors in landmark recording for both evaluated machines. However, these results must be considered in the context of the specific display conditions for digital images, because no general standard exists for this purpose. (Am J Orthod Dentofacial Orthop 2002;122:635-42)

A study of bite force, part 2: Relationship to various cephalometric measurements.

Maximum bilateral bite force, determined in 129 dental students, was evaluated with regard to six skeletal and eight dental measurements acquired from conventional lateral cephalometric radiographs. Statistically significant correlations for three of the skeletal measurements were found. Maximum bite force increased with regard to decreasing mandibular plane/palatal plane angle and to decreasing mandibular plane angles. Maximum bite force increased with an increasing ratio of posterior facial height to anterior facial height. Significant statistical correlation for only one of the eight dental measurements was found: maximum bite force related directly with increasing maxillary and/or mandibular dentoalveolar heights, and unexpected finding.

Comparison of soft-tissue enhanced and conventional cephalometric radiographs

Pretreatment evaluation of the orthognathic surgery patient includes hard-tissue and soft-tissue analysis. Although the soft-tissue analysis can be made easier by the use of a Quint intensifying screen (Quint X-Ray Co, Inc, Los Angeles) which enhances the soft-tissue image, when the enhanced cephalometric radiograph was compared with a standard, nonenhanced radiograph, it was found to have the same level of diagnostic accuracy.