Formlabs Application Guide

Dental Casting and Pressing from 3D Printed Patterns

Dental milling centers and laboratories have been casting and pressing metal and ceramic parts for over ten years, but existing CNC and 3D printing solutions are often costly and difficult to use. This application guide details the simplified process of casting and pressing dental crowns, bridges, and frames using Formlabs desktop stereolithography 3D printers and Castable Wax Resin, from start to finish.

Tested at length by dental technicians, Formlabs Castable Wax Resin provides accurate, sealed margins and contains 20% wax for reliable casting with clean burnout. Printed patterns are strong enough to handle with no post-cure required, allowing for a faster, simpler workflow.

Table of Contents


PDF Download

Dental Casting and Pressing from 3D Printed Patterns

Would you like to save this guide, print it, or share it with colleagues? Download it as a PDF.

Download as PDF


 

Essentials

Made by Third Parties:
  • Digital Impression
  • 3D intraoral scanner
  • Desktop model scanner
  • Dental CAD software
  • Dental burnout oven
  • Investment ring or form
  • Investment material
  • Casting machine
  • Metal or ceramic ingots
  • Dental lab high speed tools for finishing

 

 

1. Scan

 

Dental CAD software requires a digital impression to create a crown, bridge, or frame. Capture the digital impression either directly, using an intraoral scanner, or indirectly, using a desktop optical scanner, to scan a polyvinyl siloxane (PVS) impression or stone model. Unless working inside a complete scan and CAD system, export the scan as an open file in STL format.

 

2. Design

After capturing the digital impression, import the scan files into the dental CAD software and design the restoration or appliance. Select dental CAD software that offers open STL file export to ensure compatibility with Formlabs PreForm print preparation software.

Exact importing and design procedures vary by software package. For additional help, contact the software reseller or manufacturer.

 

2.1 Crown and Bridge Design

Design your fixed case using the material settings provided by Formlabs (see “CAD Material Settings”).

2.2 Removable Partial Denture Frame Design

To increase consistency and reduce distortion of 3D printed frame patterns, add a stabilization bar with a diameter of 2.5 mm.

When designing clasps thinner than 0.8 mm, connect the clip arms together for the most accurate results.

 

Tip

You can create the casting sprues in the CAD software and print them directly. This saves time that would be spent manually placing sprues.

CAD Materials Settings
Crown and BridgeRemovable Partial Dentures
Minimum Thickness0.5 mm0.5 mm
Drill CompensationDisabledDisabled
Cement Gap and Extra Cement Gap0.03 mm and 0.10 mm-
Margin Offset0.15 mm-
Material Files and Library

3Shape: Download DME Preset file

 

3. Print

 

 

4. Prepare

 

4.1 Wash parts

If you are using a Form Wash automated washing system, leave the printed parts on the build plate for washing. Align the top lip of the build platform with the arms of Form Wash’s platform mount, and fully insert to touch the back. Wash parts with isopropyl alcohol (IPA) with a concentration of 90% or higher (99% is recommended). Set Form Wash to 15 minutes, and start the wash cycle.

If you are using a Finish Kit, carefully remove parts from the build platform once the build is complete. Firmly insert the included scraper into the chamfer of the support raft, then twist the scraper gently from side to side. Rinse the parts in two buckets of isopropyl alcohol, with an initial bath of 10 minutes, and a second bath of 5 minutes. IPA with a concentration 99% or higher is recommended but 90% or higher will work.

Notice:

Washing Castable Wax parts will stain the IPA and future washed parts purple. To avoid staining parts printed with other resins, wash Castable Wax parts in a dedicated Form Wash or Finish Kit.

 

Air dry parts or use a compressed air hose to blow IPA away from surfaces. Inspect parts closely to ensure all uncured resin has been removed. Repeat wash if necessary. Let the patterns dry completely before use.

 

No Post-Cure Required

Castable Wax Resin was designed for use without post-curing. For the highest accuracy, we do not recommend post-curing printed patterns, as this can result in a small amount of shrinkage. Print, process, and cast or press patterns as soon as possible after printing. If this is not possible, store washed Castable Wax patterns in a cool and dark place.

 

4.2. Support Removal

Use the flush cutters included in the Finish Kit to carefully cut the supports at the touchpoints (where they attach to the part). Consider wearing safety glasses when cutting the supports, as the material may be brittle and small pieces of supports can fly off. Supports can also be removed using dental handpieces, such as cutting discs, burs, and polishing wheels.

Notice:

Very thinly designed parts, like removable partial dentures (RPDs), are easy to break during the support removal process. Using a cutting disc is recommended.

 

5. Investment

 

 

5.1 Best Practices for Setting Up an Investment Mold

 

Crowns and Bridges:

Position the crowns and bridges in the mold outside the heat center, about 5 mm from the mold wall. Individual crowns can be grown directly onto the casting mold former using a 2.5 mm wax wire (optionally with a cast reservoir). Bridges, on the other hand, should be connected to a 5 mm distribution channel with a 2.5 mm wax wire at a 45 ° angle and waxed to the casting mold shaper using a 4 mm wax wire.

Cast Partial dentures

Always fix the sprues to the most solid areas of the structure. Two curved 3.5 to 4 mm casting channels are recommended, connected to the funnel 5 to 10 mm above the highest point of the object. Thicker areas of the construction only accessed via thin areas can be optionally connected to an additional 3 mm casting channel, as the alloy will always flow from thick to thin.
Pressable Ceramics

Consider the following when designing the sprue channels of pressed ceramic patterns:
  • Crowns and bridges are sprued directly with a 2.5 to 3 mm wax wire (without corners and edges) at a 45 to 60 ° angle to the mold cavity former.
  • Place sprues on the thickest area of the pattern. For crowns, this is generally a cusp tip. Bridges should have a sprue on each abutment and pontic (do not attach a sprue to a bridge connector).
  • The casting channel should be between 4 and 8 mm long, and the total length including the press object should not exceed 16 mm long.
  • The distance to the wall of the silicone ring should be at least 10 mm.

 

6. Burnout Process

Casting with Castable Wax Resin requires a high heat bonded phosphate investment. Formlabs tested burnout schedules with two investments: BEGO Bellavest SH and WiroFine. The burnout schedules are the same for both investments with variance on the final temperature. Always refer to the investment manufacturer’s recommendations.

 

 

InvestmentIdeal forManufacturer information
BEGI Bellavest SHPressing and casting crowns and bridgesProduct details
Manufacturer guide
Bego WiroFineRPD frame castingProduct details
Manufacturer guide

 

6.1  Standard Burnout Schedule

 

DescriptionPhaseTime to tempSchedule ºCSchedule ºF
Bench SettingHold30 mnRoom Temp
Insert MoldRamp50 mn5ºC/mn41 ºF/mn
DryingHold30 mn250 ºC482 ºF/mn
Thermal TransitionRamp45 mn7 ºC/mn44.6 ºF/mn
Hold30 mn570 ºC1058 ºF
BurnoutRamp-7 ºC/mn44 ºF/mn
Hold60 mnAlloy Final Temp

 

BurnoutTime to Temp: 60 minAlloy Final Temp
MaterialSchedule ºCSchedule ºF
Precious Metal700 ºC1292 ºF
Precious metal-to-ceramic alloys850 ºC1562 ºF
Non-precious metal900 ºC1652 ºF
Pressable ceramicsUp to 900 ºCUp to 1652 ºF
Non precious RDP frame950 to 1050 ºC1742 to 922 ºC

 

6.2 Short Burnout Schedule
DescriptionPhaseTime to TempSchedule ºCSchedule ºF
Preheat oven-900 ºC1652 ºF
Bench SettingHold20 mnRoom Temp
Insert MoldHold20-30 mn900 ºC1652 ºF
BurnoutRamp-7 ºC/mn44.6 ºF/mn
Hold60 mnAlloy Final Temp-

 

BurnoutTime to Temp: 60 minAlloy Final Temp
MaterialSchedule ºCSchedule ºF
Precious Metal700 ºC1292 ºF
Precious metal-to-ceramic alloys850 ºC1562 ºF
Non precious metal900 ºC1652 ºF
Pressable ceramicsUp to 900 ºCUp to 1652 ºF
Non precious RPD frame950 to 1050 C1742 to 1922 F

 

7. Casting or Pressing Process

For a successful casting or pressing process, observe the manufacturer’s specifications, especially matching the preheating and casting or pressing temperature to the alloy.

 

To figure out the optimal amount of material to press or cast into your pattern, use the following formula: 

(Standard wax weight) x 1.21 = Castable Wax Max Weight

For example, if your alloy or ceramic recommends 1 ingot per .75 g in standard wax, the correct weight per 1 ingot of Castable Wax would be .91 g.

Alloy Manufacturers

Notice:

Castable Wax is 21% heavier than standard wax.

This application guide was written in collaboration with Stephan Kreimer.

Stephan Kreimer is a master dental technician (MDT) specializing in digital workflow solutions and is a consultant/ beta tester for several dental companies. He owns and operates Kreimer Dentallabor GmbH & Co. KG, a dental laboratory in Warendorf, Germany.

To contact him, email stephan@kreimer-dentallabor.de or visit https://kreimer-dentallabor.de