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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

1 Long Term Impact of Microimplant Assisted Rapid Palatal Expansion on Soft Tissue Nasal Morphology

Chew, Laura, Suh, Heeyeon, Park, Joorok, Oh, Heesoo 01 January 2021 (has links)
Introduction: When skeletal transverse discrepancies exist between the maxilla and mandible, they commonly manifest in dental malocclusion. If left uncorrected, the malocclusion can lead to periodontal issues, tooth fractures, tooth loss, or other significant dental problems. Utilization of microimplants in palatal expansion aims to correct transverse discrepancies between the maxilla and mandible by separating the palatal suture in a parallel manner aimed at maximizing skeletal changes and minimizing dental side effects. Overlying soft tissue changes can be affected by the induced skeletal changes. The purpose of this study is to evaluate skeletal expansion and the overlying soft tissue change that occurs using MARPEs (microimplant assisted rapid palatal expanders) at the end of orthodontic treatment in skeletally mature (Cervical Vertebral Maturation (CMV) ≥ 5) patients using cone-beam computed tomography (CBCT) imaging and to evaluate soft tissue changes that occur at the time of orthodontic treatment completion using CBCT imaging. Materials and Methods: CBCT scans from 19 patients who were treated using microimplant assisted rapid palatal expanders were traced and evaluated at three time points: Before orthodontic treatment (T1), post MARPE expansion with MARPE in place (T2), and after orthodontic treatment with MARPE removed. Fourteen hard tissue landmarks and six soft tissue landmarks in the midface and nasal cavity regions were traced by three judges at each time point. The traced landmark points were averaged among all three judges and comparisons were made between the three time points to see the amount of expansion that occurred at various anatomical 2 regions. Intraclass correlation coefficient (ICC) was used to evaluate inter-judge reliability for all measurements. A repeated measures ANOVA test was used for statistical comparison across all three time points and a Tukey post hoc test was used for comparison between time points. Significance was set to .05 and ICC was set to >.70. Results: Expansion with microimplant assisted rapid palatal expanders can affect the hard tissue of the midface region as well as the overlying soft tissue. Increases in skeletal width from the ANS down to the maxillary alveolar bone were statistically significant in both the short term (T1-T2) and long term (T1-T3). The nasal cavity width at inferior turbinate area increased significantly after expansion (T2) and remained increased at treatment completion (T3) and the increased soft tissue width of the alar base that presented after expansion therapy remained increased at treatment completion. Conclusion: Maxillary expansion with microimplant assisted expanders resulted in skeletal changes throughout the maxilla and led to a significant long-term increase in nasal cavity width. The soft tissue changes associated with MARPE treatment show that a widening of the base of the nose may be expected after expansion and can remain at treatment completion.
142

Comparison of Maxillary Expansion Between Clear Aligners and Removable Expansion Appliance in the Mixed Dentition

Zaverdinos, Micaela, Kasrovi, Paul, Chen, James, Oh, Heesoo 01 January 2021 (has links)
Introduction: Orthodontic and orthopedic expansion is necessary to create space to resolve crowding due to arch deficiency or tooth size discrepancy. The Invisalign First clear aligner appliance as a modality for early interceptive orthodontic treatment has become incorporated into orthodontic practices in very recent years. The present study aims to investigate the magnitude of expansion of the Invisalign First clear aligner appliance compared to a Schwartz removable expander in patients with mixed dentition. Additionally, the study aims to compare the efficacy and predictability of Invisalign First clear aligners in this population. Materials & Methods: In this retrospective study, a sample was collected from a single orthodontist practitioner. The sample consisted of 34 patients, 16 patients treated with Invisalign First clear aligners only (Group1) and 19 patients treated with a Schwartz removable appliance and Invisalign First clear aligners (Group 2). Intraoral scans of four timepoints, initial (T1), post-expansion for Group 2 only (T1Exp), first refinement (T2), and final (T3), and planned Clincheck goal (P) model from Clincheck software were imported to Align Technology’s digital measure program (Quantify©). Arch widths and molar inclinations were measured at each timepoint and the changes between timepoints were calculated. Predictability of arch expansion was calculated as T13 (change between initial and final) divided by the Planned dimension multiplied by one hundred. A two sample t-test was used to assess differences in the changes in arch widths and predictability of expansion between two groups. Results: There were statistically significant differences found in the magnitude of expansion and predictability of arch expansion between two groups. Group 2 showed a greater amount of expansion and predictability. Group 1 showed about 50-60% of the planned expansion at the end of treatment. In regards to magnitude of expansion when comparing the two groups, the efficacy predictability of transverse dimensional changes were significantly greater in the Group 2 compared to Group 1, 83% vs 56% (p = 0.001), respectively. The changes in inclination were similar in both groups, with no statistically significant differences.Conclusions: There is a significantly greater amount of expansion and greater predictability with the Schwartz removable appliance compared to the Invisalign First clear aligner appliance in the mixed dentition. The predictability of Invisalign First was 56% and indicates a significant overcorrection of arch expansion is required at the virtual treatment planning stage in Clincheck in order to obtain the arch expansion that was planned
143

The Effect of Recombinant Human Bone Morphogenetic Protein-2 on the Osseointegration of Temporary Anchorage Devices

Cruz, Eden E 01 May 2010 (has links) (PDF)
Titanium has been widely used for dental implants, and in particular, roughened titanium surfaces have provided a means for increasing bone apposition and strengthening the implant-to-bone interface. Finding a way to further increase osseointegration is important because there is a significant clinical benefit to patients if a stable anchor can be established instead of anchoring orthodontic hardware to the molars. In this study, the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the ability of temporary anchorage devices (TADs) to osseointegrate was investigated. The temporary anchorage devices (TADs) used in this study were manufactured from commercially pure titanium and divided into 2 types of treatments: (1) sandblasted and acid-etched (i.e. the control) and (2) sandblasted and acid-etched treated with Medtronic INFUSE® Bone Graft (recombinant human bone morphogenetic protein-2 placed on an absorbable collagen sponge). The implants were placed on the cranial bones of 10 adult male Sprague-Dawley rats. The rats were euthanized by carbon dioxide asphyxiation 6 weeks following surgery for histological examination and biomechanical testing. The results from visual inspection and biomechanical testing showed that the sandblasted and acid-etched TADs treated with rhBMP-2 promoted better osseointegration than TADs that were only sandblasted and acid-etched. Specifically, surface modified TADs treated with rhBMP-2 on bottom showed an increased surface coverage by bone and an increase in the adhesion strength at the TAD-to-bone interface.
144

THREE-DIMENSIONAL ANALYSIS OF SKELETAL CHANGES AND STABILITY IN FIXED ORTHODONTICS VS. INVISALIGN THERAPY IN PATIENTS UNDERGOING SURGERY FIRST APPROACH

Mirnia, Mojan, Hwang, Hyeon-Shik, Bianchi, Jonas 30 September 2022 (has links)
Introduction: The objective of this retrospective longitudinal study was to assess and compare the surgical changes and stability of the maxilla, mandible, and mandibular condyle, in patients who have undergone surgery first approach (SFA) followed by conventional braces or Invisalign (Inv) treatment. Methods: Thirty patients had a cone beam computed tomography (CBCT) exam taken at three timepoints: T1 (presurgery), T2 (immediately after surgery), and T3 at the completion of orthodontics treatment. After the cranial base registration, twenty-seven landmarks were located on each time point using axial, sagittal, and coronal cross-sectional views in the ITK-SNAP software. In addition, seventeen skeletal angular and linear variables were measured using the 3D Slicer software. Result: In general, both Groups had similar sugical changes (T2-T1) and stability (T3-T2). There was a statistically significant longer postsurgical orthodontic time in the Fixed Group (x̅ = five months). Skeletally, comparing T3-T2 the B point showed a statistically significant inferior position in the Fixed Group compared to the Inv Group (1.3 mm), resulting in a larger increase in mandibular plane angle in the Fixed Group (x̅ = 2.7 degrees). Conclusion: The Fixed appliances and clear aligner therapy in the surgery first approach resulted in similar skeletal changes and stability, except for the mandibular plane angle, which showed a greater increase in the Fixed Group. This result may suggest that patients with hyperdivergent skeletal pattern could benefit from aligner therapy for the postsurgical orthodontic phase.
145

Assessment of skeletal changes and mandibular plane in growing patients treated with miniscrew assisted (MARPE) and conventional rapid palatal expansion using CBCT images

Voorhees, Daniel, Bianchi, Jonas, Oh, Heesoo 30 September 2022 (has links)
Background: Maxillary expansion has long been used in children and adolescents for transverse discrepancies and dental crowding. With age, the mid-palatal suture becomes increasingly mature, requiring heavy, rapid force in order to achieve skeletal expansion. As an individual grows into adulthood, it has been demonstrated that a skeletally anchored expander can be used in order to achieve successful sutural separation. The side effects between these two types of expanders, including dental tipping with relative extrusion of buccal segments and clockwise mandibular rotation, have been demonstrated to have differences in their degrees of severity. However, most of the studies have evaluated the effects immediately following the expansion and not through a prolonged period in which growth may occur. The purpose of the present study was to investigate long-term skeletal differences in two types of expansion (RPE vs MARPE) on a growing population. Methods: This retrospective study included 39 adolescent subjects (mean age = 13.8 years) who had received maxillary expansion (20 RPE, 19 MARPE) with subsequent completion of orthodontic treatment. Initial and final CBCTs were used to analyze cephalometric and transversal changes between the two groups. Transverse measurements were repeated two weeks apart to test intra-observer reliability. Results: Cephalometric analysis demonstrated no significant differences in changes of FMA (p = 0.549) or MP-SN (p = 0.722) between the two groups following expansion and completion of orthodontic treatment. There were statistically significant differences in transverse changes between the two groups, with the MARPE group displaying more skeletal expansion. Conclusions: The results of the present study suggest that skeletally anchored expander - MARPE and conventional expander have similar skeletal effects in adolescents.
146

Complications Reported in Maxillary Skeletal Expansion

Payne, Jacqueline, Yoon, Audrey, Suh, Heeyeon, Park, Joorok, Oh, Heesoo 01 January 2021 (has links)
Introduction: The aim of this study was to determine the types and prevalence of complications following MARPE protocol at University of the Pacific and to investigate the complication of asymmetry using CBCT analysis. Methods: In the first portion of this study, 97 patients who started treatment prior to July 2020 and who had MARPE expander treatment at the University of the Pacific were included. Chart review and evaluation of progress clinical photographs were used to report the following complications: inflammation, pain, appliance malfunction, broken microscrew, and pulpitis. In the second portion of this study, 77 patients from a private practice orthodontist who started treatment prior to January 2021 were included in this study. The complication of asymmetry was measured using CBCT measurements from T1 (prior to treatment start) and T2 (immediately following MARPE expansion). The change in U6 molar angulation changes was also assessed. Results: It was determined in the first portion of this study that the most common complication was inflammation around the MARPE site, with 82% of the study population exhibiting any severity of inflammation. 3 patients exhibited severe inflammation requiring removal of MARPE. 18% reported pain in the MARPE area. 9 patients exhibited appliance malfunction, 1 patient exhibited broken microscrew, and 1 patient exhibited pulpitis. It was determined in the second portion of this study that 47% of patients exhibited asymmetry greater than 1 mm and the average asymmetry at ANS was 1.47 mm. No correlation was exhibited between amount of asymmetric expansion and the following measures: age, molar inclination, palatal thickness, posterior screw expansion and palatal vault height. 3 Conclusions: Inflammation of the MARPE is the most common complication that can result in early removal of the expander. Other complications such as asymmetry and pain are common as well.
147

The Effects of the COVID-19 Pandemic on Postgraduate Endodontic Programs in the United States

Aboubakare, Bianca, Chen, James, Galicia, Johnah C. 01 January 2022 (has links)
In December 2019, the coronavirus disease 2019 (COVID-19) was first identified as an acute infectious disease in Wuhan, China and subsequently led to an ongoing pandemic. At the onset of the pandemic, dental professionals were understood to face the greatest exposure risk to SARS-Cov-2 due to aerosolization of fluids from the oral cavity and respiratory airways . As a result, dental professionals, including academic institutions and their students and residents halted much of their operations to minimize exposure risks and potentially slow the spread of infection to peers and patients alike. Currently, there is little in the literature that describes the changes that academic institutions have implemented in the face of pandemics. This study will discuss the chronology, modifications, and possible resultant outcomes of COVID-19 related events in respect to Graduate Endodontic programs in the United States.
148

Relationship between Facial Attractiveness and Occlusal Treatment Outcomes: A Retrospective Study

Fowler, Chad Eric 01 January 2007 (has links)
The goal of this study was to determine if a relationship exists between pretreatment facial attractiveness and posttreatment occlusal outcome in orthodontic patients. A randomized sample of forty-seven patients (26 males, 21 females) was selected for inclusion in this study. Orthodontic evaluators rated pretreatment patient photographs (frontal smile, frontal, profile) using a 100 mm visual analog scale (VAS). Occlusal outomes were evaluated using percentage reduction in weighted Peer Assessment Rating (PAR) index scores and the American Board of Orthodontics objective grading system (ABO-OGS). Spearman correlation coefficients were calculated to assess the relationship between pretreatment VAS attractiveness ratings and posttreatment occlusal scores. There was a fair correlation between facial attractiveness and reduction in weighted PAR index scores for all patients (r=.41, p<.01) and for male patients (r=.48, p<.05). The results showed a good correlation between facial attractiveness and the ABO-OGS for females (r=-.55, p<.05).
149

The Effect of Pre-Cure Bracket Movement on the Shear Bond Strength of Metal Brackets

Roberts, Thomas Luther, IV 01 January 2007 (has links)
The effect on shear bond strength of bracket movement after seating the brackets and before light curing has not been reported. The purpose of this study was to determine the effect of linear and rotational pre-cure bracket movement on the shear bond strength of orthodontic brackets. 100 extracted human maxillary premolars were divided into 5 groups of 20 teeth each. The control group was bonded with no pre-cure bracket movement, and test groups were bonded with pre-cure bracket movement of 2 mm, 4 mm, 45¢ª or 180¢ª. Debonding force was measured with an Instron universal testing machine. Results were analyzed by ANOVA. Weibull survival analysis was used to determine the force required to produce a 5% bracket failure rate. Differences in the Adhesive Remnant Index (ARI) were analyzed by chi-square. No significant differences between groups were found for the mean shear bond strength or Weibull estimates. ARI scores differed significantly.
150

Comparison of surgical and non-surgical orthodontic treatment approaches on occlusal and cephalometric outcomes in patients with severe Class II division I malocclusions

Daniels, Sheila Meghnot 01 May 2017 (has links)
This study aimed to examine end-of-treatment outcomes of severe Class II Division I malocclusion patients treated with surgical or non-surgical approaches. This study tests the hypotheses that occlusal outcomes (ABO-OGS) at end of treatment will be similar while cephalometric outcomes will differ between these groups. A total of 60 patients were included: 20 of which underwent surgical correction and 40 of which did not. The end of treatment ABO-OGS and cephalometric outcomes were compared by Mann-Whitney U tests and multivariable linear regression models. Following adjustment for multiple confounders (age, gender, complexity of case, and skeletal patterns), the final deband score (ABO-OGS) was similar for both groups (23.8 for surgical group versus 22.5 for non-surgical group). Those treated surgically had a significantly larger reduction in ANB angle, 3.4 degrees reduction versus 1.5 degrees reduction in the non-surgical group (p=0.002). The surgical group also showed increased maxillary incisor proclination (p=0.001) compared to candidates treated non-surgically. This might be attributed to retroclination of incisors during treatment selection in the non-surgical group – namely, extraction of premolars to mask the discrepancy. Studies such as this are necessary because they begin to give practitioners view of not only the outcomes of a single treatment plan, but a comprehensive approach by providing evidence of the over-arching treatment used for successful treatment in both groups.

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