Written by Suzette Marie Stines, DDS Sunday, 31 August 2008 19:00
Intraoral CAD/CAM restorative techniques are becoming more and more commonplace in the United States.1,2 An increasing number of general practitioners are adopting CAD/CAM restorative techniques in their practices each year.1 As a practitioner who integrated CEREC technology (Sirona) into my general practice 8 years ago, I am continuously looking for new ways to apply this technology. At this point, we estimate that 85% of our restorations are fabricated using our chairside CAD/CAM system. In this article (the first of a 2-part series), I will discuss CAD/CAM applications for the restoration of primary molars in pediatric patients. In the next article, I will cover techniques for restoring broken-down permanent first molars in adolescent patients.
Initially, we treated only adult patients utilizing CEREC technology. However, we have now expanded our use of CAD/CAM technology to treat all of our patients, including adolescent and pediatric patients, with great success. For our pediatric patients, we place indirect composite restorations in place of preformed stainless steel crowns, which was our typical protocol prior to utilizing chairside CAD/CAM technology.
We have found this technique to be superior for several reasons. To begin with, the marginal integrity of an indirect composite is inherently better, compared to a preformed stainless steel crown, because it is a custom-fabricated restoration designed to precisely fit the preparation rather than a preformed restoration modified for the patient.3-5 I also find that the CAD/CAM method is much faster than the lengthy try-in procedure (more like try and retry until it’s just right) necessary to determine the proper size stainless steel crown, festooning, and cementing. Preparing the tooth, taking the optical impression, milling the restoration, and cementation, using the technique described, can be accomplished in about 20 minutes.6,7 Generally, these pediatric restorations mill in about 2 minutes, primarily due to their small size. By the time the cleansing of the cavity preparation is complete, the restoration is ready for bonding. In addition, I am much happier with the outcome with regard to both marginal integrity and aesthetics.3-5 The parents of my pediatric patients are also especially happy with aesthetic restorations instead of stainless steel crowns. Finally, the milled composite resin is extremely strong and durable, yet it possesses wear properties similar to natural enamel and offers a reasonable alternative to traditional stainless steel crowns for severely broken-down primary molars.8-11
CASE REPORT 1
|Figure 1. Preoperative radiograph for Case No. 1.||Figure 2. Preoperative photo of Case No. 1.|
Figure 3. Digital optical impression of the preparation.
Figure 4. Crown design proposal.
|Figure 5. Finalized and seated CAD/CAM crown for case No. 1.|
This case report presents a primary first molar restored with Dental Database CEREC 3.1 software in Standard Mode.
A 7-year-old male presented with severe decay in all his primary molars. Teeth Nos. B and I had been prematurely extracted prior to this patient joining my practice. I was very interested in maintaining his remaining primary dentition. Radiographic and clinical examination revealed a severely decayed tooth No. S with no remaining distal marginal ridge and mesial caries on tooth No. T (Figure 1). The decision was made to restore tooth No. S with a milled indirect composite restoration. Tooth No. T would be restored with a direct composite.
The patient was anesthetized and a rubber dam was placed using a slit-dam technique over the lower right quadrant from tooth Nos. 30 to R (Figure 2). Teeth Nos. S and T were prepared, removing all caries. Tooth No. T was restored with a di-rect composite placed from the mesial aspect. Tooth No. S was prepared for restoration with an indirect composite restoration designed using CEREC Version 3.1 in Dental Data-base Mode.
Tooth No. 29 was chosen from the CEREC Dental Database as a viable substitute for tooth No. S. This is because the CEREC Dental Database does not include a pediatric tooth library at this time. However, CEREC 3.1 generates proposals from a biogeneric database that utilizes morphologic data of the prepared and adjacent teeth to determine contour and occlusal morphology. By choosing a permanent analog for the primary tooth to be restored, a suitable proposal is quickly and automatically generated by the software. For example, a permanent premolar may be substituted for a primary first molar, and a permanent molar may be substituted for a primary second molar. The resultant restoration design proposal is nearly ideal, with only minimal adjustments required by the practitioner.
The preparation was prepared for an optical impression technique by contrasting with IPS Contrast Spray (Ivoclar Vivadent). In this case, only one optical impression was taken. This is because a primary tooth is small enough mesiodistally to allow sufficient information from the adjacent teeth to be captured with a single optical impression; no antagonist optical impressions are taken using this technique (Figure 3). Using Standard Mode, a proposal is quickly generated, generally in less than 20 seconds (Figure 4). Adjustments to the proposal can be accomplished quickly with the software’s built-in Form Tool.
The restoration was milled using the MC XL milling chamber (Sirona) and a Paradigm MZ100 block, Shade A1 (3M ESPE). The MC XL offers higher-speed milling than its predecessor (the Compact milling unit of the CEREC System). A restoration of this size can be milled in about 2 minutes. While the restoration was milling, the cavity preparation was cleansed and prepared for bonding. When milling was finished, the restoration was retrieved from the milling unit, cleansed, air-abraded with 50-µm powder, and treated with silane (Monobond-S [Ivoclar Vivadent]). The restoration was bonded in place with self-curing, resin-based luting cement (Multilink [Ivoclar Vivadent]). The rubber dam was removed and the occlusion was ad-justed using traditional composite finishing rotary instrumentation. The restoration was polished with composite polishing points (Diacomp [Brasseler USA]). The patient tolerated the very short appointment well. The parents were happy with the aesthetic outcome of the treatment (Figure 5).
CASE REPORT 2
|Figure 6. Preoperative radiograph for Case No.2.||
Figure 7. Preoperative photo of Case No. 2.
|Figure 8. Digital optical impressions of the preoperative teeth, and of the same teeth after being prepared.||
Figure 9. Area of the tooth to be removed is outlined.
Figure 10. Onlay design proposal.
Figure 11. Crown proposal.
Figure 12. Finalized and seated CAD/CAM onlay and crown.
This case report presents primary first and second molars restored with CEREC 3.1 Software in Correlation Mode.
A 6-year-old patient presented with severe caries in all primary molars. Radiographic and clinical exam revealed severe caries in teeth Nos. S and T (Figure 6). The decision was made to restore both primary molars with indirect composite restorations.
The patient was anesthetized and the quadrant isolated with a rubber dam utilizing a split dam technique from tooth Nos. 30 to 26 (Figure 7). Composite resin was placed in the cavity defects and cured. This was done to roughly fill in the missing tooth contours. The area was contrasted with IPS Contrast Spray, and an optical impression of the area was taken in the Occlusion Catalog of the CEREC 3.1 software in Correlation Mode. The teeth were then prepared and all caries removed. The prepared teeth were contrasted and optical impressions were taken in the preparation catalog (Figure 8). This makes 2 sets of optical impressions available to provide the CAD/CAM system with data for restoration design: one of the preoperative tooth morphology and one of the prepared tooth. The software prompts the user to define what area of the preoperative tooth to copy, and that area is outlined (Figure 9).
A proposal was generated for tooth No. T (Figure 10), and milling of the restoration was initiated in the Compact Milling Unit of the CEREC System with a Paradigm MZ100 block. This milling took about 5 minutes. Quadrant Mode was then chosen and the restoration for tooth No. S was designed with the virtual placement of the restoration for tooth No. T placed in the virtual model (Figure 11). This restoration was milled using the MC XL milling chamber in about 2 minutes. While the 2 restorations were milling, the cavity preparations were cleansed and prepared for bonding and cementation.
The restorations finished milling simultaneously. They were retrieved from the milling chambers, cleansed, air-abraded with 50-µm powder, and treated with silane (Monobond-S). The restorations were cemented in place with self-curing, resin-based luting cement (Multilink). The occlusion was adjusted with traditional composite rotary instrumentation and the restorations were polished with composite polishing points (Dia-comp). The result was one of superior marginal integrity and great aesthetics (Figure 12). The patient tolerated the very short appointment well, and the patient’s parents were pleased with the outcome and the aesthetics.
The applications for intraoral CAD/CAM technology are much broader than many general practitioners realize. By formulating CAD/CAM restorative techniques to include more of our daily operative and restorative demands, greater productivity can be realized, superior restorations can be provided for our patients, and aesthetics can be maximized.
- Liu PR. A panorama of dental CAD/CAM restorative systems. Compend Contin Educ Dent. 2005;26:507-512.
- Leinfelder KF, Kurdziolek SM. Contemporary CAD/CAM technologies: the evolution of a restorative system. Pract Proced Aesthet Dent. 2004;16:224-231.
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- Tsitrou EA, Northeast SE, van Noort R. Evaluation of the marginal fit of three margin designs of resin composite crowns using CAD/CAM. J Dent. 2007;35:68-73.
- Akbar JH, Petrie CS, Walker MP, et al. Marginal adaptation of Cerec 3 CAD/CAM composite crowns using two different finish line preparation designs. J Prosthodont. 2006;15:155-163.
- Voiers DW. One-visit/one-hour CAD/CAM crown revisited: oven stain-and-glaze technique. Dent Today. Dec 2004;23:58-63.
- Morin M. CEREC: the power of technology. Compend Contin Educ Dent. 2001;22(suppl):27-29.
- Farah JW, Powers JM (Eds). 7-year clinical performance of 3M Z100 restorative. Dental Advisor. 2000;17(4).
- Giordano R. Materials for chairside CAD/CAM-produced restorations. J Am Dent Assoc. 2006;137(suppl):14S-21S.
- Berkmeier WW, Latta MA, Ericskon RL, et al. Comparison of laboratory and clinical wear rates of resin composites. Quintessence Int. 2004;35:269-274.
- Barkmeier WW, Latta MA, Erickson RL, et al. Wear simulation of resin composites and the relationship to clinical wear. Oper Dent. 2008;33:177-182.
Dr. Stines received her DDS in 1981 from the University of North Carolina School of Dentistry, where she is currently an adjunct associate professor. She is a Fellow of the Academy of Computerized Dentistry of North America and a certified trainer of the International Society of Computerized Dentistry. She has been in private general practice since 1981, and can be reached by e-mail at email@example.com.
Disclosure: Dr. Stines is a CEREC?Trainer with Patterson Dental and is hired by Sirona to lecture from time to time.
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