Finite element stress analysis of maxillary two implants-retained overdenture according go position of implant fixtures / 대한치과보철학회지

STATEMENT OF PROBLEM: There have been a few studies about unsplinted implant retainted maxillary overdenture. PURPOSE: The purpose of this study was to examine the effect of different position of implant for 2 implants-retained maxillary overdenture. MATERIALS AND METHODS: Three-dimensional finite element models were used to reproduce an edentulous human maxilla with an implant-retained overdenture. Two implants in the canine tooth positions on both side and in the second premolar tooth positions on both side models were examined. Axial loads of 100 N were applied to the occlusal surface at the right first molar tooth positions. Maximum stress at the implant-bone interface and stress at the cortical bone surface just under the loading point were observed. RESULTS AND CONCLUSION: Within the limits of this study, maximum stresses were concentrated around implant of canine position at loading side. The second premolar area was thought to be more favorable to distribution of stress on mucosa, alveolar bone and implants than canine area for maxillary overdenture.

Surface characteristics of anodic oxidized titanium according to the pore size / 대한치과보철학회지

Statement of problem. The success of osseointegration can be enhanced with an implant that has improved surface characteristics. Anodic oxidation is one of the surface modifying method to achieve osseointegration. Voltage of anodic oxidation can change surface characteristics and cell activity. Purpose. This study was performed to evaluate MG63 cell responses such as affinity, proliferation and to compare surface characteristics of anodic oxidized titanium in various voltage. Material and method. The disks for cell culture were fabricated from grade 3 commercially pure titanium, 1 mm in thickness and 12 mm in diameter. Surfaces of 4 different roughness were prepared. Group 1 had a machined surface, used as control. Group 2 was anodized under 220 V, group 3 was anodized under 300 V and group 4 was anodized under 320 V. The microtopography of specimens was observed by scanning electron microscope (JSM-840A, JEOL, Japan) and atomic force microscope(Autoprobe CP, Park Scientific Instrument, USA). The surface roughness was measured by confocal laser scanning microscope(Pascal, LSM5, Zeiss, Germany). The crystal structure of the titanium surface was analyzed with x-ray diffractometer(D8 advanced, Bruker, Germany). MG63 osteoblast-like cells were cultured on these specimens. The cell morpholgy was observed by field emission electron microscope(Hitachi S-4700, Japan). The cell metabolic and proliferative activity was evaluated by MTT assay. Results and conclusion. With in limitations of this in vitro study, the following conclusions were drawn. 1. In anodizing titanium surface, we could see pores which did not show in contol group. In higher anodizing voltage, pore size was increased. 2. In anodizing titanium surface, we could see anatase. In higher anodizing voltage, thicker oxide layer increased crystallinity(anatase, anatase and rutile mixed). 3. MG63 cells showed more irregular, polarized and polygonal shape and developed more lamellipodi in anodizing group as voltage increased. 4. The activity of cells in MTT assay increased significantly in group 3 and 4 in comparison with group 1 and 2. However, there was no difference between group 3 and 4 at P<0.05. Proliferation of MG63 cells increased significantly in pore size(3-5.5 micrometer) of group 3 and 4 in comparison with in pore size(0.2-1 micrometer) of group 2.