MARCO REDEMAGNI*, CARLO MAIORANA (University of Milan, Chair of Odontostomatology I, Director: Prof. F. Santoro)
The precise marginal adaptation of a fixed prosthetic restoration at the abutments minimizes the intraoral exposure of the cement materials, consequently reducing the possible plaque accumulation and infiltration phenomenons.
Among the principal factors able to influence the prosthetic marginal adaptation a correct impression technique, investment material and metal deformation successive to the thermic cycle have to be found. Every time a fused structure is submitted to a thermic cycle, bringing it at a temperature near to its fusion point, some alteration at its crystalline structure leading to its deformation can happen. By this way, more than for the presence of many other advantages, usually it' s preferable the use of a prosthetic solution as monofusion bridges, avoiding soldering, achieving rigidity and reducing prosthetic realization time.
Many Authors, on the contrary, support to obtain a better marginal fit using soldering, because they reduce the distortion present in a monofusion.
Many studies, by various Authors, exist in literature about the difference of the achievable marginal precision using or monofusion or primary soldering bridges with, at time, opposing results. In this study we have been evaluating the marginal fit of bridges of three and four elements obtained by monofusion and by primary soldering noting that a monofusion bridge has a good marginal adaptation only with three elements while the primary soldering bridges have always a good marginal adaptation apart from the number of elements.