ABSTRACT
were satisfactory on the aspect of esthetic and masticatory function. (J Korean Acad Prosthodont 2020;58:137-44)
ABSTRACT
Failure of fixed implant supported prosthesis is caused by biomechanical factors such as excessive occlusal stress and biological factors such as bacterial infections andinflammation. Implants with severe bone resorption that have worsened without being resolved due to implant complications should be removed and then new treatmentsshould be planned, taking into account remaining teeth, remaining implants, and residual alveolar. The patient of this case removed some of fixed implant prosthesis of mandible.The condition of the remaining alveolar bone was reassessed for further implant replacement and a few implants were placed. Then implant assisted removable partialdenture (IAPRD) treatment is performed using implant surveyed bridge as abutment. Through this treatment, the clinical results were satisfactory on aspect of masticatoryfunction recovery and oral hygiene management. (J Korean Acad Prosthodont 2020;58:161-8)
ABSTRACT
PURPOSE@#The stress distribution and microgap formation on an implant abutment structure was evaluated to determine the relationship between the direction of the load and the stress value. @*MATERIALS AND METHODS@#Two types of three-dimensional models for the mandibular first molar were designed: bone-level implant and tissue-level implant. Each group consisted of an implant, surrounding bone, abutment, screw, and crown. Static finite element analysis was simulated through 200 N of occlusal load and preload at five different load directions: 0, 15, 30, 45, and 60°. The von Mises stress of the abutment and implant was evaluated. Microgap formation on the implant-abutment interface was also analyzed. @*RESULTS@#The stress values in the implant were as follows: 525, 322, 561, 778, and 1150 MPa in a bone level implant, and 254, 182, 259, 364, and 436 MPa in a tissue level implant at a load direction of 0, 15, 30, 45, and 60°, respectively. For microgap formation between the implant and abutment interface, three to seven-micron gaps were observed in the bone level implant under a load at 45 and 60°. In contrast, a three-micron gap was observed in the tissue level implant under a load at only 60°. @*CONCLUSION@#The mean stress of bone-level implant showed 2.2 times higher than that of tissue-level implant. When considering the loading point of occlusal surface and the direction of load, higher stress was noted when the vector was from the center of rotation in the implant prostheses.
ABSTRACT
Implant-Assisted Removable Partial Dentures (IARPDs) treatment is being performed in a fully edentulous patient using implant surveyed prosthesis as an abutment. Implant-supported prosthesis as an abutment of IARPDs is classified into screw-retained and cement-retained type according to the retention type, and each has advantages and disadvantages. The EZ crown system (Samwon DMP, Yangsan, Korea) has a cylinder combined with abutment, and the nickel-titanium spring in this cylinder provides a constant force on the zirconia ball to obtain retention in EZ crown system. In this patient, the natural abutment teeth of the mandibular overdenture was hopeless. We planned implant assisted removable partial denture using anterior implant surveyed prosthesis considering functional and esthetical rehabilitation, cost and patient's needs. When fabricating IARPDs using implant as abutment, we could compensate for the shortcomings of existing implant-supported prosthesis retention type and made the design of removable partial denture easy due to using EZ crown system.