“Ten-point” 3D cephalometric analysis using low-dosage cone beam computed tomography

progress in orthodontics 1 1 ( 2 0 1 0 ) 2–12

available at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/pio

Original article

“Ten-point” 3D cephalometric analysis using low-dosage cone beam computed tomography Giampietro Farronato a,∗ , Umberto Garagiola b , Aldo Dominici c , Giulia Periti c , Sandro de Nardi d , Vera Carletti c , Davide Farronato e a

MD, DDS, Full Professor and Head of the Department of Orthodontics, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, University of Milan, Italy b DDS, PhD, Clinical Assistant Professor, Departments of Oral Surgery and Orthodontics, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, University of Milan, Italy c DDS, Department of Orthodontics, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, University of Milan, Italy d MD, DDS, Department of Orthodontics, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, University of Milan, Italy e DDS, PhD, Clinical Assistant Professor, Departments of Oral Surgery and Orthodontics, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, University of Milan, Italy

a r t i c l e

i n f o

a b s t r a c t

Article history:

Objective: The aim of this study was to combine the huge amount of information of low dose

Received 16 June 2009

Cone Beam CT with a cephalometric simplified protocol thanks to the latest informatics

Accepted 23 December 2009

aids. Lateral cephalograms are two-dimensional (2-D) radiographs that are used to represent

Keywords:

three-dimensional (3-D) structures. Cephalograms have inherent limitations as a result of

3D cephalometric analysis

distortion, super imposition and differential magnification of the craniofacial complex. This

TC Cone Beam

may lead to errors of identification and reduced measurement accuracy.

Low dosage

The advantages of CBCT over conventional CT include low radiation exposure, imaging

Maxilla and mandible centroids

quality improvement, potentially better access, high spatial resolution and lower cost.

Skeletal malocclusion

Materials and methods: This study assessed cephalometric 2D and 3D measurements and the analysis of CBCT cephalograms of the volume and centroid of the maxilla and mandible, in 10 clinical cases. Results: With a few exceptions the linear and angular cephalometric measurements obtained from CBCT and from conventional cephalograms did not differ statistically (p > 0.01). There was a correlation between the variation in the skeletal malocclusion and growth direction of the jaws, and the variation in the spatial position (x, y, z) of the centroids and their volumes (p < 0.01). Conclusions: The 3D cephalometric analysis is easier to interpret than 2D cephalometric analysis. In contrast to those made on projective radiographies, the angular and linear measurements detected on 3D become real, moreover the fewest points to select and the automatic measurements made by the computer drastically reduced human error, for a much more reliable reproducible and repeatable diagnosis. © 2010 Società Italiana di Ortodonzia SIDO. Published by Elsevier Srl. All rights reserved.

∗ Corresponding author. Department of Orthodontics, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, University of Milan, via della Commenda 10 - 20123 Milan, Italy. E-mail address: [email protected] (G. Farronato). 1723-7785/$ – see front matter © 2010 Società Italiana di Ortodonzia SIDO. Published by Elsevier Srl. All rights reserved. doi:10.1016/j.pio.2010.04.007

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1.

Introduction

Cephalometrics appears to be a useful diagnostic tool for identifying skeletal disharmony, malocclusion, and normal occlusion for orthodontics and oro-maxillofacial surgery. To image craniofacial anatomy, low-dose cone beam computed tomography (CBCT) uses a conical beam of X-rays instead of the conventional fan beam of multi-slice computed tomography (CT). Thus, CBCT results in reduced adsorption of radiation compared with traditional CT and provides a greater quantity of information than two-dimensional (2D) exams.1–3 The effective radiation dose to which a patient is exposed is far lower with a CBCT examination than with a multi-slice CT examination. Specifically, the effective dose from an I-Cat cone beam CT machine is 20 times lower than that from a Toshiba 64-slice machine (Table 1).4–6 In addition, the dose distribution to the various organs examined differs between CBCT and multi-slice CT; the dose absorbed by organs such as the thyroid and salivary glands is 20-40 times lower with CBCT (Fig. 1).7–9 Three-dimensional (3D) diagnostic imaging using CBCT produces distortion-free and accurate images of the craniofacial anatomy, without the magnification and superimposition problems of 2D imaging. This allows unobstructed views of otherwise hidden structures. The present study evaluated the application of a new, simplified cephalometric protocol that uses a personal computer for the analysis of the enormous amount of information available from low-dose CBCT. An important advantage of this technique is that it allows real linear and angular measurements. Moreover, it is possible to analyze volumes in order to evaluate disproportions in a more representative way than with segments. This “ten-point” 3D cephalometry method has the potential to reduce time, costs, and human error. This study compared the ten-point cephalometry method using 3D images and the 2D Steiner cephalometry method taking lateral and posteroanterior cephalograms.9

2.

Materials and methods

A low-dose CBCT machine was used to acquire the radiographic images in this study of the ten-point 3D cephalometry method. The image quality of CBCT compares favorably to that of multi-slice CT, as it has minimum image noise and a maximum signal-to-noise ratio.10,11 All Conebeam scanners have preinstalled software for image manipulation, for added image functionality. Such imaging tools include: Multi Planner Reformat (MPR),

Fig. 1 – The dose to organs radiated using different devices: MDCT-Toshiba Aquilon 64 Multi-slice; I-Cat cone beam CT; and Panoramic Sirona Orthophos XGplus DS.

Panoramics, Maximum Intensity Projection (MIP), Visualization of Mandibular canal and 3D Volume Rendering (3DVR). 3D volume data is usually acquired in the axial plane of the patient (top to bottom slices). MPR creates sagittal, coronal and transverse images from those axial images (basically front view and lateral view slices). The display of the images in such formats allows the effective visualization of section to section change in the scanned structure. MPR images are available in all pre-installed Conebeam scanner software. The software also allows measurements to be taken on the slices and measure Hounsfield values. Conebeam images could be used to generate accurate 3D panoramic slices along a specified curve either using preinstalled software that comes with the Conebeam machine or other software. Panoramic images generated from Conebeam scanners are more accurate than conventional panoramic images for 2 main reasons: no tissue superimposition; no image distortion, scale images for accurate measurements. MIP algorithm evaluates each Conebeam voxel along a ray through the viewer’s line of site and the maximum voxel value is selected as the pixel to be displayed in the resulting image. Such representation allows the viewer to appreciate the depth of the rendering. 3DVR renders the entire volume of Conebeam data, by summing up the value of each voxel along the viewer’s line of sight through the complete data set. The process is done repeatedly to determine the pixel value to be displayed in the resulting image. 3D volume renderings allows: realistic visualization of 3D volume data, characterization of disease and appreciation of anatomic relationships.

Table 1 – Effective dose (background radiation 8 ␮sievert/day3 ). Devices

Scan parametres

Orthopantomography Lateral Cephalogram Posteroanterior Cephalogram CT Medical 64 Multislice CT I-Cat Cone Beam CT I-Cat Cone Beam

69kV/15mA/14,1s 80kV 80kV 120kV/400mA/0,5s 120kV/5mA/20s 120kV/5mA/10s

Scan parametres (␮Sv) - (ref.) 50 ␮Sievert - (2) 30 ␮Sievert - (4) 40 ␮Sievert - (4) 2370 ␮Sievert - (1) 110 ␮Sievert - (1) 60 ␮Sievert - (1)

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Fig. 2 – (a,b) Frontal and lateral 3D reconstruction of the skull.

Fig. 3 – (a-c) The three points (S. N. and Ba) used to construct the reference planes for the reconstruction.

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Fig. 4 – Mid-sagittal, coronal, and axial planes.

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Ten patients were selected randomly for the study. They ranged in age from 8 to 42 years; there were 8 females and 2 males. Each patient had already had lateral and posteroanterior cephalograms taken less than 6 months earlier. The cephalometric analysis was performed by three operators repeating the measurements twice (15 days apart) with a calibration meeting.12,13 The positions of the maxilla and mandible in 3D space were determined using low-dose CBCT by assigning three reference planes to obtain the (x, y, z) position of each point of the skull relative to point S with coordinates (0, 0, 0), which was automatically determined by the computer as the intersection of the reference planes (Figs. 2a,b and 3a-c). The position of the jaws in 3D space was determined by assigning 10 easily identified, repeatable cephalometric points (five each for the maxilla and mandible) to establish two solid figures representing spatial changes of points of orthodontic interest in terms of the shape or position of the jaw bones. By analyzing the relationships among the surfaces created and the angular and linear evaluations based on reported criteria,12–17 the program automatically detects the expansion of the jaws with very high precision, facial asymmetry in the three spatial planes, the skeletal class, and the anterior

Fig. 5 – (a-c) The five cephalometric points for the reconstruction of the 3D mandibular model.

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Fig. 6 – (a-c) The five cephalometric points for the reconstruction of the 3D maxillar model.

vertical dimension. In addition, the program automatically calculates the volume and centroid (midpoint of the volume) of the jaws, to predict the shape and direction of growth using a vector representation in space. In subsequent examinations, by exactly overlapping the planes of reference, this vector can inform a clinician, in a very intuitive way, about the direction in space in which the mandible has grown.18–22 To obtain a reference system that is repeatable and is not influenced by changes in the positions of cranial points due to growth, the best solution in terms of simplicity and precision is to use three reference planes, defined using three points: the sella (S), nasion (N), and basion (Ba). The three planes are the mid-sagittal plane passing through S-N-Ba, the mid-axial plane passing through S-N and perpendicular to the mid-sagittal plane, and the coronal plane passing through S and perpendicular to the other two planes. The intersection of these three planes defines the reference point S (0, 0,

0). These planes are repeatable and specific for each patient (Fig. 4). The five cephalometric points identified in the program for the 3D analysis of the mandible are the right gonion (Go r), left gonion (Go l), pogonion (Pog), right condylar point (Co r), and left condylar point (Co l) (Fig. 5a-c). The points used to study the position and direction of growth of the maxilla are the nasion (N), point (A), the right jugal point (Mx r), the left jugal point (Mx l), and the posterior nasal spine (PNS) (Fig. 6a-c). By analyzing the positions of these 10 cephalometric landmarks entered by the operator, the program automatically calculates the centroids (C1 and C2) of the solids and their coordinates in space (Figs. 7a-c and 8a-e). Comparing images with the subsequent acquisitions, the computer automatically produces a vector that indicates the direction and growth module of the jaws in three dimensions. This allows a clear graphical representation that provides

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Fig. 7 – (a-c) The geometric solids representing maxillar and mandibular 3D reconstruction.

simple, intuitive information about the forces that a clinician should consider to correct pathological growth. The 3D cephalometric analysis allows the immediate analysis of the characteristics of clinical cases, visually and simply. The Figs. 2–8 show an example of a 3D cephalometric analysis applied to a specific clinical case with class III skeletal malocclusion. The data were analyzed statistically using Student’s t-test. The author(s) declare that the work has been realized in agreement with the Helsinki Declaration principles and that the Informed Consent has been achieved from all the participants involved in the study.

3.

Results

This study assessed cephalometric measurements made using conventional 2D cephalometric analysis and our tenpoint 3D cephalometric analysis of CBCT cephalograms of the volume and centroid of the maxilla and mandible, in 10 clinical cases (Table 2).

The linear and angular cephalometric measurements obtained from CBCT and from conventional cephalograms did not differ statistically (p > 0.01). There was a correlation between the variation in the skeletal malocclusion and growth direction of the jaws, and the variation in the spatial position (x, y, z) of the centroids and their volumes (p < 0.01). The 3D cephalometric analysis allowed measurements for determining the correlations between the volumes of the right and left hemimaxilla and the right and left hemimandible. Ideally, the correlation coefficient is 1. The deviations from the ideal were minimal in all of the cases studied except case KV, in which the volume of the right hemimandible was markedly greater than that of the left (Table 3).

4.

Discussion

Three-dimensional cephalometric methods allow the analysis of anomalies in three spatial planes (sagittal, frontal, and

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Fig. 8 – (a-e) 3D reconstruction with C1 and C2 centroid visualization.

Table 2 – Misurations with the conventional 2D and the 10 points 3D cephalometry. BY

CA

GC

MF

SF

85◦ 20 86◦ 39 −1◦ 19 −5 mm

83◦ 51 82◦ 43 1◦ 08 −5 mm

81◦ 35 77◦ 23 4◦ 12 0 mm

CB

79◦ 10 76◦ 30 2◦ 40 −2 mm

83◦ 44 78◦ 32 5◦ 12 +2 mm

83◦ 58 77◦ 17 6◦ 41 0 mm

KV

78◦ 43 74◦ 13 4◦ 30 +5 mm

MC

80◦ 10 72◦ 34 7◦ 36 +1 mm

85◦ 11 83◦ 36 1◦ 35 −4 mm

80◦ 33 76◦ 47 3◦ 46 −1 mm

NS

Centroid Maxilla X-axis Centroid Mandible X-axis Centroids difference X-axis ˆ S-N Go-Gn Pc-Go-Gn Pc-Go-N N-Go-Gn

47.41 mm

40.5 mm

38.9 mm

40.2 mm

43.31 mm

41.41 mm

43.74 mm

40.25 mm

41.54 mm

43.5 mm

11.01 mm

4.56 mm

0.77 mm

0.62 mm

1.27 mm

1.02 mm

0.54 mm

4.16 mm

6.17 mm

2.3 mm

36.4 mm

35.94 mm

38.13 mm

39.58 mm

42.04 mm

40.39 mm

43.2 mm

36.09 mm

35.37 mm

41.2 mm

30◦ 06 129◦ 10 56◦ 40 72◦ 30

36◦ 58 129◦ 42 51◦ 22 78◦ 20

37◦ 31 127◦ 36 52◦ 20 75◦ 16

36◦ 47 131◦ 14 57◦ 37 73◦ 37

32◦ 56 125◦ 34 52◦ 31 73◦ 63

36◦ 12 124◦ 30 48◦ 42 75◦ 48

31◦ 57 128◦ 52 60◦ 28 68◦ 24

41◦ 47 129◦ 42 47◦ 31 82◦ 11

31◦ 13 131◦ 39 57◦ 46 73◦ 53

45◦ 30 131◦ 56 51◦ 30 80◦ 26

N - SNA SNA - Me

44 mm - 41.12% 63 mm - 58.88%

52 mm - 40.62% 76 mm - 59.37%

45 mm - 43.27% 46 mm - 43.81% 51 mm - 45.13% 52 mm - 44.06% 59 mm - 56.73% 59 mm - 56.19% 62 mm - 54.87% 66 mm - 55.93%

47 mm - 43.93% 60 mm - 56.07%

52 mm - 43.33% 48 mm - 39.34% 43 mm - 42.16% 68 mm - 56.66% 74 mm - 60.65% 59 mm - 57.84%

Centroid Maxilla Y-axis Centroid Mandible Y-axis Centroids difference Y-axis Mx r. Mx l.  Mx Go r. Go l.  Go

34.59 mm

37.19 mm

34.38 mm

33.47 mm

37.56 mm

36.39 mm

34.14 mm

36.23 mm

32.48 mm

33.87 mm

56.31 mm

61.22 mm

52.4 mm

50.66 mm

58.21 mm

58.37 mm

54.27 mm

57.05 mm

53.75 mm

54.99 mm

21.72 mm

24.03 mm

18.02 mm

17.19 mm

20.65 mm

21.98 mm

20.13 mm

20.82 mm

21.27 mm

21.12 mm

29 mm 27 mm 1 mm 46 mm 41 mm 2 mm

32 mm 29 mm 0 mm 47 mm 44 mm 5 mm

29 mm 26 mm 2 mm 40 mm 37 mm 1 mm

30 mm 28 mm 4 mm 41 mm 38 mm 3 mm

35 mm 34 mm 3 mm 45 mm 44 mm 3 mm

35 mm 32 mm 0 mm 51 mm 47 mm 4 mm

32 mm 32 mm 1 mm 45 mm 45 mm 2 mm

27 mm 27 mm 2 mm 40 mm 38 mm 4 mm

32 mm 29 mm 0 mm 44 mm 42 mm 2 mm

32 mm 31 mm 1 mm 48 mm 49 mm 2 mm

Centroid Maxilla Z-axis Centroid Mandible Z-axis Centroids difference Z-axis Volume Maxilla Volume Mandible

−0.58 mm

−1.3 mm

3.08 mm

0.46 mm

1.27 mm

2.82 mm

−1.78 mm

−0.46 mm

2.46 mm

1.6 mm

−1.15 mm

−2.66 mm

4.38 mm

0.21 mm

1.78 mm

2.73 mm

−2.96 mm

0.41 mm

3 mm

1.55 mm

0.57 mm

1.36 mm

1.3 mm

0.25 mm

0.51 mm

0.09 mm

1.18 mm

0.87 mm

0.54 mm

0.05 mm

20553 mm3 111131 mm3

26485 mm3 120130 mm3

19431 mm3 72832 mm3

22625 mm3 70825 mm3

23439 mm3 99610 mm3

30312 mm3 120268 mm3

26999 mm3 100000 mm3

23900 mm3 74968 mm3

20073 mm3 88794 mm3

25212 mm3 105642 mm3

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AE S-N-A S-N-B A-N-B Wits index

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Table 3 – Volumetric correlations between right and left half- mandible and right and left half-maxilla. Patients A.E. B.Y. C.B. C.A. G.C. K.V. M.C. M.F. S.F. N.S.

Mandib right/left 0.98 0.98 1.11 1.03 1.01 0.92 1.02 1.02 0.96 0.95

Maxilla right/left 1.03 1 0.99 1.01 1.09 0.99 1.04 1 1.02 0.96

axial), directly and visually, without the need to interpolate different measurements obtained in each of the three spatial planes. The analysis is based mainly on the volumes and centroids of the maxilla and mandible. It uses a 3D reconstruction of the patient’s skull, starting from the DICOM-3-compatible files derived from low-dosage volumetric CBCT of the patient. Using sophisticated software (Mimics® , Materialise) dedicated to medical research and supported by high-speed computers, the patient’s skull is reconstructed in three dimensions, and the orientation of the skull is determined using three well-defined perpendicular planes and a point (0, 0, 0), which allows the (x, y, z) coordinates of the patient’s skull to be mapped. For the data collected from the 10 patients analyzed here, the change in skeletal class and the growth direction of the maxilla and mandible determined with Steiner analysis corresponded to the change of position in space (x, y, z) of the centroids of the jaws and their volume. The additional information provided by 3D cephalometry helps to solve postural and growth problems more easily and faster than with 2D cephalometry. The information is presented in a highly intuitive graphical way that facilitates orthodontic diagnosis. Consequently, treatment is quick and efficient. The small number of points to be selected and the automatic measurements made by the computer drastically reduce human error, making the diagnosis much more reliable and repeatable. In addition, the inter- and intra-individual variation is decreased. The data presented here show that the ten-point 3D cephalometry method is reliable and repeatable and provides clinicians with more information than 2D methods, in a simple and intuitive graphical representation.

5.

Conclusions

Three-dimensional imaging provides information and images of craniofacial structures free from perspective distortion, with none of the magnification or superimposition associated with 2D images. The 3D cephalometric analysis seems to be easier to interpret than 2D cephalometric analysis (interpolation of cephalometric values on different projections) because it allows movement from a purely mathematical interpretation (evaluation of angles and linear measurements) to a graphical interpretation, with verification of the results using

mathematical values (volumetric). Another aid to the clinician could be the repeatability and reproducibility of this method, which would reduce human error in cephalometric analysis. Although further studies are needed, the use of the centroid has given encouraging results. We believe that this method could save time and increases precision, offering a valuable aid to orthodontic diagnosis. This preliminary study could expand the landscape of diagnostic methods, allowing for more extensive studies to confirm the clinical effectiveness and validation of the ten-point 3D cephalometric analysis. Analyzing CBCT imaging data that represent the anatomic truth of the patient’s real anatomy, accurate 3D diagnosis could be useful to treatment planning in orthodontics.

Conflict of interest The authors have reported no conflicts of interest.

Riassunto Obiettivo: L’obiettivo di questo studio è stato unire l’enorme quantitativo d’informazioni della TC Cone Beam a basso dosaggio con un protocollo cefalometrico semplificato grazie agli ultimi ausilii informatici. Materiali e metodi: È stato proposto di confrontare la nuova cefalometria dei 10 punti effettuata su un’acquisizione TC 3D con la tradizionale cefalometria 2D secondo Steiner. Questo studio ha valutato le misure cefalometriche lineari e angolari di 10 pazienti analizzandole mediante le metodiche convenzionali 2D sulle teleradiografie latero-laterali e postero-anteriori e quelle nuove 3D con le tomografie computerizzate CBCT. Inoltre, sono stati studiati i volumi e i centroidi della maxilla e della mandibola. Risultati: Con poche eccezioni le misure lineari e angolari cefalometriche ottenute dalle CBCT e dalle radiografie cefalometriche convenzionali, hanno rilevato differenze non statisticamente significative (p > 0,01). Si è evidenziata una correlazione tra la variazione della malocclusione scheletrica e la direzione della crescita mandibolare e la variazione nella posizione dello spazio (x, y, z) dei centroidi e dei loro volumi (p < 0,01). Conclusioni: Al contrario di quelle effettuate su radiografie proiettive, le misurazioni lineari e angolari rilevate sul 3D diventano reali, inoltre il minor numero di punti da selezionare e le misurazioni automatiche effettuate al computer riducono drasticamente l’errore umano a favore di una diagnosi decisamente più attendibile e ripetibile. Secondo gli autori la nuova cefalometria 3D dei 10 punti può risultare una tecnica affidabile e ripetibile, che fornisce un numero superiore d’informazioni rispetto al 2D, in modo semplice e intuitivo per tutti grazie all’utilizzo di una rappresentazione grafica.

Résumé Objectif: Le but de cette étude était de combiner la quantité considérable d’information du low dose Cone Beam CT avec un examen céphalométrique classique et une evaluation informatique. Les cephalograms latéraux sont (2-D) radiographies bidimensionnelles qui sont employées pour représenter les structures (3-D) tridimensionnelles. Les cephalograms ont des limitations inhérentes en raison de la déformation, de la superposition et de la magnification du complexe craniofacial. Ceci peut donner des erreurs d’identification et d’exactitude. Les avantages de CBCT au-dessus de CT convention-

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nel incluent la basse exposition de rx, l’amélioration de la qualité de formation image, un accès potentiellement meilleur, haute résolution spatiale et le coût. Matériaux et méthodes: Cette étude a évalué les mesures 2D -3D céphalométriques et l’analyse des cephalograms de CBCT du volume et du centre de surface du maxillaire supérieur et de la mâchoire inférieure, dans 10 cas cliniques. Résultats: Avec les mesures céphalométriques linéaires et angulaires obtenues à partir de CBCT et à partir des cephalograms conventionnels les résultats n’ont pas différé statistiquement (> de p; 0.01). Il y avait une corrélation entre la variation de la malocclusion squelettique et la direction de croissance des mâchoires, et la variation de la position spatiale (x, y, z) des centroids et de leurs volumes (< de p; 0.01). Conclusions: Il est plus facile d’interpréter l’analyse 3D céphalométrique que l’analyse céphalométrique 2D. Contrairement à ceux faits sur les radiographies projectifs, les mesures linéaires et angulaires détectées sur les 3D deviennent vraies, en plus les moins points à choisir et les mesures automatiques faites par l’ordinateur rigoureusement réduisent l’erreur humaine, pour un diagnostic reproductible et beaucoup plus fiable.

Resumen Objetivo: El objetivo de este estudio fue combinar la gran cantidad de información de bajas dosis con haz cónico CT con respecto a un protocolo de cefalométrico simplificado gracias a las ayudas de la informática. Las estructuras se analizaron con radiografías laterales (cefalometrias) en dos dimensiones (2-D) y tres dimensiones (3-D). La cefalometrias tienen limitaciones inherentes a la distorsión, por la superposición del complejo craneofacial. Esto puede conducir a errores de identificación y precisión en la medición. Las ventajas de CBCT sobre la TC convencional incluyen exposición a la radiación baja, mejora de la calidad de imagen, el acceso potencialmente mejor, la alta resolución y el menor costo. Materiales y métodos: Este estudio evaluó la cefalometria 2D y 3D sus mediciones, en 10 casos clínicos. Resultados: Con pocas excepciones, las mediciones cefalométricas lineales y angulares obtenidos con CBCT y cefalometrias convencionales no difieren estadísticamente (p > 0,01). Hubo una correlación entre la variación de la maloclusión esquelética y la dirección de crecimiento de los maxilares y la variación en la posición espacial (x, y, z) de los centroides y su volumen (p < 0,01). Conclusiones: El análisis cefalométrico 3D es más fácil de interpretar que el 2D. En contraste con las realizadas en radiografías de proyección, las mediciones angulares y lineares en 3D son mas reales, además la menor cantidad de puntos para seleccionar y las mediciones automáticas realizadas por el sistema, han reducido drásticamente los errores humanos, de esta forma es mucho más confiable el diagnóstico.

references

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