Written by Robert C. Margeas, DDS Wednesday, 28 February 2007 19:00
When a patient presents with a fractured cusp of a tooth, along with a large preexisting restoration, we must decide how to properly restore the tooth to ideal function. What type of restoration or buildup should we use? Amalgam is still taught as an ideal material for crown buildups in leading dental schools, with satisfactory results. The ability to bond to dentin and enamel has led to the development of light-cure and dual-cure composite materials. Are pins needed as an adjunct to retain buildups? For the last several years, dental schools and lecturers have tried to move away from pins in dentistry. They advocate slots, grooves, potholes, and dentin bonding agents to retain the core build-up material. However, when done properly, pins are still a viable option in our restorative armamentarium.
Temporization is also a challenge for the practitioner. Prefabricated metal crowns, polycarbonate crowns, methyl-methacrylate powder and liquid, and bis-acryl materials can all be used with success. The newest material to be introduced is Protemp Crown Temporization Material (3M ESPE). It is the first preformed, malleable, composite temporary crown. This new material allows you to trim and adapt the crown to the abutments and contacts, then simply light-cure and polish.
The following case study will show the step-by-step restoration of a fractured bicuspid using the newest temporary material to be used for provisionalization of single crowns.
Figure 1. Fractured lingual cusp.
Figure 2. Amalgam shine-through.
Figure 3. Titanium pin placed.
Figure 4. Injection of CosmeCore dual-cure composite material.
Figure 5. Core buildup after removal of matrix band.
Figure 6. Tissue Goo Hemostatic Gel injected around the sulcus.
Figure 7. Preparation after hemostasis is achieved.
Figure 8. Patient closing into metal Quad-Tray.
Figure 9. Detail of final impression.
The patient presented to the office with a previously placed large amalgam restoration and a lingual cusp fracture on tooth No. 13 (Figure 1). The patient did not like the grayness of the tooth due to amalgam shine-through (Figure 2).
The large amalgam was removed, along with recurrent decay, using a Brasseler bur. The fracture occurred horizontally about 1 mm above the free gingival margin. The facial cusp was solid, but thin. If the fracture had occurred more subgingivally, crown lengthening would have been necessary to avoid biologic width violation on the lingual aspect. It was possible to achieve a 2-mm ferrule on good tooth structure by taking the preparation 1 mm sub-gingival. This is important to retain the restoration adequately without performing endodontic therapy and a post and core procedure.
A titanium pin (Coltène/Whaledent) was placed where the missing cusp was fractured (Figure 3). This was done very carefully using an electric slow-speed latch-type handpiece with the speed reduced to a minimum; this will allow the pinhole to be placed without chattering or crazing the tooth structure. The pin is placed using the electric handpiece with minimum speed and maximum torque; this will allow the pin to shear off and be very stable. Pins weaken tooth structure, but the technique de-scribed will allow you to achieve excellent results on a predictable basis. I have used this technique successfully for more than 10 years, but only with electric handpieces. It has allowed me to prevent elective endodontic therapy when there is not enough tooth structure for crown retention.
The tooth was etched with Ultra-Etch (Ultradent Products) for 20 seconds, and a fourth-generation bonding agent (All-Bond 2 [Bisco]) was applied in numerous coats and light-cured. I believe in clinical practice it is best to use a fourth-generation bonding agent when utilizing a self-cure or dual-cure build-up material. A self-mixing, dual-cure composite core material (CosmeCore [Cosmedent]) was injected into the preparation and light-cured for 40 seconds (Figure 4). The blue material allows easy differentiation from tooth structure. The matrix was removed, and the core buildup is shown in Figure 5.
The tooth was prepared with a Brasseler diamond bur (8850-016), and a flame-shaped bur was used to bevel the preparation. This will allow us to utilize maximum tooth structure for strength.
Due to tissue bleeding, retraction was achieved using an epinephrine-impregnated cord (Siltrax No. 7 [Pascal]) that was dipped in Hemodent (Premier). This allows some of the racemic epinephrine in the cord to be diluted. Tissue Goo (CLINICIAN’S CHOICE), a gel that can be used as an additional hemostatic agent when necessary, was placed over the cord (Figure 6). Once hemostasis was achieved (Figure 7), the impression was ready to be made. The cord was removed, and light-body Af-finity (CLINICIAN’S CHOICE) was injected around the tooth twice, without removing the tip from the sulcus. This was then lightly air-thinned, and more material was injected. The metal Quad-Tray (CLINICIAN’S CHOICE) was loaded with Inflex (CLINICIAN’S CHOICE) and placed over the light-body. The patient was instructed to close into maximum intercuspation, and the material was allowed to set for approximately 3 minutes (Figure 8). The final impression showed excellent detail of the preparation (Figure 9).
The temporary crown was now ready to be fabricated. 3M ESPE recently introduced the new temporary composite crown material called Protemp Crown. This is a light-cured methacrylate com-posite crown that is designed for short-term restoration of teeth prepared for full crowns. The material is soft and malleable, therefore you can use your fingertips or dental instruments to adapt the crown to the margins and proximal contacts. The patient can bite down into the crown to form the occlusal contacts. Additional contouring or occlusal anatomy can be easily added. Once the contacts and desired anatomy are achieved, the crown is tack-cured in the mouth to hold the shape, and removed for final curing and polishing.
The material and technique allow for a greatly simplified temporization procedure. It is a fast technique that does not require a separate impression or matrix, and is less messy than conventional acrylic or resin-based systems. Additional features: Protemp Crown is available in one universal shade and 9 sizes for single-unit posterior (molar, bicuspid, and cuspid) temporization. It has excellent overall mechanical properties and wear resistance. The methacrylate resin-based material allows for easy characterization or repair with conventional composite stains or flowable composites.
BASIC TEMPORIZATION TECHNIQUE
Figure 10. Protemp Crown in protective liner.
Figure 11. Protemp Crown being placed on preparation.
Figure 12. Protemp Crown adapted with composite instrument.
Figure 13. Occlusal view of Protemp Crown.
Figure 14. Facial view of cemented Protemp Crown.
(1) Using the provided (disposable) measuring tool or caliper, the mesial-distal width of the prepared space is measured to determine the proper temporary crown size.
(2) Select the proper size and remove the preformed composite crown from the package (Figure 10). Remove the liner from the crown. Once removed from the package, the crown can be lightly rolled in the fingers to warm it and increase malleability.
(3) Measure the approximate height from the margins to the occlusal surface of the prepared tooth. Trim the gingival contour of the temporary crown to provide the proper crown height.
(4) Seat the crown onto the abutment (Figure 11) and adapt the crown margins with your finger or a composite instrument (Figure 12). The proximal contacts will be established in this method.
(5) Have the patient bite into the crown to form the occlusal contacts. With the patient closed, further adapt the buccal margin with the instrument. Once adapted, tack-cure the buccal surface for 2 to 3 seconds.
(6) Have the patient open, and while holding the adapted buccal surface, adapt the lingual margin with an instrument. Once adapted, tackcure the lingual surface and the occlusal surface for 2 to 3 seconds.
(7) Carefully remove the crown and light-cure, outside of the mouth, for 60 seconds.
(8) Finish and trim the crown as necessary.
(9) Polish the crown.
(10) Seat with desired temporary cement. The final temporary restoration in this case is seen in Figures 13 and 14.
Note: Relining the crown prior to cementation is not needed, but can be done if desired. The Protemp Crown has a high degree of aesthetics and polish, but if an additional resin glaze or characterization is desired, it can be done with conventional meth-acrylate-based materials.
Disclosure: The author is the developer of CosmeCore.
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