Browsing by Subject "Cone-Beam Computed Tomography"

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    Comparison of guided endodontic access with and without pin fixation in 3D printed teeth with simulated pulp canal obliteration
    (2021-06) Long, Jacob Daniel; Spolnik, Kenneth; Ehrlich, Ygal; Dutra, Vinicius; Bringas, Josef; Warner, Ned
    Introduction: In order to successfully treat an infected root canal system (RCS), it is required to locate all root canals and have an access path to the apex of each canal. This can be challenging in teeth with pulp canal obliteration (PCO), often leading to increased chair time and increased risk of iatrogenic errors. Guided endodontic access (GEA) combines information from a cone-beam computed tomography (CBCT) scan with an intra-oral scan to create a stent. GEA stents with or without fixation pins have been shown to be successful in accurately negotiating a RCS with PCO. Objective: Compare the degree of deviation and difference in 3D offset at the base to apical tip of the drill from the designed access path when a GEA stent with and without pin fixation is used to access tooth #8 with PCO. Materials and Methods: A 3-D printed maxillary model of an anonymous patient had a GEA stent designed using coDiagnonstiX software. The stent extended from tooth #3 to tooth #14 with the guide sleeve over tooth #8. Tooth #8 with no calcification, calcification to the cervical third, and calcification to the middle third of the RCS were designed in the coDiagnostiX software. Tooth #8 will be accessed using a 1.3 mm drill that fits a 1.3 mm sleeve used for both access and pin fixation. 15 of the 30 GEA samples will utilized pin fixation, while the other 15 samples did not utilize pin fixation. Following GEA in all 30 samples a CBCT was taken of each sample. Each post-operative CBCT was aligned with the pre-operative CBCT in the coDiagnostiX software. The coDiagnostiX software was able to calculate the degree of deviation and difference in 3D offset between the base and apical tip of the drill during GEA. Paired t-tests were used to test each group for significant differences in 3D offset between base and tip. Two-way ANOVA was used to evaluate the effects of pin fixation and calcification on the degree of deviation and the deviation of 3D offset of the entry point and tip. Results: There was a significant interaction between use of pin fixation and calcification level on the degree of deviation of GEA. GEA with pin fixation had a significantly larger degree of deviation than GEA without pin fixation with calcification extending to the middle third of the RCS. GEA with and without pin fixation did not have a significant difference when calcification extended to the cervical third of the RCS or no calcification was present. There was a significant interaction between use of pin fixation and calcification level on 3D offset difference. GEA with pin fixation had a significantly larger 3D offset difference than GEA with no pin fixation for calcification in the middle third of the RCS. For GEA with and without pin fixation there was no significant difference when calcification extended to the cervical third of the RCS or no calcification was present. Conclusion: The use of pin fixation did not result in a decrease of degree of deviation or difference in 3D offset during GEA access. It can be concluded that the use of pin fixation is not necessary for GEA of teeth with PCO when a full dentition is present to provide stability and retention of the stent.
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    Dosimetric impact of gastrointestinal air column in radiation treatment of pancreatic cancer
    (British Institute of Radiology, 2018-02) Estabrook, Neil C.; Corn, Jonathan B.; Ewing, Marvene M.; Cardenes, Higinia R.; Das, Indra J.; Radiation Oncology, School of Medicine
    OBJECTIVE: Dosimetric evaluation of air column in gastrointestinal (GI) structures in intensity modulated radiation therapy (IMRT) of pancreatic cancer. METHODS: Nine sequential patients were retrospectively chosen for dosimetric analysis of air column in the GI apparatus in pancreatic cancer using cone beam CT (CBCT). The four-dimensional CT (4DCT) was used for target and organs at risk (OARs) and non-coplanar IMRT was used for treatment. Once a week, these patients underwent CBCT for air filling, isocentre verification and dose calculations retrospectively. RESULTS: Abdominal air column variation was as great as ±80% between weekly CBCT and 4DCT. Even with such a large air column in the treatment path for pancreatic cancer, changes in anteroposterior dimension were minimal (2.8%). Using IMRT, variations in air column did not correlate dosimetrically with large changes in target volume. An average dosimetric deviation of mere -3.3% and a maximum of -5.5% was observed. CONCLUSION: CBCT revealed large air column in GI structures; however, its impact is minimal for target coverage. Because of the inherent advantage of segmentation in IMRT, where only a small fraction of a given beam passes through the air column, this technique might have an advantage over 3DCRT in treating upper GI malignancies where the daily air column can have significant impact. Advances in knowledge: Radiation treatment of pancreatic cancer has significant challenges due to positioning, imaging of soft tissues and variability of air column in bowels. The dosimetric impact of variable air column is retrospectively studied using CBCT. Even though, the volume of air column changes by ± 80%, its dosimetric impact in IMRT is minimum.
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    Evaluating the use of 3D imaging in creating a canal-directed endodontic access
    (2015-06-09) Maru, Avni Mahendra; Spolnik, Kenneth Jacob, 1950-; Ghoneima, Ahmed; Bringas, Josef; Warner, Ned A. (Ned Alan); Zunt, Susan L., 1951-; Ehrlich, Ygal
    Introduction: During root canal treatment (RCT), an opening is made through the crown of the tooth to access and to disinfect the root canal system (RCS). Traditional endodontic access (TEA) may sacrifice tooth structure and weaken the tooth. Cone beam computed tomography (CBCT) provides information about the exact location of the root canals. This information can be used for the design of a canal-directed endodontic access (CDEA). It may also be used for the 3D printing of an acrylic endodontic stent that could help to create a conservative CDEA. Objective: 1) Evaluate the ability of the Dolphin 3D imaging software to assist in creating a CDEA; 2) Compare tooth structure loss in a CDEA to that in a TEA by measuring the volume of remaining tooth structure, surface area of the access opening at the occlusal, and remaining dentin thickness at the CEJ. Materials and Methods: Thirty extracted human mandibular premolars were used. Teeth with large, wide canals were excluded. CBCT images will be taken for all teeth using Kodak 9000. Fifteen teeth were randomly assigned to the TEA group and 15 teeth were assigned to the CDEA group. The CDEA path was mapped using Dolphin 3D imaging software. Acrylic access stents were designed using Rhino 3D software and printed using a 3D printer. The teeth were accessed through the corresponding stents. The 15 teeth that are part of the traditional access group were accessed without a stent. A CBCT scan was taken post-access for all 30 teeth. Wilcoxon Rank Sum Tests were performed to compare the following outcomes for the two groups: the volume of remaining tooth structure, the surface area of the access opening at the occlusal, and remaining dentin thickness at the CEJ. Results: The remaining dentin thickness (percent loss) was not significantly larger for TEA than for CDEA. The surface area (post-treatment) was significantly larger for TEA than for CDEA, and volume (percent loss) was significantly larger for TEA than for CDEA. Conclusion: The use of the CBCT and Dolphin 3D imaging provided an accurate and more conservative CDEA with the guide of an acrylic stent.
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    Hounsfield unit change in root and alveolar bone during canine retraction
    (Elsevier, 2015-04) Jiang, Feifei; Liu, Sean S.-Y.; Xia, Zeyang; Li, Shuning; Chen, Jie; Kula, Katherine S.; Eckert, George; Department of Orthodontics and Oral Facial Genetics, IU School of Dentistry
    INTRODUCTION: The objective of this study was to determine the Hounsfield unit (HU) changes in the alveolar bone and root surfaces during controlled canine retractions. METHODS: Eighteen maxillary canine retraction patients were selected for this split-mouth design clinical trial. The canines in each patient were randomly assigned to receive either translation or controlled tipping treatment. Pretreatment and posttreatment cone-beam computed tomography scans of each patient were used to determine tooth movement direction and HU changes. The alveolar bone and root surface were divided into 108 divisions, respectively. The HUs in each division were measured. Mixed-model analysis of variance was applied to test the HU change distribution at the P <0.05 significance level. RESULTS: The HU changes varied with the directions relative to the canine movement. The HU reductions occurred at the root surfaces. Larger reductions occurred in the divisions that were perpendicular to the moving direction. However, HUs decreased in the alveolar bone in the moving direction. The highest HU reduction was at the coronal level. CONCLUSIONS: HU reduction occurs on the root surface in the direction perpendicular to tooth movement and in the alveolar bone in the direction of tooth movement when a canine is retracted.