The Passive Fit Concept- A Review of Methods to Achieve and Evaluate in Multiple Unit Implant Supported Screw Retained Prosthesis

Abstract

Obtaining the most accurate 3-dimensional location of the implant positions, facilitates the fabrication of a prosthesis that, not only conforms to the biomechanics of the rehabilitation in relation to the TM joint and surrounding musculature but also lays minimal stresses imparted onto the implant-bone interface, maximizing the longevity of any prosthetic superstructure. The passive fit concept accentuates the need for this ‘minimal-stress’ interface in order to prevent any mechanical or, biological eventualities while the prosthesis is under masticatory load in the oro-facial environment. A wide horizon of techniques have been studied and devised upon, to achieve this ‘un-eventual fit’ and also methods developed, to assess and evaluate the misfit that the prosthetic superstructure bears in relation to the implants or, the abutments into which they are screwed. This article aims to define the concept, elaborate upon the need of the same and the methods to evaluate them in a clinical and laboratory set-up.