Effect of inadequate fits of superstructures on surrounding tissue

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 09672004
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 補綴理工系歯学
• Research Institution: Ohu University
• Principal Investigator: YAMAMORI Tetsuo Ohu University, School of Dentistry, Department of Removable Prosthodontics, Associate Professor, 歯学部, 講師 (30200851)
• Project Period (FY): 1997 – 1999
• Keywords: Dental implant / Superstructure / Fit

Research Abstract

Bilateral mandibular fourth premolars and first molars from 2 beagle dogs were extracted, and 3 fixtures for each site were inserted 3 months later. Abutments were connected on each fixture 4 months after insertion of the fixture, followed by impression taking. A connected superstructure was set on 3 abutments in each side of mandible and gold screws were tightened with a torque of 10 Ncm. Superstructures were passively fit to the abutments expect for the middle ones of the experimental side, which were given vertical clearance of about 140〜200 μ m between the superstructures and abutments.
The tissue blocks including the implants sampled after 5 or 14-week observation were used for the histological examination. Histological findings from both the fit and the misfit groups resembled to each other, and large percentage of the fixture surface directly faced to the bone tissue. In both fit and misfit groups, standardized rentogenographs showed no obvious change in the bone height around the fixtures.
For the finite element analysis, the simplified model was created at first. Then the model with reference to the bucco-lingual section of the tissue blocks was made.