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Influence of Alveolar Support on Stress in Periodontal Structures
M. Ona1 and
N. Wakabayashi1,2,*
1 Removable Partial Prosthodontics, Masticatory Function Rehabilitation, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo 113-8549, Japan; and
2 Department of Removable Prosthodontics, School of Dentistry, Iwate Medical University, 1-3-27, Chuodori, Morioka, Iwate 020-8580, Japan
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Figure 1. The FE models and their characteristics. (A) Parts of the FE model; the maxillary central incisor (I), the PDL (P), the cortical bone (Co), the cancellous bone (Ca), and completed models with normal bone height (N) and reduced height (R). (B) Load-deflection curves of the incisors under horizontal force, from labial to lingual. The solid lines indicate the load-deflection relation reported by in vivo data (Mühlemann, 1951), and the 4 dotted curves represent those of the FE models of the present study: the models of normal bone height with normal and widened PDL space, and those of reduced bone height with normal and widened PDL space. (C) Stress-strain relation used to express the non-linear material property of the PDL used in the models of this study.
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Figure 2. Displacements indicated by arrows on the surface nodes of the incisor viewed mesially, with the resultant stress contour graphics of the PDL under the simulated bite forces of 1 N and 20 N. Each color of arrow represents the displacement path of each node. Lines hidden inside the tooth surface are not displayed. The color of each line represents the magnitude of displacement: The red lines indicate the greatest displacement, while the blue lines indicate the smallest displacement. Each contour graphic (upper right of each arrow graphic) indicates the 1st principal (tensile) stress distribution on the inner surface of the sectioned half of the PDL. The maximum tensile stress is found at the lingual cervical region in the PDL under 20 N of bite force. The scales indicate the maximum and minimum values, as well as the boundary values between each level for the displacement or the stress. The upper left illustration represents the direction of the simulated bite force.
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Figure 3. Stress distributions of the PDL and bone. (A) The contour graphics of the 1st principal (tensile) stress in the cervical area of the PDL, viewed lingually. The 4 models were: those of normal bone height with normal and widened PDL space, and those of reduced bone height with normal and widened PDL space. Each contour graphic was divided into 10 parts, with different colors according to the stress level, shown in the scale below the Figs. The red area represents the highest tensile stress, while the gray area indicates the stress below the reported tensile strength of the PDL (2.4 MPa). (B) The contour graphics of the 3rd principal (compressive) stress in the labial side of the cortical bone. The red area represents the highest compressive stress, as shown in the scale below the Figs. The enlarged grey-scale view of a contour graphic highlights the principal stress distributions, with directions generated at nodes on the labial cervical bone. The blue internal arrows represent compressive stresses, the black external arrows tensile stresses. The arrows were traced from the original data graphic and superimposed on the grey-scale graphic.
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Journal of Dental Research, Vol. 85, No. 12,
1087-1091 (2006)
DOI: 10.1177/154405910608501204
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