Written by Andrew M. Spector, DMD, FAGD, FICOI Tuesday, 31 December 2002 19:00
Over the years there has been a persistent frustration in diagnostic restorative dentistry that has left practitioners unsure regarding when to initiate treatment. Radiographic evidence of decay occurs only after a significant 30% decalcification of tooth structure.1 Further, with the advent of fluoridation, surface enamel can be impervious to our traditional dental explorers, hiding decay from diagnosis. From a radiographic perspective, large, old amalgam restorations block our view of buccal and lingual areas. Digital x-rays, as large as they are, lack the resolution of traditional film.2 Thus, we are left with a “diagnostic void” between the clinical and radiographic diagnosis of decay. In addition to the need to close this diagnostic void, patient demands for conservative, aesthetic restorative dentistry delivered in an efficient, time-saving manner have created the need for technology that can meet these demands.
Technologies are currently available that address such needs. This article reviews the merging of two technologies in a case report that combines modern caries diagnosis with conservative, aesthetic restorative dentistry provided in an efficient manner.
The diagnostic technology used in this case report is called Digital Fiber Optic TransIllumination or DIFOTI (EOS, DIFOTI) (Figures 1 and 2). DIFOTI has marketing approval from the FDA for the detection of incipient, frank, and recurrent caries. It safely and instantly creates high-resolution digital images of occlusal, interproximal, and smooth surfaces, and enables dentists to discover or confirm the presence of decay that cannot be seen radiographically, visually, or through use of an explorer3 (Figures 3 through 5).
|Figure 1. The DIFOTI transillumination device.||Figure 2. The DIFOTI transillumination handpiece in position.|
|Figure 3. Clinical view of tooth No. 13.||Figure 4. Radiographic examination of tooth No. 13.|
|Figure 5. DIFOTI occlusal image. Black area reveals recurrent decay under the buccal cusp. The lingual margin of the amalgam is relatively clean.||Figure 6. The Sirona CEREC 3 Restorative System.|
The second technology used in this case is the CAD/CAM system Cerec 3 (Sirona) (Figure 6), which currently is capable of milling porcelain or polyceramic restorations chairside to provide a single-visit solution in restorative dentistry that was unimaginable just 12 years ago.
|Figure 7. Radiographic examination of tooth No. 29.||Figure 8. Completed DIFOTI examination.|
A 40-year-old female presented to the hygiene department for a routine prophylaxis and examination. Four bite-wing radiographs were taken. Upon clinical and radiographic examination some significant areas of decay were found (Figure 7). A DIFOTI transillumination examination was performed to confirm and illuminate hidden decay. The patient was seated, and the disposable CCD camera tip was placed on the handpiece. The DIFOTI software was activated. The patient’s name was entered and the “take picture” icon was activated. Using foot pedal activation, occlusal images of numerous teeth were acquired to illuminate decay hiding under cuspal areas (Figure 8). The entire process was completed in 2 to 3 minutes.
Upon examination of the transillumination images recurrent decay was confirmed under cuspal areas of teeth Nos. 4, 13, 14, 15, and 29. A Cerec onlay, milled from ProCad material (Ivoclar Vivadent), was chosen to restore tooth No. 29 (Figure 9). The restoration was chosen to maximize conservation of enamel, eliminate polymerization shrinkage, be kind to the periodontium, and yield a single-visit restoration with enamel-like properties. Cerec restorations can be milled from three different blocks: ProCad, leucite-reinforced porcelain; Vita (Vident), a compressed feldspathic porcelain; or Paradigm (3M ESPE), a polyceramic material. Cerec blocks have similar strength, wear rates, and coefficients of thermal expansion to that of enamel.4
|Figure 9. DIFOTI occlusal image of tooth No. 29. Note gray recurrent decay under buccal and lingual cusps.||Figure 10. Preoperative view of tooth No. 29.|
|Figure 11. Tooth No. 29 after amalgam removal revealing gross decay.||Figure 12. Final preparation of tooth No. 29 MOD.|
The patient presented for treatment and was anesthetized using one carpule of 4% septocaine 1:100,000. A preoperative intraoral camera picture was taken (Figure 10). The defective amalgam restoration was removed using a pear-shaped inverted-cone 330 carbide bur. Evaluation of the inner wall of the defect clearly showed the decay detected by DIFOTI. A defect intraoral camera picture was taken (Figure 11). The decay was removed and the tooth was prepared using the Cerec Prep and Glaze bur system (AXIS Dental). The Cerec preparation is a very simple derivation of traditional onlay technique. It is a gold onlay preparation with 0° to 15° taper and no bevels. Because the Cerec camera “automatically“ blocks out undercuts, an alternative preparation is to leave the occlusal undercut (preserving cuspal enamel) and have the proximal boxes taper 0° to 15°, again leaving the cavosurface margin butt joint. This technique is a true breakthrough as it allows for the most conservative onlay preparation possible. Cuspal areas are reduced 2 mm as needed. They should be smooth with no sharp peaks. A final preparation intraoral camera picture was taken (Figure 12). The patient was now ready for fabrication of the Cerec CAD/CAM restoration.
As with any restorative dentistry there are fundamental goals we seek to achieve to obtain a successful result. For a bonded restoration we need isolation and perfected technique. For successful crown and bridge we need to refine our retraction and impression technique. There are three key fundamentals that need to be achieved when fabricating a Cerec restoration, called the “3 p’s” (Prep [described above], Powder, and Picture).
The Cerec Powdering technique can be compared with tissue retraction in traditional crown and bridge. When we take a silicone-style impression we need the material to wet and “see” the whole tooth, thus capturing the extent of our margins. In Cerec dentistry we need the camera, which replaces our impression material, to “see” the surface of the tooth. We achieve this with a process called Powdering. The Cerec camera acquires an image by reading the tooth’s surface with an infrared beam; if the beam penetrates below the enamel surface it can give us an inaccurate scan. A light layer of reflective powder sprayed on top of the tooth ensures an accurate scan and a superior restoration.
The Cerec Picture is a simple process that patients truly appreciate because they do not have to tolerate any impression material. After activation of the camera with the unit’s foot pedal, a live digital image of the tooth appears on the screen. The preparation is centered in the middle of the screen. After visualizing the path of draw and defined gingival margins, we release our foot and the image is acquired. A restoration can now be fabricated. After a short learning curve, designing a Cerec onlay or crown should take no more than 3 to 5 minutes; the milling time will vary from 5 minutes for a simple onlay to 14 minutes for a larger crown. The restoration can be highly polished or glazed.
|Figure 13. Preparation and adjacent teeth after application of reflective powder.||Figure 14. Cerec 3 optical impression.|
|Figure 15. ProCad leucite-reinforced porcelain block (Ivoclar Empress family) being inserted into Cerec 3 milling chamber.||Figure 16. Milled restoration of tooth No. 29 MOD.|
The lower right quadrant was isolated using cotton rolls and high-speed evacuation. Two pieces of gingival retraction cord were placed in the proximal box areas (Figure 12), one to be removed after powdering and one left in through cementation. ProCad liquid adhesive was painted on the preparation and adjacent teeth to facilitate adherence of the reflective powder. After air blowing the adhesive to a thin layer the tooth was powdered using an aerosol can delivery device (Figure 13). An optical impression was acquired (Figure 14). The restoration was designed using the Cerec 3 software, and a ProCad block was placed in the milling chamber (Figure 15). Nine minutes later the restoration was completely fabricated (Figure 16).
|Figure 17. Initial try-in of tooth No. 29 Cerec restoration.||Figure 18. Matrix band in place prior to cementation.|
|Figure 19. Final Cerec restoration tooth No. 29 MOD. Note previously completed Cerec restoration of tooth No. 28 DO.|
The restoration was tried in. Contacts and seat were verified (Figure 17). The restoration was etched with hydrofluoric acid for 60 seconds, silanated, and properly wetted. A tofflemire matrix band was placed around the tooth for isolation and wedged (Figure 18). Clearfill Bond Liner 2V (Kuraray), a dual-cure self-etching bonding agent, was used. A and B Self-Etching dentin primer and dual-cure catalyst were mixed. After placement on the tooth for 30 seconds it was dried to a thin layer. The A enamel adhesive and B dual-cure catalyst were mixed, and enamel was placed and blown dry. Variolink (Ivoclar Vivadent) dual-cure cement was mixed and loaded into a syringe (Centrix). After filling the preparation the onlay was seated using a Pic-N-Stic (Pulpdent). Initial cleanup was accomplished. The restoration was cured, the occlusion was checked, and the restoration was polished (Figure 19). A postoperative radiograph was then taken.
Early caries detection is sometimes difficult in daily dental practice, resulting from “blind spots” in our diagnostic technique as well as ineffective methods of communication that can prevent patients from acting early. As illustrated in the case report described, DIFOTI assists in definitive diagnosis and gives us a communication device to help patients see the problems that exist in their mouths. Further, the advent of the CEREC 3 single-visit porcelain restoration has both clinical and patient-centered advantages.
1. Goaz PW, White SC. Oral Radiology: Principles and Interpretation. St Louis, Mo: CV Mosby Company; 1987.
2. Sung K. Digital imaging fiber-optic transillumination. Ann Arbor, MI: UMI, Bell & Howell Company; 1997.
3. Schneiderman A, Elbaum M, et al. Assessment of dental caries with digital imaging fiber-optic transillumination (DIFOTI): in-vitro study. Caries Res. 1997;31:103-110.
4. Sorensen JA. Three-body in-vitro wear of enamel against dental ceramics. J Dent Res. 1999;78:909.
Dr. Spector served as clinical associate professor at New York University, teaching surgical/ restorative implantology from 1996 to 1999. He is a fellow of the Academy of General Dentistry and The International Congress of Oral Implantology. He can be contacted at (201) 384-1611.
Disclosure: Dr. Spector has been teaching basic and advanced Cerec Technique for 3 years for Patterson/Sirona.
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