(800) 560-6066When a patient needs a crown, a provisional (or temporary) restoration is usually in the cards — unless the office is equipped with a computer-aided design and computer-aided manufacturing (CAD/CAM) setup that can deliver same-day service.
But plenty of practices have yet to make this particular digital leap. In such cases, provisional restorations can fill the gap, playing functional, protective and esthetic roles while the patient waits for the final restoration, which can take a couple of weeks or much longer.1
Dress Rehearsal
Temporary restorations can be useful in treatment planning, and ensuring the patient will be happy with the look and feel of the final restoration. Long-term temporaries can even provide the opportunity for a denture wearer’s musculature and soft tissues to adjust to the new kind of prosthetic.2
From shade matching and contouring, to assuring good functional, facial and phonetic aspects — particularly in full-arch implant cases — provisionals give both patient and dentist a chance to get it right.2
Temporary Materials
Provisional crowns and bridges may be made of prefabricated metal, trimmed to fit each patient. More esthetic temporary materials have included polymethyl methacrylate (PMMA). In common use today are dual-curing bis-acrylic (or bis-acryl) composite resins, said to be popular because of their easy handling characteristics, color stability, and low odor, heat and shrinkage during polymerization.1,3
Provisional crowns may be lab-fabricated (indirect), created chairside (direct), or sometimes a mix of the two. The direct method may employ a variety of techniques, including the use of prefabricated crowns or crown forms. In the latter case, rather than taking an impression, a hollow form is filled with provisional material and positioned onto the prepared tooth.1
Once the material sets, the form and newly formed provisional crown are removed from the tooth and separated prior to final cementation.1 Finishing and polishing is critical, as a polished surface is more esthetically pleasing, easier to keep clean and more comfortable in the mouth. Formulations containing nanoparticles may require less finishing time to attain a high gloss.3 Varnishes that glaze the surface of finished provisionals can eliminate the need for hand polishing.4
Luting Cements
Of course, temporaries don’t stay put through wishful thinking. They must be luted with cements that offer many of the same properties as permanent cement, but with some special characteristics. They should be biocompatible, create good marginal seals and good retention without causing sensitivity. They must also offer easy removal and cleanup.5
The two main categories of temporary cements are zinc-oxide eugenol (ZOE), and noneugenol-containing resin cements. ZOE offers protection against sensitivity, but sometimes causes inflammation, and may interfere with composite resin polymerization.5
Many noneugenol formulations offer easy cleanup, although they may cause sensitivity. Resin-based products are strong, retain well, and are easy to clean up. But they can leak and discolor. Glass ionomers are a favorite among some clinicians due to their fluoride-releasing ability. Newer formulations include one with rubberized urethane chemistry that’s said to improve stability and strength, and another featuring Giomer technology that is fluoride releasing.4,5
Isolation
It’s often prudent when using materials such as resins to keep the area of operation dry and contaminant free. Therefore, an evacuation/isolation system can become a dentist’s best friend. Easy to use, the Isolite systems, featuring protective mouthpieces, can boost office efficiency, freeing up assistants, thanks to hands-free suction and retraction. Add in the bonus of cure-safe illumination, and you’ve got the Isolite 3 — a prescription for restorative excellence.
It’s likely to be a while before every practice is outfitted with CAD/CAM, so the need for provisional restorations is not likely to disappear any time soon. With the right kinds of materials and technologies at hand, dentists won’t mind the wait.
REFERENCES
- Henson N. Fabrication of provisional crowns and bridges. CDE World. Available at: https://cdeworld.com/courses/20908-Fabrication_of_Provisional_Crowns_and_Bridges. Accessed February 25, 2019.
- Steigmann M. A temporary bridge to develop a patient’s smile for fixed maxillary implant restorations. Compend Contin Educ Dent. 2018;39:20–21
- Schwantz JK, Oliveira-Ogliari A, Meereis CT, Leal FB, Ogliari FA, Moraes RR. Characterization of bis-acryl composite resins for provisional restorations. Braz Dent J. 2017;28:354–361.
- Farmer C. Quick fix. Mentor. 2015;6(9):34–37.
- Stone R. Fleeting glory. Mentor. 2013;4(8):24–27,29.
