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October 2008 | Dental Lab Products
Forward Trends

Alloy usage

Read the full article, Maxing Metals.

Casting Coach

A few simple techniques can help improve castings, minimize remakes, and maximize valuable alloy inventory:

• Weigh sprues, crucible formers, runner bars, and waxup; then use the alloy’s density to determine the precise amount of metal needed for the casting, leaving little or no cast button (Fig. A).

• Use preformed wax sprues (Fig. B), 3D printed resin patterns (Fig. C), or milled resin forms (Fig. D) to standardize and speed waxing for precision.

• Dip 3D printed resin patterns in wax to create a space for proper burnout.

• Use adequate clearances in the investment ring to lessen stress (Fig. E).

• Use the manufacturer-recommended investment material depending on ringed or ring-less technique.

• Use a dual-stage burnout program if combining 3D printed resin patterns and wax additions (Fig. F).

• Add new metal to reused buttons when possible to refresh alloy constituents.


FIG. A	FIG. B

FIG. C	FIG D.

FIG. E	FIG. F
Photos: (Figs. A, B, E) Reproduced with Permission from Introduction to Metal-Ceramic technology, 2nd Ed., by Quintessence Publishing Co Inc.; (Fig C) Zahn Dental; (Fig D) Sirona Dental; (Fig F) Jelrus.


	A

	B

	C

	D

	E

	F

Cast Away

Several new alternatives are available to labs that want to meet the continued demand of metal-based restorations, but need to offset the unpredictability of noble metal prices or want to better control coping thickness..

Printed metal copings

Combining the esthetics and biocompatibility of high-noble gold alloy with the speed, precision, and automation of rapid manufacturing, the RX-D 3D metal printer from Imagen (www.x1-imagen.com) creates crown copings (Fig. A) by depositing micro-thin layer upon layer of the proprietary HNB material (87.2% gold, 4.5% platinum, 5.8% palladium, 2.5% silver, and trace elements) from a CAD-produced virtual waxing. The rapid-manufacturing system is designed to increase production, consistency, and quality while reducing labor and training costs associated and allowing full product traceability.

For non-precious outsourced options, labs equipped with Sirona’s inLab or inEos digital scanners can order inCoris NP CoCr-alloy frameworks (Fig. B) through Sirona’s infiniDent Internet-based service concept (www.infinident.com). The high-strength, non-precious material is suitable for single copings and bridge frameworks up to 8 units, can be veneered with all porcelains for non-precious alloys, and reportedly produce a stronger framework than conventionally cast metals.

Nano-enhanced gold alloy

Specifically formulated to increase productivity and cost control as well as coping strength and accuracy, the nano-enhanced Captek Bridge and Implant material and the Captek Universal material (Fig. C) from Captek-Precious Chemicals Inc. (www.captek.com) maximize esthetics and biocompatibility. Both feature a 30% increase in strength, expanding indications to high-stress clinical situations including implant restorations and long-span bridgework. The original Captek Crown material combines the advantages of high-purity gold, without sacrificing the strength of lower-gold-content dental materials.

Milling titanium

While not the most common material used for CAD/CAM processing, a small number of CAD/CAM systems are available that do handle milling of high-strength metals such as titanium, including the Everest system (Fig. D) from KaVo Dental (www.kavo-everest.com), Custom Milling Center’s (www.custom-milling.com) Hint-els system (Fig. E), or the Zeno 4030 M1 from Wieland Dental (www.wieland-dental.com).

Base-noble alloy

For situations where casting is desirable, but the price of noble alloy is intimidating, Callisto CP+ noble alloy from Ivoclar Vivadent (www.ivoclarvivadent.com) is formulated with 25% palladium for nobility and biocompatibility as well as cobalt to help control overall pricing. Offering exceptional casting characteristics using both torch and induction casting, it exhibits a low density of 8.9. and a CTE of 14.4 for compatibility with a broad range of porcelains, including IPS InLine Press-on-Metal (PoM), and demonstrates exceptional polishing characteristics, producing thin, sharp margins. It is available in 3.1-gram ingots for casting single or multiple units (Fig. F).

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