In this chapter:
■ Direct provisionals
■ Eggshell provisionals
■ CAD/CAM provisionals
On the one hand, provisional restorations protect the abutment teeth from thermal, chemical, and bacterial irritations3–5, while on the other they maintain the mesiodistal and coronoapical position of the prepared abutment teeth6 (Fig 1-7-1). But, most importantly, they are an important means for the communication of the treatment goal and for the trial of the planned tooth shape, position, and function before final restoration.
Different types of provisionals exist. In the following the most relevant fixed provisionals will be discussed and compared: the direct provisionals, the eggshell provisionals and, finally, the more recent computer-aided design and computer-aided manufacturing (CAD/CAM) provisionals, illustrated by a clinical case example (Fig 1-7-1).
The direct provisionals can either be fabricated as a copy of the pre-existing dental situation, or as a copy of the diagnostic wax-up. They are manually fabricated in the dental office after the preparation of the abutment teeth, using a silicone index to deliver the shape. The direct provisionals are fabricated out of self-polymerizing polymethylmethacrylate (PMMA) or composite resins, which polymerize intraorally (Fig 1-7-2).
The advantage of the direct provisionals is that they are fabricated fast and easily and do not cost very much. One downside is that both the clinician as well as the patient come into contact with not yet polymerized monomers, which can cause allergic reactions in susceptible people. Another downside may be the esthetic outcome. The provisional resins for the direct provisional restorations are rather monochromatic and direct provisionals may not fulfill highest esthetic demands2,7,8.