By Bob Cullivan, Director of Quality Control, Trident Dental Laboratories
There is an ever-growing need for all-ceramic restorations as patients' expectations for highly esthetic crowns and bridges increase. Over the past 20 years, there have been a number of all-ceramic systems. However, most have had certain drawbacks that reduced their acceptance as a practical dental option. Some lacked the ability to produce posterior bridges or build bridges in one piece, and most systems had severe bridge span constraints.
Wol-Ceram is a versatile system allowing the ability to produce single units, anterior or posterior bridges, and a much more relaxed constraint on the span because bridges are made in one piece and derive considerable strength as a result.
What makes Wol-Ceram unique and revolutionary is the method by which the coping material is applied to the die. Using a unique process called EPC (electrophoretic ceramic procedure), the Vita In-Ceram slip material is applied in a dense and consistent thickness to the die.
For optimum results
The following key components will enable our technicians to fabricate your Wol-Ceram case more efficiently and effectively.
1. Full upper and lower impressions/opposing model should be provided using rigid trays to reduce the possibility of distortion. The full arch models allow our technicians to match the size and shape of existing dentition as well as providing lateral and protrusive excursions.
2. A blue mousse or wax bite is especially useful in cases where the centric occlusion is difficult to determine and there are no wear facets to use as a guide for articulation. Other instances where a bite is critical are bridges that have no natural teeth distal to the bridge abutments, or in cases with open anterior or posterior bites.
3. Although there are no special preparation requirements, the chamfer margin preparation will achieve the optimum results in strength and esthetics. The following preparation guidelines should be adhered to — approximately 0.8 to 1 mm reduction axially, 1.5 to 2 mm reduction incisally or occlusally, with all sharp points and line angles rounded.
4. The desired shade selection should be noted on the prescription form. Using the Vita Classical or 3D-Master guides will produce the best results as the restorations are made using Vitadur Alpha porcelain, which is available in all of these shades.
5. The model is prepared in the same way as a typical crown or bridge case.
6. The Wol-Ceram system creates an all-ceramic substructure on the actual working die, ensuring optimum fit. For bridges, the dies are dipped into the slip material and the pontics are built up on the working model creating a one-piece bridge.
7. The copings and substructures are sintered then infiltrated, providing shading options and superior strength.
8. The Vitadur Alpha veneering porcelain is applied and finished in the same manner as a typical PFM.
9. Wol-Ceram restorations are cemented conventionally, so there are no special kits or steps required.
10. Minor chairside adjustments to the porcelain may be made easily with a rubber wheel followed up with a small amount of diamond polishing paste on a brush.
For more information on the fabrication of Valplast partials, call Trident Dental Laboratories at (800) 221-4831.
