Browsing by Subject "orthodontics"

Now showing 1 - 4 of 4
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    Associations between cephalometric values and radiographic osseous temporomandibular joint diagnoses in an adolescent orthodontic population
    (2015-06) Knudsen, Kyle
    AIMS: To identify skeletal features and relationships associated with the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) osseous temporomandibular joint (TMJ) diagnoses in an adolescent population undergoing comprehensive orthodontic treatment, and to evaluate the reliability and validity of the cervical vertebral maturation (CVM) method for predicting mandibular growth. METHODS: Fifty-nine orthodontic patients were included in the study. Pre-treatment and post-treatment diagnoses of each TMJ were previously made by Anderson1 using the RDC/TMD. For each subject, a lateral cephalometric radiograph was extracted from existing pre-treatment and post-treatment cone beam computed tomography (CBCT) images. Each radiograph was assessed with cephalometric analysis and staged using the CVM method. Statistical analyses were performed with one-way ANOVA and Pearson and Spearman correlation coefficients. RESULTS AND CONCLUSIONS: The pre-treatment mandibular plane angle (FMA) and Wits appraisal had a fair degree of positive correlation with the pre-treatment TMJ diagnosis. However, no associations were found when the change in TMJ diagnosis over the course of orthodontic treatment was compared to cephalometric variables or measures of growth, nor did the pre-treatment cephalometric measurements predict changes in the TMJ diagnosis. The pre-treatment CVM stage was inversely correlated to mandibular growth observed during treatment, with no growth seen in subjects with a pre-treatment CVM stage of 6.
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    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.
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    Reproducibility of Dental Bite Registrations Using A Direct Intraoral Scanner
    (2020-06) Bonamici, Jennifer
    Abstract Aim: The aim of this study was to determine if a direct intraoral scanner is a reliable method to record dental bite registrations. Methods: Intraoral scans and bite registrations were taken on 41 adult patients at an initial time point (T1) and at a second time point (T2), one week later, using the iTero Element intraoral scanner. The difference in the number of teeth with occlusal contacts between the two time points was calculated for each subject using OrthoCAD. Statistical analysis using a paired t-test was performed to analyze the differences in the occlusal contacts from T1 and T2. Results: There was a significant difference in the number of teeth with occlusal contact at the heavy occlusal contact strength of < 0.0mm (2.17, p <0.0001) and at the moderate occlusal contact strength of < 0.2mm (0.59, p= 0.0002), between T1 and T2. When comparing tooth types and individual teeth, all teeth had significant changes in occlusal contacts between T1 and T2, except for the moderate contacts on the premolar tooth type and the moderate contacts on the left posterior premolar and molar individual teeth. There was a significant negative correlation (-0.6) between number of initial contacts and the change of occlusal contacts between T1 and T2. Conclusions: Direct intraoral scanners are not reliable in the capturing of reproducible dental bite registrations for orthodontic treatment planning and case analysis. Soft tissue interferences and changes in patient bite force during acquisition could pose a limitation in the precision of occlusal contacts. Additional studies should be carried out with tissue interferences eliminated and proper instructions given to patients for biting force.
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    Wear and Fatigue Resistance: An In-Vitro Comparison of Three Materials for Vacuum-Formed Retainers
    (2022-06) Bitner, Timothy
    AbstractAim: To test the wear and fatigue resistance of three materials for the fabrication of vacuum-formed retainers in a simulated oral environment. Methods: Three materials were tested: Essix ACE, Taglus, and Zendura. To test wear resistance, 21 maxillary retainers of each material (63 overall) were mounted on zirconia models into an Artificial Resynthesis Technology machine to simulate wear in an oral environment. Each sample underwent 12,000 cycles of wear at 75 Newtons to simulate one year of retainer wear with moderate nighttime bruxing. Lateral movement was set to 2 mm with a frequency of 2 Hertz. Post-wear retainer thickness was measured using a digital micrometer and compared to baseline measurements to calculate the depth of wear. To test fatigue resistance, 15 maxillary retainers of each material (45 overall) were mounted and flexed at an angle of 25 degrees for 1825 cycles at a frequency of 1 Hertz to simulate one year of removing and reinserting a retainer at a rate of 5 times per day. Retainers were visually inspected for fractures. Pairwise t-tests with correction using Tukey’s method were conducted to determine which pairs of material groups were significantly different at α=0.05. Results: For the wear resistance test, the mean baseline thickness was 0.51 ± 0.033 mm, 0.492 ± 0.029 mm, and 0.515 ± 0.047 mm for Essix ACE, Taglus, and Zendura, respectively. The mean post-wear thickness was 0.354 ± 0.033 mm, 0.323 ± 0.038 mm, and 0.42 ± 0.027 mm for Essix ACE, Taglus, and Zendura, respectively. The overall wear was 0.155 ± 0.021 mm, 0.168 ± 0.031 mm, and 0.096 ± 0.033 mm for Essix ACE, Taglus, and Zendura, respectively. The wear depth of Zendura was significantly lower than both Essix ACE (P < 0.001) and Taglus (P < 0.001). There was no significant difference in wear depth between Essix ACE and Taglus (P = 0.312). Under the parameters set for the fatigue resistance test, visual fractures did not occur on any of the retainer materials for Essix ACE, Taglus, or Zendura. Conclusions: Under the assumption of moderate nighttime bruxing for one year, Zendura is the most resistant to wear among the materials tested. With the assumption of retainer removal and reinsertion five time daily for one year, all three materials tested exhibit the same ability to resist fatigue.