• The korean journal of orthodontics
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• v.24 no.2
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• pp.303-317
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• 1994

This study was designed to measure the changes in the titer of tooth root antibodies accompanying root resorption associated with orthodontic tooth movement in dogs to explore a role of the specific immune response in root resorption during orthodontic tooth movement. Five adult mongrel dogs, 2 years of age, were used in the study. Six lower incisors were extracted as sources of homologous antigen in the dogs. Tooth root antigen preparations were made from a 6M Guanidine-HCl-10% EDTA(pH5.0) extract of these root dentins. Root resorption was elicited by intrusion of six maxillary incisors with 200-250gm intrusive force. In 9th week, resorbing six maxillary anterior teeth were extracted. Serum samples were taken from each dog prior to intrusion and weekly for 11 consecutive weeks. Serum autoantibody titers were determined with an enzyme-linked immunosorbent assay. As controls for antibody specificity, sera which were previously incubated with tooth root antigen as well as sera to an unrelated bacterial antigen (Porphyromonas gingivalis 33277) for 3 hours at 25 were measured in all runs. Root resorption was monitored monthly using occlusal radiographs. And then root resorption patterns were observed with a zoom stereo microscope (Model SZH-121, Olympus optical Co. Ltd.). Incisors did not show clear radiographic evidence of significant and progressive root resorption, but periodontal ligament space had widened. But root resorption was observed on the apical regions of the maxillary incisors with a zoom stereo microscope. Teeth showed the shallow depression generally accompanying deep resorption. These demonstrate a slight tendency for an immediate decrease followed by rebound to levels above the pre-treatment baseline. A peak titer of autoantibody to dentin antigen occurred on day 28, then steadily decreased during the 9th week period as the roots resorbed and then rapidly spiked in animals when the resorbing teeth were extracted. When sera is incubated with tooth root antigen, serum activity in the ELISA was almost absent. This is because serum activity in the ELISA could be removed by absorption of the serum with dog dentin antigen. Serum ELISA activity to the unrelated bacterial antigen remained essentially unchanged in all animals throughout the experimental period. When the time course of changes in autoantibody to homologous tooth root antigen prepatration and unrelated bacterial antigen was compared, no significant differences were found(${\alpha}=0.05$). In general, the overall pattern of changes in autoantibody was similar to the two antigens. These findings suggest the possibility that these immunologic changes precede a significant development of root resorption lesions rather than merely reflecting their presence. Therefore, this suggests that the changes of antibody levels may have some predictive value for root resorption.

• Restorative Dentistry and Endodontics
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• v.34 no.4
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• pp.324-332
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• 2009

The purpose of this study was to investigate the effect of rigidity of post core systems on stress distribution by the theoretical technique, finite element stress-analysis method. Three-dimensional finite element models simulating an endodontically treated maxillary central incisor restored with a zirconia ceramic crown were prepared and 1.5 mm ferrule height was provided. Each model contained cortical bone, trabecular bone, periodontal ligament, 4 mm apical root canal filling, and post-and-core. Six combinations of three parallel type post (zirconia ceramic, glass fiber, and stainless steel) and two core (Paracore and Tetric ceram) materials were evaluated, respectively. A 50 N static occlusal load was applied to the palatal surface of the crown with a $60^{\circ}$angle to the long axis of the tooth. The differences in stress transfer characteristics of the models were analyzed. von Mises stresses were chosen for presentation of results and maximum displacement and hydrostatic pressure were also calculated. An increase of the elastic modulus of the post material increased the stress, but shifted the maximum stress location from the dentin surface to the post material. Buccal side of cervical region (junction of core and crown) of the glass fiber post restored tooth was subjected to the highest stress concentration. Maximum von Mises stress in the remaining radicular tooth structure for low elastic modulus resin core (29.21 MPa) was slightly higher than that for high elastic modulus resin core (29.14 MPa) in case of glass fiber post. Maximum displacement of glass fiber post restored tooth was higher than that of zirconia ceramic or stainless steel post restored tooth.