Maintaining provisional volumes in relation to framework design

To achieve the best results in terms of provisional volumes, it is essential to use two techniques such as Matching (digital coupling) via two scans:

1. The digital model representing the finalized provisionals
2. The digital model of the abutments with gingiva

Both steps are fundamental and necessary for the construction of a framework with the suitable characteristics to provide our project with maximum safety regarding mechanical, technical, and aesthetic properties. The great advantage of using zirconia is that it allows us to model dentin-shaped structures (dentin color), as the project’s cut-back provides the correct minimal and calibrated thickness for the enamels (Luster).

Therefore, we can layer small portions of enamel over the reduced structure—a systematic approach we cannot perform on metal frameworks, as the primary focus there is maintaining the necessary space for layering to hide the grayness of the metal and successfully maintaining optimal translucency conditions of at least 1.5. 2 mm for the layering of the aesthetic coating.

To achieve a good framework design, the clinician must have measured the thickness of the finalized provisional, which must be at least 2.5 mm (2.5 provisional thickness – 1.5/2 layering – 0.5 framework). Through these parameters, the clinician can use a correct guide to model the digital structure within the already designed and defined volume of the provisional.

Frameworks for zirconia or metal (framework design) have no design differences, as the principles of retention, support, and compressive zones are identical. The design of a titanium-ceramic framework requires a different design than projects for zirconia-ceramic and metal-ceramic. Titanium is an unstable metal; therefore, the structure must be free of concavities and convexities, as these designs can create stress points that may lead to dangerous chipping during the ceramic application process.