An important player in anterior CAD/CAM restorations
Dhaval Patel, DDS
Restoring single central incisors can be challenging, and attempting them with CAD/CAM technology can add further challenges. Although there are many factors that need to be taken into consideration, including material choice, stump shade, restorative thickness, line angles, incisal embrasures, facial anatomy, and texturing and staining, it all starts with photography. Taking quality pictures is a must for anterior CAD/CAM restorations, not only for them to be properly planned, but also for them to be well executed.1,2 Viewing preoperative pictures on a large screen provides extensive information that cannot be matched by simply looking in the mouth.
A female patient came into the office during the holiday season after losing a crown on tooth No. 9. Preoperative photographs were taken and mounted on a screen to view with the patient (Figure 1 and Figure 2). When asked what she didn't like about her smile other than the missing crown, she immediately indicated the chipped incisal edge of tooth No. 8. This presented the opportunity to discuss her options for treatment. After reviewing several options, the decision was made to do some enameloplasty to smooth out the edges and make the incisal edge more harmonious.
A buildup was performed with packable composite (Figure 3), and the case was scanned (CEREC® Omnicam, Dentsply Sirona) and loaded into the design software (CEREC® SW 4.5.2, Dentsply Sirona). Because the patient was happy with the shape, size, and form of tooth No. 8, it was used as a model in the "Biogeneric Reference" feature to design the restoration for tooth No. 9 (Figure 4 and Figure 5).3
There was only about 0.8 mm of clearance on the lingual surface; therefore, a lithium disilicate glass ceramic restorative material (IPS e.max® CAD MT, Shade A1; Ivoclar Vivadent) was chosen to provide the strongest
option (ie, flexural strength of 360 to 400 MPa) with natural looking esthetics.4,5 The crown was milled and tried in. At this time, Tooth No. 8 was used as a reference again to further develop the shape and line angles (Figure 6). Next, the crown was crystallized without any stain or glaze so that the base shade could be verified in the mouth. After crystallization, the crown was tried in, and a picture was taken and evaluated on a larger screen (Figure 7). The shade was found to be acceptable, but there were some key elements missing. Some translucency was still needed on the facial line angles as well as some chroma on the middle of the incisal edge. A shade mixture (ie, Incisal 1 [blue] and Incisal 2 [purple]) was applied on the mesial and distal line angles, and the facial surface was stained to better match it to tooth No. 8. After the second firing, the crown was tried in, and a photograph was taken and shown to the patient. She was very pleased with the final result (Figure 8).
Two weeks later, the patient returned to the office for a postoperative checkup to evaluate the health of the gingiva and see if any further changes were needed. Patients are usually asked in advance to make a note of anything that they may want to modify during this appointment. After additional photos were taken and viewed with the patient (Figure 9 and Figure10), she pointed out that she really liked the rounded distoincisal edge of tooth No. 9 and asked if it could be replicated on tooth No. 8. To this end, a slight modification was made to the distoincisal edge of tooth No. 8, which helped it to look a little softer and more feminine. The patient was thrilled with the final result and offered compliments on a job well done (Figure 11). She mentioned that, in the past, dentists had never used photography for her dentistry and that she noticed how the pictures and their evaluation played a major role in achieving the final result.
For anterior restoration cases, CAD/CAM users are encouraged to use digital SLR photography because visualizing each step improves patient communication, facilitates better results, and helps the clinician learn from any mistakes.
1. Khanna N. Why Dental Photography is Important to an Accurate Diagnosis. The Dawson Academy Blog. http://dental.thedawsonacademy.com/photography-important-for-diagnosis. Published May 2013. Accessed on April 13, 2018.
2. Yoo A. 10 reasons why dental photography should be an essential part of YOUR practice. Dental Economics. 2014;104(9):86.
3. Kollmuss M1, Jakob FM, Kirchner HG, Ilie N, Hickel R, Huth KC. Comparison of biogenerically reconstructed and waxed-up complete occlusal surfaces with respect to the original tooth morphology. Clin Oral Investig. 2013;17(3):851-857.
4. Culp L, McLaren EA. Lithium disilicate: the restorative material of multiple options. Compend Contin Educ Dent. 2010;31(9):716-720,722,724-725.
5. IPS e.max Lithium Disilicate. Ivoclar Vivadent website. http://www.ivoclarvivadent.com/en/p/all/products/all-ceramics/ips-emax-dentist/ips-emax-lithium-disilicate. Accessed on April 13, 2018.