- There are a number of recent studies aimed to evaluate the effect of different mechanical parameters especially implant thread design on the primary stability of dental implants in different bone densities and qualities.
- We all know that, the success of the surgery is achieved by the synergistic combination of mechanical stability and biological safety factors. Here, we are interested to focus on the mechanical parameters. From the mechanical aspects of the view, macro-design parameters are mainly classified in the following items such as:
- • Thread shape (profile type and shape),
- • Thread width, pitch and depth,
- • Apical and #coronal face angles, thread helix angle,
- • Inner, outer and main diameters,
- • other mechanical factors (having double-threading,
micro-thread, cutting edge, ... ).
• This classification considers almost all of the affecting parameters in the mechanical stability. Considering that each dental implant system has a range of products in different sizes (As an example #AvitaDentalSystem has 22 fixture sizes), the general format of thread shape does not change much in sizes, but there might be some changes in the thread width in the length from apical to coronal direction.
• From the experimental points of the view, standards ask experts to use the weakest size in mechanical tests. We have ISO14801:2016 for static, fatigue and torsion tests of the assembly. ISO/TR18130:2016 is also used for the screw loosening of the assembly. There are also two torques that needs to be measured while opening the screw (before and after #fatigue test).
• Geometrical parameters are significant to optimize:
• 1- Stress_distribution (which is an important factor and can be evaluated through finite element analysis tools of ANSYS, ABAQUS, COMSOL, ...),
• 2- Implant surface area (to achieve higher surface for bone connection and consequently higher resisting torque which comes from roughness),
• 3- Bone remodeling responses during the process of osseointegration.