Surg Radiol Anat DOI 10.1007/s00276-014-1325-3
Original Article
Evaluation of the zygomatic bone by cone beam computed tomography Helena Aguiar Ribeiro Nascimento · Maria Augusta Portella Guedes Visconti · Paulo de Tarso Silva Macedo · Francisco Haiter‑Neto · Deborah Queiroz Freitas
Received: 21 January 2014 / Accepted: 6 June 2014 © Springer-Verlag France 2014
Abstract Purpose The zygomatic bone (ZB) has been an effective option in the rehabilitation of the atrophic edentulous maxilla, in restoration of the low projection of the maxilla and in insertion of miniplates in maxillofacial fracture; it is situated near to air cells. In this way, the aim of this study was to evaluate the ZB by means of cone beam computed tomography (CBCT) images to determine if this bone can present characteristics similar to pneumatizations (CSPZB) and, in affirmative case, to determine its distribution concerning the age, gender, laterality and type. Materials and methods CBCT of 698 patients (1.396 ZB) were evaluated to determine the presence of CSPZB. The age and gender were recorded for all patients and, for the cases of CSPZB, laterality and type (unilocular or multilocular) were noted. Its prevalence was correlated with gender, age and laterality by statistical analyses (Chi-squared test). Results 3.3 % of individuals presented CSPZB. If we consider all zygomatic bones, CSPZB was in 2.8 %. Of these cases, 30.5 % were unilateral and 69.5 % bilateral; all presented multilocular pattern. There was no statistical correlation between CSPZB and gender or age (p = 0.15 and 0.63, respectively), neither between CSPZB and laterality (p = 0.39). Conclusion It was found an altered pattern similar to pneumatization in ZB; however, its prevalence was low (3.3 % of the studied population). Our results indicate that
H. A. R. Nascimento · M. A. P. G. Visconti · P. T. S. Macedo · F. Haiter‑Neto · D. Q. Freitas (*) Oral Radiology Area, Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Avenida Limeira, 901, Areião, Piracicaba, SP 13414‑400, Brazil e-mail: [email protected]
the ZB should be evaluated in tomographic images prior to surgical treatments carefully. Keywords Zygoma · Cone beam computed tomography · Anatomy
Introduction The zygomatic bone (ZB) is a quadrangular structure that can also be compared to a pyramid that articulates with other four bones: the maxillary, the frontal, the temporal and the sphenoidal. Its anatomic contour and position together with maxilla are responsible for harmony of the midface [1–4, 6, 8–10]. It shows regular trabeculae and compact bone with an osseous density of up to 98 % [18]. Nowadays, the importance of this bone is highlighted in several clinical conditions. In dental implants, when there is no adequate bone volume permitting their anchorage, zygomatic implants are long screw-shaped implants developed as a partial or complete alternative to bone augmentation procedures for the severely atrophic maxilla. The potential main advantages of zygomatic implants could be that bone grafting may not be needed and a fixed prosthesis could be fitted sooner [3]. Another indication for zygomatic implants could be maxillary reconstruction after maxillectomy in cancer patients. Also, in these patients, zygomatic distraction seems an excellent option to restore the low projection of the maxilla [1]. Moreover, ZB can be used for the insertion of miniplates in maxillofacial fractures [18]. Furthermore, reduction malarplasty has been one of the most frequently performed procedures for aesthetic facial contouring in Asian countries [7, 22]. Due to great clinical interest, it is important that evaluation of ZB has been performed in imaging exams appropriately.
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The bones of the skull contain many air-filled cavities which are referred to as pneumatization. These pneumatic areas can arise at different locations, in addition to paranasal sinuses. The development of the air cells is preceded by a formation of bone cavities and a physiological process related to periosteal activity that promotes the increase of the air cells [13]. The principal bone indicated as able to exhibit air cells is the temporal in which the pneumatizations could be found in ten locations. For that reason, several studies had evaluated the prevalence of pneumatization in temporal bone areas as zygomatic process of the temporal bone which is termed pneumatized articular eminence (PAT) [2, 6, 8, 9, 11, 14–17, 20, 21] and glenoid fossa (PGF) [4, 9]. We hypothesized that the air cells could also develop in ZB; however, we did not find studies that evaluated this condition in the researched literature. Considering our hypothesis, the clinical importance of ZB and that cone beam computed tomography (CBCT) is the ideal image to evaluate this condition once it does not present superimposition of images, the aim of this study was to evaluate the ZB to identify if this bone can present characteristics similar to pneumatizations (CSPZB) and, in affirmative case, to determine its distribution concerning the age, gender, laterality and type using CBCT images.
Materials and methods Images This study was approved by the Ethics Committee in Research of the State University of Campinas and a written consent from each patient was obtained. All CBCT images dating from 2010 to 2013 filed on the Oral Radiologic Clinic at FOP/UNICAMP were evaluated. In this period, 698 among all patients examined in our clinic were in accordance with the following selection criteria: (1) Caucasian patient without maxillofacial fracture history, (2) exam required with field of view in which the right and left ZB were adequately seen. The exams were acquired for different treatment purposes. All CBCT exposures were performed using a Classic i-CAT scanner (Imaging Sciences International, Inc, Hatfield, PA, USA), operating at 120 kVp and 8 mA, 512 × 512 matrix, 14 bits grayscale and no added filtration. Images analysis The CBCT images were evaluated by two oral radiologists with at least 2 years experience with CBCT images, under dim light conditions, independently. They used the XoranCat software version 3.1.62 (Xoran Technologies,
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Surg Radiol Anat
Ann Arbor, MI, USA). To analyze the axial, coronal and sagittal images. The contrast and brightness of the images could be adjusted using the image processing tool in the software to ensure optimal visualization. When a consensus could not be reached between the two examiners, another radiologist would assist them in making the decision. The examiners looked for images with characteristics similar to those described by Tyndall and Matteson [20] for pneumatization of articular eminence: a radiolucent (hypodense) defect with the appearance similar to mastoid air cells, with no enlargement or cortical destruction; however, such characteristics were researched in ZB. The condition was determined on both sides. The frequency of the characteristics similar to pneumatization was quantified. The age and gender were recorded for all patients; additionally, for the cases similar to pneumatization, laterality and type were also noted. The type was also classified adapted from the study by Tyndall and Matteson [20] as unilocular or multilocular. Unilocular aspect was identified as a single hypodense oval defect with well-defined bony borders, whereas multilocular aspect was identified as numerous hypodense small cavities. Statistical analysis The statistical analyses were performed using SPSS version 17.0 (SPSS Inc, Chicago, USA). The frequency of ZB images with characteristics similar to pneumatization was correlated with gender and age. These correlations were determined and assessed by the Chi-squared test. This analysis was also used to determine if there was correlation between pneumatization and laterality. p values
Original Article
Evaluation of the zygomatic bone by cone beam computed tomography Helena Aguiar Ribeiro Nascimento · Maria Augusta Portella Guedes Visconti · Paulo de Tarso Silva Macedo · Francisco Haiter‑Neto · Deborah Queiroz Freitas
Received: 21 January 2014 / Accepted: 6 June 2014 © Springer-Verlag France 2014
Abstract Purpose The zygomatic bone (ZB) has been an effective option in the rehabilitation of the atrophic edentulous maxilla, in restoration of the low projection of the maxilla and in insertion of miniplates in maxillofacial fracture; it is situated near to air cells. In this way, the aim of this study was to evaluate the ZB by means of cone beam computed tomography (CBCT) images to determine if this bone can present characteristics similar to pneumatizations (CSPZB) and, in affirmative case, to determine its distribution concerning the age, gender, laterality and type. Materials and methods CBCT of 698 patients (1.396 ZB) were evaluated to determine the presence of CSPZB. The age and gender were recorded for all patients and, for the cases of CSPZB, laterality and type (unilocular or multilocular) were noted. Its prevalence was correlated with gender, age and laterality by statistical analyses (Chi-squared test). Results 3.3 % of individuals presented CSPZB. If we consider all zygomatic bones, CSPZB was in 2.8 %. Of these cases, 30.5 % were unilateral and 69.5 % bilateral; all presented multilocular pattern. There was no statistical correlation between CSPZB and gender or age (p = 0.15 and 0.63, respectively), neither between CSPZB and laterality (p = 0.39). Conclusion It was found an altered pattern similar to pneumatization in ZB; however, its prevalence was low (3.3 % of the studied population). Our results indicate that
H. A. R. Nascimento · M. A. P. G. Visconti · P. T. S. Macedo · F. Haiter‑Neto · D. Q. Freitas (*) Oral Radiology Area, Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Avenida Limeira, 901, Areião, Piracicaba, SP 13414‑400, Brazil e-mail: [email protected]
the ZB should be evaluated in tomographic images prior to surgical treatments carefully. Keywords Zygoma · Cone beam computed tomography · Anatomy
Introduction The zygomatic bone (ZB) is a quadrangular structure that can also be compared to a pyramid that articulates with other four bones: the maxillary, the frontal, the temporal and the sphenoidal. Its anatomic contour and position together with maxilla are responsible for harmony of the midface [1–4, 6, 8–10]. It shows regular trabeculae and compact bone with an osseous density of up to 98 % [18]. Nowadays, the importance of this bone is highlighted in several clinical conditions. In dental implants, when there is no adequate bone volume permitting their anchorage, zygomatic implants are long screw-shaped implants developed as a partial or complete alternative to bone augmentation procedures for the severely atrophic maxilla. The potential main advantages of zygomatic implants could be that bone grafting may not be needed and a fixed prosthesis could be fitted sooner [3]. Another indication for zygomatic implants could be maxillary reconstruction after maxillectomy in cancer patients. Also, in these patients, zygomatic distraction seems an excellent option to restore the low projection of the maxilla [1]. Moreover, ZB can be used for the insertion of miniplates in maxillofacial fractures [18]. Furthermore, reduction malarplasty has been one of the most frequently performed procedures for aesthetic facial contouring in Asian countries [7, 22]. Due to great clinical interest, it is important that evaluation of ZB has been performed in imaging exams appropriately.
13
The bones of the skull contain many air-filled cavities which are referred to as pneumatization. These pneumatic areas can arise at different locations, in addition to paranasal sinuses. The development of the air cells is preceded by a formation of bone cavities and a physiological process related to periosteal activity that promotes the increase of the air cells [13]. The principal bone indicated as able to exhibit air cells is the temporal in which the pneumatizations could be found in ten locations. For that reason, several studies had evaluated the prevalence of pneumatization in temporal bone areas as zygomatic process of the temporal bone which is termed pneumatized articular eminence (PAT) [2, 6, 8, 9, 11, 14–17, 20, 21] and glenoid fossa (PGF) [4, 9]. We hypothesized that the air cells could also develop in ZB; however, we did not find studies that evaluated this condition in the researched literature. Considering our hypothesis, the clinical importance of ZB and that cone beam computed tomography (CBCT) is the ideal image to evaluate this condition once it does not present superimposition of images, the aim of this study was to evaluate the ZB to identify if this bone can present characteristics similar to pneumatizations (CSPZB) and, in affirmative case, to determine its distribution concerning the age, gender, laterality and type using CBCT images.
Materials and methods Images This study was approved by the Ethics Committee in Research of the State University of Campinas and a written consent from each patient was obtained. All CBCT images dating from 2010 to 2013 filed on the Oral Radiologic Clinic at FOP/UNICAMP were evaluated. In this period, 698 among all patients examined in our clinic were in accordance with the following selection criteria: (1) Caucasian patient without maxillofacial fracture history, (2) exam required with field of view in which the right and left ZB were adequately seen. The exams were acquired for different treatment purposes. All CBCT exposures were performed using a Classic i-CAT scanner (Imaging Sciences International, Inc, Hatfield, PA, USA), operating at 120 kVp and 8 mA, 512 × 512 matrix, 14 bits grayscale and no added filtration. Images analysis The CBCT images were evaluated by two oral radiologists with at least 2 years experience with CBCT images, under dim light conditions, independently. They used the XoranCat software version 3.1.62 (Xoran Technologies,
13
Surg Radiol Anat
Ann Arbor, MI, USA). To analyze the axial, coronal and sagittal images. The contrast and brightness of the images could be adjusted using the image processing tool in the software to ensure optimal visualization. When a consensus could not be reached between the two examiners, another radiologist would assist them in making the decision. The examiners looked for images with characteristics similar to those described by Tyndall and Matteson [20] for pneumatization of articular eminence: a radiolucent (hypodense) defect with the appearance similar to mastoid air cells, with no enlargement or cortical destruction; however, such characteristics were researched in ZB. The condition was determined on both sides. The frequency of the characteristics similar to pneumatization was quantified. The age and gender were recorded for all patients; additionally, for the cases similar to pneumatization, laterality and type were also noted. The type was also classified adapted from the study by Tyndall and Matteson [20] as unilocular or multilocular. Unilocular aspect was identified as a single hypodense oval defect with well-defined bony borders, whereas multilocular aspect was identified as numerous hypodense small cavities. Statistical analysis The statistical analyses were performed using SPSS version 17.0 (SPSS Inc, Chicago, USA). The frequency of ZB images with characteristics similar to pneumatization was correlated with gender and age. These correlations were determined and assessed by the Chi-squared test. This analysis was also used to determine if there was correlation between pneumatization and laterality. p values
