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Effect of cyclic loading on surface morphology of implant screws

Objectives: To analyze the impact of cyclic loading on the integrity of implant/abutment connective screws. Methods: Six types of implant/abutment assemblies were tested: ITI Internal Taper (IT ITI); AstraTech Internal Taper (IT Astra); Sulzer Dental Spline (S SD); Sulzer Dental Internal Hex (IH SD); Nobel Biocare External Hex (EH NB); Steri-Oss Replace Internal connection (IC SO). Screws were numbered and each received an indentation mark in order to compare same surfaces under SEM. For cyclic loading, six assemblies of each implant type were aligned 30-degree off-axis and loaded 1,000,000 cycles to 200 N at 1.6 Hertz. After disassembling changes to both screw thread geometry and surface condition were analyzed. SEM measurements were verified by optical microscope with calibrated reticle.

Results:

 

Implant

assembly

type

 

# of

threads

Distance between first two threads (micrometers)

 

Change

Thread condition after cyclic loading

before cyclic

loading (SD)

after cyclic

loading (SD)

IT ITI

    5

  366     (7)

 380      (32)

   3,7%

flattened

IT Astra

    6

  387     (0)

 377      (0)

   2    %

smoothed

S   SD

    6

  330     (36)

 360      (10)

   9   %

scratched

IH SD

    6

  283     (32)

 319      (45)

   13 %

scratched

EH NB

    6

  291     (38)

 398      (22)

   37 %

scratched

IC SO

    8

  398     (23)

 265      (23)

   67  %

 

pealed coating

No change to thread spacing was observed beyond the 3rd thread except for IC SO were all threads showed changes.

Conclusions: IT connection screws were the least affected by cyclic loading. Flat interface designs showed more thread deformation. The degree of screw deformation is most likely related to assembly design.


Division: IADR/AADR/CADR General Session
Meeting: 2004 IADR/AADR/CADR General Session (Honolulu, Hawaii)
Location: Honolulu, Hawaii
Year: 2004
Final Presentation ID: 92
Abstract Category|Abstract Category(s): Implantology Research
Authors
  • Butkevica, Alena  ( Boston University, Boston, MA, USA )
  • Nathanson, Dan  ( Boston University, , , USA )
  • Pober, Richard  ( Boston University, Boston, MA, USA )
    • SESSION INFORMATION
    Oral Session
    Mechanical Implant Studies
    03/10/2004