Lava Technical Specs >> Marginal Fit >> Marginal Fit Cont.
Marginal fit is an important characteristic that can contribute to
clinical performance. Having said that, the maximum tolerance
needed to prevent damage of the pulp and/or development of
secondary caries by intrusion of bacteria and toxins is still a
matter of debate among researchers.
Nevertheless, the dentist and dental technician need to precisely
control and optimize the fit of the restoration with the respective
production technology used for fabrication. When using CAD/
CAM technology, the fit can be set for each abutment tooth in
the software (e.g., 3M™ ESPE™ Lava™) which customizes the
marginal gap for the clinical situation. The accuracy and ability
of all CAD/CAM technologies to implement the predetermined
fit depends on the accuracy of the entire system from the
scanning device, milling material and milling unit. In the case
of pre-sintered ceramic (e.g. Zirconia), the homogeneity of the
material is especially important as it controls shrinkage during
the final sintering process. The accuracy of the entire CAD/
CAM system is a responsibility of the manufacturers.
Different methods were used in the literature to determine the fit
of a restoration, which made it difficult to compare the various
studies. The first important step was done by Holmes et al1
(1989) who established uniform terminology including marginal
gap, absolute marginal gap, vertical marginal gap, horizontal
marginal gap, as well as over- and under-extension. [fig. 1]
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