Dental CAM

written by Danie AlterSubtractive Technology

April 16, 2015

The Ci ty Univers i ty of New YorkNew York City College of Technology

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This material is based upon work supported by the National Science Foundation under Grant Numbers 1141234.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Dental Computer Aided Manufacturing

Subtractive Computer Aided Manufacturing

Over the past 50 plus years, most large manufacturing industries have used Computer Numerically Controlled (CNC) machining process. This is based on a process in which a power driven tools (Mill) are to mechanically cut material with the desired geometry while every step controlled by a computer.

Computer Aided Manufacturing is not unique or new to the dental discipline. In fact, CAM has been in dentistry since the 70’s with the first operatives to explore its applications for dentistry being Duret and Preston2,3, followed by the innovative work of Moermann in the 80’s; this led to the development of the CEREC system. (Fig. 1 on page 3)

3Fig. 1 - Subtractive Computer Aided Manufacturing

Dental Computer Aided Manufacturing

Digital Manufacturing Workflow

• Choosing the machining strategy.

• Depends on the type of material and degree of complexity for the part.

• The software will virtually attempt milling as a test. (Fig. 2 on page 4)

The benefits of Subtractive CAM

• Differently than the previously made restorations, Computer Aided Design files are stored for the patient and can be easily and quickly reproduced in the event necessity arises.

• The dental laboratory can easily achieve sustainable consistency by utilizing CAD/CAM and eliminating many of the unpredictable variables. (Fig. 3 on page 4)

• The production rate are significantly increased utilizing this technology. (Fig. 4 on page 4)

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Fig. 2 - Digital Manufacturing

Fig. 4 - Production using TechnologyFig. 3 - Eliminating Unpredictable Variables

Dental Computer Aided Manufacturing

Multiple Axes Milling

3 Axes Milling Machine

• The more simplistic of all CNC milling apparatuses is the 3 axis milling machine, which has the machine’s tool schematic simultaneously control bur movement along the X,Y, and Z planes. (Fig. 5 on page 5)

• This type of milling machine is appropriate and applicable for most dental non-complex restorations or applications that don’t pose an occult surface. (Fig. 6 on page 5)

5 Axes Milling Machine

• A 5-axis milling machine is more versatile because it controls its tool paths in five motions continuously and simultaneously. Two concurrent motions within the milling machine occur; the X,Y, and Z axis movement and an A,B axis movement in either the cutter spindle or the block table. (Fig. 5 on page 5)

• The unique advantage to such a tool path schematic is that continuous adjustment of the bur’s orientation while cutting facilitates a significantly heightened precision in the milled product necessary for complex cases like implants. (Fig. 7 on page 5)

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Fig. 5 - Axis/Plane Diagram

Fig. 6 - 3 Axis Milling Machine Fig. 7 - 5 Axis Milling Machine