Images Of Dentition Research Articles

Accuracy of a surface-based fusion method when integrating digital models and the cone beam computed tomography scans with metal artifacts

The aim of this study was to evaluate the intra- and inter-observer reliability of maxillary digital dental model integration into cone-beam computed tomography (CBCT) scans to reconstruct three-dimensional (3D) skeletodental models for orthognathic patients. This retrospective study consisted of CBCT and digital maxillary dentition images of 20 Class III orthognathic patients. After two repeated fusions of digital cast images with reconstructed CBCT images by a digital engineer and an orthodontist respectively, the 3D coordinate values of the canines, first molars, and central incisors were evaluated. The intra- and inter-observer reliability of 3D positions of maxillary teeth were compared using intraclass correlation coefficients (ICCs). Intra-observer reliability of x-, y-, and z-coordinate values of maxillary teeth showed significant and excellent agreement in an engineer (0.946 ≤ ICC ≤ 1.000) and an orthodontist (0.876 ≤ ICC ≤ 1.000). The inter-observer reliability of the y- and z-coordinates of each tooth was significantly excellent or good, but that of the x-coordinates showed insignificantly poor to moderate agreement. This study showed that the integration of maxillary digital models into CBCT scans was clinically reliable. However, considering the low inter-observer reliability on the x-coordinates of dentition, clinical experience and repeated learning are needed for accurate application of digital skeletodental model in orthognathic patients.

Intraoral Scan for Virtual Skull-Dentition Hybrid Images of Young Patients

Additional dentition images are needed because the dentitions are distorted in cone-beam computed tomography (CBCT) due to streak artifacts and non-uniformity of the x-ray beam. The purpose of this study is to evaluate the feasibility of improving the dentition image of CBCT scan with intraoral scanner instead of plaster models. Maxilla images from plaster models, two intraoral scanners, and CBCT of 20 patients aged 12 to 18 were used in this study. With one of the intraoral scanners, the full arch was scanned by three segments and combined into a complete full arch. Virtual skull-dentition hybrid images from intraoral scanners were superimposed with the images from plaster models to evaluate the coordinate value difference and distance at reference points. The results showed that the coordinate value difference and distance were smallest with segmented intraoral scan, which showed only 2 ㎛ distance. Intraoral scan may provide good dentition images for virtual skull-dentition images.

Three-dimensional superimposition of digital models for individual identification

Dentition is an individualizing structure in humans that may be potentially utilized in individual identification. However, research on the use of three-dimensional (3D) digital models for personal identification is rare. This study aimed to develop a method for individual identification based on a 3D image registration algorithm and assess its feasibility in practice. Twenty-eight college students were recruited; for each subject, a dental cast and an intraoral scan were taken at different time points, and digital models were acquired. The digital models of the dental casts and intraoral scans were assumed as antemortem and postmortem dentition, respectively. Additional 72 dental casts were extracted from a hospital database as a suspect pool together with 28 antemortem models. The dentition images of all of the models were extracted. Correntropy was introduced into the traditional iterative closest point algorithm to compare each postmortem 3D dentition with 3D dentitions in the suspect pool. Point-to-point root mean square (RMS) distances were calculated, and then 28 matches and 2772 mismatches were obtained. Statistical analysis was performed using the Mann-Whitney U test, which showed significant differences in RMS between matches (0.18±0.03mm) and mismatches (1.04±0.67mm) (P<0.05). All of the RMS values of the matched models were below 0.27mm. The percentage of accurate identification reached 100% in the present study. These results indicate that this method for individual identification based on 3D superimposition of digital models is effective in personal identification.

Study of the dimensional accuracy of jaw models obtained by 3d printing using stereolithography

Aim. To study the dimensional accuracy of dentition models produced by digital and conventional methods using an experimental model and digital technologies.Materials and methods. This article presents an assessment of the dimensional accuracy of jaw models created using an Asiga Max UV 3D printer from digital images of dentition created by an iTero Cadent intraoral scanner and plaster jaw models obtained from one-stage two-layer A-silicone impressions. The DentalCAD software and the Meshlab computer program were used to study the dimensional accuracy of the as-obtained digital images. The nonparametric Wilcoxon rank test was used for statistical analysis of the obtained data.Results. It is established that jaw models made of DETAX Freeprint model UV photopolymer using an Asiga Max UV 3D printer, based on digital impressions obtained by an iTero Cadent intraoral scanner, have a greater dimensional accuracy in comparison with plaster jaw models obtained from single-stage double-layer A-silicone impressions by 31.6% with a signifi cance level p &lt; 0.05.Conclusion. Jaw models created using an Asiga Max UV 3D printer are characterized by high dimensional accuracy as compared to plaster models.

Study of the quality of the marginal gap of artificial crown frames made with the use of traditional and digital technologies

The aim of the study is to evaluate the quality of the marginal gap of the frames of artificial crowns made with the use of CAD/CAM system and by casting method.&#x0D; Materials and methods. The article presents an assessment of the quality of the edge fitting of artificial crown frames made by means of CAD/CAM system KaVo ARCTICA on digital images of dentition created by intraoral laser scanner iTero Cadent and frames made of Co-Cr by the method of casting. The Image J computer program was used to study the quality of the marginal gap of artificial crown frames. For statistical analysis of the obtained data nonparametric Wilcoxon-Mann-Whitney test was used for the evaluation of the related samples.&#x0D; Results. We found that the average value of the marginal gap between the tooth stump of the experimental model and the frames of artificial crowns made in the KaVo ARCTICA Engine milling and grinding machine from the titanium blank Titan-Blank is 21.79 microns. The average value of the cement gap of the frames of artificial crowns made by the traditional casting method is 77.18 microns. The value of the marginal gap of artificial crown frames made by using the CAD/CAM system KaVo ARCTICA was 2.8 times less than the value of the marginal gap of frames made by the traditional casting method with a significance level of р 0.05 (V-Wilcoxon criterion for related samples = 0, р = 0.001).&#x0D; Conclusion. The results of our study indicate that the frames of artificial crowns made with the use of CAD/CAM system KaVo ARCTICA have a greater dimensional accuracy of the marginal gap compared to the frames of artificial crowns made by the traditional casting method.

精度の高い歯列画像を有する三次元顎顔面頭蓋画像の再構成

精度の高い歯列画像を有する三次元顎顔面頭蓋画像の再構成

Application of 3D Simulation Surgery to Orthognathic Aurgery : A Preliminary Case Study

The aim of this report is to evaluate accuracy using3D surgical simulationand digitally printedwafer in orthognathic surgery. 22-year-old female was diagnosed with mandibular prognathism and apertognathia based on 3D diagnosis using CT. Digital dentition images were taken by laser scanning from dental cast, and each STL images were integrated into one virtual skull using simulation software. Digitalized intermediate wafer was manufactured using CAD/CAM software and 3D printer, and used to move maxillary segment in real patient. Constructed virtual skull from 1 month postoperative CT scan was superimposedinto simulated virtual model to reveal accuracy. Almost maxillo-mandibular landmarks were placed in simulated position within 1 mm differences except right coronoid process. Thus 3D diagnosis, surgical simulation, and digitalized wafer could be useful method to orthognathic surgery in terms of accuracy.

Registration accuracy in the integration of laser-scanned dental images into maxillofacial cone-beam computed tomography images

A precision 3-dimensional (3D) head model can be fabricated by integrating a digital dental model into a maxillofacial 3D image. The integration requires accurate registration of 2 image modalities. The aims of this study were to determine the registration errors for implementation of laser-scanned dental images into cone-beam computed tomography (CBCT) scan data and to examine the influence of the registration area on the accuracy of registration. The CBCT scans were obtained from 30 adults, and the maxillofacial 3D images were reconstructed. Maxillary and mandibular dental casts were taken from the same subjects and scanned with a 3D laser scanner. The laser-scanned maxillary and mandibular dentition images were incorporated into the CBCT images of each arch in 3 ways according to the registration area: only the buccal surfaces, only the lingual surfaces, and both the buccal and lingual surfaces. Surface-based registration was performed by using an iterative closest point algorithm, and its errors were evaluated by measuring the 3D Euclidean distances between the surface points on the 2 images. The registration errors ranged from 0.27 to 0.33 mm. The mandibular arch did not show significant differences in registration errors according to the selected area for the registration. The maxillary arch, however, showed significant differences according to the registration area. When the lingual surfaces only were used for registration, the errors were greater than for the other 2 methods. The errors were least when both the buccal and lingual surfaces were used for registration. The results of this study indicate that accuracy in the integration of laser-scanned dental images into the maxillofacial CBCT images increases when a broad area is used for registration.

Comparative analysis of traditional radiographs and cone-beam computed tomography volumetric images in the diagnosis and treatment planning of maxillary impacted canines

In this prospective study, we compared differences in the diagnosis and treatment planning of impacted maxillary canines between 2 imaging modalities. Twenty-five consecutive impacted maxillary canines were identified from the pool of patients seeking orthodontic treatment. The first set of radiographs consisted of traditional 2-dimensional (2D) images including panoramic, occlusal, and 2 periapical radiographs. The second set comprised prints of 3-dimensional (3D) volumetric dentition images obtained from a cone-beam computed tomography (CBCT) scan. Seven faculty member completed a questionnaire for every impacted canine and diagnostic radiographic modality (2D and 3D). The data show that the judges produced different decisions regarding localization depending on the x-ray method. There were 21% disagreement (or discordance) in the perceived mesiodistal cusp tip position and 16% difference in the perceived labiopalatal position. In the perception of root resorption of adjacent teeth, there was 36% lack of congruence. Twenty-seven percent of the teeth that were planned to be left, recovered, or extracted with the 2D radiographs had different treatment plans when the judges viewed the 3D CBCT images (McNemar test, chi-square, 4.45; P = 0.035). The clinicians' confidence of the accuracy of diagnosis and treatment plan was statistically higher for CBCT images (P <0.001). These results showed that 2D and 3D images of impacted maxillary canines can produce different diagnoses and treatment plans.