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An in vivo quantitative analysis of the fit of Nobel Biocare implant superstructures
Author(s) -
CHESHIRE P.D.,
HOBKIRK J.A.
Publication year - 1996
Publication title -
journal of oral rehabilitation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 93
eISSN - 1365-2842
pISSN - 0305-182X
DOI - 10.1046/j.1365-2842.1996.d01-193.x
Subject(s) - abutment , implant , materials science , osseointegration , superstructure , orthodontics , biomedical engineering , dentistry , medicine , structural engineering , surgery , engineering
Loss of osseointegration of implant fixtures and mechanical failure of superstructures have been attributed to failure to achieve a passive fit between the superstructure and the transmucosal abutment (TMA). The fit of five mandibular superstructures, fabricated on Nobel Biocare implants, was investigated in vivo , using a polyvinyl siloxane impression material to record the discrepancies. Following sectioning of the impressions, the vertical and horizontal discrepancies were analysed at four locations using a travelling microscope. The discrepancies obtained were measured both when the gold cylinder screws were maximally tightened by hand and when tightened with a torque driver to the recommended value of 10 Ncm. The vertical discrepancies for the hand tightened abutments ranged from 0 μm to 63 μm with a mean of 14 μm. In the mechanically tightened group, the vertical discrepancies ranged from 0 μm to 130 μm with a mean of 21 μm. The horizontal discrepancies for the mechanically tightened abutments ranged from 0 μm to 140 μm with a mean of 31 μm, compared with a mean of 46 μm and range of 0 μm to 113 μm, for the hand‐tightened abutments. A close fit was seldom achieved. It is concluded that considerable discrepancies existed around superstructures that had been judged to have a clinically acceptable fit. These were reduced in the vertical direction by hand tightening of the gold screws.