Browsing by Subject "Periodontal ligament"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Estimation of periodontal ligament’s equivalent mechanical parameters for finite element modeling
    (Elsevier, 2013) Xia, Zeyang; Jiang, Feifei; Chen, Jie; Mechanical and Energy Engineering, Purdue School of Engineering and Technology
    Introduction: Young's modulus (E) and Poisson's ratio (v) of the periodontal ligament are needed in a finite element analysis for investigating the biomechanical behavior of a tooth, periodontal ligament, and bone complex. However, large discrepancies in E (0.01-1,750 MPa) and v (0.28-0.49) were reported previously. The objective of this study was to narrow the ranges and to provide equivalent E and v pairs suitable for finite element modeling of a tooth, periodontal ligament, and bone complex by using a reported crown load-displacement relationship as the criterion. Methods: A 3-dimensional finite element model of a 3-tooth, periodontal ligament, and bone complex, consisting of a maxillary central incisor with 2 adjacent teeth, from a cone-beam computed tomography scan was created. The dimensions, constraints, and loading condition were kept similar to those reported in the human study. With the load applied to the crown, both v and E were adjusted independently, and the corresponding crown displacements were calculated. The resulting load-displacement curves were compared with those reported in the human study. The mean absolute displacement difference method was used to find the best fit. The E and v pairs that generated the minimum mean absolute displacement difference were identified. Results: The finite element model with 1 of the 3 E and v pairs (v = 0.35, E = 0.87 MPa; v = 0.4, E = 0.71 MPa; and v = 0.45, E = 0.47 MPa) simulated the tooth, periodontal ligament, and bone complex well. The mean absolute displacement differences were 0.0135, 0.0138, and 0.0138 mm, respectively; these are less than 8% of 0.175 mm, which was the crown displacement of the tooth, periodontal ligament, and bone complex under the load of 500 cN. Conclusions: The E and v values close to the 3 pairs might be used for finite element modeling of the tooth, periodontal ligament, and bone complex.
  • Thumbnail Image
    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.
  • Thumbnail Image
    Item
    The significance of loading profile on the occlusion mechanics of a viscoelastic periodontal ligament analogue-supported tooth
    (2020-06) Thompson, James P.; Katona, Thomas R.; Eckert, George J.
    Background: Benchtop studies of occlusal contact forces have used teeth that were rigidly attached or supported by readily available viscoelastic (VE) materials that served as periodontal ligament (PDL) substitutes. More recent specimens have incorporated a precisely dimensioned VE PDL-behavior matched analogue. Objectives: The objectives of this study were to evaluate a modified loading protocol (step function) that is more appropriate to VE support than the previously used ramp function. The occlusion manifestations of the time-dependent behaviors (creep and recovery) of the PDL analogue were examined using the revised protocol. Methods: A mandibular 1st molar denture tooth was set into a precision-machined root/socket assembly. The PDL substitute was then cured to tight dimensional tolerances. The matching rigidly fixed maxillary denture tooth was aligned into a Class I centric molar relationship in a testing apparatus. The weighted maxillary assembly was then cycled onto and off of the load cell-supported mandibular assembly. For statistical purposes, three loading schedules were tested in 21 0.05 mm shifted occlusal relationships. Rigid attachment served as control. Results: Statistical analyses were performed on the peak values of Flateral, the net in-occlusal plane force component of the occlusal contact forces. It was found that there were statistically significant differences between: chomp-to-chomp (p < .038), PDL vs. rigid (p < .001) and loading schedules (p < .044 for PDL only). Conclusion: The loading protocol affects outcomes, and the step functions maintained consistent timing with prescribable creep and recovery periods.
  • Thumbnail Image
    Item
    The effects of different types of periodontal ligament material models on stresses computed using finite element models
    (Elsevier, 2022-12) Wang, Dongcai; Akbari, Amin; Jiang, Feifei; Liu, Yunfeng; Chen, Jie; Mechanical and Energy Engineering, Purdue School of Engineering and Technology
    Introduction: Finite element (FE) method has been used to calculate stress in the periodontal ligament (PDL), which is crucial in orthodontic tooth movement. The stress depends on the PDL material property, which varies significantly in previous studies. This study aimed to determine the effects of different PDL properties on stress in PDL using FE analysis. Methods: A 3-dimensional FE model was created consisting of a maxillary canine, its surrounding PDL, and alveolar bone obtained from cone-beam computed tomography scans. One Newton of intrusion force was applied vertically to the crown. Then, the hydrostatic stress and the von Mises stress in the PDL were computed using different PDL material properties, including linear elastic, viscoelastic, hyperelastic, and fiber matrix. Young's modulus (E), used previously from 0.01 to 1000 MPa, and 3 Poisson's ratios, 0.28, 0.45, and 0.49, were simulated for the linear elastic model. Results: The FE analyses showed consistent patterns of stress distribution. The high stresses are mostly concentrated at the apical area, except for the linear elastic models with high E (E >15 MPa). However, the magnitude varied significantly from -14.77 to -127.58 kPa among the analyzed patients. The E-stress relationship was not linear. The Poisson's ratio did not affect the stress distribution but significantly influenced the stress value. The hydrostatic stress varied from -14.61 to -95.48 kPa. Conclusions: Different PDL material properties in the FE modeling of dentition do not alter the stress distributions. However, the magnitudes of the stress significantly differ among the patients with the tested material properties.
  • Thumbnail Image
    Item
    Validation of an artificial tooth-periodontal ligament-bone complex for in-vitro orthodontic research
    (2015-08) Favor, Trevor E.; Chen, Jie; El-Mounayri, Hazim A.; Katona, Thomas R.
    Orthodontics research investigates the methods in which tooth displacement may be directed in the tooth-periodontal ligament-bone-complex. In the biological environment, the periodontal ligament is the soft tissue responsible for the absorption of forces on teeth and has a direct connection to tooth mobility. Current research is limited in that it must be conducted in an in-vivo capacity. A major advancement in orthodontics research would be a testing method that allows for the development and analysis of orthodontic devices without a patient present. This study outlines the development and testing methods for the validation of an artificial periodontal ligament to be used in conjunction with an artificial-tooth-periodontal ligament-bone-complex. The study focused on finding the criteria in which consistent results were produced, the mixture that best simulated the human periodontal ligament’s mechanical behavior, and the robustness of the artificial-periodontal ligament-bone-complex. This study utilized a geometrically accurate denture mold filled with varying compositions of an artificial periodontal ligament for testing. Experiments focused on findings of viscoelasticity, curing times, and instantaneous responses of the teeth under direct orthodontic loading, as well as the changes in response from different teeth within the denture mold. Tests confirmed that a mixture composed of 50\% Gasket Sealant No. 2 and 50\% RTV 587 Silicone produced a substance that could adequately serve as an artificial periodontal ligament.