Use of gray values in CBCT and MSCT images for determination of density: influence of variation of FOV size.

PURPOSE: To determine the effect of field of view (FOV) size on gray values in cone beam computed tomography (CBCT) and multislice computed tomography (MSCT) images. MATERIAL AND METHODS: A phantom made up of 3 cylinders containing distilled water, plaster, and motor oil was constructed and inserted into an acrylic cylinder filled with distilled water. The phantom was scanned with a CBCT and MSCT device using 3 FOV sizes. Gray value of each material was evaluated in 40 axial slices, and the comparison between the results obtained with the same FOV size was made. RESULTS: In CBCT examinations, there was significant difference between the gray values of different FOVs for the 3 materials. In the MSCT, there was significant difference for the oil. Gray values showed significant difference between the CBCT and MSCT examinations for the 3 materials in the 3 different FOV sizes. CONCLUSIONS: Gray values determined in CBCT images are significantly influenced by the FOV size. Although the gray values obtained in MSCT have shown statistically significant differences between some acquisitions, the analysis of those differences seems to indicate low clinical relevance.

Anteroposterior condylar position: a comparative study between subjects with normal occlusion and patients with Class I, Class II Division 1, and Class III malocclusions.

BACKGROUND: The present study aimed to determine and compare the anteroposterior position of the condyle in the mandibular fossa between groups of asymptomatic subjects with normal occlusion and asymptomatic subjects with Class I, Class II Division 1, and Class III malocclusions. MATERIAL AND METHODS: Thirty persons with normal occlusion, 30 with Class I malocclusion, 30 with Class II Division 1, and 30 with Class III had computed tomography scans of their temporomandibular joints. The anterior joint space/posterior joint space (AJS/PJS) ratio was determined for the right and left joints. The paired t test was used to analyze the AJS/PJS ratio between both sides for each group. The ANOVA test was applied to verify the differences between the groups for the measurements of the right and left sides. In case the ANOVA test confirmed significance, the Dunnett's t test was performed to compare the groups of malocclusion with that of normal occlusion. RESULTS: The paired t test between the AJS/PJS relationships in the right and left sides showed the following p values: Class I (0.168), Class II Division 1 (0.662), Class III (0.991), and normal occlusion (0.390). The ANOVA test showed a p value of 0.445 for the comparisons of the right side and 0.040 for the left side. The Dunnett's t test demonstrated a statistically significant difference between the Class II group and the normal occlusion group (p value of 0.026) in the joints of the left side. CONCLUSIONS: Bilateral symmetry and lack of condyle centralization were common characteristics among all groups. The greatest condylar decentralization was observed in the Class II group, whereas the least condylar decentralization was found in the normal occlusion group.

Temporomandibular joint and normal occlusion: Is there anything singular about it? A computed tomographic evaluation.

INTRODUCTION: The purpose of this study was to investigate the condyle-fossa relationship, the position of the condyles in their respective mandibular fossae, and the dimensional and positional symmetries between the right and left condyles in a sample with normal occlusion. METHODS: Thirty subjects from 15 to 32 years of age with normal occlusion had computed tomography scans of their temporomandibular joints. The images obtained from the axial slices were evaluated for possible asymmetries in size and position between the condylar processes. The images obtained from the sagittal slices were used to assess the depth of the mandibular fossa, the condyle-fossa relationship, and the centralization of the condyles in their respective mandibular fossae. Paired Student t tests were applied, and Pearson product moment correlations were determined after measurements on both sides were obtained. RESULTS: The largest mediolateral diameter of the mandibular condylar processes (P = 0.022) and the posterior joint spaces (P = 0.048) showed statistically significant differences between the right and left sides. Statistically significant (P <0.05) anterior positioning of the condyles (noncentralized position) was observed. CONCLUSIONS: No singular characteristic in the temporomandibular joints of the normal occlusion group was verified. The largest mediolateral diameter of the mandibular condylar processes and the posterior joint spaces showed statistically significant differences between the right and left sides. Evaluation of the position of the condyles in their respective mandibular fossae showed noncentralized positioning for the right and left sides.

Fatores comprometedores para a inserção do implante dentário em crianças e adolescentes / Compromising factors for implant insertion in children and adolescents

Diversas situações encontradas em pacientes jovens fazem com que seja indicada a utilização dos implantes osseointegráveis na reabilitação oral. O propósito desse estudo foi ampliar o conhecimento sobre os critérios e em que condições se torna viável a utilização de implantes dentários em crianças e adolescentes em fase de crescimento ósseo e dental, através de uma revisão literária. A utilização de implantes dentários em crianças e pacientes jovens é menos frequente e tem sido bastante discutida em função destes pacientes se encontrarem em fase de desenvolvimento ósseo. A escassez de casos clínicos relatados na literatura e as controvérsias na utilização de implantes nesta fase aumentam a discussão. É evidente que o crescimento dos ossos maxilares pode comprometer o resultado da reabilitação oral usando próteses implantossuportadas, mesmo se os implantes são integrados com sucesso. A falta de oclusão adequada e as situações antiestéticas podem ocorrer especialmente na região anterior. O prazo para o desenvolvimento alveolar pode variar bastante, especialmente nos casos de tipos faciais longos e curtos. Os riscos apresentados pela erupção dental contínua na fase adulta também devem ser considerados. Concluiu-se que, frequentemente, a criança e o adolescente em crescimento são considerados desafios, no entanto, o cuidado odontológico é de extrema importância para assegurar melhores condições estéticas, funcionais e psicológicas para o paciente, proporcionando melhor qualidade de vida a esses pacientes e tranquilidade à sua família.

Certain conditions found in young patients indicate the use of dental implants in the oral rehabilitation process. The aim of this study was to broaden knowledge on the criteria and conditions of use for dental implants in children and adolescents. In this way, Pediatric Dentistry and Hebiatric Dentistry play an important role in various treatment stages in conjunction with the multidisciplinary team. A literature review was performed on the subject. The use of dental implants in children and young patients is less frequent and has been widely discussed because these patients are at the stage of bone development. The paucity of clinical cases reported in the literature and controversies about the use of implants increase the discussion. It is clear that the jaw growth may compromise the outcome of implant-supported oral rehabilitation, even if implants are successfully integrated. The lack of proper occlusion and unsightly situations may occur especially in the anterior region. The outcome of alveolar development can vary greatly, especially in cases of long and short facial types. The risks presented by the continuous dental eruption in adulthood should also be considered. We conclude that, often, child and adolescent growth are considered challenges; however, dental care is extremely important to ensure better aesthetic, functional, and psychological conditions for the patient, providing them a better quality of life, and tranquility to their family.

Computed tomography evaluation of the temporomandibular joint in Class I malocclusion patients: condylar symmetry and condyle-fossa relationship.

INTRODUCTION: The purpose of this study was to investigate the condyle-fossa relationship, the concentric position of the condyles, and the dimensional and positional symmetries between the right and left condyles in subjects with Class I malocclusion. METHODS: Thirty subjects from 13 to 30 years of age with Class I malocclusion had computed tomography imaging of the temporomandibular joints. The images obtained from axial slices were evaluated for possible asymmetries in size and position between the condylar processes associated with this malocclusion. The images obtained from sagittal slices were used to assess the depth of the mandibular fossa, the condyle-fossa relationship, and the concentric position of the condyles of this malocclusion. Paired Student t tests were applied, and Pearson product moment correlations were determined after measurements on both sides were obtained. RESULTS: We found no statistically significant asymmetries between the condylar processes in this sample. No statistically significant asymmetries were found in the mandibular fossa depth, the anterior joint space, and the superior joint space. The posterior joint space showed statistically significant asymmetry (P <0.05) between the right and left sides. Statistically significant (P <0.05) anterior positioning of the condyles was observed (nonconcentric positioning). CONCLUSIONS: Only the posterior articular space had a statistically significant difference between the right and left sides. There was a higher mean for posterior articular space on the right temporomandibular joint. Evaluation of the concentric position of the condyles in their mandibular fossae showed nonconcentric positioning for the 2 sides.

Computed tomography evaluation of the temporomandibular joint in Class II Division 1 and Class III malocclusion patients: condylar symmetry and condyle-fossa relationship.

INTRODUCTION: The purpose of this study was to investigate the condyle-fossa relationship, the concentric position of the condyles, and the dimensional and positional symmetries between the right and left condyles in Class II Division 1 and Class III malocclusion samples. METHODS: Thirty subjects from 12 to 38 years of age with Class II Division 1 malocclusion and 16 subjects from 13 to 41 years of age with Class III malocclusion had computed tomography of the temporomandibular joints. The images obtained from the axial slices were evaluated for possible asymmetries in size and position between the condylar processes associated with these malocclusions. The images obtained from the sagittal slices were used to assess the depth of the mandibular fossa, the condyle-fossa relationship, and the concentric position of the condyles associated with these malocclusions. Paired Student t tests were applied, and Pearson product moment correlations were determined after measurements on both sides were obtained. RESULTS: In the Class II Division 1 sample, the distance of condylar process/midsagittal plane (P = 0.019) and posterior joint space (P = 0.049) showed statistically significant differences between the right and left sides. In the Class III sample, there was no statistically significant difference between sides. Statistically significant (P <0.05) anterior positioning of the condyles was observed (nonconcentric positioning) in both the Class II Division 1 group and the Class III group. CONCLUSIONS: In the Class II Division 1 malocclusion sample, the distance of condylar process/midsagittal plane and posterior articular space had statistically significant differences between the right and left sides. In the Class III sample, there was no statistically significant difference between sides. Evaluation of the concentric position of the condyles in their mandibular fossae showed nonconcentric positioning for the right and left sides in both the Class II and Class III malocclusion groups.

Aplicações da tomografia computadorizada na odontologia / Applications of computed tomography in dentistry

Introdução: O exame tomográfico é um método radiológico quepermite obter a reprodução de uma secção do corpo humano comfinalidade diagnóstica. Os cortes tomográficos apresentam espaçosentre si e, quanto mais finos e próximos, melhor será a resoluçãoda imagem. Esses cortes podem estar unidos artificialmente porprograma de computador e permitir reconstrução tridimensional doobjeto radiografado, de tal forma que se pode escolher avisualização em outro plano (axial, sagital e coronal).Objetivo: Descrever as principais técnicas tomográficas existentese suas aplicações na Odontologia. Realizou-se uma revisão daliteratura sobre os avanços das principais técnicas tomográficasque resultaram em maior acurácia no diagnóstico, menor tempo deexame e menor quantidade de radiação. Este é o exame de eleiçãopara imagens do tecido ósseo do complexo maxilo-mandibular. Atomografia computadorizada pode ser usada na Odontologia paraidentificar e delinear processos patológicos (tumores benignos emalignos, cistos odontogênicos e corpos estranhos), visualizardentes retidos, avaliar os seios paranasais (maxilar, frontal, etmoidale esfenoidal), diagnosticar trauma (plano axial, sagital e coronal),mostrar os componentes ósseos da articulação temporomandibular(anomalia congênita, trauma, doenças do desenvolvimento,neoplasias, infecções, erosões, cistos subarticulares e osteófitos)e os leitos para implantes dentários (forma, altura e largura dorebordo alveolar, localização do canal mandibular, canal incisivo,assoalho da cavidade nasal e do seio maxilar).

Preparo ortodôntico nas más oclusöes classe II associado à cirurgia ortognática / Orthodontic preparation in orthognathic surgery cases of class II malocclusions

O presente estudo descreve as características principais das más oclusöes classe II em pacientes adultos a serem submetidos à cirurgia ortognática. Realizou-se uma revisäo bibliográfica sobre o preparo ortodôntico pré-cirúrgico, nos casos de má oclusäo classe II, para a correçäo das relaçöes ântero-posteriores, das relaçöes verticais e das relaçöes transversais. Frequentemente, a mecânica ortodôntica empregada é a oposta, em todas três dimensöes, daquelas que poderiam ser usadas em casos tratados através de métodos ortodônticos convencionais. O preparo ortodôntico para realizaçäo da cirurgia ortognática é uma condiçäo irreversível e, uma vez executado, näo se consegue realizar o tratamento sem a cirurgia