Provisional and Temporization Procedure
Rationale for Temporization
Provisional restorations stabilize and protect tooth structure during the time span from final impression through the cementation of a final laboratory-fabricaxted prosthesis. "Temporary" and "provisional" are terms that are synonymous in dentistry. Crown and bridge procedures tend to put a high degree of stress on tooth structure due to the removal of enamel and the exposure of dentinal tubules. A provisional restoration must protect traumatized tooth structure from the rigors of the oral environment until a more permanent restoration is placed without harming the gingiva.
Provisional restorations must provide adequate pulp protection, thermal insulation, marginal integrity, soft tissue compatibility, patient function, space maintenance and adequate esthetics. Generally, a provisional crown or bridge is fabricated by a dentist or dental auxiliary and cemented in place using a temporary crown and bridge cement.
Figure 1. Proximal contacts of natural tooth structure.
A provisional crown or bridge should exhibit good contact with adjacent tooth structure. This will help prevent tooth migration, maintain interproximal tissue health, and keep the proper space maintenance for a final laboratory fabricated crown or bridge (see figure 1).
Figure 2. Occlusal contacts of natural tooth structure.
A provisional restoration must maintain good occlusion and occlusal contact with the opposing dentition. Providing proper occlusal contact keeps opposing teeth from supra-erupting (see figure 2).
Provisional restorations need a smooth surface finish in order to promote good gingival health. The final surface of a temporary crown or bridge should be resistant to plaque build-up and non-irritating to gingival tissue.
Proper Emergence Profile
Figure 3. Proper emergence profile.
The natural shape of tooth structure has many advantages. The proper emergence profile of a tooth deflects food away from the gingival tissue so that natural soft tissues are not harmed by mastication (see figure 3). A provisional restoration must provide adequate function for its duration in a patient's mouth.
Adequate Marginal Seal
Figure 4. Poor marginal contour.
A sound margin between natural tooth structure and any type of restoration is important for many reasons. Eliminating microleakage, minimal plaque retention and promotion of gingival healing are a few of the most important benefits of a good marginal fit. Provisional restorations that are over-contoured (A), or overhang the finish line of the preparation (B), can lead to plaque build-up and consequently, gingival recession. (see figure 4).
Provisional materials are generally classified into two distinct categories. They are prefabricated and chemically-cured materials. Prefabricated materials have become popular over the years because of ease-of-use and time savings. Chemical systems are used widely due to versatility, custom fit and esthetics.
Prefabricated crowns are available in many forms for a variety of single-unit applications. Since 1975, 3M ESPE has been the market leader in prefabricated crowns. Their use has a broad application base from short-term to long-term coverage. Prefabricated temporary crowns are manufactured for the following uses: 3M™ ESPE™ Iso-Form crowns or 3M™ ESPE™ gold anodized crowns for adult molar coverage, and 3M™ ESPE™ polycarbonate crowns for adult anterior use.
3M ESPE offers a full line of prefabricated stainless steel crowns that meet both adult and pediatric patient needs. They are a viable method of single-unit temporization for both short- and long-term coverage.
Chemically-cured systems are generally classified into two distinct categories including acrylics and resins. Within each of these groups there is a further distinction between self-cured, dual-cured and light-cured materials.
These systems are generally considered as improvements over traditional acrylic materials in the areas of reduced volumetric shrinkage, heat generation, taste and odor.
Minimal heat generation
Very good esthetics
Some systems use auto-mix delivery
Can be repaired using composite
A preformed, malleable crown for single posterior units, especially suited for long-term temporization and indications such as implant temporization, digital workflows, and temporaries when no matrix is available.
Acrylic materials have been used for provisional restorations since the late 1930's for both single- and multiple-unit temporary restorations. The appeal of acrylic materials has been their low cost, esthetics and versatility.
Acrylic materials, although versatile and inexpensive, have several undesirable characteristics. Acrylic materials are prepared by mixing a polymeric powder and liquid (monomer) until a honey-like consistency is reached. This takes approximately 30-45 seconds. Acrylics exhibit a strong and objectionable odor to both patients and dental staff. Acrylic materials also give off significant heat during their exothermic setting reaction which could cause pulpal damage if not carefully controlled. In addition, acrylic undergoes significant shrinkage.
Two basic types of acrylic materials with minor variations are sold in today's market. They are polymethyl methacrylate and poly-R' methacrylates. The R' represents either an ethyl, vinyl or an isobutyl functional methacrylate system.
Following is the recommendation for the cementation of 3M™ ESPE™ Prefabricated Crowns:
|3M™ ESPE™ Stainless Steel Crowns
3M™ ESPE™ Unitek™ Stainless Steel Crowns
|RelyX™ Luting Plus and Ketac-Cem™ Cement (releases fluoride and is easy-to-use).
|3M™ ESPE™ Polycarbonate Crowns
|3M™ ESPE™ Iso-Form™ Crowns
||RelyX™ Temp NE Temporary cement
|3M™ ESPE™ Unitek™ Gold Anodized crowns
||RelyX™ Temp E Temporary cement
Protemp™ Plus Temporization Material
Protemp™ Crown Temporization Material
It is recommended to use a non-eugenol temporary cement, as eugenol containing cements may affect the subsequent adhesion of permanent composite resin luting agents.
If a eugenol containing temporary cement is used, clean the preparation with alcohol prior to cementation.
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