The purpose of this study was to evaluate the diagnostic quality of MR images taken on subjects with different types of orthodontic lingual retainers in place. The study provides guidelines and recommendations for use of lingual retainer materials in those patients who are or may potentially undergo routine magnetic resonance imaging. Ten subjects had impressions taken and models made for retainer tray fabrication. Removable trays with each lingual retainer material incorporated in them were fabricated from the models. Subjects underwent scans with each of the five test trays in place. T1 sagittal (T1), T2 axial (T2), gradient echo (GRE), and diffusion weighted imaging (DWl) were evaluated independently by three neuroradiologists for degree of distortion and diagnostic ability. The Freidman test, a repeated measures one-way ANOVA correlation, established statistically significant differences (p<.05) in distortion ranking of images due to lingual retainer material. Post-hoc comparison using a paired Wilcoxon signed rank test determined statistically significant differences to be between stainless steel and all other materials for T1, T2, and GRE imaging modalities. An intraclass correlation coefficient of .706 showed good agreement between readers with associated 95% confidence intervals. The results of this study show that stainless steel mandibular retainers caused statistically significant distortion in MR images at the base of the tongue, body of the mandible and hard palate in the T1, T2 and GRE imaging modalities. The distortion scores indicate images are nondiagnostic. Ribbond™, gold, and TMA did not cause a statistically significant amount of distortion of any of the images.
","abstract_html":"<p>The purpose of this study was to evaluate the diagnostic quality of MR images taken on subjects with different types of orthodontic lingual retainers in place. The study provides guidelines and recommendations for use of lingual retainer materials in those patients who are or may potentially undergo routine magnetic resonance imaging. Ten subjects had impressions taken and models made for retainer tray fabrication. Removable trays with each lingual retainer material incorporated in them were fabricated from the models. Subjects underwent scans with each of the five test trays in place. T1 sagittal (T1), T2 axial (T2), gradient echo (GRE), and diffusion weighted imaging (DWl) were evaluated independently by three neuroradiologists for degree of distortion and diagnostic ability. The Freidman test, a repeated measures one-way ANOVA correlation, established statistically significant differences (p<.05) in distortion ranking of images due to lingual retainer material. Post-hoc comparison using a paired Wilcoxon signed rank test determined statistically significant differences to be between stainless steel and all other materials for T1, T2, and GRE imaging modalities. An intraclass correlation coefficient of .706 showed good agreement between readers with associated 95% confidence intervals. The results of this study show that stainless steel mandibular retainers caused statistically significant distortion in MR images at the base of the tongue, body of the mandible and hard palate in the T1, T2 and GRE imaging modalities. The distortion scores indicate images are nondiagnostic. Ribbond™, gold, and TMA did not cause a statistically significant amount of distortion of any of the images.</p>","abstract_has_math":false,"creators":["Carter, Norman E."],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Thesis","degree_discipline":"Orthodontics and Dentofacial Orthopedics","degree_department":null,"school":null,"contributors":["V. Leroy Leggitt","Joseph Caruso","Udo Oyoyo"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2008,"date_issued":"2008-03-01T08:00:00Z","date_published":"2008-03-01T08:00:00Z","updated_at":"2026-07-24T02:54:17Z","subjects":["Orthodontics and Orthodontology","Other Dentistry","Orthodontic Retainers; Mandible; Magnetic Resonance Imaging; Skull -- radiography; Temporomandibular Joint"],"languages":["English"],"rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsrepository.llu.edu/etd/1230","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["V. Leroy Leggitt","Joseph Caruso","Udo Oyoyo"]},{"key":"dc:creator","label":"Author","values":["Carter, Norman E."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Orthodontics and Dentofacial Orthopedics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Orthodontics and Orthodontology","Other Dentistry","Orthodontic Retainers; Mandible; Magnetic Resonance Imaging; Skull -- radiography; Temporomandibular Joint"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsrepository.llu.edu/etd/1230"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The purpose of this study was to evaluate the diagnostic quality of MR images taken on subjects with different types of orthodontic lingual retainers in place. The study provides guidelines and recommendations for use of lingual retainer materials in those patients who are or may potentially undergo routine magnetic resonance imaging. Ten subjects had impressions taken and models made for retainer tray fabrication. Removable trays with each lingual retainer material incorporated in them were fabricated from the models. Subjects underwent scans with each of the five test trays in place. T1 sagittal (T1), T2 axial (T2), gradient echo (GRE), and diffusion weighted imaging (DWl) were evaluated independently by three neuroradiologists for degree of distortion and diagnostic ability. The Freidman test, a repeated measures one-way ANOVA correlation, established statistically significant differences (p<.05) in distortion ranking of images due to lingual retainer material. Post-hoc comparison using a paired Wilcoxon signed rank test determined statistically significant differences to be between stainless steel and all other materials for T1, T2, and GRE imaging modalities. An intraclass correlation coefficient of .706 showed good agreement between readers with associated 95% confidence intervals. The results of this study show that stainless steel mandibular retainers caused statistically significant distortion in MR images at the base of the tongue, body of the mandible and hard palate in the T1, T2 and GRE imaging modalities. The distortion scores indicate images are nondiagnostic. Ribbond™, gold, and TMA did not cause a statistically significant amount of distortion of any of the images.
"]},{"key":"dc:title","label":"Title","values":["Influence of Mandibular Fixed Retainers on Diagnostic Quality of Cranial MRI"]}]}],"canonical_facts":{"dc:contributor":["V. Leroy Leggitt","Joseph Caruso","Udo Oyoyo"],"dc:creator":["Carter, Norman E."],"dc:description.abstract":["The purpose of this study was to evaluate the diagnostic quality of MR images taken on subjects with different types of orthodontic lingual retainers in place. The study provides guidelines and recommendations for use of lingual retainer materials in those patients who are or may potentially undergo routine magnetic resonance imaging. Ten subjects had impressions taken and models made for retainer tray fabrication. Removable trays with each lingual retainer material incorporated in them were fabricated from the models. Subjects underwent scans with each of the five test trays in place. T1 sagittal (T1), T2 axial (T2), gradient echo (GRE), and diffusion weighted imaging (DWl) were evaluated independently by three neuroradiologists for degree of distortion and diagnostic ability. The Freidman test, a repeated measures one-way ANOVA correlation, established statistically significant differences (p<.05) in distortion ranking of images due to lingual retainer material. Post-hoc comparison using a paired Wilcoxon signed rank test determined statistically significant differences to be between stainless steel and all other materials for T1, T2, and GRE imaging modalities. An intraclass correlation coefficient of .706 showed good agreement between readers with associated 95% confidence intervals. The results of this study show that stainless steel mandibular retainers caused statistically significant distortion in MR images at the base of the tongue, body of the mandible and hard palate in the T1, T2 and GRE imaging modalities. The distortion scores indicate images are nondiagnostic. Ribbond™, gold, and TMA did not cause a statistically significant amount of distortion of any of the images.
"],"dc:identifier":["https://scholarsrepository.llu.edu/etd/1230"],"dc:language":["English"],"dc:rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"dc:subject":["Orthodontics and Orthodontology","Other Dentistry","Orthodontic Retainers; Mandible; Magnetic Resonance Imaging; Skull -- radiography; Temporomandibular Joint"],"dc:title":["Influence of Mandibular Fixed Retainers on Diagnostic Quality of Cranial MRI"],"thesis:degree_discipline":["Orthodontics and Dentofacial Orthopedics"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T02:54:17Z"}