The use of 4 implants or inclined implants increased stress on peri-implant cortical bone. However, when used in conjunction with a short cantilever, inclined implants decreased stress on peri-implant cortical bone.
The aim of this study was to observe the influence of prosthesis design and loading condition on the stress distributions of tooth-implant supported prostheses. Six 2D finite element models, two reference models, and four experimental models were computed to simulate different prosthesis designs. Six different loading conditions were applied to investigate the stress distributions of tooth and implant, respectively. The stresses of reference models were considered as 100%; the stresses of experimental models at the same locations were compared with those of reference models. The stresses around implants were higher than those around teeth. When vertical loading was applied only on the implant, the stresses to both the implant and teeth were at their lowest. The highest stress to the tooth was in the model TTPF and the lowest in the model TPFF. The highest stress to the implant was in the model TPPF and the lowest in the model TPFF. These data indicated that the loading on the tooth-implant supported prosthesis was mainly supported by the implant. Minimizing the loading on the tooth decreased the stress to both the tooth and the implant. Adding fixtures as abutment was more effective in decreasing the stress than adding tooth as abutment in tooth-implant supported prosthesis.
With a wide and shallow palate, it is necessary to design a reinforced palatal strap. With a narrow palate, the anteroposterior width of the palatal strap can be narrower. With a deep palate, it is not necessary to change the palatal strap design according to the palatal shape.
Resonance frequency has been measured in order to evaluate the rigidity in peri-implant tissue.We found that although the trabecular structure of the peri-implant bone changed in response to functional loading, no marked change was noted in the implant stability quotient (ISQ) value.
AbstractPurpose: The objective of this study was to clarify the effect of mechanical loading on the trabecular structure of peri-implant bone and determine its correlation with the implant stability quotient (ISQ) value.Methods: This study used 3 immunologically mature male dogs. Three months after bilateral extraction of the mandibular premolars of the dogs, 4 implants were placed in these sites for each dog. After 3 months to allow healing of the implant sites, superstructures were prepared on the right side (loaded side). The implants on the left side were covered with mucosa (non-loaded side). The ISQ values of all implants were measured 3 months after placing the superstructures; subsequently, the animals were sacrificed. After the mandible was excised and fixed, micro-CT images were acquired and three-dimensional analysis, performed.
Results:The means and S.D. of the ISQ value for the 12 implants were 69.6±6.2 and 62.9±13.8 for the loaded and non-loaded sides, respectively. No significant difference was noted between the 2 sides. Mean and S.D. of bone volume fraction (BV/TV) were 13.0±6.6 and 9.3±3.8; trabecular thickness (Tb.Th), 97.7±27.7 µm and 91.0 ± 24.0 µm; and trabecular number (Tb.N), 1.24±0.30/mm and 0.99±0.20/mm for the loaded and non-loaded sides, respectively. BV/TV and Tb.N values were higher for the loaded side.
Conclusion:Morphological changes occurred in response to functional loading. However, lamellar bone was observed around the implants on both sides. These findings revealed that changes in the bone structure due to functional loading of implants had negligible or no effect on the ISQ value.
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