RESTORATIVE CHALLENGE: A 40-year-old male presented with esthetically compromised PFM restorations on teeth #8 and #9. The patient also requested improved alignment and closure of diastemas between the maxillary and mandibular anterior teeth (see Figure 1). Invisalign orthodontic treatment was provided prior to fabrication of the final pressed all-ceramic restorations.
Restorative team: William Mrazek, BS, CDT, Mrazek Prosthodontics, Ltd., Naperville, Illinois and Joseph O'Donnell, DDS, Oak Forest, Illinois
Treatment plan: It was decided that teeth #8 and #9 would be prepared to receive full-coverage 3G-HS all-ceramic crowns. Teeth #6, #7, #10 and #11 were restoration free and would be prepared to accept a more conservative treatment--Avanté pressed porcelain laminate veneers.
Each of the veneers would be contoured to mesially close the adjacent diastemas, allowing the central incisors to also be shifted mesially, effectively closing the midline diastema without drastic over-contouring. Due to the fact that the all-ceramic copings for the two central incisors would need to be built out mesially, the 3G-HS lithium disilicate pressable core material was chosen because of its high strength. Because teeth #6, #7, #10 and #11 didn't exhibit any discoloration, the more translucent Avanté core was chosen over the more opaceous 3G-HS core material.
Although one might be concerned about compromised esthetics when seating different types of all-ceramic or even PFM restorations adjacent to each other, using ceramic systems designed by the same manufacturer helps provide consistency and confidence when designing combination cases. Because Avanté comes in both powder and leucite-reinforced pressed pellet form, it can be used for many types of restorations, including PFM, all-ceramic pressable and pressed-to-alloy. The lithium disilicate-reinforced 3G-HS system offers higher strength, greater ' "hiding" capability, three-unit bridge (second bicuspid forward) capability, and esthetic compatibility with the Avanté system. 3G powders can even be layered over LavaTM, Cercon and Procera® zirconia frameworks.
Case study: Dr. O'Donnell removed the existing PFM restorations from teeth #8 and #9. He then refined the preparations by creating a 360o shoulder and eliminating any sharp line angles and undercuts. Teeth #6, #7, #10 and #11 were prepared for porcelain laminate veneers with champher margination on the distal, gingival and lingual of the incisal edge. The mesial aspects were prepared only slightly, leaving as much tooth structure as possible to support the extension of ceramic that would close the diastemas. A full-arch impression was then taken and sent to the laboratory with a pre-operative maxillary study cast, bite registration and opposing mandibular cast.
At the laboratory, Bill Mrazek made transfer dies and a solid cast to maintain tissue levels from the impression. After mounting and trimming the dies, he waxed all of the restorations to full contour. Once the final contours and function were verified, the central incisor waxups were cut back to allow room for 1.5-2mm of porcelain overlay. The veneer waxups were also cut back, maintaining 0.7mm of remaining wax thickness for pressing. The mesial portion of the veneers was proportionately thicker for strength and to support the overlay. The wax patterns were invested, burned out and pressed according to the manufacturer's instructions.
After devesting and seating, the 3G-HS copings were tinted with A-2 core stain and fired. They were then built up with 3G low-wear overlay powders, incorporating A-2 dentin with segmented neutral, clear and white enamels. Because the pressed Avanté core material is pre-shaded, the veneers didn't require an application of dentin overlay; they were simply layered with the corresponding enamels from the Avanté porcelain kit. After seating and contouring, the restorations were fired to a natural glaze.
Once Dr. O'Donnell bonded the final restorations in place with a dual-cure adhesive, the final result provided a dramatic contrast and improvement to the patient's appearance (see Figure 2).
Contact information: Avanté and 3G are manufactured by Pentron Ceramics, Inc. and available exclusively from http://zahndental.com">Zahn Dental; 800-243-3100