Nano-computed tomography: current and future perspectives

Root canal conicity determination of primary second molars using nanotomography: An in vitro study

BACKGROUND

The conicity of the root canals of primary teeth is an important measure for endodontic therapies. However, determining this conicity depends on the methods employed, which requires further investigation.

AIM

The aim of this study was to determine the conicity of the root canals of the upper and lower primary second molars using nanotomography (nCT).

DESIGN

An in vitro study was performed using nine primary second molars, both upper and lower, subjected to nCT. Comparisons between the diameters of root canals were performed between the thirds (cervical-D0, middle-D5, and apical-D7). The conicity (%) was determined for each root canal from cervical to apical. Data were statistically analyzed with a significance level of 5%.

RESULTS

The conicity ranged from 2% to 8% for the upper primary second molars. Significant differences in root canal diameter between the thirds (D0, D5, and D7 points) were observed in the mesio- and distobuccal roots (p < .05), but not in the palatal roots (p > .05). For the lower primary second molars, the conicity ranged from 2% to 17%, as well as significant differences in root canal diameter between the thirds (D0, D5, and D7 points) were observed in all roots (distal, mesiobuccal, and mesiolingual; p < .05).

CONCLUSION

The conicity of the upper primary second molars was different from that of the lower ones, which showed a greater variability.

Comparative evaluation of remaining dentin thickness, canal centering ability and apical deformity between ProFit S3 and Protaper gold - A nano CT study

Purpose

For the root canal treatment to be successful, the root canal system must be cleaned and shaped, and must be gradually widened from the apical to the coronal region in order to preserve dentin thickness. ProFit S3 (Profit Dental, India) patented rotary file with variable taper design preserves dentin. The study employs ultra-high-resolution nano-computed tomography to assess the volumetric changes of two new rotary files in permanent mandibular premolars.

Materials and methods

Based on inclusion and exclusion criteria, this in-vitro investigation used extracted premolars. Before the pre-operative scan, samples were made and the working length was determined using a high-precision nano-CT (SkyScan 2214, Bruker, Kontich, Belgium). A single skilled pediatric dentist used ProFit S3 (Profit Dental, India) and Protaper Gold (PTG; Dentsply, Tulsa Dental Specialties, Tulsa, OK, USA) to prepare the canals. Post-op scans were similar to pre-ops. For 3D root canal visualization and analysis, NRecon software was used to rebuild images.

Results

Profit S3 has a mean value of 0.65500 and Protaper gold 1.38800, indicating a significant range. Protaper gold followed Profit S3 in canal volume differential. The two rotating file systems differed significantly (p 0.05). ProFit S3 maintained mesiodistal and buccolingual dentin thickness at 4 mm, 8 mm, and 12 mm, followed by Protaper Gold.

Conclusions

ProFit S3 exhibited the lowest mean canal volume difference compared to Protaper gold. Unlike Protaper Gold, ProFit S3 offers a variable taper design that preserves root canal anatomy, peri cervical dentin, and dentin thickness.

Comparative evaluation of volumetric changes following rotary and hand files' canal preparation of primary maxillary canine: an in vitro nano-CT analysis

PURPOSE

To evaluate the volumetric changes of two recently introduced paediatric rotary file systems in comparison with conventional hand file systems in primary maxillary canines using an ultra-high-resolution nano-computed tomography.

METHODS

This in vitro study was performed in extracted primary maxillary canines based on certain inclusion and exclusion criteria. Samples were prepared, and working length was determined after the pre-operative scan using a high-resolution nano-CT device (SkyScan 2214, Bruker, Kontich, Belgium). A single well-experienced paediatric dentist prepared the canals using three file systems: Kedo-S plus, Kedo-SG blue and hand K-files. All samples were subjected to post-operative scans performed similar to pre-operative scans. Image reconstruction was performed with NRecon software for 3D volumetric visualisation and analysis of the root canals.

RESULTS

Kedo-SG blue file systems had the highest mean difference in the canal volume (4.05%). Hand K-files had the least difference at (3.71%) of canal volume. Kedo-S plus file system had a moderate mean canal volume difference (3.82%) which is closer to hand K-files. Intergroup comparison between the three groups showed that the mean difference in canal volume was statistically significant between all three file systems (p = 0.000).

CONCLUSION

Within the limitations of the current study, rotary file systems produced a significant enlargement of canals as compared to hand files. Kedo-SG blue created a uniform preparation of the canal cervico-apically. Kedo-S plus files were prepared more coronally with minimal preparation apically as close to the preparation of hand files.

TRIAL REGISTRATION

Trial registration number: IHEC/SDC/PEDO-2103/22/651, Date of registration: 2022.

Generating 3D images of material microstructures from a single 2D image: a denoising diffusion approach

Three-dimensional (3D) images provide a comprehensive view of material microstructures, enabling numerical simulations unachievable with two-dimensional (2D) imaging alone. However, obtaining these 3D images can be costly and constrained by resolution limitations. We introduce a novel method capable of generating large-scale 3D images of material microstructures, such as metal or rock, from a single 2D image. Our approach circumvents the need for 3D image data while offering a cost-effective, high-resolution alternative to existing imaging techniques. Our method combines a denoising diffusion probabilistic model with a generative adversarial network framework. To compensate for the lack of 3D training data, we implement chain sampling, a technique that utilizes the 3D intermediate outputs obtained by reversing the diffusion process. During the training phase, these intermediate outputs are guided by a 2D discriminator. This technique facilitates our method's ability to gradually generate 3D images that accurately capture the geometric properties and statistical characteristics of the original 2D input. This study features a comparative analysis of the 3D images generated by our method, SliceGAN (the current state-of-the-art method), and actual 3D micro-CT images, spanning a diverse set of rock and metal types. The results shown an improvement of up to three times in the Frechet inception distance score, a typical metric for evaluating the performance of image generative models, and enhanced accuracy in derived properties compared to SliceGAN. The potential of our method to produce high-resolution and statistically representative 3D images paves the way for new applications in material characterization and analysis domains.

Contrast-enhanced nano-CT reveals soft dental tissues and cellular layers

AIM

To introduce a methodology designed to simultaneously visualize dental ultrastructures, including cellular and soft tissue components, by utilizing phosphotungstic acid (PTA) as a contrast-enhancement agent.

METHODOLOGY

Sound third molars were collected from healthy human adults and fixed in 4% buffered paraformaldehyde. To evaluate the impact of PTA in concentrations of 0.3%, 0.7% and 1% on dental soft and hard tissues for CT imaging, cementum and dentine-pulp sections were cut, dehydrated and stained with immersion periods of 12, 24 h, 2 days or 5 days. The samples were scanned in a high-resolution nano-CT device using pixel sizes down to 0.5 µm to examine both the cementum and pulpal regions.

RESULTS

Dental cementum and periodontium as well as odontoblasts and predentine were made visible through PTA staining in high-resolution three-dimensional nano-CT scans. Different segments of the tooth required different staining protocols. The thickness of the cementum could be computed over the length of the tooth once it was made visible by the PTA-enhanced contrast, and the attached soft tissue components of the interior of the tooth could be shown on the dentine-pulp interface in greater detail. Three-dimensional illustrations allowed a histology-like visualization of the sections in all orientations with a single scan and easy sample preparation. The segmentation of the sigmoidal dentinal tubules and the surrounding dentine allowed a three-dimensional investigation and quantitative of the dentine composition, such as the tubular lumen or the ratio of the tubular lumen area to the dentinal surface.

CONCLUSION

The staining protocol made it possible to visualize hard tissues along with cellular layers and soft tissues in teeth using a laboratory-based nano-CT technique. The protocol depended on both tissue type and size. This methodology offers enhanced possibilities for the concomitant visualization of soft and hard dental tissues.

Root canal conicity estimation of primary maxillary central and lateral incisors-A study by Nano-CT

AIM

The objective of the study was to estimate the conicity of the root canals of maxillary central and lateral incisors by computed nanotomography (Nano-CT).

DESIGN

This in vitro study included nine extracted primary maxillary central incisors and 12 maxillary lateral incisors, which were subjected to Nano-CT analysis. The resulting images of each tooth were reconstructed using the OnDemand3D software, and root canal area, volume, and taper analysis were performed using the free FreeCAD 0.18 software for the 3D computer-aided design (CAD) model. Data were statistically analysed using the Stata v14.0 software, adopting a significance level of 5%.

RESULTS

The results presented the mean value of the diameter and area of the root canal of primary central and lateral incisors. In addition, the taper values for both dental groups between points D0-D5, D5-D7, and D7-D10 were determined. Considering the diameters obtained over the entire length of the root, with a length of 12 mm, a conical model was constructed.

CONCLUSION

Detailed knowledge of root morphology of maxillary central and lateral incisors of primary dentition by means of Nano-CT is important to achieve faster, more accurate, and efficient endodontic treatments.

Nano-CT as tool for characterization of dental resin composites

Technological advances have made it possible to examine dental resin composites using 3D nanometer resolution. This investigation aims to characterize existing dental nano-hybrid and micro-hybrid resin composites through comparing and contrasting nano-computed tomography (nano-CT) with micro-CT and high-resolution SEM images. Eight commercially available and widely used dental resin composites, 2 micro-hybrid and 6 nano-hybrid were researched. Cured samples were examined and characterized using nano-CT (resolution 450 nm) and compared with micro-CT images (resolution 2 µm). Acquired images were reconstructed and image analysis was carried out to determine porosity and pore morphology. A comprehensive comparison of scanning micrograph images unsurprisingly revealed that the nano-CT images displayed greater detail of the ultrastructure of cured dental resin composites. Filler particle diameters and its volumes were lower when measured using nano-CT, porosity being higher where analysed at higher resolution. There were large variations between the examined materials. Fewer voids were found in Tetric EvoCeram and IPS Empress Direct, the smallest pores being found in Universal XTE and Tetric EvoCeram. Nano-CT was successfully used to investigate the morphology of dental resin composites and showed that micro-CT gives a lower porosity and pore size but overestimates filler particle size. There were large discrepancies between the tested composites. Evidence of porosities and pores within a specimen is a critical finding and it might have a detrimental effect on a material’s clinical performance.

Combination of electrospinning with other techniques for the fabrication of 3D polymeric and composite nanofibrous scaffolds with improved cellular interactions

The development of three-dimensional (3D) scaffolds with physical and chemical topological cues at the macro-, micro-, and nanometer scale is urgently needed for successful tissue engineering applications. 3D scaffolds can be manufactured by a wide variety of techniques. Electrospinning technology has emerged as a powerful manufacturing technique to produce non-woven nanofibrous scaffolds with very interesting features for tissue engineering products. However, electrospun scaffolds have some inherent limitations that compromise the regeneration of thick and complex tissues. By integrating electrospinning and other fabrication technologies, multifunctional 3D fibrous assemblies with micro/nanotopographical features can be created. The proper combination of techniques leads to materials with nano and macro-structure, allowing an improvement in the biological performance of tissue-engineered constructs. In this review, we focus on the most relevant strategies to produce electrospun polymer/composite scaffolds with 3D architecture. A detailed description of procedures involving physical and chemical agents to create structures with large pores and 3D fiber assemblies is introduced. Finally, characterization and biological assays including in vitro and in vivo studies of structures intended for the regeneration of functional tissues are briefly presented and discussed.

Porosity analysis of MTA and Biodentine cements for use in endodontics by using micro-computed tomography

Background

The purpose of this study is to compare the porosity of two repair cements, White ProRoot® MTA and Biodentine®. These samples were analyzed by using micro-computed microtomography.

Material and Methods

Sixteen samples were used in the study that were divided according to the composition of the materials used. White ProRoot® MTA (n = 8) and Biodentine® (n = 8) were the samples prepared according to the manufacturer’s instructions. They were placed in silicone molds of 5 ± 0.1mm in height and an internal diameter of 5 ± 0.1mm, 24 hours after its preparation, the samples were scanned through a micro-CT, the porosity results were analyzed statistically by independent “t” tests.

Results

It is evident that Biodentine® has better porosity properties than ProRoot® MTA. The results of the study quantify a smaller number of pores per surface, a smaller volume in each pore per mm3 and a lower total porosity present in samples of Biodentine® unlike ProRoot® MTA samples which is larger in both.

Conclusions

The results obtained in computerized microtomography endodontic biomaterial samples concluded that Biodentine® has a lower porosity than ProRoot® MTA.

Key words:Porosity, microleakage, micro-CT, endodontic cements.

Porosity analysis of mineral trioxide aggregate Fillapex and BioRoot cements for use in endodontics using microcomputed tomography

Aim:

The purpose of this study is to compare the porosity of two sealant cements, mineral trioxide aggregate (MTA) Fillapex^® and BioRoot^® root canal sealer (RCS). These samples were analyzed using microcomputed tomography.

Materials and Methods:

Sixteen samples were used in the study that were divided according to the composition of the materials used. MTA Fillapex^® (n = 8) and BioRoot^® RCS (n = 8) were the samples prepared according to the manufacturer's instructions. They were placed in silicone molds of 5 ± 0.1 mm in height and an internal diameter of 5 ± 0.1 mm; 24 h after its preparation, the samples were scanned through a microcomputed tomography, and the porosity results were analyzed statistically by independent t-tests.

Results:

It is evident that MTA Fillapex^® has better porosity properties than BioRoot^® RCS. The results of the study quantify a smaller number of pores per surface, a smaller volume in each pore per mm³, and a lower total porosity present in samples of MTA Fillapex^® unlike BioRoot^® RCS samples which is larger in both.

Conclusions:

The results obtained in computerized microtomography endodontic biomaterial samples concluded that MTA Fillapex^® has a lower porosity than BioRoot^® RCS.