The greater the potential inaccuracies between the structure of the bridge and the implants, the greater the tension on the implants caused by these inaccuracies.The load on the implants is greater the longer the distal extension of the suprastructure.The load on the implants in extended suprastructures is greater the small the distance between the anterior and the posterior implants. A length ratio of 1:2 or 1:3 between the clinical crown and the implant is ideal for reducing flexion. Primary or secondary attachment of more than 3 implants to a polygon can reduce extra-axial loading.
The implant/Crown length ratio is important if non-axial force are applied.The load on the implants of an implant-supported bridge structure is the stronger the larger the distance between the anterior and the posterior implant. Flexion force on implants can be reduced through a reduction of the occlusal surface and a favourable crown/implant length ratio.