Evaluation of Threshold Values for Root Canal Filling Voids in Micro-CT and Nano-CT Images

While several materials and techniques have been used to assess the quality of root canal fillings in micro-CT images, the lack of standardization in scanning protocols has produced conflicting results. Hence, the aim of this study was to determine a cutoff voxel size value for the assessment of root canal filling voids in micro-CT and nano-CT images. Twenty freshly extracted mandibular central incisors were used. Root canals were prepared with nickel titanium files to an ISO size 40/0.06 taper and then filled with a single cone (40/0.06 taper) and AH Plus sealer. The teeth were scanned with different voxel sizes with either micro-CT (5.2, 8.1, 11.2, and 16.73 μm) or nano-CT (1.5 and 5.0 μm) equipment. Images were reconstructed and analyzed with the NRecon and CTAn software. Void proportion and void volume were calculated for each tooth in the apical, middle, and coronal thirds of the root canal. Kruskal-Wallis and post hoc Mann–Whitney U tests were performed with a significance level of 5%. In micro-CT images, significantly different results were detected among the tested voxel sizes for void proportion and void volume, whereas no such differences were found in nano-CT images (p>0.05). Micro-CT images showed higher void numbers over the entire root length, with statistically significant differences between the voxel size of 16.73 μm and the other sizes (p<0.05). The values of the different nano-CT voxel sizes did not significantly differ from those of the micro-CT (5.2, 8.1, and 11.2 μm), except for the voxel size of 16.73 μm (p<0.05). All tested voxel sizes enabled the detection of root canal filling voids except for the voxel size of 16.73 μm. Bearing in mind the limitations of this study, it seems that a voxel size of 11.2 μm can be used as a reliable cutoff value for the assessment of root canal filling voids in micro-CT imaging.Publisher's Versio

Study of the superior alveolar canals and infraorbital canal using cone beam computed tomography

Para oferecer mais informações aos cirurgiões no planejamento de intervenções cirúrgicas maxilofaciais, o presente estudo teve como objetivo avaliar a presença, localização e tamanho dos canais alveolares superiores (CAS), anterior (CASA) e posterior (CASP), canal infra-orbital (CI) e forame infra-orbital (FI) em imagens de tomografia computadorizada de feixe cônico (TCFC) de 100 pacientes adultos (&#x2265; 20 anos), obtidas pelo aparelho i-CAT Classic®. Um examinador calibrado observou a presença dos CAS, CI e FI bilateralmente. Quando presentes, eram medidos comprimento (parte descendente, parte do assoalho da órbita e total), largura e altura do CI; altura, largura e distância ao rebordo inferior da órbita (RIO) do FI; distância da borda inferior dos CAS a crista do rebordo alveolar em 5 regiões: canino (CAN), primeiro pré-molar (1PM), segundo pré-molar (2PM), primeiro molar (1M) e segundo molar (2M); e os diâmetros dos CAS. Foram também observados a localização dos CAS em relação ao seio maxilar e a presença de reparos anatômicos como canal duplo/múltiplo, anastomose intra-óssea e extensão do CASA para a abertura piriforme. Associações entre homens e mulheres, lados direito e esquerdo e regiões foram investigadas para todas as medidas e visibilidade, utilizando separadamente os métodos estatísticos. A presença do CI e FI foi de 100%. A visibilidade do CASA/CASP foi de: 99%/0% (CAN), 99%/21% (1PM), 89%/41% (2PM), 46%/44% (1M) e 7%/61% (2M). As médias dos comprimentos da parte descendente, da parte do assoalho da órbita e total do CI foram de 8,82mm, 19,44mm e 28,35mm, respectivamente. Altura e largura médias do CI foram, respectivamente, 2,08mm e 3,91mm. As médias da altura, largura e distância ao RIO do FI foram: 4,43mm, 5,18mm e 7,52mm, respectivamente. As distâncias médias do CASA ao rebordo alveolar foram: 18,54mm (CAN), 25,47mm (1PM), 28,43mm (2PM), 30,78mm (1M) e 33,21mm (2M); e do CASP: 22,3mm (1PM), 17,65mm (2PM), 15,34mm (1M) e 16,87mm (2M). As médias dos diâmetros do CASA e do CASP foram 0,90mm e 0,83mm, respectivamente, sendo que 77,5% dos CASA e 82% dos CASP eram &#x2264; 1mm e 22,5% dos CASA e 18% dos CASP eram entre 1-2 mm. Em relação ao seio maxilar, 53% e 44% dos CASA foram encontrados no terço superior e médio, respectivamente, e 64% e 36% dos CASP foram encontrados no terço inferior e médio, respectivamente. Houve diferença estatisticamente significativa (p<0,05) entre homens e mulheres para o comprimento, altura e largura do CI; para a altura, largura e distância ao RIO do FI; e para as distâncias dos CAS ao rebordo alveolar. CASA duplo, anastomose intra-óssea e extensão do CASA para a abertura piriforme foram detectados em 24,5%, 38,5% e 84% dos casos, respectivamente. A localização da anastomose foi teve maior ocorrência entre o CAN e 1PM (43%). Os resultados sugerem que a TCFC seja uma ferramenta adequada para examinar os CAS, CI e FI no planejamento de procedimentos cirúrgicos do terço médio da face, a fim de evitar danos a estruturas neurovasculares importantes.To provide more information to clinicians in planning maxillofacial surgical interventions, the present study evaluated the presence, location and size of the superior alveolar canals (SAC), anterior (ASAC) and posterior (PSAC), infraorbital canal (IC) and infra-orbital foramen (IF) in cone beam computed tomography (CBCT) of 100 adult patients (&#x2265; 20 years old), obtained by i-CAT Classic®. One calibrated examiner observed SAC, IC and IF presence, bilaterally. When present, were measured: length (descending part, orbital floor part and total), width and height of the IC, height, width and distance from the IF to the inferior orbital rim (IOR), distance from the lower border of SAC to the alveolar crest in 5 regions: canine (CAN), first premolar (1PM), second premolar (2PM), first molar (1M) and second molar (2M); and the diameters of SAC. It was also observed the location of SAC in relation to the maxillary sinus floor and the presence of anatomical landmarks such as doble/multiple canal, intraosseous anastomosis and ASAC extension to the piriform aperture. Associations between men and women, right and left sides and regions were investigated for all measurements and presence using statistical methods separately. The presence of the IC and IF was 100%. The presence of ASAC/PSAC was: 99%/0% (CAN), 99%/21% (1PM), 89%/41% (2PM), 46%/44% (1M) e 7%/61% (2M). The mean lengths of the IC descending part, IC orbital floor part and total lenght of the IC were 8.82mm, 19.44mm and 28.35mm, respectively. The mean height and width of the IC were, respectively, 2.08mm and 3.91mm. The mean height, width and distance to the IOR of IF were: 4.43mm, 5.18mm and 7.52mm, respectively. The mean distances of ASAC to the alveolar crest were: 18.54mm (CAN), 25.47mm (1PM), 28.43mm (2PM), 30.78mm (1M) and 33.21mm (2M); and of PSAC: 22.3mm (1PM), 17.65mm (2PM) 15.34mm (1M) and 16.87mm (2M). The mean diameters of ASAC and PSAC were 0.90mm and 0.83mm, respectively, and that, 77.5% of ASAC and 82% of PSAC were &#x2264; 1mm and 22.5% of ASAC and 18% of PSAC were between 1-2 mm. In relation to the maxillary sinus, 53% e 44% of the ASAC were found in the upper and middle third of maxillary sinuses, respectively, and 64% and 36% of the PSAC were found in lower and middle third, respectively. There was a statistically significant difference (p<0.05) between men and women for the length, height and width of the IC, for the height, width and distance to the IOR of IF, and for distances of SAC to the alveolar crest. Double ASAC, intraosseous anastomosis and ASAC extension to the piriform aperture were present in: 24.5%, 38.5% and 84% of the cases, respectively. The location of the anastomosis had more incidence between the CAN and 1PM (43%). The results suggest that CBCT is a suitable tool to evaluate the SAC, IC and IF, assisting surgeons in planning surgical procedures of the midface, in order to avoid damage to important neurovascular structures

Relationship between trabecular bone architecture and early dental implant failure in the posterior region of the mandible

OBJECTIVE: To investigate the relationship between preoperative trabecular bone structure and implant outcome based on bone morphometric bone parameters from CBCT scans. MATERIALS AND METHODS: Twenty consecutive cases with early implant failure in the posterior region of the mandible were matched with 20 control patients with a successful implant osseointegration selected. All patients had taken a preoperative CBCT image according to a standardized acquisition protocol. On these CBCT scans, the trabecular bone of each implantation site was selected and segmented, after which 3D morphometric bone parameters were calculated and used in a cluster analysis to objectively differentiate trabecular bone patterns. Fisher's exact test was used to determine whether there is a significant association between trabecular pattern and implant outcome. RESULTS: A sparse, intermediate, and dense trabecular bone pattern was distinguished by cluster analysis. The relationship between the trabecular bone pattern and early implant failure was significant (z = 9.6; p < .05). Early implant failure was more likely to occur in the sparse bone types, while implant survival was associated with intermediate bone types. CONCLUSION: Prior to implant placement, attention should be given to extreme deviations in trabecular structure at the planned implant sites. Very sparse or very dense bone should be carefully evaluated at the potential implant site, while intermediate bone types seem favorable for implant survival.status: publishe

Computer-based automatic classification of trabecular bone pattern can assist radiographic bone quality assessment at dental implant site

OBJECTIVE:: To develop and validate an automated classification method that determines the trabecular bone pattern at implant site based on three-dimensional bone morphometric parameters derived from CBCT images. METHODS:: 25 human cadaver mandibles were scanned using CBCT clinical scanning protocol. Volumes-of-interest comprising only the trabecular bone of the posterior regions were selected and segmented for three-dimensional morphometric parameters calculation. Three experts rated all bone regions into one of the three trabecular pattern classes (sparse, intermediate and dense) to generate a reference classification. Morphometric parameters were used to automatically classify the trabecular pattern with linear discriminant analysis statistical model. The discriminatory power of each morphometric parameter for automatic classification was indicated and the accuracy compared to the reference classification. Repeated-measures analysis of variances were used to statistically compare morphometric indices between the three classes. Finally, the outcome of the automatic classification was evaluated against a subjective classification performed independently by four different observers. RESULTS:: The overall correct classification was 83% for quantity-, 86% for structure-related parameters and 84% for the parameters combined. Cross-validation showed a 79% model prediction accuracy. Bone volume fraction (BV/TV) had the most discriminatory power in the automatic classification. Trabecular bone patterns could be distinguished based on most morphometric parameters, except for trabecular thickness (Tb.Th) and degree of anisotropy (DA). The interobserver agreement between the subjective observers was fair (0.25), while the test-retest agreement was moderate (0.46). In comparison with the reference standard, the overall agreement was moderate (0.44). CONCLUSION:: Automatic classification performed better than subjective classification with a prediction model comprising structure- and quantity-related morphometric parameters. ADVANCES IN KNOWLEDGE:: Computer-aided trabecular bone pattern assessment based on morphometric parameters could assist objectivity in clinical bone quality classification.status: publishe

Comparative evaluation of cone beam CT and micro-CT on blooming artifacts in human teeth filled with bioceramic sealers

AimTo assess blooming artifacts caused by root canal sealers in CBCT images compared with those that appeared in micro-CT scan images used as references.Materials and methodThirty freshly extracted human mandibular central incisors were used. Root canals were prepared with nickel titanium files with an ISO size 40/0.06 taper and filled with a single cone (40/0.06 taper) and three different sealers. The samples were divided into the following three groups with 10 roots each: (I) AH Plus sealer; (II) Sure Seal Root; and (III) Total BC sealer. Teeth were scanned with the same voxel sizes (0.2mm) in different CBCT devices and the micro-CT images were acquired as reference images.ResultsSignificantly different results in terms of blooming artifacts were detected between CBCT and micro-CT images, as well as among the CBCTs images. The canals filled with AH Plus sealer showed more blooming artifacts than those filled with bioceramic sealers (p<0.05). Additionally, the worst blooming artifact was observed when the images were acquired with lower kilovoltage peak.ConclusionThe appearance of blooming artifacts is dependent on sealer and CBCT, and their effects are significantly worse than they are in micro-CT images. The differential effect of different sealers and distinct CBCT protocols should be further investigated to enable the use of bioceramic sealers without a significant impact on post-treatment imaging.Clinical relevanceRoot canal sealers showed a different extent of blooming artifact in CBCT images. Hence, researchers and clinicians should be aware of these artifacts before conducting endodontic evaluations using CBCT images2383267327

Micro-CT and nano-CT analysis of filling quality of three different endodontic sealers

Objectives: To investigate voids in different root canal sealers using micro-CT and nano-CT, and to explore the feasibility of using nano-CT for quantitative analysis of sealer filling quality

A quantitative analysis of metal artif'et rediutign algorithm performance in volume correction with 3 CBCT devices

OBJECTIVE: The aim of this study was to quantitatively assess the performance of metal artifact reduction (MAR) algorithms on the volume of metal cylinders, considering the influence of materials, positions, and fields of view (FOVs), by using 3 cone beam computed tomography (CBCT) devices (NewTom VGi evo, Picasso Trio, and ProMax 3-D Max). STUDY DESIGN: Nine phantoms containing cylinders of amalgam, copper-aluminum (CuAl) metal alloy, and titanium, combined in up to 3 positions, were scanned by using 2 different FOVs. MATLAB software was used to evaluate the differences between volumes before and after MAR application, and the possible interference of materials, positions, and FOVs. Wilcoxon's test and the Kruskal-Wallis test were used at a level of significance of 5%. RESULTS: In general, images containing amalgam and CuAl showed a significant difference in volume before and after MAR application. However, no significant difference after MAR was observed (P > .05) relative to positions and FOVs. MAR had an impact on the cylinder volumes only in the NewTom VGi evo and ProMax 3-D Max scanners. CONCLUSIONS: The performance of MAR algorithms in volume correction of metal objects is dependent on the materials and the CBCT unit.status: publishe

The performance of metal artifact reduction algorithms in cone beam computed tomography images considering the effects of materials, metal positions, and fields of view

OBJECTIVE: The aim of this study was to assess the performance of 2 metal artifact reduction (MAR) algorithms in cone beam computed tomography (CBCT) imaging, considering different materials, metal positions, and fields of view (FOVs). STUDY DESIGN: Nine phantoms containing cylinders of amalgam, copper-aluminum (Cu-Al) alloy, and titanium were scanned by using Picasso Trio and ProMax 3D CBCT units with small and medium FOVs. Scans were made with and without MAR algorithms. The standard deviation (SD) of voxel gray values was measured in the neighborhood of the cylinders. Differences in SD were statistically evaluated for effects of MAR and the other parameters, with a significance level of 5%. RESULTS: Significant differences between images with MAR and those without MAR for both devices (P ≤ .0001) were observed. Amalgam showed the largest artifact expression, followed by Cu-Al and titanium. After correction, differences remained only in Picasso Trio images (P = .002). Considering positions, no significant difference in the performance of the MAR algorithm was observed in either device. Considering FOVs, significant differences were observed for ProMax 3D (P = .005), with less artifact expression in the medium FOV after MAR correction. CONCLUSIONS: MAR algorithms were effective for artifact reduction despite variation in performance according to device, FOV, and material properties. The position of the metal cylinder within the FOV had no significant effect.status: publishe

The performance of metal artifact reduction algorithms in cone beam computed tomography images considering the effects of materials, metal positions, and fields of view

The aim of this study was to assess the performance of 2 metal artifact reduction (MAR) algorithms in cone beam computed tomography (CBCT) imaging, considering different materials, metal positions, and fields of view (FOVs). Study Design. Nine phantoms containing cylinders of amalgam, copper-aluminum (Cu-Al) alloy, and titanium were scanned by using Picasso Trio and ProMax 3D CBCT units with small and medium FOVs. Scans were made with and without MAR algorithms. The standard deviation (SD) of voxel gray values was measured in the neighborhood of the cylinders. Differences in SD were statistically evaluated for effects of MAR and the other parameters, with a significance level of 5%. Significant differences between images with MAR and those without MAR for both devices (P <= .0001) were observed. Amalgam showed the largest artifact expression, followed by Cu-Al and titanium. After correction, differences remained only in Picasso Trio images (P = .002). Considering positions, no significant difference in the performance of the MAR algorithm was observed in either device. Considering FOVs, significant differences were observed for ProMax 3D (P = .005), with less artifact expression in the medium FOV after MAR correction. MAR algorithms were effective for artifact reduction despite variation in performance according to device, FOV, and material properties. The position of the metal cylinder within the FOV had no significant effect12717176FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2014/17744-