Written by Suzette Marie Stines, DDS Tuesday, 30 September 2008 19:00
In the United States, CAD/CAM restorative dentistry is becoming more common-place in the general practice, and practitioners who utilize this technology are always looking for new ways to implement it into their daily work.1,2 Last month, in Part 1 of this 2-part article series, we looked at techniques for restoring primary molars in pediatric patients with indirect CAD/CAM composite restorations. This month, we look at intraoral CAD/CAM solutions for restoring severely broken-down permanent first molars in the adolescent patient. These patients present a restorative challenge for the dentist, since an economical and long-lasting restoration must be provided.
While I have been integrating intraoral CAD/CAM technology into my general practice over the last 8 years, I have searched for new ways to solve my restorative challenges utilizing this technology. My reasons for wanting to expand the application of this technology in my practice are mainly twofold: First, the marginal integrity of the restoration is extremely precise, and second, the materials used in CAD/CAM dentistry are very durable, resulting in long-lasting restorations.3-6 In addition, for many adolescent patients presenting with this condition, economic considerations are influential in determining the restoration choice that parents make. Generally, an adolescent doesn’t present with just one broken-down first permanent molar, but with 2 to 4 molars in need of attention. If we are to gain treatment plan acceptance from parents, we must present them with alternatives that fit into the economics of families raising children.
The longevity of these restorations must be considered as well. Large, direct posterior composites are not an acceptable choice because of their lack of durability and longevity. Full-coverage crowns are not our first choice because of the loss of tooth structure required to prepare them properly, and the cost to the patient. Preformed stainless steel crowns, by the very nature of their being preformed and modified for the patient, do not possess the marginal integrity of an indirect composite. Indirect composites created using an intraoral CAD/CAM system fulfill the requirements of tooth structure conservation, durability, excellent marginal integrity, and aesthetics.3-6 Furthermore, these restorations can be completed in very short appointments, increasing practice productivity and enhancing patient care.7,8
CASE REPORT NO. 1
This case report presents the restoration of bilateral, mandibular first permanent molars with Dental Database CEREC 3.1 software (Sirona) in Standard Mode.
Figure 1. Deep distal caries present in tooth No. 30.
Figure 2. Deep distal caries present in tooth No. 19.
A 15-year-old patient presented with advanced caries in both mandibular first permanent molars. Radiographic and clinical examination revealed deep, distal-occlusal caries in teeth Nos. 19 and 30 (Figures 1 and 2). A treatment plan was developed for indirect composite restorations in both molars. The restorations were to be placed in 2 separate clinical appointments.
Figure 3. Tooth No. 30 is isolated using the split rubber dam technique.
Figure 4. Optical impression of the preparation.
Figure 5. Only one line is necessary to develop a proposal for milling.
|Figure 6. A virtual restoration design (inlay) is proposed by the Biogeneric CAD/CAM software and easily adjusted as necessary with the built-in Form Tool.|
The patient was anesthetized and the lower right quadrant was isolated with a rubber dam using a split-dam technique (Figure 3). Tooth No. 30 was prepared, and all caries were removed. The completed preparation was quite extensive and would have been unsuitable for direct composite placement due to its size.
Next, the preparation was contrasted with IPS Contrast Spray (Ivoclar Vivadent) to prepare it for an optical impression, which was subsequently taken with the CEREC 3D System. Only one optical impression is taken when employing this indirect composite technique (Figure 4). The resulting restoration can be quickly and easily adjusted with conventional composite finishing techniques; therefore, no antagonist optical impression of the opposing occlusion is required. A virtual model was then generated. In CEREC 3.1 Standard Mode, only one line defining the restoration margin need be drawn to complete the restoration proposal. The entire restoration proposal was generated by the “intelligent” Biogeneric software in less than one minute (Figures 5 and 6). Any design modifications, if necessary, can be quickly accomplished using the software’s built-in Form Tool.
|Figure 7. Postoperative photo showing CAD/CAM inlay seated in tooth No. 30.|
The restoration was milled from a Paradigm MZ100 composite block (3M ESPE) in the MC XL milling chamber (Sirona). This high-speed milling unit is able to mill a restoration of this size in about 3 minutes. While the restoration was milling, the cavity preparation was cleansed and prepared for bonding. The restoration was retrieved from the milling chamber, cleaned, and air-abraded with 50-µm powder. The internal surface of the restoration was treated with silane (Monobond-S [Ivoclar Vivadent]) and bonded into place using self-curing adhesive resin cement (Multilink [Ivoclar Vivadent]), following the manufacturer’s directions. The occlusion was adjusted using traditional composite finishing rotary instrumentation and polished with composite polishing points (Diacomp [Brasseler USA]; Figure 7).
|Figure 8. Completed preparation of tooth No. 19.||
Figure 9. Postoperative photo showing CAD/CAM onlay seated in tooth No. 19.
The patient was anesthetized and the lower left quadrant isolated with a rubber dam using a split-dam technique. Tooth No. 19 was prepared, and all caries were removed with careful hand excavation because of the very deep extent of the defect. The floor was prepared with Xeno self-etching primer (DENTSPLY?Caulk). A flowable composite base (Filtek Supreme Plus [3M ESPE]) was placed and light-cured (Figure 8). The same procedure was followed to generate the indirect composite restoration for tooth No. 19 that was used to restore tooth No. 30. It was bonded in the same fashion as well (Figure 9). The patient tolerated the procedures very well, and the parents were pleased with the results.
CASE REPORT NO. 2
Figure 10. Radiograph confirms failed composite and impacted tooth.
Figure 11. Split rubber dam technique is used to isolate the teeth for preparation.
Figure 12. Optical impression of the preparation.
|Figure 13. A virtual restoration design (inlay) is proposed by the Biogeneric CAD/CAM software, and easily adjusted as necessary with the built-in Form Tool.|
|Figure 14. Postoperative photo showing cemented CAD/CAM onlay.|
This case report presents the replacement of a failed, direct composite restoration in a first permanent molar with CEREC 3.1 in Standard Mode.
A 15-year-old patient presented with a failed mesiofacial composite on tooth No. 30. Clinical and radiographic examination substantiated this finding (Figure 10), and revealed an impacted No. 29. The treatment plan was to replace the failed composite with an indirect composite CAD/CAM restoration.
The patient was anesthetized and the quadrant isolated with a rubber dam using a split-dam technique from tooth No. 31 to No. 27 (Figure 11). The failed composite was removed, and all caries were excavated. IPS Contrast Spray was applied to the tooth to prepare it for an optical impression using the CEREC 3D System. Once again, only one optical impression in the preparation catalog is necessary utilizing this technique (Figure 12). The restoration design software’s Standard Mode only requires the outlining of the margin. With the margin defined, the software generates a proposal of the full Biogeneric restoration in less than one minute. Any modifications to the proposal can be easily accomplished using the software’s built-in Form Tool (Figure 13).
The restoration was milled in the MC XL milling chamber in about 3 minutes from a single solid block of Paradigm MZ100 composite. While the restoration was milling, the cavity preparation was cleansed and the tooth prepared for bonding with the priming agents of the Multilink Resin Bonding System. When the milling was complete, the restoration was retrieved from the chamber, cleaned, and air-abraded with 50-µm powder. The internal surface of the restoration was treated with silane (Mono-bond-S). The restoration was then bonded into place with self-curing adhesive-resin cement (Multilink), following the manufacturer’s directions. The occlusion was adjusted using conventional composite rotary instrumentation and polished with composite polishing points (Diacomp; Figure 14). The patient tolerated the rapid procedure well, and the parents were very happy with the treatment outcome.
DISCUSSION OF COMPOSITE RESIN MATERIALS USED
A composite resin material, the Paradigm MZ100 block, is available for use in the CEREC 3D System. This material is a machinable version of the popular Z100 composite manufactured by 3M ESPE.9 This material is 85% filled by weight with 0.6-µm zirconia silicate.9 The advantages of this material include ease of adjustment and outstanding durability.9 The homogeneous nature of the machinable resin block results in a restoration that is stronger than a traditionally stacked composite. The milled composite resin withstands the forces of occlusion without breaking down, as may occur in large direct composites.10,11 There is no polymerization shrinkage to be concerned with, as there would be utilizing a di-rect composite technique.9
Because the restorations can be easily adjusted using conventional composite finishing techniques, no antagonist bite is necessary. The Biogeneric software generates an amazingly well-fitting proposal in Standard Mode, in under one minute. Once milled, I have found that these restorations require only minimal adjustment, if any. After completing the preparation, the restoration is ready for bonding in about 5 minutes.
Expanding the applications of intraoral CAD/CAM dentistry in the general restorative practice is inevitable and, as a result, the number and types of CAD/CAM restorations being placed continues to increase. Using indirect composite restorations for adolescent patients expands the applications for intraoral CAD/CAM dentistry. These restorations can be completed in about 30 minutes of chair time thus increasing productivity for the practitioner. Adolescent patients often present with severely broken-down primary molars and first permanent molars. This 2-part article explored CAD/CAM restorative techniques for giving these adolescent patients long-lasting, economical, and aesthetic indirect composite restorations.
- Liu PR. A panorama of dental CAD/CAM restorative systems. Compend Contin Educ Dent. 2005;26:507-512.
- Leinfelder KF, Kurdziolek SM. Contem-porary CAD/CAM technologies: the evolution of a restorative system. Pract Proced Aesthet Dent. 2004;16:224-231.
- Fasbinder DJ. Clinical performance of chairside CAD/CAM restorations. J Am Dent Assoc. 2006;137(suppl):22S-31S.
- Giordano R. Materials for chairside CAD/CAM-produced restorations. J Am Dent Assoc. 2006;137(suppl):14S-21S.
- 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(6 suppl):27-29.
- Farah JW, Powers JM (Eds). 7-year clinical performance of 3M Z100 restorative. Dental Advisor. 2000;17(4).
- Barkmeier WW, Latta MA, Erickson 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.
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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