Restorative Problem The patient wanted to improve the esthetics of her smile, which was dominated by two unattractive porcelain-to-metal restorations on her maxillary central incisors (see Figure 1 below).
Treatment Plan Dr. Daren Becker, DDS, and I developed a plan to restore the maxillary centrals and lateral incisors which would address the spacing, size and proportion of her teeth.
The need for very thin translucent restorations to restore the lateral incisors and several millimeters of unsupported ceramic in the incisal areas of the centrals made this case ideal for restoration with IPS e.max, a lithium disilicate material from Ivoclar Vivadent. Its flexural strength of 400MPa can easily support the incisal area of the centrals and, when combined with a micro-layering technique, we're able to deliver nice esthetics while maintaining a maximum amount of the lithium disilicate material.
Removal of the PFM restorations revealed compromised underlying color and aggressively prepared dentition consistent with PFM preparation design (see Figure 2 below). Although the color of the preparations on teeth #8 and #9 would normally discourage me from using bonded ceramic restorations, the fact that we had 1.5mm of clearance on the facial surface of the centrals made masking with an e.max HT BL2 ingot possible. If the restorations had been thinner than .8mm with the same dark underlying color, it would have been problematic.
I chose an ingot one shade brighter for the central incisors because:
- The dark preps could potentially influence the final color.
- The fact that centrals can be slightly brighter than laterals with no detrimental effect on the smile.
The lateral incisors had very nice underlying color and could be prepared very conservatively (see Figure 3 below); I selected an e.max HT BL3 ingot to slightly brighten the canine and blend into the e.max HT BL2 material used for the central incisors.
The ability to successfully press restorations as thin as .2mm allowed Dr. Becker to very conservatively prep the patient's lateral incisors. The recent New York University studies by Dr. Van Thompson reinforce what we have observed clinically: IPS e.max from Ivoclar Vivadent is a very strong material that resists chipping better than anything I've worked with previously.
Fabrication Process I fabricated a diagnostic waxup to establish ideal shape, and then made a silicone matrix of the waxup from which I created the provisional restorations. I made a waxup of the definitive restorations to improve on the shape of the provisional restorations, and cut back the wax to allow room for micro layering of the incisal fluorapatite ceramic material (see Figure 4 below).
I invested, burned out and pressed the restorations according to the manufacturer's technique. I made composite dies to help predict the influence of the underlying color of the preps, shaded the restorations to compensate for the underlying color and blend with the patient's natural dentition, and then fired to maturity (see Figure 5 below).
Next, I added a glaze layer and fired to 770oC on all surfaces of the pressed restorations prior to layering (see Figure 6 below). I completed the incisal layering to achieve the desired internal effects and recontoured the restorations in the incisal area to blend with the pressed gingival portions (see Figure 7 below). Once I achieved the final contour, I glazed the restorations at 725oC. (Note: I only use 770oC as a glaze temperature prior to application of layering ceramic.) I completed the final fitting to a solid model, polished with a rubber wheel and diamond polishing paste and delivered the restorations (see Figures 8 and 9 below).
For more information on IPS e.max, contact Ivoclar Vivadent at 800-833-6825, 800-263-8182 (in Canada) or visit http://www.ivoclarvivadent.com">www.ivoclarvivadent.com.
