Department of Orthodontics and Oral Facial Genetics Works
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Item A Qualitative Engineering Analysis of Occlusion Effects on Mandibular Fracture Repair Mechanics(SAGE-Hindawi, 2011-08) Katona, Thomas R.Objectives. The purpose of this analytical study was to examine and critique the engineering foundations of commonly accepted biomechanical principles of mandible fracture repair. Materials and Methods. Basic principles of static equilibrium were applied to intact and plated mandibles, but instead of the traditional lever forces, the mandibles were subjected to more realistic occlusal forces. Results. These loading conditions produced stress distributions within the intact mandible that were very different and more complex than the customary lever-based gradient. The analyses also demonstrated the entirely different mechanical environments within intact and plated mandibles. Conclusions. Because the loading and geometry of the lever-idealized mandible is incomplete, the associated widely accepted bone stress distribution (tension on top and compression on the bottom) should not be assumed. Furthermore, the stress gradients within the bone of an intact mandible should not be extrapolated to the mechanical environment within the plated regions of a fractured mandible.Item The effects of bracket, wire conformation and size on the load systems during orthodontic sliding mechanics(2015-07) Mika, David E.; Katona, Thomas R.Objective: The purpose of this laboratory study was to compare all 6 load components (3 force and 3 moment) acting on 2 different stainless steel brackets as they slide along 3 sizes of stainless steel archwires with 3 different conformations. Materials and Methods: Brackets were attached to a load cell and elastomeric ligated to the wires. As the load cell was pulled along a precision track, the 6 load components (forces and moments in the 3 orthogonal coordinate system) acting on the bracket were recorded. ANOVA was applied to the data. Results: Overall, there were significant differences for all effects (bracket, wire size and wire configuration), for all outcomes (the loads), except the effect of bracket on the force of friction and one of the moment components. Conclusion: The results demonstrate that the force of friction associated with sliding mechanics should not be considered in isolation, because factors that affect it also affect the other 5 load components.Item Bracket, ligation, and misaligned straight wires effects on load systems during orthodontic sliding mechanics(2015-07) Hannah, Richard D.; Katona, Thomas R.Objective: The objectives of this study were to measure and compare the complete, not solely friction, load components (forces and moments) experienced by brackets as they slide along straight wires that are angled relative to the path of bracket travel. Materials and Methods: Three types of brackets (stainless steel mandibular canine and central incisor, and an all-ceramic mandibular canine) were ligated with stainless steel or elastomeric modules to 2 sizes of stainless steel wire (0.021” x 0.021” and 0.016” x 0.016”) at 0°, 1° and 2° bracket-wire misalignments. All 3 force and 3 moment components experienced by the brackets were measured as they slid along the wire. Results: Overall, all 36 permutations of the 3 brackets, 2 ligations, 2 wires and 3 alignments produced statistically different (predominantly P < .0001) load components on the bracket. Conclusions: The type of bracket, wire, ligation, and relatively small misalignments (1° and 2°) between bracket and wire affect all force and moment components applied to the bracket. Traditional friction-focused “pull through” studies miss the attendant effects on the other 5 load components.Item Orthognathic Surgery past, present, and future(Taylor & Francis, 2022-09-14) Conley, R ScottOrthognathic surgery has been performed for over two centuries with the first procedure occurring in the 1860s. It was not until the late 1950s with the pioneering work of Obwegeser that the modern orthognathic surgery era began. From the beginning, oral surgeons and orthodontists have worked in parallel fashion; advances in both disciplines have led to what is now routinely performed. New and exciting developments are underway not only in diagnosis but also in treatment planning with computer aided surgical simulation and the use of artificial intelligence (AI) to enhance patient treatment outcomes. The purpose of this article is to briefly review the history of orthognathic surgery, to examine the present status and to highlight emerging technologies and advancements.Item Responses to letter to the editor: "Does the presence of an occlusal indicator product affect the contact forces between full dentitions?"(John Wiley & Sons, 2018-06) Mitchem, Jesse A.; Katona, Thomas R.; Moser, Elizabeth A. S.Item The roles of wedging and friction in the mechanics of dental occlusal contacts(2019-04) Katona, Thomas R.; Eckert, George J.Objective: The primary aim of this project is to elucidate the basic mechanical engineering principles that govern and explain unexpected and counter-intuitive occlusal contact force measurements. Methods: Forces were measured on matched pairs of first molar denture, ceramic and stainless steel crowns during occlusion and disclusion, with human saliva and dry (control). The weighted maxillary assembly, guided by a precision slide, was lowered onto, and raised from, the mandibular crown. The forces experienced by the mandibular tooth were continuously measured by the load cell that supported it. Statistical analyses included LOESS smoothing splines and generalized additive models. Principles of basic statics and classic friction were applied to explain and validate the results. Results: It was determined that within the span of a single chomp, the in-occlusal plane force component (Flateral) on the tooth is highly variable in direction and/or magnitude. The most salient observations were that Flateral was higher in disclusion than in occlusion, and the largest Flateral did not necessarily occur when the bite force was maximum. Furthermore, saliva significantly affected the results. Conclusions: The results demonstrated that contacting teeth experience complex transient mechanical environments that can be readily explained with elementary engineering principles involving wedging and friction at the occlusal contacts.Item A Qualitative Engineering Analysis of Occlusion Effects on Mandibular Fracture Repair Mechanics(SAGE-Hindawi, 2011-08) Katona, Thomas R,Objectives. The purpose of this analytical study was to examine and critique the engineering foundations of commonly accepted biomechanical principles of mandible fracture repair. Materials and Methods. Basic principles of static equilibrium were applied to intact and plated mandibles, but instead of the traditional lever forces, the mandibles were subjected to more realistic occlusal forces. Results. These loading conditions produced stress distributions within the intact mandible that were very different and more complex than the customary lever-based gradient. The analyses also demonstrated the entirely different mechanical environments within intact and plated mandibles. Conclusions. Because the loading and geometry of the lever-idealized mandible is incomplete, the associated widely accepted bone stress distribution (tension on top and compression on the bottom) should not be assumed. Furthermore, the stress gradients within the bone of an intact mandible should not be extrapolated to the mechanical environment within the plated regions of a fractured mandible.Item Predictors of orthodontic residency performance: An assessment of scholastic and demographic selection parameters(Allen Press, 2019-05) Grillo, Andrew C.; Ghoneima, Ahmed A.M.; Garetto, Lawrence P.; Bhamidipalli, Surya S.; Stewart, Kelton T.; Orthodontics and Oral Facial Genetics, School of DentistryObjective: To evaluate the association between resident selection criteria, including Graduate Record Examination (GRE) scores, and student performance in an orthodontic residency program. Materials and methods: This retrospective study evaluated the academic records of 70 orthodontic residency graduates from the Indiana University School of Dentistry. The following demographic and scholastic data were extracted from the student academic records: applicant age, gender, ethnicity, race, country of origin, dental school graduation year, GRE score, and graduate orthodontic grade point average (GPA). In addition, student American Board of Orthodontics (ABO) written examination quintiles were obtained from the ABO. Scatterplots, analysis of variance, and correlation coefficients were used to analyze the data. Statistical significance was established at .05 for the study. Results: No associations were found with any component of the GRE, except with the quantitative GRE section, which displayed a weak association with ABO module 2 scores. Dental school GPA demonstrated weak correlations with all ABO modules and moderate correlations with overall and didactic orthodontic GPAs. When assessing demographic factors, significant differences (P < .05) were observed, with the following groups demonstrating higher performance on certain ABO modules: age (younger), race (whites), and country of origin (US citizens). Conclusions: Findings suggest the GRE has no association with student performance in an orthodontic residency. However, dental school GPA and/or class rank appear to be the strongest scholastic predictors of residency performance.Item Precision of the virtual occlusal record(Allen Press, 2019-09) Botsford, Keyan P.; Frazier, Michael C.; Ghoneima, Ahmed A.M.; Utreja, Achint; Bhamidipalli, Surya S.; Stewart, Kelton T.; Orthodontics and Oral Facial Genetics, School of DentistryObjectives: To evaluate the precision of the virtual occlusal record using the Carestream CS3600 Intraoral Scanner (Carestream Dental, Atlanta, Ga). Materials and methods: A total of 20 participants were recruited for this prospective study using preestablished inclusion/exclusion criteria. A complete intraoral scan and two bite registrations were obtained. The participants were instructed to bite with normal pressure when bite registrations were acquired. Contact locations, size (circumference), and intensity were identified on the maxillary first molars and canines. Agreement between contact size and intensity was assessed with intraclass correlation coefficients. Kappa statistics evaluated agreement in contact locations. Statistical significance was set at P < .05. Results: All participant data were included for statistical analysis. Between the two bite registrations, nonstatistically significant differences were observed in the proportion of locations with contacts (P = .7681). A nonstatistically significant difference (-0.25 mm, P = .8416) in mean contact circumference size was observed. A statistically significant difference in mean contact intensity was observed (P = .0448). When evaluating agreement between the bite registrations, a weak correlation for size (intraclass correlation coefficient = 0.35) and intensity (intraclass correlation coefficient = 0.32) was observed as well as a moderate agreement for contact location (κ coefficient = 0.67). Conclusions: The findings suggest that the Carestream intraoral scanner software possesses adequate precision when acquiring the location and size of the contacts in bite registrations. The scanner failed to demonstrate adequate precision when acquiring contact intensities in bite registrations. Additional research is warranted to further investigate the precision of virtual occlusal records with currently available software systems.Item A proposed mechanism for non-carious cervical lesions, root resorption and abutment screw loosening(2022-01-13) Katona, Thomas R.; Eckert, George J.Objectives The purpose of this paper is to present a mechanism for the shared etiologies of non-carious cervical lesions (NCCLs), orthodontics-associated root resorption and implant abutment screw loosening. These are persistent clinical problems with equivocal etiologies. Methods A matched pair of 1st molar denture teeth was set into occlusion within a testing apparatus. The weighted maxillary assembly, guided by slides, was cyclically lowered onto, and raised from, the mandibular tooth. The forces and moments on the mandibular tooth were continuously recorded by a load cell. The maxillary crown was rigidly fixed (ankylosed or implant supported). The mandibular tooth was rigidly fixed or supported by a PDL analogue. For statistics, 21 occlusal relationships were tested. Results The measurements confirmed earlier non- and counter-intuitive results. The directly relevant data were that the measured loads on the tooth, during the span of an individual chomp, are characterized by a wide range of magnitudes and directions. Moreover, these load profiles change with rigid vs. PDL support (p = 0.001), occlusal relationship (p < 0.001) and occlusion vs. disclusion (p = 0.002). Conclusion The demonstrated transient loads within the span of a single chomp produce complex mechanical environments. Thus, it is proposed that NCCLs, orthodontic root resorption and abutment screw loosening result from load component combinations, not from solitary occlusion forces as typically applied in experimental and numerical investigations. In principle, the loading combination concept applies to all phenomena that involve occlusal contacts, including occlusal trauma, implant loading, jaw fracture repairs, etc.