In this chapter:
■ Direct provisionals
■ Eggshell provisionals
■ CAD/CAM provisionals
Provisional restorations play an important role for the rehabilitation of patients with fixed restorations1,2.
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.
Fig 1-7-1 Abutment tooth preparations for full crown restorations, prior to provisionalization.
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).
Figs 1-7-2a and 1-7-2b Direct provisionals made out of a self-curing composite provisional resin (Protemp).
Fig 1-7-2c Inserted provisionals; note the transparency of the resin. As the initial situation was used for fabrication of the provisionals, and not the diagnostic wax-up where a change in shape and position was foreseen for the final restorations, the provisional crown 21 was very thin and the abutment tooth was shining through, leading to esthetic limitations.
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.
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