Secure primary stability is positively associated with successful long-term implant integration to ensure a successful clinical outcome. Initial implant stability is defined as biomechanical stability upon insertion, which is influenced by factors such as bone quantity and quality, geometry of the implant, surgical technique, and insertion torque (IT). New bone develops around the surface of the implant and subsequently undergoes biological fixation (secondary implant stability or osseointegration). Insufficient primary stability is associated with micromotions. After the implant is installed, micromotions > 100 μm may influence osseointegration and bone remodeling by inducing the formation of fibrous tissues and bone resorption at the bone-implant interface.

Optimal implant design is required for sufficient primary stability. For example, thread design is critically important to achieving primary stability. The relevant characteristics of the thread that determine its functional surface and distribute the biochemical load are as follows: depth, thickness, pitch, and face and lead angles. Certain manufacturers have developed double- or triple-threaded implants. Compared with single-threaded implants, multiple-threaded implants can be inserted faster. However, finite element analysis (FEA) revealed that a single-lead thread provides maximum primary stability, followed by the double-lead threaded implant. A triple-threaded implant is the least stable. The implant body design can be modified to improve initial stability to increase the success of immediate loading. The thread improves initial stability by maximizing the initial contact area. Further, the thread depth, thread morphology, pitch, and helix angle affect the biomechanical load distribution of the implant. Therefore, commercially available implant systems require better screw designs.

Differences in implant body pitch include an increase in spiral angle with increasing pitch, as represented by multi-threading, and in the pitch itself. To date, however, no studies have used torque or ISQ values that actually reflect the effect of torsion angle and thread compactness on the stability of implants implanted into low bone density bone.