Vertical Bone Measurements From Cone Beam Computed Tomography Images Using Different Software Packages

This article aimed at comparing the accuracy of linear measurement tools of different commercial software packages. Eight fully edentulous dry mandibles were selected for this study. Incisor, canine, premolar, first molar and second molar regions were selected. Cone beam computed tomography (CBCT) images were obtained with i-CAT Next Generation. Linear bone measurements were performed by one observer on the cross-sectional images using three different software packages: XoranCat (R), OnDemand3D (R) and KDIS3D (R), all able to assess DICOM images. In addition, 25% of the sample was reevaluated for the purpose of reproducibility. The mandibles were sectioned to obtain the gold standard for each region. Intraclass coefficients (ICC) were calculated to examine the agreement between the two periods of evaluation; the one-way analysis of variance performed with the post-hoc Dunnett test was used to compare each of the software-derived measurements with the gold standard. The ICC values were excellent for all software packages. The least difference between the software-derived measurements and the gold standard was obtained with the OnDemand3D and KDIS3D (-0.11 and -0.14 mm, respectively), and the greatest, with the XoranCAT (+0.25 mm). However, there was no statistical significant difference between the measurements obtained with the different software packages and the gold standard (p > 0.05). In conclusion, linear bone measurements were not influenced by the software package used to reconstruct the image from CBCT DICOM data.29

Validation Of Cone-beam Computed Tomography As A Predictor Of Osteoporosis Using The Klemetti Classification

This study aimed at evaluating the validity of cone-beam computed tomography (CBCT) for assessing mandibular bone quality using the Klemetti classification. The morphology of the endosteal mandibular cortex of 30 (60 hemi-mandibles) postmenopausal women between the ages of 45 and 80 years was evaluated based on the Klemetti classification in panoramic radiographs used as reference images. Afterwards, panoramic reconstruction and cross-sectional slices of CBCT examinations of these patients were analyzed and categorized according to the same classification. All the images were assessed by two oral radiologists. The McNemar-Bowker test compared the agreement between the CBCT images and the reference images. No differences were found between the diagnostic results based on panoramic radiography and panoramic reconstruction. However, the mean scores for the cross-sectional evaluation were higher, and the results, statistically different from the others. Based on the disagreement found between the panoramic radiographs and the CBCT cross-sectional slices, the Klemetti classification is not an adequate means of assessing bone quality with CBCT. On the other hand, the higher values found for the cross-sectional slices could be associated with better visibility on the CBCT images.30

Assessment of zirconium-implants-related artifact production on cone beam computed tomography images

Orientador: Deborah Queiroz de Freitas FrançaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: A produção de artefatos em imagens de tomografia computadorizada de feixe cônico (TCFC) é o principal limitador do uso dessa técnica na avaliação pós-operatória de implantes; no entanto, a quantidade de artefato é variável de acordo com o tipo de material presente na área de interesse, e o ajuste dos parâmetros de exposição é um meio capaz de aprimorar a qualidade da imagem. Atualmente, os implantes constituídos por material cerâmico, como a zircônia, podem representar uma alternativa às desvantagens do titânio; por outro lado, seu comportamento quanto à produção de artefatos e o efeito da variação dos parâmetros são ainda pouco conhecidos. Com isso, o objetivo nesse estudo foi avaliar a produção de artefatos derivados de implantes de zircônia nas imagens por TCFC, bem como comparar sua produção quando diferentes parâmetros de exposição são utilizados. Um implante de zircônia foi instalado no rebordo de uma mandíbula humana seca, e um bloco com densidade semelhante à do osso foi fixado na cortical vestibular, na região do implante, com a finalidade de padronizar a seleção das imagens a serem avaliadas. Água e cera utilidade foram utilizadas para atenuação do feixe de radiação e a posição do phantom foi padronizada com auxílio de material de moldagem de precisão. As imagens foram adquiridas com diferentes protocolos de exposição, que incluíram variação da kilovoltagem (kVp) (70, 76, 80, 86 e 90), dois modos de resolução (voxels 0,32 e 0,16) e ativação da ferramenta de redução de artefato (FRA), no aparelho ProMax 3D (Planmeca Oy, Helsinki, Finland), o qual fornecia as doses de exposição ao fim de cada escaneamento Para as avaliações, uma mesma reconstrução axial foi selecionada em todas as imagens, utilizando o bloco como referência, na região média do implante. Posteriormente, as imagens axiais selecionadas foram avaliadas no software ImageJ, no qual foram adquiridos histogramas para duas áreas de interesse (ROI): área controle e área implante, determinadas na água e no osso próximo ao implante, respectivamente. Os valores do desvio padrão dos tons de cinza (SD) foram obtidos, a taxa de contraste-ruído (CNR) foi calculada e os resultados avaliados através da análise de regressão linear múltipla e análise de variância. Os valores de SD diminuíram com o aumento do kVp e a ativação da FRA. Já a CNR foi significativamente afetada pela variação do protocolo (p = 0.0025), e a influência foi relacionada ao uso da FRA. A associação entre FRA e baixa resolução promoveu um aumento da CNR de acordo com a elevação da kVp utilizada. Assim, pôde-se concluir que, apesar da produção significativa de artefatos na presença de implante de zircônia, determinados protocolos de exposição são capazes de reduzir o ruído e a variação de cinza produzidos nas imagens. Por isso, o ajuste desses parâmetros deve ser realizado, ponderando-se também a dose de radiação, sendo o protocolo de maior kVp, baixa resolução e uso da FRA o mais indicado, por apresentar dose de radiação reduzida e significativa melhora da qualidade da imagemAbstract: Artifacts produced by high-density materials in CBCT images is one of the main Oral Radiology¿s concern that usually restrain the use of this exam modality on post implant evaluation. Nevertheless, the amount of artifact generation may vary widely regarding the material density, and different exposure settings can provide some reduction on it, improving the image quality. Nowadays, ceramic-based implants, as the zirconium ones, might be used as an alternative to titanium disadvantages, although, its artifact production on those images and their response to different settings are still unknown. Due to this, the aim of the present study was to quantify artifacts produced by zirconium implants on CBCT images, obtained from a wide range of exposure protocols, comparing their related production. In a superior border of a dry human mandible, a zirconium implant was placed, and an epoxy resin¿based tissue substitute block (ERB) was fixed in contact with the buccal cortical plate, in the middle region of the implant, in order to be used as a reference of the implant position at the image evaluation. Water and wax were used to simulate soft tissue attenuation, and the phantom position was standardized in a plastic box with impression material. Twenty scans were performed in a ProMax 3D (Planmeca Oy, Helsinki, Finland) unit under different exposure protocols, involving Kilovoltage (kVp) settings (70, 76, 80, 86 e 90), 2 resolution modes (voxels sizes 0,32 and 0,16) and the metallic artifact reduction tool (MAR) activation. By the end of each scanning process, the exposure dose was available. Using the ERBS block as a reference, a same axial slice, in the middle region of the implant, were chosen in each dataset and these images were analysed using the ImageJ software. The area histogram were calculated in two regions of interest (ROI), control and implant area, determined at water and bone respectively. The gray voxel level standard deviation (SD) and the contrast-to-noise ratio were determined (CNR), and the variables were analyzed using multiple linear regression analysis and one-way ANOVA. The SD values decreased with increasing KVp and the MAR activation, and the CNR was significantly affected by the settings (p = 0.0025), mainly related to the MAR use. On the other hand, when the MAR function was activated and the resolution was low, the CNR was greatly affected by a higher kVp. Thus, despite of a significant artifact production, some exposure protocols settings leads to a smoother image and decreases the gray level variation. Due to this, the exposure protocol adjustment should be highly recommended, considering the radiation dose; highlighting the higher kVp, low resolution and MAR activation protocol, as its presents a lower dose while improves the image qualityDoutoradoRadiologia OdontologicaDoutora em Radiologia Odontológic

Influence of milliamperage variation on cone-beam computerized tomography image quality

Orientadores: Plauto Chrisptopher Aranha Watanabe, Deborah Queiroz de FreitasDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Imagens por tomografia computadorizada de feixe cônico (TCFC) são frequentemente utilizadas; no entanto, seu uso envolve doses de radiação que não podem ser indiscriminadas. A redução da miliamperagem (mA) é um dos meios mais práticos para se reduzir a dose de radiação; porém, ainda não se sabe o efeito isolado de protocolos de baixa mA na qualidade das imagens, fundamental para uma correta análise dessas. Com isso, o objetivo desse estudo foi avaliar a influência da variação da miliamperagem na qualidade da imagem de TCFC de diferentes regiões ósseas de mandíbulas edêntulas. Os exames tomográficos foram realizados em oito mandíbulas secas, utilizando os diferentes valores de miliamperagem disponíveis (2, 4, 6,3, 8, 10, 12 e 15 mA), em um aparelho de tomografia computadorizada de feixe cônico (K9000, Kodak). Após a obtenção das imagens, os cortes parassagitais das regiões correspondentes às de incisivos, caninos, prémolars, 1º molares e 2º molares foram avaliados por três radiologistas, de duas maneiras. Inicialmente, foi realizada uma avaliação subjetiva da qualidade, na qual foi adotada uma escala de quatro pontos (0 a 3), de acordo com a visibilidade das estruturas; posteriormente, os avaliadores realizaram uma avaliação objetiva, através da obtenção de medidas nas imagens, as quais foram posteriormente comparadas com medidas obtidas diretamente nas mandíbulas. Vinte e cinco por cento das imagens foram reavaliadas pelos examinadores, após 30 dias, para avaliação da concordância intraexaminador. Os resultados intra e interexaminador variaram entre bom a muito bom para avaliação da qualidade da imagem e foram excelentes quando foram avaliadas as medidas. Após a aplicação do teste estatístico de Tukey, foi possível observar que existiu uma influência da corrente utilizada na qualidade da imagem; entretanto, essa influência foi limitada ao uso de mA baixas (2 e 4). Após a mA 6,3, as imagens apresentaram desempenho semelhante, demonstrando não haver associação linear entre aumento dessa e melhora da qualidade da imagem. As medidas da altura óssea não sofreram influência da mA utilizada; porém, as imagens obtidas com 6,3 mA apresentaram a menor diferença em relação às medidas reais. Assim, pôde-se concluir que a mA 6,3 apresenta um equilíbrio adequado entre dose de radiação e qualidade da imagem no aparelho avaliado, devendo assim ser utilizada, e que o uso de mA maiores deve ser evitado, uma vez que não resultaram em imagens de maior qualidade e, com isso, apresentariam maior dose de radiação sem benefícios para o pacienteAbstract: Despite cone beam computed tomography (CBCT) images are often used; this involves radiation doses that require attention. The milliamperage (mA) reduction is an easy way to reduce radiation dose; however, the isolated effect of low mA settings on image quality is not knowed. This study aimed to evaluate the milliamperage in the image quality of the CBCT in different edentulous bone regions. The examinations were done in eight dry mandibles with different milliamperage values (2, 4, 6.3, 8, 10, 12 and 15) using the KODAK 9000 CBCT unit. The cross-sectional slices of the incisive, canine, premolar, first and second molar were analyzed by three oral radiologists, in two ways. Initially, a subjective evaluation of the visibility of the anatomical structures was performed based on a four grade scale and, afterwards, an objective evaluation through bone height measurement, which was compared with the real measures obtained in the mandible. After 30 days, 25% of the sample was re-evaluated by the observers, in order to obtain the intraobserver reproducibility. The intra and interobserver values varied between good and very good for the image quality evaluation, and they were excellent when evaluating the measurements. The Tukey test showed the influence of the milliamperage in the image quality, but only in the lowest values (2 and 4). The other milliamperage values had a similar performance. The measurements of bone height were not influenced by milliamperage, but the images obtained with 6.3 mA showed the lowest difference compared to the real measurements. Thus, it was concluded that the 6.3 mA provides an appropriate balance between radiation dose and image quality, and therefore the use of higher milliamperage values should be avoided since it does not provide an improvement of the image quality and it uses higher radiation dose without any benefit for the patientMestradoRadiologia OdontologicaMestra em Radiologia Odontológic

Diagnosis of vertical root fracture in teeth close and distant to implant: an in vitro study to assess the influence of artifacts produced in cone beam computed tomography

Objectives To evaluate the influence of artifacts produced by zirconium implant on the diagnosis of vertical root fracture (VRF) in teeth close and distant to the implant in cone beam computed tomography (CBCT) images. We also determined if kilovoltage (kVp) and metal artifact reduction (MAR) tool could influence this diagnosis.Materials and methodsTwenty single-root teeth were divided in control and fractured groups (n=10). The teeth were randomly positioned in the first and second and right and left pre-molar alveoli of a dry human mandible. CBCT exams were acquired using a ProMax 3D unit with varying kVp (70, 80, or 90kVp), with or without MAR, and with and without a zirconium implant placed in the alveolus of first right molar. The images were evaluated by five observers. The area under the receiver operating characteristic curve (ROC), sensitivity, and specificity were calculated and compared by analysis of variance with a significance level of 5%.ResultsIn general, ROC and sensitivity were not affected by the factors studied (p>0.05). The main effects occurred in specificity; when implant was used without MAR, the values were lower for tooth 45 for all kVps (p=0.0001).ConclusionsArtifacts produced in the vicinity of teeth with suspected VRF impair the diagnosis by decreasing the specificity, because they can mimic the VRF line generating false positives. However, MAR improves the specificity, being its use recommended when metallic objects are present near teeth with suspected VRF.Clinical RelevanceSince nowadays, many patients who undergo CBCT show implants and they definitively produce artifacts, it is important to evaluate the influence of such artifacts in the diagnosis of teeth that are close to the generator-artifact object23312631270CAPES - Coordenação de Aperfeiçoamento de Pessoal e Nível Superior88881.118874/2016–0

Vertical Bone Measurements From Cone Beam Computed Tomography Images Using Different Software Packages.

This article aimed at comparing the accuracy of linear measurement tools of different commercial software packages. Eight fully edentulous dry mandibles were selected for this study. Incisor, canine, premolar, first molar and second molar regions were selected. Cone beam computed tomography (CBCT) images were obtained with i-CAT Next Generation. Linear bone measurements were performed by one observer on the cross-sectional images using three different software packages: XoranCat®, OnDemand3D® and KDIS3D®, all able to assess DICOM images. In addition, 25% of the sample was reevaluated for the purpose of reproducibility. The mandibles were sectioned to obtain the gold standard for each region. Intraclass coefficients (ICC) were calculated to examine the agreement between the two periods of evaluation; the one-way analysis of variance performed with the post-hoc Dunnett test was used to compare each of the software-derived measurements with the gold standard. The ICC values were excellent for all software packages. The least difference between the software-derived measurements and the gold standard was obtained with the OnDemand3D and KDIS3D (-0.11 and -0.14 mm, respectively), and the greatest, with the XoranCAT (+0.25 mm). However, there was no statistical significant difference between the measurements obtained with the different software packages and the gold standard (p> 0.05). In conclusion, linear bone measurements were not influenced by the software package used to reconstruct the image from CBCT DICOM data

Influence of cone beam computed tomography settings on implant artifact production: zirconia and titanium

This in vitro study assessed the artifact production related to titanium and zirconia implants in cone beam computed tomography (CBCT) and compared the effect of different protocol settings on image quality for both materials. Materials and Methods: A titanium implant and a zirconia implant were placed in a dry mandible. CBCT scans were obtained separately for each implant using the ProMax 3D (Planmeca) unit; 20 protocols were tested with varying kilovoltage (70 to 90 kVp) and resolution (high and low), and with and without a metal artifact reduction tool. Standard deviation and contrast-noise ratio were calculated in regions of interest adjacent and distant to the implant. Results: The zirconia produced more artifacts and its images were more affected by the different protocols than titanium. High kVps and an activated metal artifact reduction tool decreased the standard deviation values related to both implants. Activation of the metal artifact reduction tool also increased contrast-noise ratio values for both implants, whereas increasing kVp improved them only on titanium images. The standard deviation and contrast-noise ratio were not affected by resolution. Conclusion: The zirconia implant generated more image artifacts than the titanium implant. Increasing kVp and the metal artifact reduction tool are efficient in decreasing the CBCT artifacts for both implants, whereas resolution does not affect their production3451114112

Oblique Or Orthoradial Cbct Slices For Preoperative Implant Planning: Which One Is More Accurate

Aim: To assess which slice inclination would be more accurate in measuring sites for implant placement: the oblique or the orthoradial slice. Methods: Five regions of eight edentulous mandibles were selected (incisor, canine, premolar, first molar and second molar). The mandibles were scanned with a Next Generation i-CAT CBCT unit. Two previously calibrated oral radiologists performed vertical measurements in all the selected regions using both the oblique and orthoradial slices. The mandibles were sectioned in all the evaluated regions in order to obtain the gold standard. The Wilcoxon signed rank test compared the measurements obtained in the oblique and orthoradial slices with the gold standard. Results: The bone height measurements for the first and second molar regions using the orthoradial slices were statistically different from the gold standard. Conclusions: Using the orthoradial slices to obtain cross-sectional images may offer insufficient accuracy for implant placement in the posterior region.132104-10

Double mental foramina

The knowledge of the location, trajectory, and characteristics of the neurovascular bundles in the jaws is fundamental to reduce risk of injuries to this structure during surgical procedures, especially when anatomical variations are present. The presence of anatomical variations associated with the mental foramen has been reported in some cases and is frequently undervalued in clinical procedures. Sensorial disturbances, such as paresthesia in the lower lip or cheeks, may occur as result of pressure on the mental foramen. These anatomical variations can be detected in clinical practice by imaging exams. Computed tomography has been established as a valuable imaging modality capable of providing in-depth information about maxillofacial structures, allowing detailed evaluation of their topography and anatomical variations, such as additional mental foramina. The objective of this article was to describe a case with double mental foramina that only could be observed in computed tomography images. The use of cone beam computed tomography has increased in dentistry, thus anatomical variations that may have an influence on the diagnosis and treatment planning must be recognized. Have a good knowledge of additional mental foramina may contribute to adequate anesthetic techniques and to avoid misdiagnosis of bone lesions and eventual damages to the nerves and vessel during surgical procedures in that region