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Stability of immediate loaded miniscrew implants according to force levels

Other Titles
 미니스크류 임플란트 식립 직후에 가해준 힘의 크기가 안정성에 미치는 영향 
Authors
 조용민 
Issue Date
2009
Description
Dept. of Dental Science/박사
Abstract
[한글]



[영문]

The main purpose of this study was to evaluate the initial stability in immediate loaded miniscrew implants loaded with different force levels. Two adult Mongrel dogs (12 months) with an initial weight of 29 kg were used in this study. The first two premolars and the 1stmolar were extracted both in the maxilla and mandible bilaterally three months prior to the experiment under general anesthesia. 54 newly designed titanium self tapping miniscrew implants with a diameter of 1.8 mm and a length of 7mm (Ortholution Orlus Seoul,Korea) were implanted in the edentulous areas. The miniscrews were loaded with high and low forced in both the maxilla and the mandible. The miniscrews were immediately loaded with 500g and 200g in the mandible and 300g and 100g in the maxilla with NiTi coil springs. The insertion torque was measured right after implantation. Periotest values (PTV) obtained from the Periotest (Periotest, Siemens, Germany) and the Implant stability Quotient (ISQ) obtained from OstellMentor (IntegrationDiagnostics.AB,Sweden) were measured at time of implantation, and 3 and 6 weeks after implantation. After sacrifice of the dogs, histomorphometrical analysis was performed, bone implant contact and bone bolume measured. The overall failure rate was 16.6 %. There was no significant difference in failure rates between high force (17.9 %) and low force (23.1%) loading groups.The initial stability of the miniscrew implants decreased for all groups in the first 3 weeks after implantation. The initial ISQ values right after implantation decreased significantly after 3 weeks from 44.5 to 41.8 (p<0.05). The Periotest values increased significantly after 3 weeks from 6 to 8 (p< 0.05). High force and Low force loaded groups did not show a significant difference in regard to clinical stability measurements with Resonance Frequency Analysis and Periotest. The histological analysis did not show a significant difference in regard to bone implant contact and bone volume between high force and low force groups.In this animal study, most of the miniscrew failure happened in the first 3 weeks after immediate loading with high and low forces. The initial stability is descreased in the first 3 weeks due to the weakening effects of bone remodeling. High force and low force groups did not show a significant difference both in regard to failure rate,force magnitude, mechanical evaluation and histological evaluation. It is assumed that force is not the primary factor for miniscrew failure and future studies have to evaluate other factors or combinations of factors as reason for miniscrew failure.
Files in This Item:
T011212.pdf Download
Appears in Collections:
2. College of Dentistry (치과대학) > Others (기타) > 3. Dissertation
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/125020
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