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Written by Ara Nazarian, DDS Thursday, 02 June 2011 17:50
In my practice, we have seen many baby boomers presenting with large amalgam restorations with either failing margins or fractured portions of tooth and restoration. Most of these patients have had these restorations in their mouths for more than 15 to 20 years with no problems; however, due to stress, wear, size, caries, or fatigue, these teeth are splitting and losing cusps. Because of this, full-coverage crowns continue to be accomplished in significant numbers, and it does not appear that this trend will decline. Many of these teeth being restored require endodontic therapy as a part of the tooth preparation or due to pain. In addition, post-and-core buildups are very often necessary in these teeth.
This article focuses on utilizing new materials and methods to accomplish these procedures in a quick and effective manner.
Diagnosis and Treatment Planning
A patient presented with discomfort in the lower right region of her mouth. Upon clinical examination, it was evident that tooth No. 28 had a large previously placed amalgam restoration that had fractured off and also presented with recurrent caries (Figure 1). The radiograph exhibited the extent of the decay; it had extended into the pulpal area, and a periapical radiolucency was also observed. The patient complained of constant throbbing pain.
|Figure 1. Photo showing the preoperative condition of tooth No. 28.||Figure 2. A DemoDent (demo-dent.com) patient education model used to educate patients about their specific condition and treatment options.|
|Figure 3. Endodontics using Twisted Files (SybronEndo).||Figure 4. Matrix band applied.|
Once I captured the images of the failing amalgam restoration on the monitor, I asked a series of questions. "Mrs. Smith, how long ago was the amalgam filling done?" The patient answered that it was hard to remember exactly, but she thought it was placed more than 20 years ago. Using the DemoDent (demo-dent.com) patient education model (Figure 2), I then described the portion illustrating what can happen to a tooth when a restoration starts to fail. "Mrs. Smith, nothing lasts forever, especially when it is subject to the harsh conditions in the mouth…for example, hot and cold, biting forces, chewing, and constant acidic changes. It appears that your filling had cracked at some point, allowing bacteria to leak underneath the filling. Over time, this severely damaged the nerve in your tooth and that is the reason you are now having pain. Often, the damage is not seen or felt right away because there are no major symptoms until the decay reaches the nerve of the tooth. Since there is little tooth structure remaining, the tooth will need a core buildup and a crown to restore it to proper form and function after a root canal procedure is done." After explaining the situation using the image on the screen and the anatomical model, I have found that patients seem to understand their dental condition better. The patient elected to have the root canal and core and crown preparation performed in one visit.
Prior to the administration of a local anesthesia, shade selection was done (A1) and an estimated working length was determined from the preoperative radiograph. After anesthetic was administered (1.8 mL 4% Septocaine [Septodont]) with 1:100,000 epinephrine, a carbide bur (H31 [KOMET USA]) was used to remove all the caries and to access the pulp chamber. The access opening was widened utilizing an endo-safe bur (H269GK [KOMET USA]) in order to achieve straight-line access. The preparations were extended to clearly visualize the canals bucco-lingually. Using a No. 15 K-File (SybronEndo), the canals were identified and a working length was established.
Rotating at 500 rpm, a .08/25 Twisted File (TF) (SybronEndo) was inserted approximately 3 to 5 mm into the canal orifices, brushing up and away from the orifice (Figure 3). This was done to brush away the cervical dentinal debris and to allow greater volumes of irrigant into the canals as rapidly as possible. "TFs are created by twisting nickel titanium in the rhombohedral crystalline phase configuration, an intermediate crystalline phase configuration between austenite (nickel titanium at rest) and martensite (nickel titanium under stress). In other words, the file does not have the scratches and machining marks of nickel titanium files resulting from manufacturing that uses a grinding process. This is noteworthy because these machining marks become the focus of cyclic fatigue and torsional stresses that might otherwise fracture the file. As a result of its manufacturing process, TF can be used in many roots (approximately 75%) to shape the basic preparation to a .08 taper in 2 to 4 insertions without the use of rotary nickel titanium orifice openers or other instruments such as Gates Glidden drills."1
|Figure 5. Core material (Build-It Light Cure Core [Pentron Clinical]) is syringed into the tooth.||Figure 6. Light-curing the core with an LED curing light (Demi Plus Curing Light [Kerr]).|
|Figure 7. Tissue management was accomplished with gingival retraction paste (Expasyl [Kerr]) before using a dual-arch tray (Exacta Dental) to take the final impression with a fast setting impression material (Correct Plus [Pentron Clinical]).||Figure 8. The completed all-ceramic crown (Lava [3M ESPE]).|
After withdrawal, the canal was irrigated with 5.25% sodium hypochlorite, recapitulated, and then a .06/25 TF was reinserted. Once complete, the smear layer was cleared with a 2-minute soaking of a liquid 17% EDTA solution. Distilled water was used to flush the 17% EDTA solution out of the canal and then it was dried with paper points.
RealSeal (SybronEndo) was the material used for obturation in this case. This material was utilized exactly as gutta-percha; it is available both in a master cone-based form and in obturator-based form. A thin coat of sealer was applied to the walls of the canal and then the master cone was placed to length.
Once tooth No. 28 was isolated by the matrix band (Figure 4), it was dried and a seventh-generation adhesive (Bond 1 SF [Pentron Clinical]) was applied for 20 seconds to all internal aspects of the preparation, including the cavosurface margins. The solution was gently agitated with a regular microbrush applicator tip (Microbrush). Another layer of bond was placed and dried, then cured for 20 seconds with an LED curing light (Demi Plus Curing Light [Kerr]). In order to achieve a coronal seal and to wet the tooth surface, a flowable resin (Flow-It ALC [Pentron Clinical]) (shade A-1) was placed as the initial layer of composite resin material.
Core material (Build-It Light Cure [Pentron Clinical] was syringed directly into the preparation (Figure 5) and adapted with a small composite instrument (Dental USA). It was then light-cured prior to bulk-filling the preparation. The tooth was then filled and sculpted to full contour in a single increment and light-cured for 20 seconds (Figure 6). I chose this core material due to its physical properties, handling characteristics, and its ability to easily adapt to the residual tooth structure using a composite instrument. "Build-It Light Cure is a bisphenol A-free composite resin material specifically formulated to permit a depth of cure of up to 10 mm and to have ideal handling properties to permit bulk adaptation to both vital core preparations and endodontic posts, without stickiness or voids. It comes in a single chameleon-like, radiopaque, translucent shade that optically mimics the surrounding residual tooth structure and does not negatively affect the final shade of even the most translucent ceramic system."2
Using a coarse grit diamond bur (5878K [KOMET USA]), the tooth was prepared for an all-ceramic (zirconium oxide) crown (Lava [3M ESPE]). Utilizing Expasyl (Kerr) for tissue management prior to taking the impression, we not only controlled hemorrhaging, but also achieved gingival retraction (Figure 7). After approximately 2 minutes in the sulcus, the Expasyl paste was rinsed off with copious amounts of water. Utilizing a dual-arch tray (Exacta Dental) and a fast set impression material (Correct Plus [Pentron Clinical]), an impression was taken for the final restoration. Since the tooth was severely broken down, a preoperative impression was not utilized for the fabrication of a provisional. Instead, a prefabricated moldable composite temporary crown (Protemp [3M ESPE]) was used to make the provisional and seated with temporary cement (Tempspan Transparent Temporary Cement [Pentron Clinical]).
Two weeks later, the patient retuned for placement of the all-ceramic crown. The provisional restoration was removed and the preparation was inspected for final cementation. After a bite-wing radiograph was taken to confirm full seating and fit of the crown, and the contacts and margins verified, the crown restoration was cemented using an appropriate dual-cured resin cement (Cement-It Universal C&B [Pentron Clinical]).
The patient was very pleased with the restoration of tooth No. 28 (Figure 8) and was eager to start treatment on her remaining teeth that had similar failing restorations.
This case demonstrates very well how one can achieve an acceptable aesthetic result. Using modern materials and techniques, the clinician can efficiently and effectively accomplish multiple services within one appointment. With patients' schedules getting more and more hectic, it is essential to minimize the number of appointments for them while delivering a great service.
Dr. Nazarian would like to thank the talented dental laboratory team at Burbank Dental Lab (Burbank, Calif) for the technical work done in this case.
- Mounce RE. Shaping root canal systems: a "real world" case. Dent Today. Nov 2010;29:138-146.
- Blank JT. Restoring severely compromised teeth with a core build-up. Inside Dentistry. Nov 2010;6(10):111-114.
Dr. Nazarian maintains a private practice in Troy, Mich, with an emphasis on comprehensive and restorative care. He is a Diplomate in the International Congress of Oral Implantologists. His articles have been published in many of today's popular dental publications. Dr. Nazarian is the director of the Reconstructive Dentistry Institute in Michigan, where general dentists have the opportunity to train in the various services necessary to rebuild a dentition to proper form and function. He has conducted lectures and hands-on workshops on aesthetic materials and dental implants throughout the United States, Europe, New Zealand and Australia. Dr. Nazarian is also the creator of the DemoDent patient education model system. He can be reached at (248) 457-0500 or at aranazariandds.com.
Disclosure: Dr. Nazarian is the creator and owner of the DemoDent patient education model system and has a financial interest in this product.
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