Browsing by Subject "CBCT"

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Cone Beam Computed Tomography Evaluation of Buccal Alveolar Bone Changes Following Rapid Maxillary Expansion and Fixed Appliance therapy
(2020-06) Sperl, Adam
Introduction: Rapid maxillary expansion (RME) and fixed appliance therapy are commonly used to treat maxillary transverse deficiencies, but the treatment causes buccal displacement of appliance anchor teeth, which can damage the periodontium. Clinical decision making may be improved by better understanding how this treatment affects the periodontium. Objectives: The purpose of this study was to assess factors that might affect buccal bone changes adjacent to the permanent maxillary first molar after RME and fixed appliance therapy. Methods: Pre-treatment (T1) and post-treatment (T2) cone-beam computed tomography (CBCT) scans were obtained from 45 patients treated with RME and fixed appliance therapy. Measurements of buccal alveolar bone thickness adjacent to the mesiobuccal root of the maxillary first molar were made on CBCT images at 4 mm (B4), 6 mm (B6), and 8 mm (B8) from the CEJ. Anatomic defects of the buccal bone were recorded. T-tests were performed to compare T1 and T2 alveolar bone thickness and to determine whether teeth with post-treatment anatomic defects had thinner initial bone. Correlation analyses were conducted to examine the relationship between buccal alveolar bone thickness changes and the following variables: prescribed expansion, age at T1, time between T1 and T2, post-expansion retention time, and initial bone thickness. Results: There was a statistically significant reduction in buccal alveolar bone thickness from T1 to T2. 47.7% of teeth and 60% of patients had anatomic defects after treatment. Teeth with T2 anatomic defects had significantly thinner buccal bone at T1. Reduction in alveolar bone was correlated with only one tested variable: initial bone thickness. Conclusions: RME and fixed appliance therapy can result in a significant reduction in buccal alveolar bone thickness and an increase in anatomic defects adjacent to the expander anchor teeth. Anchor teeth with greater initial buccal bone thickness are likely to have a greater reduction in buccal bone thickness. Anchor teeth with thin initial buccal bone are more likely to develop post- treatment anatomic defects of the buccal bone plate.
Dense bone islands in orthodontic patients: a cross-sectional imaging (CBCT) study of location and interactions with teeth
(2024-06) Caple, Nathaniel
Aim: To use CBCT imaging taken before and after orthodontic treatment to evaluate the interactions between dense bone island (DBI) lesions and teeth. Specific aims were to evaluate 1) where dense bone islands reside in the buccal-lingual dimension of the jaw bones, 2) if DBIs tend to occur in areas of potential orthodontic tooth movement, 3) presence of root resorption on teeth adjacent to DBIs, and 4) presence of hindered orthodontic tooth movement of teeth adjacent to DBIs.Methods: This project reviewed 2243 CBCT radiology reports on patients undergoing treatment at the University of Minnesota Graduate Orthodontics Program between the years of 2018 and 2022. Patients were included in this study if at least one of their CBCT radiology reports contained one of the following words: dense bone island, idiopathic osteosclerosis, or enostosis. For the 87 dense bone islands included in the study, the pre- and post-orthodontic CBCT images were analyzed using the linear measurement tool in Dolphin Software to identify changes to the dense bone islands and adjacent teeth over time. Information related to dense bone island location, shape, size, evidence of root resorption, evidence of hindered root movement, and the patient demographics were recorded. Prevalence of root resorption and root movement hindrance and prevalence of DBIs in various buccal-lingual locations were reported. Results: Of the 87 DBIs included in the study, 65 of them (74.7%) were deemed to be located in areas of potential orthodontic tooth movement. Of the 65 DBIs located in areas of potential orthodontic tooth movement, 8 of them (12.3%) showed evidence of root resorption and 6 of them (9.2%) exhibited signs of hindered tooth movement. In the post-orthodontic scans, 39.1% of the DBIs were connected to the lingual plate alone, 31.0% of the DBIs were bi-cortical, 17.2% were connected to the buccal plate alone, and 12.6% were intracortical without evidence of contact with either cortical plate.
Dentists' Attitudes and Perspectives on Viewing Cone-beam Computed Tomography of Impacted Teeth in Virtual Reality
(2024-06) Liu, Deborah
Introduction: Three-dimensional (3-D) radiographic imaging has transformed the dental field since its inception by giving clinicians a wealth of data impossible to glean from two-dimensional (2-D) imaging. However, current viewing modalities were designed for 2-D and analog data, with no way to view 3-D imaging in its natural 3-D state, such as the case with cone-beam computed tomography (CBCT). Virtual reality (VR) has become increasingly widespread in recent years and poises itself as a new potential tool for viewing volumetric datasets.Aim: The aim of this study is to evaluate dentists’ attitudes and perspectives on using VR medical imaging application Medicalholodeck to view CBCT of impacted teeth using Oculus Quest 2 immersive VR headsets. This study also aims to investigate whether viewing 3-D data in VR allows for improved visualization and/or efficiency compared to 2-D viewing modalities. Methods: CBCT datasets of three patients with impacted teeth were uploaded to Quest 2 headsets. Participants underwent a VR tutorial and viewing session to become familiar with navigating 3-D data in VR and then completed a survey on their experience. As a proof-of-concept study, data were descriptive in nature and no statistical hypotheses were tested. Results: Results revealed varying perceptions of visualization and/or accuracy for impacted teeth and their surrounding craniofacial structures when viewed in VR. For many factors that oral surgeons, orthodontists, and periodontists consider in treating cases with impacted teeth, clinicians found VR to be beneficial, especially when used in conjunction with traditional 2-D viewing modalities. Clinicians perceived VR to provide heightened global visualization with its immersive capabilities, to be easy to use, and highly enjoyable. Current shortcomings of VR include its accompanying learning curve, mediocre resolution, and decreased ability to visualize small structures. Conclusions: Few studies have been completed thus far evaluating VR as a tool for viewing 3-D data in dentistry. Data from this study showed VR has promise for enhanced viewing of CBCT images, despite not currently being perceived to improve clinicians’ efficiency. Dentists believed VR provided improved visualization for certain morphological characteristics and will likely be most useful as an adjunctive tool for complex cases. As this study was descriptive in nature, further in-depth research is needed to provide additional insight on the clinical utility of viewing 3-D data in VR.
The effect of root and bone visualization on perceptions of the quality of orthodontic treatment simulations
(2016-05) Brownrigg, Danae
Introduction: Technological advances in three-dimensional imaging of the dentition have provided orthodontists with more diagnostic information than ever. This study evaluated the effect of root and bone visibility on perceptions of the quality of treatment simulations to assess how the use of advanced imaging such as cone-beam computed tomography (CBCT) may influence treatment planning decisions. Methods: An online survey was used to present 141 orthodontists with setups (digital models of teeth) generated for 10 patients in 2 different types of view: with and without bone and roots as modeled from a cone-beam computed tomography scan. Using a 100-point visual analog scale, the orthodontists were asked to rate the quality of the setups from poor to ideal, and, if applicable, to identify features of concern that led them to giving a setup a less than ideal rating. Results: The quality ratings were significantly lower when roots and bone were visible in the setups (P<0.0001). Buccolingual inclination and periodontal concerns were selected significantly more often as reasons for a less-than-ideal rating when roots and bone were shown, whereas occlusal relationship, overjet, occlusal contacts, and archform were selected significantly more often as reasons for a less-than-ideal rating when roots and bone were not shown. The odds of selecting periodontal concerns as a reason for a less-than-ideal setup rating were 331 times greater when roots and bones were visible than when they were not. Conclusions: Additional diagnostic information derived from CBCT scans affects orthodontists’ perceptions of the overall case quality, which may influence their treatment planning decisions.
The Effect Of Rotary Instrumentation On Dentin Thickness In The Danger Zone Of The Maxillary 1St Molar: A Cbct Analysis
(2020-08) Heyse Jr, Jeffrey
PURPOSE: To quantitively measure initial and remaining dentin wall thickness in the danger zone of the second mesiobuccal (MB2) canal of extracted human maxillary first molars after rotary instrumentation using cone beam computed tomography (CBCT) imaging. MATERIAL AND METHODS: Each tooth was scanned multiple times after instrumentation by files of increasing taper. Repeated- measures ANOVA and post hoc Tukey test were used to compare the changes in the remaining wall thickness. RESULTS: The preoperative dentin thickness in the danger zone of the MB2 area had a mean of 0.82 +/- .17mm. Multiple comparison test found significant levels of mean dentin removal in the danger zone for all groups. CONCLUSION: The Sx orifice opener does significantly reduce the remaining dentin thickness removing an average of 32% of the dentin in the distal wall. There is a safe area of dentin thickness toward the mesial wall of the MB2 danger zone.
The findings and natural history of radiographic signs of temporomandibular osseous changes in an orthodontic population
(2013-08) Anderson, Brian Craig
AIMS: Evaluate the natural history of radiographic temporomandibular joint (TMJ) findings in an orthodontic sample population by interpreting cone-beam CT (CBCT) scans, made before and after comprehensive orthodontic treatment, according to Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) imaging criteria. METHODS: 348 subjects were included in the study. Pre-treatment CBCTs were interpreted and screening diagnoses were given. Subjects were categorized: control (normal), indeterminate (remodeling), and case (degenerative joint disease [DJD]); these were matched for age and gender. The pre-treatment and post-treatment CBCTs of 76 matched subjects (152 joints) were interpreted and definitive diagnoses were given for each joint. RESULTS AND CONCLUSIONS: There was no statistical evidence that, on average, a worse joint diagnosis existed pre-treatment or post-treatment. The likelihood of having a worse diagnosis post-treatment was statistically significant given a pre-treatment diagnosis of DJD or indeterminate. From pre-treatment to post-treatment 52.6% of diagnoses were unchanged, 25% worsened, and 22.4% improved.
Mandibular Ramus Heights In Patients With Unilateral Posterior Crossbite
(2020-06) Gerkowicz, Lauren
Introduction: Unilateral posterior crossbite, if left untreated, may lead to mandibular and facial asymmetry. Aim: To assess differences in mandibular ramus height in patients with unilateral posterior crossbites before and after correction with orthodontic appliances. Materials and Methods: Ramus heights were measured as the linear distance between the most anterior point of the condyle and gonion inferius on pre-treatment (T1) and post-treatment (T2) cone-beam computed tomography scans of 59 adolescent patients (mean age at T1 = 12.4, age range 8 - 16 years) who underwent rapid maxillary expansion followed by comprehensive orthodontic treatment with fixed appliances. Paired and two-sample t-tests were used to determine if the change in ramus height from T1 to T2 was associated with the crossbite side. Results: The difference between ramus heights of the crossbite and non-crossbite sides at T1 was not significant (P = 0.86). On both the crossbite and non-crossbite sides, the change in ramus height from T1 to T2 was significant (P < 0.0001). However, the difference between crossbite and non-crossbite side change from T1 to T2 was not significant (P = 0.39). There was no difference between males and females for any variable tested. Conclusions: Unilateral posterior crossbite in adolescents was not associated with shorter ramus height on the side of the crossbite. Hence, crossbite correction did not lead to more symmetrical ramus heights. Despite the lack of long-term controlled studies, early treatment of unilateral posterior crossbite may allow for more symmetrical mandibular growth.
On the Relationship between Condylar Cortication and Mandibular Growth Activity
(2021-07) Sharp, John
Introduction: Mandibular growth prediction is central to orthodontics, yet little is known of the condylar bone density that accompanies this growth. Aims: To determine the bilateral symmetry of condylar cortical (CC), condylar trabecular (CT) and otic capsule (OC) grey values (GVs). To determine the relationship between condylar and OC GVs with age. To determine the relationship between three-dimensional mandibular growth and age. To determine the relationship between condylar cortication and mandibular growth activity. Methods: Mandibular growth rate was measured on CBCTs of orthodontically treated adolescents and young adults. OC, CC, and CT GVs were collected, and a bone density ratio calculated. Results: Significant differences exist in bilateral CC and OC GVs. CC, CT, and OC GVs significantly vary with age. Intercondylar width and mandibular growth rate significantly vary with age. Condylar cortication significantly predicts mandibular growth rate. Conclusions: A novel method to assess mandibular growth activity is introduced.
Stability of The Mental Foramen And Its Potential Use As A Landmark For Three-Dimensional Superimposition of Human Mandibles on Cone-Beam Computed Tomograms
(2018-06) Hamdan, Hani
The purpose of this study was to examine the mental foramina as possible stable landmarks for three-dimensional superimposition of 2 cone-beam computed tomography (CBCT) images of the same human mandible taken during a long period of growth. The ultimate goal was to use the mental foramina as landmarks in a superimposition protocol. This retrospective study used CBCT scans taken at the University of Minnesota’s Department of Orthodontics, which were oriented and measured using Dolphin 3D Imaging software. 55 patients were selected. For each CBCT, the distance between the two mental foramina as well as the distance between protuberance menti (PM) and each mental foramen were measured. Differences in these measurements between the earlier (T1) scan and the later (T2) scan were then tested for statistical significance using a paired t-test. The results showed a significant distal movement of the mental foramen in growing patients, enough to hamper superimposition accuracy. The increase in the distance between each mental foramen and PM was symmetrical. Therefore, it can be concluded that the mental foramina are not suitable landmarks for three dimensional superimposition of the mandible in growing patients. However, the symmetry in the increase in the distance between PM and each mental foramen is a significant finding and indicates that the mental foramina can be used indirectly for 3D superimposition, helping to detect and quantify posterior mandibular growth asymmetry.
Survey of recommended referral patterns for incidental maxillary sinus and airway findings on CBCT analysis in an orthodontic population.
(2017-07) Gaalaas, Sara
Introduction: Cone beam computed tomography (CBCT) is an increasingly more common form of radiography, and dental professionals are obligated to manage all incidental findings identified on scans. Clarification of standards for management of CBCT findings would help the practitioner, especially for findings of the airway and sinuses. Aims: The primary aim was to evaluate recommendations of otolaryngologists to dentists for follow up of sinus and airway findings identified on CBCT analysis. The secondary aim was to report on prevalence of maxillary sinus and airway findings on CBCT analysis in an orthodontic population. Methods: A survey with CBCT images of 22 sinus and airway findings was submitted to otolaryngologists (n = 269) for review, and de-identified CBCT reports of orthodontic patients were reviewed to evaluate the prevalence of sinus and airway findings. Frequencies were calculated for responses and findings. Results: Thirty-six otolaryngologists participated in the survey. The most commonly recommended actions were to 1) immediately refer the patient to an otolaryngologist, and 2) ask additional questions regarding sinonasal symptoms before referring. In the orthodontic population studied, a total of 53.8% patients had maxillary sinus or airway findings listed on CBCT scan reports. The most commonly reported finding was mucosal thickening. Conclusions: Incidental maxillary sinus and airway findings are commonly found on CBCT scans. When such findings are identified on CBCT analysis, otolaryngologists generally recommend evaluating the patient for symptoms, and referring the patient to an otolaryngologist for follow up. For findings that are variants of normal, the recommendation is to not refer the patient for follow up unless they are positive for sinonasal symptoms. For findings that demonstrate inflammatory conditions, the recommendation is to refer the patient for follow up, especially if they have sinonasal symptoms. For findings with changes in the bony wall of the sinuses, the recommendation is to immediately refer the patient to the otolaryngologist for follow up. Consultation with an oral and maxillofacial radiologist or otolaryngologist is recommended to best manage incidental sinus and airway findings present on CBCT scans.

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