Abstract
Statement of problem
Internal conical connections have become the primary choice for implant-supported
restorations. However, studies that identified the risk indicators for mechanical
complications and diagnosed the prognosis of the implant-supported restorations are
lacking.
Purpose
The purpose of this retrospective clinical study was to evaluate the incidence and
consequences of mechanical complications in components of internal conical connection
implants and to analyze the risk indicators.
Material and methods
A total of 428 patients with 898 internal conical connection implants were included
in the study, and mechanical complications over the 14-year observation period were
evaluated. The Cox proportional hazard regression model was used to analyze significant
effects on mechanical complications, which were presented as hazard ratio and 95%
confidence interval.
Results
Mechanical complications occurred in 430 (47.9%) implants and 248 (57.9%) patients:
screw loosening (46.4% of implants, 56.8% of patients); screw fracture (2.6% of implants,
4.4% of patients); abutment fracture (11.4% of implants, 21.3% of patients); and implant
fracture (3.5% of implants, 5.4% of patients). Implant restorations replacing molars
showed the highest risk for mechanical complication (hazard ratio 12.82; 95% confidence
interval 2.73-60.31) and for fracture of all components. Men had a higher risk of
mechanical complication than women (hazard ratio 2.00; 95% confidence interval 1.55-2.59),
and the risk of fracture was higher in all components. With increased splinted implants,
the risk of mechanical complication (hazard ratio 0.67; 95% confidence interval 0.49-0.93)
and component fracture (hazard ratio 0.73; 95% confidence interval 0.29-0.89) decreased.
Gold screws had a lower risk of screw loosening (hazard ratio 0.74; 95% confidence
interval 0.58-0.94) than titanium screws, but a higher risk of fracture (hazard ratio
3.45; 95% confidence interval 1.42-8.36). The smaller the implant diameter, the higher
the risk of implant fracture (hazard ratio 0.01; 95% confidence interval 0.00-0.05).
Conclusions
Abutments were most frequently fractured among the components of internal conical
connection type implants. Molar implant-supported restorations and male patients had
higher risks of mechanical complications, and as the number of splinted implants in
a prosthesis increased, the risk decreased. Gold screws showed less risk of screw
loosening and higher risk of fracture than titanium screws. Narrow-diameter implants
had a higher risk of fracture.
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Article info
Publication history
Published online: September 01, 2021
Footnotes
Supported by the Korea Medical Device Development Fund grant funded by the Korea government (the Ministry of Science and ICT, the Ministry of Trade, Industry and Energy, the Ministry of Health & Welfare, Republic of Korea, the Ministry of Food and Drug Safety) (Project Number: 202011A02).
Identification
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© 2021 by the Editorial Council for the Journal of Prosthetic Dentistry.
