Dentistry – Fatigue test for endosseous dental implants

Report No.: 1 ASTRA System Ti Design

Client	NT - Trading
Time of execution	July 2009
Subject of work	- S - 24613 Implant OsseoSpeed® - S - 24285 Abutment Ti Design® - S – 800 Abutment NT-Trading

1. Identification of the endosseous dental implant and its components

: S - 24613 Implant OsseoSpeed

: S - 24285 Abutment TiDesign

: S – 800 Abutment NT-Trading

1.1. Test procedure

The test was performed according to the requirements of the International Standard ISO 14801 "Dentistry – Fatigue test for endosseous dental implants”. The test was set up and computed within an analytical FEA (Finite Element Analysis) tool. The Implant and the abutments which were tested were selected to demonstrate the difference between the two systems.

Schematic diagram of fatigue testing.

The FE Analysis computes the stress distribution inside of a mechanical system, it displays the areas where the material deforms and therefore where it first collapses. Furthermore the Analysis delivers the actual force required for the strain of the system.

The Wöhler curve shows the fatigue behaviour of the material.

: Fig. 1 Wöhler diagram: Ti6Al4V (Titan grade 5)

From the Wöhler diagram, the fatigue limit of the material can be determined, being the maximum stress for which fatigue does not occur even at an infinite number of loading cycles or at the number of cycles, Nf, selected for termination of each test that does not result in failure.

Thus stress distribution, computed from the FE Analysis, may not exceed a certain level that the system endures 5 × 10⁶ cycles. As mentioned above the stresses are induced by a force applied on the system, and as a result you get the value of bearable force for the system.

	S - 24613 Implant OsseoSpeed	S - 24285 Abutment TiDesign	S – 800 Abutment NTTrading
Type of endosseous dental implant body (e.g. threaded, tapered, cylindrical)	screw-shaped implant with a defined surface roughness	-	-
Type of connecting part(s) (e.g. screw-retained, cemented, taper-fit, cylindrical, conical)	-	Conical	Conical
Manufacturer	ASTRA TECH AB P.O. Box 14 SE-431 21 Mölndal, Sweden	ASTRA TECH AB P.O. Box 14 SE-431 21 Mölndal, Sweden	NT Trading
Material(s) of the tested parts, including any coating material(s) and other surface treatments	Commercially pure titanium, grade 5	Commercially pure titanium, grade 5	Commercially pure titanium, grade 5
Diameter and length of the endosseous dental implant body	Diameter: 3,5 mm Length: 13,0 mm	-	-
Diameter and length of the endosseous dental implant body	Diameter: 3,5 mm Length: 13,0 mm	-	-
Geometric dimensions of the connecting part(s)	-	Diameter: 4,5 mm	Diameter:2,0 mm

2. Results

2.1. Maximum endurable load at 5 × 10⁶ cycles or, for tests at frequency of 2 Hz, 2 × 10⁶ cycles (fatigue limit) and Nominal bending moment for the maximum endurable load

	Maximum endurable load	Nominal bending moment for the maximum endurable load	Load where first signs of plastic deformation appears
S - 24613 Implant OsseoSpeed / S - 24285 Abutment TiDesign	278 N	1.53 Nm	449 N
S - 24613 Implant OsseoSpeed / S – 800 Abutment NT-Trading	372 N	1.36 Nm	620 N

2.2. Summary

Due to the shorter configuration of the NT-Trading Abutment, the system with the NT-Trading abutment resists a 34% higher endurable load, than the original system. This caused by the stiffer assembly of the complete system and therefore a decrease in the bending moment by 12%.